MISCELLANEOUS PAPER S71-17

EARTHQUAKE RESISTANCE OF EARTH AND ROCK-FILL DAMS

Report 2

ANALYSIS OF RESPONSE O F RIFLE.GAP DAM TO PROJECT RULISON UNDERGROUND NUCLEAR

DETONATION bv

J. E. Ahlberg, J. Fowler, L W. Heller ........ ........-..... ..........-..- ...... *- , .... . ..- ->-w-J- * -: -

. .

June 1972

s~omsored by Office, Chief of Engineers, U. S. Army

Conducted by U. S. A m y Engineer Waterways Experiment Station

Soils and Pavements Laboratory

Vicksburg, Mississippi

APPROVED FOR WBLlC RELEASE: DISTRIBUTION UNLIMITED

L i s t o f Associated Reports

Previous reports under Engineering Study 540 are:

"A Comparative Summary o f Current Earth Dam Analysis Methods for Earthquake Response," issued by Office, Chief o f Engineers, as Inclosure 1 to Engineer

, . , - . Jeihnical Let ter No. 11 10-2-77, 9 December 1969. - 0 1 . \ , -

v , - . r i '. ../. +c_Eaithquake Studies for Earth and Rock- f i l l Dams," issued by Office, Chief o f %A P , . a 3 Engineers, as Engineer Technical Le t t e r NO. 11 10-2-79, 12 January 1970.

"Motion o f R i f l e Gap Dam, Rif le, Colorado; Proiect Rul ison Underground Nuclear Detonation," published by the Waterways Experiment Station as Miscellaneous Paper 5-70-1, January 1970.

"Earthquake Resistance of Earth and Rock- f i l l Dams; Report 1, Discuss ions by Professors H. B. Seed and R. V. Whitman," published by the Waterways Experi- ment Station as Miscellaneous Paper 5-7 1-17, h a y 1971.

Destroy th i s report when no longer needed. Do not return it to the originator.

The findings in th is report are no t to be construed as an o f f i c i a l Department of the Army pos i t i on unless so designated

by other author ized documents.

MISCELLANEOUS PAPER S-71-17

EARTHQUAKE RESISTANCE OF EARTH AND ROCK-FILL DAMS

Report 2

ANALYSIS OF RESPONSE OF RIFLE GAP DAM TO PROJECT RULISON UNDERGROUND NUCLEAR

DETONATION

by

J. E. Ahlberg, J. Fowler, L W. Heller

June 1972

Sponsored by Office, Chief of Engineers, U. S. Army

Conducted by U. S. Army Engineer Waterways Experiment Station

Soils and Pavements Laboratory

Vicksburg, Mississippi

A R Y V - Y R C V I C K S O U I Q . YtSm.

APPROVED FOR PUBUC RELEASE; DISTRIBUTION UNLIMITED

T H E CONTENTS OF T H I S REPORT ARE NOT T O BE

USED FOR ADVERTISING, P U B L I C A T I O N , OR

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DORSEMENT OR APPROVAL O F T H E USE OF SUCH

COMMERCIAL PRODUCTS.

iii

FOREWORD

This repor t p resen ts an ana lys i s o f t he motion of R i f l e Gap Dam

during t h e underground nuclear explosion, ProJect RULISON. This analy-.

s i s was made f o r t he Off ice , Chief of Engineers ( O C E ) , by t h e U. S. A r v

Engineer Waterways Experiment S t a t i o n (WES) dur ing f i - s ca l year 1971

under Engineering Study 540, " ~ a r t h q u a k e Resistance of Earth and Rock-

f i l l D a m s . "

Engineers of . t h e S o i l s and Pavements Laboratory, WES, a c t i v e l y en-

gaged i n d i r e c t i n g t h e work .and r e p o r t p repara t ion were Messrs . S . J.

Johnson, R . W . Cunny, J. Fowler, D r . L. W . Hel ler , 1 L T J. E. Ahlberg,

and SP5 W. C . Moss. The work was under t h e genera l supervis ion of

M r . J. P. Sale, Chief, S o i l s and Pavements Laboratory. This r e p o r t was

prepared by 1LT Ahlberg with minor cont r ibu t ions by M r . Fowler and

D r . Heller . Director of WES during t h e ana lys i s and t h e prepara t ion of t h i s

report was COL Ernest D . Peixot to , CE, and Technical Director was

M r . F. R . Brown.

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CONTENTS

Page

FOREWORD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

CONVERSION FACTORS, B R I T I S H TO M E T R I C U N I T S O F MEASUREMENT. . . . i x

P A R T I -. INTRODUCTION . . .. . . . . . . . . . . . . . . . . . . . 1

PART I1 : F I E L D OBSERVATIONS. . . . . . . . . . . . . . . . . . . . 3

P A R T I1 I : MATERIAL P R O P E R T I E S . . . . . . . . . . . . . . . . . . 5

P A R T IV : CALCULATIONS. . . . . . . . . . . . . . . . . . . . . . 8

G e n e r a l . . . . . . . . . . . . . . . . . . . . . . . . . . O n e - D i m e n s i o n a l A n a l y s e s of Foundation. . . . . . . . . . . T w o - D i m e n s i o n a l A n a l y s e s of E m b a n k m e n t a n d Foundation . . .

P A R T V: COMPARISONS OF OBSERVED AND CALCULATED R E S P O N S E S . . . . 11

M e t h o d . . . . . . . . . . . . . . . . . . . . . . . . . . . O n e - D i m e n s i o n a l A n a l y s i s . . . . . . . . . . . . . . . . . . T w o - D i m e n s i o n a l A n a l y s i s ' . . . . . . . . . . . . . . . . . .

PART V I : D I S C U S S I O N . . . . . . . . . . . . . . . . . . . . . . . o n e - ~ i m e n s i o n a l A n a l y s i s . . . . . . . . . . . . . . . . . . T w o - D i m e n s i o n a l A n a l y s i s . . . . . . . . . . . . . . . . . .

PART V I I : CONCLUSIONS. . . . . . . . . . . . . . . . . . . . . . L I T E R A T U R E C I T E D . . . . . . . . . . . . . . . . . . . . . . . . . T A B L E S 1-4

P L A T E S 1-40

A P P E N D I X A: OBSERVED MOTIONS

P L A T E S A1-A12

A P P E N D I X B: ACCEIXRATION R E S P O N S E S P E C T R A FROM ONE-DIMENSIONAL A N A L Y S I S

P L A T E S ~ 1 - B 6

A P P E N D I X C: ACCELERATION R E S P O N S E S P E C T R A FROM TWO-DIMENSIONAL A N A L Y S I S

P L A T E S ~ 1 - C 8

A P P E N D I X D: S E I S M I C F I E L D STUDY

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. .

CONVERSION FACTORS, BRITISH TO METRIC UNITS OF MEASUREMENT

~ r i t i s h u n i t s o f measurement u s e d i n t h i s r e p o r t c a n be c o n v e r t e d t o

metr ic u n i t s as f o l l o w s :

Mul t ip ly By To Ob ta in

inches 2.54 c e n t i m e t e r s

f e e t

miles (u. S. s t a t u t e )

' pounds

pounds p e r squa re i n c h ,

k ips per square f o o t

pounds pe r cub ic f o o t

. inches per second

f e e t pe r second

me te r s

. k i l o m e t e r s

k i l o g r a m s

newtons p e r s q u a r e c e n t i m e t e r

k i l o n e w t ons p e r s q u a r e meter

k i l o g r a m s p e r c u b i c me te r

c e n t i m e t e r s p e r second

me te r s p e r seco'nd

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SUMMARY

The motion of R i f l e Gap D a m w a s measured i n September 1969 dur ing the Pro jec t 'RULISON underground nuc lear explosion. The observed re- sponse was then compared with t h e response computed i n a mathematical model. Observed and computed responses were s i m i l a r . From t h i s study it appears t h a t the mathematical models used a re app l i cab l e t o t h e de- sign and ana lys i s of s o i l s t r u c t u r e s , a t l e a s t f o r ground motion inten- s i t i e s comparable t o those observed a t R i f l e Gap Dam.

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6 EARTHQUAKE RESISTANCE OF EARTH AND ROCK-FILL DAMS

ANALYSIS OF RESPONSE OF RIFLE GAP DAM TO PROJECT

RULISON UNDERGROUND NUCLEAR DETONATION

PART I : INTRODUCTION

1. The U. S. A r m y Engineer Waterways Experiment S t a t i o n (WES) was

requested by the Off ice , Chief of Engineers (OCE) , t o measure and t o an-

a lyze t he response of R i f l e Gap Dam t o ground motions generated by the

P ro j ec t RULISON detonation because it was thought t h a t t he se motions

would be s imi l a r t o those generated by earthquakes. The ob j ec t i ve of

t h i s study was t o determine t h e a p p l i c a b i l i t y of seismic design proce-

dures i n designing Corps of Engineers ( C E ) e a r t h and r o c k - f i l l dams t o

withstand earthquake loadings .

2. Pro jec t RULISON, p a r t of t he PLOWSHARE program of t h e Atomic

Energy Commission ( A E C ) , was one o f a s e r i e s of detonat ions f o r i nves t i -

ga t ing s t imulat ion of t h e production of n a t u r a l gas by t h e use of nu-

c l e a r explosives. The Aus t r a l O i l Company conducted t h i s experiment as

a p r iva t e commercial venture with t h e a s s i s t a n c e o f t h e AEC, which was

responsible f o r sa fe ty and t h e detonat ion of t h e nuclear device.

3. The WES instrumented R i f l e Gap Dam w i t h t h e cooperation o f the

owner, the Bureau of Reclamation (BU Rec). Other dams instrumented fo r

ground motion measurements dur ing P r o j e c t RULISON were Harvey Gap D a m ,

instrumented by the National Ocean Survey and analyzed by the Environ-

mental Research Corporation f o r t h e AEC , and Vega Dam, instrumented and

analyzed by t h e Bu Rec. The a n a l y s i s o f R i f l e Gap Dam includes an as-

sessment of t h e geology and e l a s t i c p r o p e r t i e s of t h e s i t e and the dam,

ca l cu l a t i ons of the expected su r f ace motions using ava i l ab l e procedures,

and a comparison of ca l cu l a t ed responses of t h e dam with measured r e -

sponses r e s u l t i n g from P r o j e c t RULISON.

4. Ground zero ( G Z ) f o r Pro jec t RULISON was loca ted southwest of

R i f l e , Colorado, a t a depth of 8442.5 ft.* The nuc lear device was deto-

nated at 3:00 p.m. MST, 1 0 Septeniber 1969, and had a design y i e l d of

40 k t .

5 . R i f l e Gap Dam,. an e a r t h - f i l l s t r u c t u r e , w a s completed i n 1966

and i s loca t ed north of R i f l e , Colorado, 1 8 . 5 miles from RULISON GZ (see

p l a t e .l) . Spec i f ica t ions f o r t he dam a r e presen ted i n r e f e r ence 1. The

dam has a c r e s t l eng th of 1500 f%, a maximum base width o f 800 f t , and a

maximum he igh t of 120 ft. The dam c o n s i s t s o f a mixture o f c l a y , s i l t ,

sand, g r ave l , and cobbles. A c ro s s s e c t i o n i s shown i n p l a t e 2 . The

r e s e r v o i r l e v e l was 41 ft below t h e c r e s t du r ing P ro j ec t RULISON. Two

Bu Rec bor ings (see bo r ing logs i n p l a t e 3 and l o c a t i o n s i n p l a t e 4 ) in-

d i c a t e t h a t t h e foundation mater ia l s are a l l u v i a l s o i l s cons i s t i ng of

in terbedded c lays , s i l t s , sands, and grave ls t o depths g r e a t e r than

100 f t . Bedrock was not reached i n t he se bor ings . A~ assumed p r o f i l e

of t h e foundation s o i l s i s shown i n p l a t e 5 . The method used t o produce,

t h e assumed p r o f i l e i s d i scussed i n paragraph 11.

* A t a b l e o f f a c t o r s f o r conver t ing B r i t i s h u n i t s o f measurement t o metr ic u n i t s i s p resen ted on page i x .

r : , PART 11: FIELD OBSERVATIONS

6 . The observed motions o f R i f l e Gap D a m during Pro jec t RULISON

are repor ted i n r e f e r ence 2. The ins t ruments used fo r t h e measurements

cons i s t ed of p a r t i c l e v e l o c i t y t r an sduce r s (PVT) and p a r t i c l e acce le ra -

t i o n t ransducers (PAT) , and t h e measurements were recorded by o .sc i l lo-

graphs and t a p e r eco rde r s . The l o c a t i o n s o f t h i s equipment are shown i n

p l a t e 4, and a l ist of equipment i s given i n t a b l e 1 along wi th peak ob-

served motions. H i s t o r i e s o f t h e f i r s t 6 sec ' o f observed motion and re-

sponse s p e c t r a a r e p resen ted i n Appendix A f o r v e r t i c a l and r a d i a l (nor-

m a l t o c r e s t o f dam) components o f motion. Transverse ( p a r a l l e l t o

c r e s t o f dam) motions are r epo r t ed by ~ o w l e r , ' bu t a r e not analyzed

he r e in .

7. There i s e x c e l l e n t agreement between t h e ve loc i ty h i s t o r i e s

observed a t l o c a t i o n 6 ( p l a t e ~ l l ) and t hose ca lcu la ted a t l o c a t i o n 5

( p l a t e s A9 and A10) by t h e i n t e g r a t i o n of t h e acce le ra t ion h i s t o r i e s .

Comparison o f t h e c a l c u l a t e d v e i o c i t y h i s t o r i e s a t loca t ion 1 ( ~ l a t e s A 1

a n d ~ 2 ) i n t h e r a d i a l and v e r t i c a l d i r e c t i o n s with those observed at lo-

c a t i o n 7 (plate A12) i n d i c a t e s remarkably good agreement, even though

l o c a t i o n s 1 and 7 were approximately 200 ft a p a r t along t h e c r e s t o f t h e

dam. However, r a d i a l components o f l o c a t i o n s 1 and 7 do i nd i ca t e a con-

s i d e r a b l e phase s h i f t .

8. Location 4 w a s i n t h e g a t e chamber, loca ted i n t h e l e f t 'abut-

ment of t h e dam. The motion observed a t t h i s loca t ion i s assumed t o be

r e p r e s e n t a t i v e of bedrock motion i n t h e v a l l e y , and motions f o r t h e

f i r s t 6 s ec were used f o r i npu t i n t h e a n a l y s e s , described l a t e r .

9 . The Bu Rec took p r e sho t and pos t sho t survey readings from se t -

t lement markers on t h e dam and found t h a t no permanent displacements oc- '

cur red as a result of P r o j e c t RULISON.

0 The shea r wave v e l o c i t i e s of t h e mate r ia l s i n t he foundat ion

and embankment were de te r rdned dur ing a WES seismic f i e l d i n v e s t i g a t i o n

( ~ ~ ~ e n d i x D ) . P l a t e 6 shows t h e shea r wave ve loc i ty a s a func t ion o f . .. depth f o r t h e foundat ion p r o f i l e ob ta ined from t h e surface v ib r a to ry

tes t da t a , and shea r wave v e l o c i t i e s ob t a ined from t h e Rayleigh wave

!

dispers ion da ta a re shown in plate 7. Curro ( ~ p p e n d i x D) suggested t h a t

the' v ib ra to ry shear wave velocity data be used as a lower bound and the

maximum Rayleigh wave veloci ty data be. used as an upper bound f o r t h e

mater ia l property descr ipt ion.

where

G = shear modulus

v = shear wave v e l o c i t y S

P = mass dens i ty

These moduli a re compared i n p l a t e 8 with t h e shear moduli computed from

Hardin ' s equat ion : 3

where

G -4

= shear modulus ( a t low s t r a i n amplitudes , i. e. c0.25 x 10 max

percent ), ' p s i

e = void r a t i o

OCR = overconsol idat ion r a t i o (1.0 assumed)

k = va r i ab l e t h a t i s a func t ion o f t he p l a s t i c i t y index

, . PART 111: MATERIAL PROPERTIES

11. The foundation shea r wave ve loc i ty p r o f i l e s ( ~ p p e n d i x D ) and

Bu Rec bor ings DH21 and DH22 ( p l a t e 3) were combined t o produce t h e as-

sumed foundation p r o f i l e shown i n p l a t e 5. This was accomplished with

some d i f f i c u l t y due t o t he he te rogene i ty of t he se s o i l s , which i s typ i -

c a l of a l l u v i a l depos i t s . Location 5 w i l l be used as t h e l o c a t i o n f o r

which t h e observed and c a l c u l a t e d responses of t h e foundation a re com-

pared. However, no borings were made a t t h i s l o c a t i o n and bor ings DH21

and DH22 a r e over 500 f t and 400 f t away, respec t ive ly . Seismic mea-

' surements were made over a considerable a r e a a t t h e downstream t o e of

t h e dam. ( ~ p p e n d i x D ) . 12. The shear moduli were determined from t h e shear wave v e l o c i t y

d a t a using t h e fol lowing equat ion:

2 G = v s p

^ _ _ _ _ _ _ _ _ . _ _ _ . _ _ . _ . _ _ _ - . _ . - . _ __.. - . _-- - -. - . .- - - . . - - - ---.--.-- - - -.-- --.- .. --- ' - - - - - & - - A A_ - - - A. - A. L - &

' a = mean p r i n c i p a l e f f e c t i v e s t r e s s , p s i ( ho r i zon ta l normal 0

s t r e s s e s were assumed e q u a l )

The shear moduli c a l c u l a t e d u s i n g equa t ion 2 compare favorab ly with

those ob ta ined u s i n g t h e v i b r a t o r y t echn ique excep t a t t h e bedrock-

alluvium i n t e r f a c e . Thus, t h e p r o p e r t i e s i n t h e foundat ion a t l o c a t i o n

. 5 c a l c u l a t e d from t h e v i b r a t o r y t echn ique were modif ied accord ing t o

equation 2 and w e r e used t o e s t i m a t e s h e a r modulus d i r e c t l y under t h e

dam, where it was no t measured. This m o d i f i c a t i o n i s necessa ry because

the weight of t h e dam w i l l i n c r e a s e t h e c o n f i n i n g p r e s s u r e , t h u s i n c r e a s -

ing t h e modulus as compared wi th t h a t measured i n t h e foundat ion away

from t h e dam. Confining p r e s s u r e s w e r e ob ta ined from a s t a t i c f i n i t e

element code (FESS 4 1 ) developed at WES. A p l o t o f s h e a r modulus ve r sus

depth of t h e foundat ion d i r e c t l y under t h e c e n t e r l i n e of t h e dam i s

shown i n p l a t e 9 .

13. T e s t d a t a from t h e Bu Rec showed t h a t t h e enibankment mate-

r i a l s had a n average d* u n i t weight o f 119.6 p c f and an average mois-

t u r e c o n t e n t of 12.6 p e r c e n t . The s h e a r wave v e l o c i t y p r o f i l e ob ta ined

using t h e v i b r a t o r y technique i s , shown i n p l a t e 10 . A Po i s son ' s r a t i o

of 0.4 w a s assumed f o r t h e dam and t h e foundat ion m a t e r i a l .

1 4 . The s h e a r moduli and damping va lues used i n t h e f i n a l re-

sponse c a l c u l a t i o n s were ob ta ined by m o d i f i c a t i o n f o r t h e computed s h e a r . 4

s t r a i n l e v e l . The s h e a r moduli .and damping curves are shown i n

p l a t e s 11 and 1 2 , r e s p e c t i v e l y , f o r sand and i n p l a t e s 1 3 and 1 4 , re-

s p e c t i v e l y , f o r s a t u r a t e d c l a y s . The s h e a r moduli a s determined from

f i e l d d a t a o r equa t ion 2 were assumed t o be a t a s h e a r s t r a i n o f -4

10 p e r c e n t .

15. The depth t o bedrock, measured ' us ing s e i s m i c t echn iques ,

ranged from 80 t o 120 ft ( ~ p ~ e n d i x D ) . The bedrock p r o f i l e v a r i e d con-

s ide rab ly , and d i f f e r e n t depths were used i n t h e ana lyses . For t h e two-

dimensional ( 2 ~ ) a n a l y s e s , a h o r i z o n t a l bedrock p r o f i l e w a s assumed f o r

reasons o f s i m p l i f i c a t i o n and l a c k o f s p e c i f i c in fo rmat ion on depth o f

bedrock under t h e embankment.

16 . The fundamental pe r iod of t h e s t r u c t u r e w a s computed us ing C

Arnbrasey' s equat ion: '

T = fundamental pe r i od o f t h e dam, sec

H = he igh t o f dam, k. 120 f t

V = shea r wave v e l o c i t y i n dam, x 950 f t / s e c ( p l a t e 1 0 ) s

This computation gives a fundamental period of 0.33 sec .

PART I V : CALCULATIONS

General

17. The c a l c u l a t i o n s o f t h e response of t h e a l luvium 500 f t down-

s t ream from R i f l e Gap Dam were made using th r ee d i f f e r e n t methods o f

ana lys i s ; these were :

a . One-dimens i o n 1 ( 1 ~ ) lumped-mass a n a l y s i s o f foundation - a l l u v i urn only 8

b. .1D Four ie r ana lys i s o f foundation a l luvium only - 7

c. TWO-dimensional ( 2 D ) f i n i t e element a n a l y s i s , us ing mo a1 - supe rpos i t i on techniques , of foundat.ion and embankment 2

The same 2D f i n i t e element ana lys i s was a l so used t o c a l c u l a t e t h e re-

sponse of the embankment.

18. The response o f t h e .foundation mater ia l downstream from t h e

dam us ing the 1 D lumped-mass a n a l y s i s i s evaluated i n r e f e r ence 6 as

follows :

. ~ s s e n t i a l l ~ a s o i l deposi t i s represented by a s e r i e s of l a y e r s . . . , t h e m a s s of each l aye r i s lumped at t h e top and bottom o f each l a y e r and the masses a r e con- nected by shea r spr ings whose c h a r a c t e r i s t i c s a r e de- termined by t h e s t r e s s - s t r a i n r e l a t i onsh ips of t h e s o i l s i n t h e var ious layers . Similar ly , t h e damping c h a r a c t e r i s t i c s ,of t h e system are determined by the . s o i l p roper t ies ' .

Modal superposi t ion techniques are used t o evaluate t h e response o f the

depos i t t o the i npu t base motion. The base i s assumed t o be r i g i d .

19. The dynamic Four i e r ana lys i s of layered systems al lows con-

s i d e r a t i o n of energy r a d i a t i o n i n t o t h e bedrock and, "uses a one-

dimensional Four ie r t rans form ana lys i s t o compute t h e response of l i n e a r ,

v i s c o e l a s t i c , nonuniform s o i l depos i t s , subjected t o a base e x c i t a t i o n . 118

S o i l p roper t ies assumed were those obtained from t h e 1 D lumped-mass

a n a l y s i s taken from t h e f i e l d v ib ra to ry t e s t s and modified f o r t he ap-

p r o p r i a t e shear s t r a i n l e v e l . The base is assumed t o be e l a s t i c i n t h i s

ana lys i s . The amount of energy radiated. i n t o t h e bedrock depends upon

t h e r e l a t i v e s t i f f n e s s o f t h e s o i l and bedrock.

20. The f i n i t e element method of ana lys i s c o n s i s t s of developing

' a f i n i t e element network, obta in ing t h e s t f f f n e s s of each element,

assembling t h e elements i n t o a s t r u c t u r e , so lv ing t h e equat ions o f

equilibrium using modal superposit ion techniques, and eva lua t ing t h e

response of t h e s t r u c t u r e . The f i n i t e element mesh ( p l a t e 1 5 ) was gen-

e ra ted t o account f o r . ma te r i a l zones, s t r e s s zones, and t h e p h r e a t i c

surface. The element s i z e s were based on recommendations p resen ted i n

reference .9. The loca t ions f o r comparison of t h e observed and ca lcu-

l a t e d motions a re a l s o i n p l a t e 1 5 . The s o i l p roper t i e s were modified

fo r t h e shear s t r a i n l e v e l s obtained during e x c i t a t i o n . A h o r i z o n t a l

r i g i d base a t t h e depth of bedrock was assumed.

One-Dimensional Analyses of Foundation

21. The cases inves t iga ted using t h e ID analyses a r e l i s t e d i n

t a b l e 2. Cases 1-18 were analyzed using t h e lumped-mass a n a l y s i s , and

cases 19-21 were analyzed using t h e Fourier ana lys i s . The s h e a r modulus

p r o f i l e used was t h a t obtained from surface v ib ra to ry da ta ( p l a t e 6 ) ex-

cept i n cases 14-18, i n which t h e p r o f i l e used was t h a t from t h e

Rayleigh wave dispers ion da ta ( p l a t e 7 ) . The shear moduli o f t h e

. clay s o i l i n cases 9-13 and 19 were adjus ted by a f a c t o r of 1.875 t o

produce ,more comparable r e s u l t s . In a l l o t h e r cases , t h e modulus pro-

f i l e used was t h a t observed from i t s respect ive f i e l d measurement.' The

damping value is t h a t value used i n t h e f i n a l response c a l c u l a t i o n s

a f t e r t h e s o i l p roper t i e s have been modified f o r shear s t r a i n . The ex-

ac t depth t o bedrock was unknown; the re fo re , many depths were analyzed '

and t h e value l i s t e d i n t a b l e 2 i s t'hat f o r each respec t ive case . The

mater ia l c l a s s i f i c a t i o n r e f e r s t o t h e curves f o r modifying m a t e r i a l

proper t ies f o r shear s t r a i n . S r e f e r s t o sand and t h e modi f i ca t ion

curves i n p l a t e s 11 and 12 , C r e f e r s t o c l a y and t h e curves i n p l a t e s 13

and 1 4 , and M r e f e r s t o a layered mixture, a s designated i n t h e t y p i c a l

foundation p r o f i l e ( p l a t e 5 ) i n which t h e respec t ive curve was used f o r

each l ayer of mater ia l . S ix seconds of hor izon ta l input motion w e r e

used i n most analyses. The e f f e c t of using 1 2 sec of motion w a s

determined i n c a s e 13. I n case 12 , t h e e f f e c t o f using raw input d a t a

t h a t had no t been c o r r e c t e d fo r base-l ine s h i f t was inves-tigated. The

c a l c u l a t e d response s p e c t r a and maximum acce le ra t ions f o r t h e ID analy-

ses a r e g iven i n Appendix B. .

Two-Dimensional Analyses of Embankment and Foundation

22. Table 3 l i s t s t h e cases inves t iga ted us ing t h e 2D analyses.

For all c a s e s , t h e s h e a r moduli ( G) were conrputed from t h e v ib ra to ry

s h e a r wave v e l o c i t y p r o f i l e s f o r t h e -foundation and embankment. Because

no f i e l d measurements were taken d i r e c t l y under t h e embankment, t h e

s h e a r moduli p r o f i l e ' f o r . tha t loca t ion was modified, a s shown i n p l a t e 9 ,

from t h e v a l u e s computed us ing Hardinls e q ~ a t i o n . ~ Void r a t i o s of t h e

f o m d a t i o n m a t e r i a l were computed from v ib ra to ry da ta . The s o i l proper-

t i e s of s h e a r modulus and damping were modified f o r computed shear

s t r a i n s , and t h e 'damping value l i s t e d i s t h a t used i n t h e f i n a l ca lcula-

l a t i o n s . I n some of t h e ana lyses , t h e moduli and damping values were

changed as shown i n t a b l e 3 t o determine t h e e f f e c t s on t h e computed re-

sponse. For example, i n case 27 a t r i a l was made using a l a r g e r modulus

t h a n was measured. The modulus of t h e mate r i a l i n t h e embankment w a s

m u l t i p l i e d by 2 .5 , whi le t h a t of t h e mate r i a l .in t h e foundation was m u l -

t i p l i e d by 1 .5 . The damping value of t h e e n t i r e system w a s 4.6 percent .

I n c a s e 26, t h e foundat ion depth was 80 f t ; a depth of 100 f t was used

i n a l l o t h e r 2D ana lyses . Ninety modes of v i b r a t i o n were used i n t h e 2D

a n a l y s e s . S ix seconds o f hor izon ta l and v e r t i c a l a c c e l e r a t i o n d a t a were

used as i n p u t motion. It was important t o i.nclude t h e v e r t i c a l compo-

nent i n t h e s e a n a l y s e s because t h e energy source , an underground nuclear

exp los ion , produced l a r g e v e r t i c a l acce le ra t ions at R i f l e Gap Dam. The

c a l c u l a t e d response s p e c t r a and maximum acce le ra t ions a r e presented i n

Appendix C . A damping r a t i o of 5 percent was used f o r a l l s p e c t r a l

c a l c u l a t i o n s .

PART V: COMPARISONS OF OBSERVED AND CALCULATED RESPONSES

Method

23. A systematic method was needed t o compare the amplitudes and

frequency contents of observed motion records with those of computed mo-

I t i o n records . The amplitudes can be compared by us ing maximum accelera-

I t i o n s , while t h e frequency contents can be compared using response spec-

I tra. The number of peaks, periods at which peaks occurred, and r e l a t i v e

magnitudes of peaks a r e used i n t h e s p e c t r a l comparisons. One-

dimensional analysis r e s u l t s were compared with mot ions a t l oca t ion 5 ,

on. the surface of t h e alluvium. Two-dimensional ana lys i s r e s u l t s were

compared with motions a t l oca t ion 5 and a t dam loca t ions 1-3.

One-Dimens i o n a l Analysis

. ,

Observed

24. The maximum obse'rved h o r i z o n t a l acce l e ra t ion o f ' the alluvium

( loca t ion 5 ~ ) w a s 0.051 g. The acce l e ra t ion response spectrum ( p l a t e ~ 1 )

of the observed motion contained t h r e e peaks. The l a r g e s t occurred a t a

period o f 0.15 sec. A peak approximately two-thirds t h e s i z e of t h e

l a r g e s t peak occurred a t a period o f 0.33 sec , and a ' r e l a t i v e l y minor

peak occurred at a per iod of 0.51 s e e .

Cases 1-5 ( e f f e c t of depth of a l luv ium)

25. The e f f e c t ' of t h e depth t o bedrock , which var ied from 80 f t

i n case 1 t o 110 f't i n ca se 5 , was inves t iga t ed i n t hese cases . For

cases 1-5, the lumped-mass ana lys i s was used t o analyze a sand p r o f i l e

with shear moduli obtained from t h e su r f ace v ib ra to ry t e s t s . The re- . .

sponses o f cases 1-5 showed seve ra l marked s i m i l a r i t i e s t o t h e observed

responses ( p l a t e B 1 ) . One. s i m i l a r i t y .was the r e l a t i v e magnitudes of

I peaks, a s the second peak w a s two-thirds t h e s i z e o f t h e maximum peak

and the t h i r d peak (when' p r e s e n t ) w a s r e l a t i v e l y minor. The per iods a t

which peaks occurred were a l s o similar. The maximum peak of t h e re -

sponse spec t ra occurred i n the p e r i o d range of 0.15 t o 0.19 sec . In a l l

cases , a subsequent peak occurred i n t h e period range o f 0.31 t o

0.33 sec . A minor peak occurred i n t h e period range o f 0.49 t o 0.51 sec

for cases 4 and 5 bu t was not present f o r cases 1, 2, and 3. The maxi-

muin acce lera t ions ranged from 0.035 t o 0.04'6 g; t h e acce lera t ions were

l e s s than those observed.

26. A comparison of t h e response spec t r a f o r cases 1 and 5 i s

shown i n p l a t e 16. The peaks of t h e shallower depth p r o f i l e (80 f t ,

case 1) a r e s h i f t e d upwards and t o t h e l e f t , i n d i c a t i n g more response at

lower periods. of higher frequencies. P l a t e 17 shows a comparison of t h e

response spec t r a f o r the observed motion and t h a t ca lcu la ted i n case 2 ,

which had a depth t o bedrock of 85 f t . The da lcula ted response, case 2 ,

compares favorably with t h e observed and ind ica te s t h a t response can be

predicted using the 1D analys is method.

Cases 6 and 7 ( e f f e c t of a l l u v i a l s o i l type )

. 27. The e f f e c t of using a c l a y p r o f i l e was inves t iga ted i n cases

6 and 7 ( p l a t e ~ 2 ) . For cases 6 and 7, t h e curves i n p l a t e s 13 and 14

were used t o modify s o i l p roper t ies f o r shear s t r a i n . On t h e response

spec t ra f o r cases 6 and 7 , t h e maximum peaks occurred a t periods of 0.23

and 0.25 sec , and another peak, two-thirds t h e s i z e o f the maximum, oc-

curred a t periods of 0.14 and 0.15 sec. The maximum acce lera t ions cal-

culated were 0.033 and 0.044 g. The depth o f s o i l deposit i n case 6 w a s

90 f t and i n case 7 was 110 f t . ' A comparison of case 6 (c lay p r o f i l e )

with case 3 (sand p r o f i l e ) i s shown i n p l a t e 18. The response curve f o r

case 3 i s s h i f t e d upwards and t o t h e l e f t o f t h a t f o r case 6 , i nd ica t ing

more response at lower per iods f o r case 3 (sand) than for case 6 ( c l a y ) . '

The average shear s t r a i n used t o modify t h e s o i l p rope r t i e s f o r t h e

f i n a l response ca lcu la t ion i n case 3 w a s 6.5 x percent and i n

case 6 w a s 3.7 x percent . These s t r a i n s modulus reductions

of 15 and 32 percent i n cases 3 and 6 , respec t ive ly .

28. The s h i f t i n response s p e c t r a of case 3 ( sand) versus case 6

( c l a y ) ( p l a t e 18) is s imi l a r t o t h e s h i f t obtained ' i n case 1 versus case

5 ( p l a t e 16), where the depth increased from 80 t o 110 f t . The equation

f o r the fundamental period ( ~ ~ ) i of ho r i zon ta l s o i l l a y e r s , each

!

I having uniform mater ia l p roper t i es ( re fe rence l o ) , i s :

where Hi i s the thickness of t h e i t h

l a y e r , Gi

i s t h e shea r

modulus, g i s accelera t ion due t o g r a v i t y , and 'i i s t h e dens i ty .

This equation shows t ha t a deposi t w i l l 'have a s i m i l a r change i n funda-

mental per iod by increasing t h e depth and decreas ing t h e modulus, o r

vice versa. This i s i l l u s t r a t e d by t h e s i m i l a r response s p e c t r a s h i f t s

i n p l a t e 16 (case 1 versus case 5 ) f o r an i nc r ea se i n depth and i n

p la te 18 ( ca se 3 versus case 6 ) f o r a decrease i n modulus.

29. A comparison of the observed motion wi th t h a t c a l c u l a t e d i n

case 6 ( c l a y p r o f i l e ) i s shown i n p l a t e 19. The agreement between mea-

sured and computed responses w a s b e t t e r f o r c a se 2 ( p l a t e 17) t h a n f o r

case 6 ( p l a t e . 19 ) . I Cases 8-11 ( e f f e c t of l ayer ing)

30. P l a t e B3 shows comparisons o f observed and computed s p e c t r a

for cases 8-11. The assumed foundation p r o f i l e ( p l a t e 5 ) o f in terbedded

c lays , s i l t s , sands, and gravels was used i n ca se 8. The shea r moduli

were computed from the v ibra t ion da ta and modified f o r shea r s t r a i n by

the appropr ia te curves fo r sand o r c lay. Depth t o bedrock was 90 f t f o r

I cases 8 and 9. The response o f t h e motion i n case 8 w a s s i m i l a r t o t h e

response of case 6 fo r a 9 0 - f t ' p r o f i l e o f e n t i r e l y c l a y ma te r i a l . A

comparison o f computed spectra f o r cases 6 and 8 i s shown i n p l a t e 20.

Pla te 21 shows moduli versus depth p l o t s of, t h e v i b r a t o r y shea r d a t a ,

which have been modified fo r shea r s t r a i n , f o r cases 6 ( c l a y ) , 3 ( s a n d ) ,

and 8 ( l ayered mixture ) . The responses of cases 6 and 8 a r e s i m i l a r ,

showing t h a t t h e response a t t h e su r f ace ( l o c a t i o n 5R) i s c o n t r o l l e d by

low-velocity o r low-modulus l a y e r s i n t h e p rof i - l e , even though ca se 8

has sbme l aye r s - with higher modulus values t h a n does ca se 6.. A compar-

ison of t h e 'response spec t ra o f . the motions c a l c u l a t e d i n c a s e 8 with

, .those which were observed i s shown i n p l a t e 22 ; t he se spec t ra a r e not

s imilar .

31. Cases 9-11 used m a t e r i a l t ypes such a s t hose shown i n p l a t e 5 ,

but with the shea r moduli f o r t h e cohesive ma te r i a l increased by 87.5

percent. This w a s done t o produce a. c a l c u l a t e d response s imi la r t o t he

observed response. There were s i m i l a r i t i e s between t h e computed re-

sponses f o r cases 9-11 and t h e observed responses. The maximum peak of

the response s p e c t r a was a t a p e r i o d of 0.15 s e c i n c a s e 8 and a t a pe-

r iod of 0.16 i n ca se 9. The magnitude of t h e second peak i n a l l cases

was approximately two-thirds as g r e a t as t h a t o f t h e maximum peak.

Cases 10 and 11 had t h r e e peaks i n t h e , response s p e c t r a , while only two

peaks were v i s i b l e i n case 8. The maximum acce l e r a t i ons f o r cases 9,

10, and 11 were 0.042, 0.039, and 0.040 g, r e spec t ive ly .

Cases 12 and 13 ( e f f ec t of input motion)

32. The e f f e c t of base- l ine s h i f t of t h e observed accelerat ion a t

locat ion 4~ (bedrock ) was s tud i ed i n c a s e 1 2 , which w a s exactly the same

as case 11 except t h a t t h e i npu t d a t a i n case 1 2 were not corrected fo r

base-line s h i f t . A s shown i n p l a t e s , B3 (case 11) and ~4 (case 1 2 ) ,

there was no appreciable d i f f e r e n c e i n t h e response spec t ra . Both cases

12.and 1 3 had a maximum a c c e l e r a t i o n of 0.040 g.

33. The e f f e c t of ' us ing 1 2 s e c o f input motion was investigated

i n case 13. Case 13 was e x a c t l y t h e same a s ca se 11 except t h a t 6 sec

of input motion -was used i n c a s e 11. Because t h e r e was no appreciable

di f ference between t h e response s p e c t r a f o r cases '13 and 11 (p la t e B & ) o r

between the maximum a c c e l e r a t i o n s (0.040 g i n both c a s e s ) , 6 sec of in-

put motion was used i n a l l o t h e r cases .

Cases 14-18 ( e f f e c t o f f i e l d moduli)

34. As prev ious ly s t a t e d , t h e s o i l p rope r t i e s f o r cases 14-18

were determined from t h e Rayleigh wave d i spe r s ion d a t a , a s shown i n

p l a t e 7. The only s i m i l a r i t y o f t h e c a l c u l a t e d response with t he ob-

served response was t h a t case 1 5 had a maximum. acce l e r a t i on of 0.053 g 1 and case 1 4 had a maximum a c c e l e r a t i o n o f 0.044 g. Comparisons a re

shown i n p l a t e B5. Case 1 4 had a number of peaks , wi th t h e maximum peak

obcurring a t a period of 0.24 sec . Cases 15-17 each had two peaks, with

- the maximum occurring a t a per iod of 0.31 t o 0.35 sec and a lesser peak

occurring at a period of 0.14 t o 0.17 sec . The maximum accelerations

ranged from 0.070 t o 0.074 f o r cases 16 and 17 . The s o i l properties in

case 1 4 were m d i f i e d f o r shear s t r a i n using p l a t e s 1 3 and 1 4 ; plates 10

and 11 were used t o modify t h e s o i l p roper t ies f o r shear s t r a i n for

cases 15-17. P la t e s 23 and 24 compare t h e observed responses with the

ca lcu la ted responses i n cases 1 4 and 1 5 , respect ively. These plates do

not show as good a comparison a s do p l a t e s 1 7 and 1 9 , which used the

modulus determined from the sur face v ibra tory data.

Cases 19-21 ( e f f e c t of analysis method and damping )

35. P la t e ~6 shows comparisons o f observed and computed responses

for cases 19-21, which used t h e 1D Fourier ana lys is fo r computations of

response. The e f fec t of using t h i s type ana lys is a s opposed t o the 1 D

lumped-mass ana lys is is given i n p l a t e 25. This p l a t e shows a compari-

son of t h e response spec t ra f o r case 20 (Fourier ana lys is ) with the re-

sponse spec t ra f o r case 2 (lumped-mass a n a l y s i s ) . Both cases had the

same foundation mater ial proper t ies .and input motion. The assumed shear

wave veloci ty of t h e bedrock was approximately f i v e times greater than

the shear wave veloci ty of t h e overlying s o i l l ayer . 'Note tha t the re-

sponse spec t ra a r e s imi l a r f o r cases 20 and 2. The response for case 20

i s l e s s than t h a t f o r case 2. The maximum acce lera t ion f o r case 20 i s

0.033 g, whereas f o r case 2 it is 0.041 g. A l i k e comparison can be

made of cases 19 (p la t e ~ 6 ) and 8 ( p l a t e B3).

36. The e f f e c t of reducing the i n t e r n a l s o i l damping in the

Fourier analysis was s tudied i n case 21, which was s imi l a r t o case 20

except t h a t t h e damping was reduced by 100 percent . The maximum accel-

e ra t ion for case 21 was increased t o 0.035 g , as compared t o 0.033 g for

case 20. The response s p e c t r a were a l s o very s i m i l a r ( see plate ~6 ) . Although it w a s expected t h a t t he re would be a grea ter difference i n the

damped calculated responses, t h i s was not t r u e f o r the condition a t

R i f l e Gap D a m .

Two-Dimens i o n a l A n a l y s i s

General

37. The observed r a d i a l and v e r t i c a l motions at l o c a t i o n s 1, 2 ,

3, and 5 were compared with t h e c a l c u l a t e d motions. Transverse motions

were measured, but could not be c a l c u l a t e d u s i n g a 2 D a n a l y s i s method.

P l a t e 4 shows t h e loca t ions o f t h e PAT'S which measured t h e observed mo-

t i o n s , and desc r ip t ions 'of t h e l o c a t i o n s a r e g iven i n table 1. The lo -

ca t ions from which t h e c a l c u l a t e d motions were t a k e n a r e shown on t h e

f i n i t e element network ( p l a t e 1 5 ) . It w a s necessa ry f o r 2D a n a l y s i s

t h a t a l l loca t ions be i n t h e same v e r t i c a l p lane . Although t h i s i s not

t h e t r u e f i e l d case , the l a t e r a l o f f s e t s between PAT and t h e v e r t i c a l .

plane assumed f o r ana lys i s were not cons ide red l a rge . w i t h r e s p e c t t o t h e

hor izon ta l d is tances i n t h e f i n i t e element network. The d e t a t l e d com-

par isons of t h e observed and c a l c u l a t e d responses f o r t h e r a d i a l and

v e r t i c a l components at l o c a t i o n s 1, 2, 3, .and 5 a r e g iven i n t a b l e 4.

The response s p e c t r a f o r t h e observed and c a l c u l a t e d motions f o r loca-,

t i o n s 1, 2, 3, and 5 . a r e p resen ted i n p l a t e s ~ 1 ~ 8 .

Case 22 ( 2 ~ compared with 1D a n a l y s i s )

38. Case 22 w a s a 2D f i n i t e element a n a l y s i s of t h e 120-ft-high

embankment and 100-ft-deep foundat ion a s shown i n p l a t e 15. Although

b e t t e r comparisons could be made i n t h e 1 D ana lyses f o r s h a l l o w e r foun-

da t ions a t l o c a t i o n 5 (a l luvium), t h e se i smic p r o f i l e s ( ~ p p e n d i x D) ' i n -

d i c a t e d t h a t an average depth o f 100 f t would be a more v a l i d assumption.

The shear moduli of t h e m a t e r i a l s w e r e computed from t h e v i b r a t o r y s h e a r

wave v e l o c i t i e s . The shear wave v e l o c i t y p r o f i l e s are shown i n p l a t e 10

, f o r t h e embankment and i n p l a t e 6 f o r t h e founda t ion a t l o c a t i o n 5

(a l luvium). The shear modulus p r o f i l e o f t h e founda t ion d i r e c t l y under

t h e c e n t e r l i n e of t h e embankment, which was t a k e n from t h e v i b r a t o r y

d a t a and modified f o r conf in ing p r e s s u r e s , i s shown i n p l a t e 9 . The ma-

t e r i a l i n t h e foundation was assumed t o respond as a sand, and t h e

curves i n p l a t e s 11 and 1 2 w e r e used t o modify m a t e r i a l p r o p e r t i e s f o r

shear s t r a i n . The mate r i a l i n t h e embankment i s a c o h e s i v e material,

and t h e curves i n p l a t e s 1 3 and 1 4 were used t o modify material

. .

p r o p e r t i e s f o r s h e a r s t r a i n . The damping value o f 5.3 p e r c e n t was t h e

, average used d u r i n g t h e f i n a l response c a l c u l a t i o n a f t e r t h e m a t e r i a l

p r o p e r t i e s had been modified f o r s h e a r s t r a i n ( s e e t a b l e 3).

39. Case 22 c a l c u l a t e d motions were s i m i l a r t o t h e observed mo-

t i o n s . The p e r i o d s of t h e maximum c a l c u l a t e d peaks were s i m i l a r t o t h e

observed maximum peaks f o r t h e r a d i a l components at al l l o c a t i o n s . The

maximum c a l c u l a t e d a c c e l e r a t i o n s a t a l l r a d i a l and v e r t i c a l l o c a t i o n s

were on ly s l i g h t l y l e s s t h a n t h e observed a c c e l e r a t i o n s except a t loca -

t i o n s 2R and 2V where t h e c a l c u l a t e d a c c e l e r a t i o n s were h i g h e r than t h e

observed. The pe r iods a t which t h e peaks occurred i n t h e v e r t i c a l

motion response s p e c t r a were d i f f e r e n t from t h o s e observed. The ca lcu-

l a t e d response had a maximum peak at t h e pe r iod where t h e . observed

response had t h e second o r t h i r d l a r g e s t peak. In t h e same way, t h e

maximum observed peak occur red i n t h e same p e r i o d s as t h e second o r

t h i r d l a r g e s t peaks on t h e c a l c u l a t e d response curves:

40. The e f f e c t o f t h e a d d i t i o n o f t h e v e r t i c a l a c c e l e r a t i o n s t o

t h e response of l o c a t i o n 5R can be seen i n p l a t e 26, which shows t h e re-

sponse s p e c t r a and maximum a c c e l e r a t i o n s f o r c a s e s 4 and 22. Note t h a t

t h e response s p e c t r a and maximum a c c e l e r a t i o n s a r e similar. The founda-

t i o n s o i l p r o p e r t i e s assumed i n c a s e 22 a r e t h e same as t h o s e assumed i n .

c a s e 4. Case 4 w a s a 1D a n a l y s i s and on ly t h e h o r i z o n t a l input motion

could be used. Case 22 w a s a 2D a r ia lys i s and used b o t h t h e h o r i z o n t a l

and v e r t i c a l bedrock a c c e l e r a t i o n h i s t o r i e s a s i n p u t .

Case 23 ( e f f e c t o f i n c r e a s e d modulus)

41. Case 23 was computed t o show t h e e f f e c t o f . inc reas ing t h e

shear modulus of t h e material i n t h e enibankment and foundat ion. Other

assumptions were t h e same as i n c a s e 22 with a 120-f t c l a y embankment

and a 100-f t sand foundat ion. The v a l u e o f 4.7 p e r c e n t damping w a s used

i n t h e f i n a l response c a l c u l a t i o n . R e s u l t s are shown i n . p l a t e s 27-34.

The c a l c u l a t e d responses i n c a s e 23 of t h e v e r t i c a l motions a t l o c a t i o n s

3V and 5 V w e r e s i m i l a r t o t h o s e observed. The peaks on t h e computed re-

sponse s p e c t r a occurred at t h e s a m e p e r i o d s a s d i d t h o s e observed, ' and

t h e . r e l a t i v e magnitudes w e r e s i m i l a r . The maximum a c c e l e r a t i o n s of t h e

v e r t i c a l components were h i g h e r t h a n t h o s e observed excep t at l o c a t i o n 5V.

The computed hor izonta l maximum acce lera t ions were usual ly lower except

a t loca t ion 2R, and the computed acce lera t ion a t loca t ion 5R w a s 0.050 g,

as compared with an observed acce le ra t ion of 0.051 g. The response

spectra f o r t h e observed and ca lcula ted components o f the r a d i a l motion

had peaks occurr ing a t the same per iods , but t h e maximum observed w a s

often a t a period corresponding t o the second o r t h i r d ca lcu la ted maxi-

mum, and vice versa.

Case 24 ( e f f e c t of reduced modulus)

42. The e f f e c t of a reduct ion o f .shear modulus was computed i n

case 24. The assumptions were s imi l a r t o those i n cases 22 and 23 except

tha t i n case 24 the shear moduli of t h e foundation and embankment were

mult ipl ied by the value 0.5. The ca lcula ted motion f o r case 24 had only

a few s i m i l a r i t i e s t o the observed motion. The maximum acce le ra t ions a t

locat ions 2V and 5V were. 0.042 and 0.092 g, respec t ive ly , and were simi- '

l a r t o those observed. The' hor izonta l maximum acce lera t ions were usu-

a l l y lower than those observed except a t loca t ion 2R. The computed

v e r t i c a l acce lera t ions a t l oca t ions 1 V and 3V were lower and h igher , re-

spect ively, than t h e observed acce lera t ions . The pe r iod - of t h e maximum,

and usual ly only, peak on t h e response spec t r a occurred i n the range of

-0.30 t o 0.34 sec , and the period of t h e second peak, present only i n the

v e r t i c a l motion response spec t r a , , was i n the range o f 0.14 t o 0.18 sec. .

Case 25 ( e f f e c t of reduced dampint?)

43. Case 25 invest igated t h e e f f e c t of reducing t h e damping value

used i n response ca lcula t ions . The only difference between cases 22 and

25 was t h a t t h e damping value used f o r case 25 was only two-thirds as

great a s t h a t used for case 22. Consequently, t h e maximum acce lera t ions

for case 25 were grea ter than those f o r case 22 , ' e s p e c i a l l y i n the ra-

d i a l components of locations 1-3 on t h e dam. The computed response spec-

t r a ' for cases 22 and 25 had t h e same shape except t h a t a few more minor

spikes were present i n the response spec t r a f o r case 25. This means

tha t only the amplitude of t h e motion was changed and t h e frequency con- .

t en t remained e s s e n t i a l l y unal te red between cases 22 and 25.

Case 26 ( e f f e c t of depth of alluvium)

44. The e f f e c t of an 80-ft-deep foundation w a s inves t iga ted i n

c i s e 26. This analysis was .made because better comparisons could be

made i n the 1D analysis a t locat ion 5R, downstream from t h e dam, with

t he shallower p ro f i l e . A 120-ft c l a y .embankment , sand foundation, and

moduli obtained from the surface v ib ra to ry d a t a were used a s i npu t , as

i n case 22. The maximum accelerat ions computed a t l oca t ions 1 and 3

were s imilar t o those observed. Similar per iods of t h e p e a k s . f o r the

v e r t i c a l components a t locations 1-3 i n t h e dam were measured. Compari-

sons of the computed -responses with t h e observed responses a t l oca t ions

3R and 3V are shown ' in p la tes 35 and 36, r e spec t ive ly . The computed re-

sponses a t locations 2R and 2V were g r e a t e r than t h e observed, and a t

loca t ions 5R and 5V were smaller t h a n t h e observed. The peaks occurr ing

i n t h e range of 0.12 t o 0.17 sec i n t h e observed response spec t r a f o r

loca t ions 1 R and 1 V were only minor i n t h e computed response f o r case 26.

Note t h a t not as good a comparison could be made a t l o c a t i o n 5 R f o r

case 26 (p l a t e ~ 7 ) as could be made with t h e 1 D ana lys i s i n case 1

( p l a t e ~ 1 ) . This may be due t o t h e increased s t r a i n i n t h e mater ia l

from the inclusion of the v e r t i c a l acce le ra t ion .

Case 27 (e f fec t of s t i f f foundation under s t i f f e r dam)

45. In case 27, the e f f ec t of increas ing t h e shea r modulus of t h e

mater ia l i n the foundation by a f a c t o r d i f f e r e n t from t h a t i n t h e embank-

ment was investigated. The shear modulus of t h e ma te r i a l i n t he founda-

t i o n was increased by the f ac to r 1 .5 , as i n ca se 23. A f ac to r o f 2.5

was used t o increase the shear modulus o f t h e ma te r i a l i n the embank-

ment. ' As expected, the responses measured a t t h e alluvium loca t ions 5R

and 5V were s i m i l a r t o those measured i'n case 23 ( p l a t e s 37 and 38 ) .

The response i n the embankment was similar t o t h a t observed. The maxi- . '

mum accelerat ion and response s p e c t r a computed at loca t ions 2R and 2~

were very s imilar t o the observed (p l a t e s 39 and 40). A t locat ions 3R

and 3 V , peaks of the calculated response s p e c t r a occurred a t t he same

per iods as those i n the observed spec t r a , b u t t h e maximum acce le ra t ion

a t loca t ion 3V was much higher t han the observed. The computed maximum

acce le ra t ion a t locat ion 1 V was s imi l a r t o t h e observed acce le ra t ion ,

but a t locat ion l R , the computed a c c e l e r a t i o n was much lower than the

observed acceleration.

PART V I : DISCUSSION

One-Dimens i o n a l Analysis

46. The U> ana lys i s is used t o determine t h e response of semi-

i n f i n i t e hor izonta l s o i l l ayers . For t h i s reason , t h e 1 D analysis could

b e used only t o ca l cu l a t e response at l o c a t i o n 5R on the alluvium down-

stream of Ri f le Gap Dam. During t h e a n a l y s i s , it became apparent t h a t

many f a c t o r s were vital i n accura te ly s imula t ing response. These fac-

t o r s include t h e following:

a. Shear moduli ,of t h e i n s i t u medium - b . - Depth t o bedrock

c . Relat ionship of shear modulus and damping t o s t r a i n am- - p l i t ude f o r modification o f s o i l p roper t ies

47. Use of the i n s i t u shear moduli as measured by WES i n t he

seismic f i e l d i nves t iga t ion using t h e s u r f a c e v ibra tory technique gave

computed r e s u l t s comparable t o the f i e l d observat ions . The data deter-

mined by the Rayleigh wave d ispers ion technique d id not give calculated

results a s good a s those ca lcu la ted us ing t h e v ibra tory technique.

48. The depth t o bedrock i n t h e foundation mater ia l varied con-

s ide rab ly throughout t h e Ri f le Gap Dam a rea . No borings were made a t

t h e s i t e of l oca t ion 5 on the alluvium downstream from the dam.' Thert-

f o r e , no accurate determination of s o i l depth could be used i n the lD

analyses . The e f f e c t of depth t o bedrock is shown i n p l a t e 16, which

compares t he response of an 80-ft-deep depos i t with t h a t of a 110-ft-

deep depos i t . Be t te r agreement wi th t h e observed response was obtained

us ing t h e shallower bedrock depths.

49. The type o f mater ia l used, sand o r c lay , determined the re-

l a t i o n s h i p used t o modify the ma te r i a l p r o p e r t i e s f o r shear ' s t ra in l eve l .

The comparison o f mater ia l types i s made i n p l a t e 18 f o r cases 3 and 6.

Both t h e maximum acce le ra t ions and response s p e c t r a were considerably

d i f f e r e n t for t h e two cases i nves t iga t ed . For t h e foundation material

a t R i f l e .Gap Dam, b e t t e r agreement with t h e observed data was obtained by

cons ider ing t h e mater ia l as sand. The g ranu la r mater ia l was present i n

bdth Bu Rec borings ( p l a t e . 3 ) , but cohesive m a t e r i a l was a l s o present

and r e s u l t s comparable t o those observed could be obtained only by mul-

t i p l y i n g t h e cohesive modulus by a f a c t o r of 1.875, which a c t u a l l y gave

about t h e same modulus a s t h a t f o r t h e sand curves a t t h a t shear s t r a i n

l e v e l . Because t h e exact s o i l p r o f i l e i s no t known a t l o c a t i o n 5 , it

can only be concluded t h a t t h e m a t e r i a l i n t h e p r o f i l e a t l o c a t i o n 5

responded more c lo se ly t o the sand curves used i n modification of s o i l

p rope r t i e s ( ~ l a t e s 11 and 12) .

50. For t h e motions measured a t R i f l e Gap Dam, the responses did

no t change i n cases 11-13 ( p l a t e ~ 4 ) . Case 11 used 6 .sec o f input mo-

t i o n t h a t had been corrected f o r base- l ine s h i f t , whereas t h e input mo-

t i o n i n case 1 2 w a s not cor rec ted . Case 1 3 used 1 2 sec of input motion.

The agreement of cases 11 and 1 2 showed t h a t t h e a c t u a l acce l e r a t i on

d a t a a t l o c a t i o n 4~ d id not have an apprec iab le ba'se-line s h i f t . The ' (

comparison of cases 11 and 1 3 showed t h a t , when us ing an e l a s t i c analy-

s i s , t h e maximum response occurred b e f o r e 6 s ec and was not changed by

t h e addi t ion of 6 sec more of e x c i t a t i o n .

51. The input motion f o r a l l analyses was t h a t observed a t loca-

t i o n 4 on bedrock i n t h e gate chamber ' ( see p l a t e 4 ) . The motion at lo - ,

ca t ion 4 was assumed t o occur i n t h e bedrock under lying t h e foundation

p r o f i l e a t l o c a t i o n 5 . Most o f t h e analyses i nd i ca t ed t h a t t he response

a t l oca t i on 5R could be pred ic ted wi th t h e 1 D ana lys i s ; t hus , t h e as-

sumption t h a t t he motion observed a t l o c a t i o n 4 w a s bedrock motion was

apparent ly a v a l i d assumption.

52. The 1 D ana lys i s gave r e s u l t s very s i m i l a r t o those observed

f o r t he al luvium ( l o c a t i o n 5 ~ ) . With t h e a d d i t i o n o f the. v e r t i c a l mo-

t i o n input i n t he 2D ana lys i s , p l a t e 26 shows t h a t good agreement be-

tween t h e 1 D and 2D ana lys i s r e s u l t s i s obtained. This means t h a t the

much simpler and cheaper U) a n a l y s i s can b e used t o p red ic t t h e hor i -

zon t a l motion i n a semi- inf ini te s o i l depos i t even during three-dimensional

dimensional e x c i t a t i o n .

~wo-~ imens i o n a l Analys i s

53. S imi l a r r e s u l t s were obtained at l o c a t i o n s 5R and 5V f o r

, - . . .... - . ; - > - . -:::- 3 - 7 - -= ,-..-; - =. . - - . - . , - - I.-..., ..i..- ' I . 7. = _ _-.. : . .: . . . - - - - C - - . -.----.--A -. - . A , - ' L i. A.

, cases 23 and 27, as shown i n p la tes 37 and 38. The only d i f fe rence i n

t h e two cases was the increase of modulus i n t h e embankment f o r case 27

over t h a t for case 23. This shows t h a t t h e instrument loca ted more than

520 ft downstream from the 120-ft-high dam w a s a t a s u f f i c i e n t d is tance

from t h e dam tha t ' i ts response was not a f f e c t e d by t h e s t r u c t u r e .(gener-

a l l y ca l l ed free-f ie ld response 1. . 54. The response of t h e ' foundation mater ia l was b e s t p red ic t ed by

case 23 (p la tes 33 and 34) i n which t h e v ib ra to ry shea r modulus was mul -

t i p l i e d by 1.5. However, comparable r e s u l t s were obtained f o r case 22

i n which the -shear modulus was t h a t computed from t h e f i e l d measurements. 4

Thus, t he shear wave v e l o c i t i e s measured us ing t h e ' sur face v ibra tory

technique can be used i n t h e 2D f i n i t e element models.

5 5 . The responses computed a t loca t ions 2R and 2V were usua l ly

g r e a t e r than those observed. Bet ter agreement was obtained by increas-

i n g t h e modulus i n t h e s t ruc tu re , and s i m i l a r r e s u l t s were obtained f o r

case 27, as shown i n p l a t e s 39 and 40.

56. A change i n the damping value f o r t h e s t r u c t u r e , as i n case

25, had only a s l i g h t e f f e c t on the magnitude of t h e response. The ra-

d i a l components of motion were more a f f e c t e d than t h e v e r t i c a l compo-

nents. Changing the damping value d id not cause a noticeab1.e change i n

t h e periods of the peaks.

57. The response a t the c r e s t of t h e dam was t h e most d i f f i c u l t

t o p red ic t . Most cases produced s in i i la r maximum acce lera t ions but had

only one peak a t a per iod o f 0.30 t o 0.33 s e c , which i s near t h e f'unda-

mental period of the s t r u c t u r e , and did not have s u b s t a n t i a l response a t

lower periods, as w a s observed. Attempts t o produce a g rea te r response

a t the lower periods by increasing t h e modulus of t h e dam were success-

ful, b u t the maximum accelerat ions were reduced considerably.

58. The change of modulus produces d i f f e r e n t modal frequencies of

t h e s t r u c t k e . I f these a r e d i f f e r e n t .from t h e major frequencies o f the

inpu t , the responses a re low. This could have been t h e reason f o r t h e '

low response i n case 27 a t locat ions 1 R and lV, where a grea ter response

' , was expected. Thus, it is 'important i n design and ana lys is t h a t a num-

b e r of inputs be used t o produce a smooth response spectrum so t h a t the

PART V I I : CONCLUSIONS

59. The following conclusions can be drawn from t h e 1 D analyses :

a. The response of horizontal s o i l layers can be predicted - using a ID analysis.

b_. The lumped-mass and Fourier analyses give s imi l a r r e s u l t s for a p r o f i l e i n which t h e r e i s a 'def in i te change i n shear wave veloci t ies between the bedrock and s o i l . For the ana lys is of Rif le Gap Dam, the ve loc i ty of the bed- rock mater ia l was approximately f ive times t h a t of t h e s o i l .

c . It is important t o have an accurate determination of the - s o i l p r o f i l e .

d. It is important t o determine t h e exact depth t o Sedrock. - e . The s o i l property modification curves ' for shear s t r a i n -

l e v e l are applicable.

f . The shear wave veloci t ies determined using t h e surface - vibratory technique can be used i n t h e 1D analyses.

60. The following conclusions can b e drawn from the 2D analyses:

a . An instrument placed a t a d is tance f i v e times the height - of t h e dam w i l l give f r ee - f i e ld response.

b. The shear wave veloci t ies measured using t h e surface v i - b ra tory technique can be used i n the 2D analyses, bu t due t o t h e inclusion of the v e r t i c a l input motion, a more similar response was ca lcu la t ed a t ~ i f l e Gap Dam when the modulus was increased by 50 percent.

c . -Due t o the complex geometry and mater ia l propert ies . o f - t he s t r u c t u r e , use of the f i n i t e element ana lys is is nec- essary t o predic t the response o f various loca t ions i n

' t he s t r u c t u r e .

d. It is important t o use more t h a n one input motion t o . ana- - lyze a s t ruc ture . A v a r i e t y of input frequencies is nec- essary t o f i n d the maximum response.

e . here was c lose r agreement between computed aqd observed - maximum accelerations than between shapes o f computed and observed response spec t ra .

61. For t h e ana lys is of Ri f le Gap Dam, t he following assumptions

provided the b e s t agreement between the observed and ca lcula ted motions :

a. One-dimensional analysis ( l o c a t i o n 5R on alluvium) - ( 1 ) Lumped-mass analysis method

- . ( 2 ) Shear modulus determined from vibra tory t e s t d a t a

4 ( 3 ) Damping from re l a t i onsh ips by Seed and I d r i s s f o r

, shear s t r a i n

( 4 ) Modulus modified from re la t io r i sh ips by seed and Idriss fo r shear s t r a i n

( 5 ) Sand ma te r i a l

( 6 ) 85-f t depth t o bedrock

- b . TWO-dimens i o n a l ana lys i s

('1) F i n i t e element modal superposing ana lys i s method

( 2 ) Shear modulus determined from v ibra tory t e s t d a t a and increased 50 percent

( 3 ) Damping from r e l a t i o n s h i p by Seed and I d r i s s f o r shear s t r a i n

( 4 ) Modulus modified from re l a t i onsh ips by Seed and I d r i s s fo r shea r s t r a i n

( 5 ) Sand i n foundation

( 6 ) Clay i n embankment

( 7 ) Average 100-ft depth t o bedrock

LITERATURE CITED

U. S. Department of I n t e r i o r , Bureau o f Reclamation, "R i f l e Gap Dam and Road Relocation," Spec i f ica t ion NO. DC-6120, 1964, Washing- t o n , D . C .

Fowler, J. , "Motion of R i f l e Gap Dam, R i f l e , Colorado; P r o j e c t Rul ison Underground Nuclear Detonation ," Miscellaneous Paper S-70-1, Jan 1970, U. S. Army Engineer Waterways Experiment S t a t i o n , CE, Vicksburg, Miss.

Hardin, B. 0. and Drnevich , V. P. , "Shear Modulus and Damping i n S o i l s ," Technical Report UKY 27-70-CE 3 , s o i l Mechanics S e r i e s No. 2 , Jul 1970, Univers i ty of Kentucky, Lexington, Ky.

Seed, H. B. and I d r i s s , I. M . , "So i l Moduli and Damping Fac to r s f o r Dynamic Response Analyses, " Report No. EERC 70-10 , Dec 1970, Uni- v e r s i t y of Ca l i fo rn i a , College o f Engineering, Earthquake Engineer- i n g Research Center , Berkeley, C a l i f . O f f i c e , Chief o f ~ n ~ i n e e r s , "Earthquake Studies f o r Earth and Rock- f i l l Dams ," Engineer Technical L e t t e r No. 1110-2-79 , 12 J a n 1970, Washington, D. C .

I d r i s s , I. M . , Dezfulian, H. , and Seed, H. B. , "Computer Programs f o r Evaluat ing t h e Seismic Response o f So i l Deposi ts wi th Non- Linear C h a r a c t e r i s t i c s Using Equivalent Linear Procedures , I f

Apr 1969, Univers i ty of Ca l i fo rn i a , Geotechnical Engineering, Berkeley, Ca l i f .

Roesset , J. M.. and Whitman, R . V . , " ~ h e o r e t i c a l Background f o r Amplif icat ion Studies ," So i l s Engineering Div is ion Publ ica t ion No. 231, Mar 1969, Department of C i v i l Engineering, Inter-American Program, Massachusetts I n s t i t u t e o f Technology,. Cambridge, Mass.

Roesset , J. M. and Hagann, A. J. , "Users Manual, Program Dyfals I ," Jul 1969, Department of C i v i l Engineering, Div is ion of S o i l Mechan- i c s , Massachusetts I n s t i t u t e of Technology, Cambridge, Mass.

I d r i s s , I. M. , " ~ i n i t e Element Analysis f o r Seismic Response o f Ear th Banks , I 1 J ou rna l , S o i l Mechanics and Foundations D iv i s ion , American Soc ie ty of C i v i l Engineers. Vol 94, No. SM3, Paper 5929, May 1968, pp 617-636.

I1 I d r i s s , I. M. and Seed, H. B. , Seismic' Response o f Horizontal S o i l Layers," J o u r n a l , S o i l Mechanics and Foundat i ons Divis ion , American Soc i e ty o f C i v i l Engineers, Vol 94, No. S M ~ , Paper 6043, Jul 1968, pp 1003-1031.

Table 1

Summary of Equipment Used, Locations, and Field Measurements

Pa r t i c l e P a r t i c l e Peak Peak Transducer Acceleration Velocity Acceleration Velocity

No. - Location* Orientation Transducer Transducer g ' s i p s

1 Crest of dam Vertical x 0.062 Radial x : 0.094

2 ' Downstream face Vertical of dam Radial

3 ' Near toe of dam Vertical Radial

4 Gate chamber Vertical Radial Transverse

5 Alluvium

6 Alluvium

Vertical Radial Transverse

. Vertical Radial Transverse

7 Crest o f dam Vertical Radial Transverse

- - -- -- - -

Note: I n i t i a l a r r i v a l of motion was 6.9 sec a f t e r detonation. See p l a t e 4 .

Table 2

Cases for One-Dimensional Analyses, Location 5R

on Alluvium 500 Ft Downstream from Toe of Dam

F ie ld Test from Which Material Depth t o Material

Case Type Propert ies Were Shear Damping Bedrock Class i - No. Analysis - Determined Modulus % ft f i ca t ion* Remarks

1 Lumped-mass Vibratory . C 3.9 80 S 2 Lumped-mass Vibratory C 3.8 85 S 3 Lumped-mass Vibratory C 3:7 90 S ' b Lumped-mass Vibratory G 3.5 i00 S 5 Lumped-mass Vibratory C 3.7 110 S

6 Lumped-mass Vibratory C 3.2 90 C 7 Lumped-mas-s Vibratory C 3.3 110 C 8 Lumped-mass Vibratory C 3.3 90 M 9 Lumped-mass Vibratory 1.875G4' 3.3 90 M

10 Lumped-mass Vibratory 1.8750- 3.2 100 M

11 Lumped-mass Vibratory 1.875G*+ 3.2 110 M 12 Lumped-mass Vibratory 1.875G** 3.2 110 M Original acce lera t ion

da t a used fo r input 1 3 Lumped-mass Vibratory 1.875c** 3.2 110 M 12 sec of input fo r

ca lcula t ing response , 1 4 Lumped-mass Rayleigh 2 C 4.0 110 C

15 Lumped-mass . Rayleigh 2 C 4.7 110 S

16 Lumped-mass Rayleigh 1 G b.7 125 S 17 Lumped-mass Rayleigh 1 C 5.9 80 S 18 Lumped-mass Rayleigh 1 C 3.2 80 C 19 Fourier Vibratory 1.875c+* 3.4 80 M 20 Fourier Vibratory C 3.8 85 S 21 Fourier Vibratory C 1.9 85 . S 1/2 damping of case 20

* S r e f e r s t o sand and the modification curves i n p l a t e s 11 and 12 , C r e f e r s t o clay and the curves in p l a t e s 13 and 1 4 , and M refers t o a mixture as designated i n the t yp i ca l foundation p r o f i l e in p l a t e 5. ** Only the shear moduli of the clay layers were changed by t h i s f ac to r .

Table 3

Cases f o r Two-Dimensional Analyses

Foundation Case Damping Depth No. - Shear Modulus % ft Remarks

27 1.5G ( foundation) 4.6 100 2 . 5 ~ (dam) .

2/3 damping of case 22

~ - ~

Note: Six seconds o f ho r i zon ta l and v e r t i c a l acce le ra t ion data were used as input motion. The modal superpos i t ion analysis method was used. Ninety modes o f v i b r a t i o n 'were considered.

Table b

C-arison of Observed'and Calculated Responses f o r 2D Analysis

Amplitude Ratio Period of Peak, sec of Peaks

Maximum Number Second Third Second Third Case Acceleration of Maximum Largest Largest t o t o NO. - K' s Peaks Peak Peak Peak Mkximum Maximum Remarks

Location l R , Radial Component, Crest of Dam

Observed 0.094 3 0.32 0.12 0.17 3/4 3/4 22 0.073 1 0.31 23 0.052 3 0.27 0.32 0.14 t o 0.18 4/5 2 /3 24 0.041 1 0.32 25 0.119 2 0.31 0.19 1 / 3 26 0.091 1 0.29 Minor spike a t 0.17 sec 27 0.035 3 0.29 0.15 t o 0.18 0.52 2 / 3 1 / 3

Location l V , Vert ical Component, Crest of Dam

Observed 22

' 23 24 25 26 27

Observed 22 23 24 25 26 27

Observed 22 23 24 25 26 27

0.13 . 0.31. 0.21 2 / 3 i/ 3 0.33 0.30 0.14 1 /2 0.34 0.16 1 / 4 0.32 - 0.19 1 / 3 0.36 0.15 t o 0.17 1 / 3 0.30 0.13 1 /2

Location 2R. ~ a d i a l Component. Halivay D o v n Face of Dam

0.32 0.13 314 0.29 0.16 1 / 3 0.24 0.14 0.31 1/1 7/10 0.33 0.31 0.16 1 / 3 0.30 0.16 2/5 0.15 0.30 2/3

Location 2V. Vert ical Component. Hal*ay D m Face of Dam

0.08 t o 0.13 ' 0.30 4/5 0.31 0.14 1 / 3 0.29 O.lb 5/8 0.33 0.14 1 /2 0.30 0.14 1 / 3 0.30 0.14 2/5 0.29 0.14 1/1

Minor peak a t 0.56 sec

Minor peak a t 0.19 sec

Location 3R. Radial Component. Near Toe of Dam

Observed 0.052 3 0.13 0.20 0.31 5 /6 1 / 2 22 . 0.039 3 0.27 0.24 0 . 9 1/1 2/3 Minor peak a t 0.49 sec

Observed

Observed 0.051 22 0.032

0.050 28 23 0.046 25 0.039 26 0.032

Location 3V. Vertical Comonent. Near Toe of Dam

Relatively minor peak a t 0.51 sec

l / b 3/4

Location 5R. Radial Component. Alluvium

0.52 3/5 1 / 2 'I4 Minor spikes present 9/10

1 0.30 4 0.19 t o 0.23 0.28 0.32 2 / 3 112 . Fourth. peak a t 0.49 sec 2 0.19 0.31 9/10 Tvo minor Desks a t 0.24

and 0.47-sec 27 0.061 3 0.15 0.35 0.27 8/10 1 /2 Minor peak

Location 5V. Vert ical Component. Alluvium

Observed 0.088 2 0.08 t o 0.4 0.29 1/2 22 0.061 3 0.29 0.13 0.20 9/10 8/10

0.072 2 0.14 t o 0.19 0. Y 1 / 2 24 23 0.092 2 0.32 0.14 3/10

0.063 4 0.22 0.29 0.24 1/1 Fourth peak a t 0.14 sec 26 25 0.050 3 0.19 0.14 0.28 'I1 3/4 '2/3 27 0.069 2 0.14 t o 0.19 0.31 1 / 2

SCALE Or NlLLS

KEY MAC

.LOCATION MAP

RIFLE GAP DAM

PLATE I

C Crest o f dom... ... J I

J Riprop on

10 LLLLLLW.1

0 M 100 a I belor E L 5910

S C I L L O F FEE1

M A X I M U M S E C T I O N

E M B A N K M E N T E X P L A N A T I O N Cloy, silt. sand ond qrorel compacted by tompinq rol lers t o 6 -inch layers. ,

11 Cloy, si l t , sond,qrovrl and cobblts tomllortcd by tompinq rallcrs b Q- lnm Iayers, 8 @ Miscelloneour clor. s r l t , sond. grovel. ond cobbles or rock fropments compocled .

by tomplnp r o l l e r s t o 12-inch l o p r s .

@ Selected sond,qravel ond cobbles or r ock t rogmrnts p l o r t d in 2,. Inch loyerr.

GENERAL PLAN AND SECTION

RIFLE GAP DAM

D H 2 2 a L O w , I * l .

S A N D . F l N E W l T H L I T T L E C L A V . L O O S E L Y P A C K E D . T A N

2 0

21 ' -36 ' G R A V E L A N 0 C L A V . S I L T Y . W l T H L E N S E S O F S A N D A N D G R A V E L L O O S E T O M E D I U M D E N S I T Y

.o

S I L T Y . G R A Y . C O N S I S T E N C Y I S S T I F F

I , D E N S I T V

ee.-a!o C L A Y ; S I L T Y . MEDIUM' CONSISTENCY

a o a,,?

1 .11 01 ' -94 ' S A N D . F l N E W I T H S O M E C L A V : M E O l U M C O N S I S T E N C Y

ma , 94 ' -100 ' G R A V E L . e O U L D E R S . A N D S A N D . D E N S E T O V E R Y D E N S E OW

12-#B-a.

N O T E : A L L M A T E R I A L F R O M 0-100' A R E S T R E A M C H A N N E L A N D F L O O D PLAIN DEPOSITS. N X C S 0-100.. ALTERNATING W A S H AND D R I V E S A M P L E S .

NOTE: SEE P L A T E 4 FOR BORING LOCATIONS.

!

PLATE 3 \

t

O H 2 1 . I L O W I I ~ ~ .

0 t o r o eo EL 5861.2

N O T E : N I S I Z E H O L E . N I C S 0-100' . D R I V E S A M P L E S 0-55.. A N D 80'-01)'. W A S H S A M P L E S 51'-80' .

BORING LOGS HOLES DH21 AND OH22

4

1 PLATE 4

*

. . L O C 5 AND 6

C Crest of d o m - . .

L O C 1 AND 7 -cres t €1.5978

set t lement potnt (projected1

M A X I M U M S E C T I O N

NOTE: LOCATION 4 IS OFFSET 560 FT EAST OF A L I N E THROUGH L O C 1. AN0 LOC 3 A T E L 5878.81.

L O C A T I O N S O F M O T I O N M E A S U R I N G

S T A T I O N S i

ASSUMED PROFILE OF FOUNDATION SOILS

PLATE 5

L O G OF

W T p --- -- - 2 0

4 0

I- LL

f 6 0 - a. W 0

80

I00

120-

BORING DESCRIPTION 0;-

SAND (120 PCF)

SAND, GRAVEL, BOULDERS (130 PCF)

- SILTY CLAY (125 PCF)

- C L A Y (125 PCF)

GRAVEL, BOULDERS (130 P C F )

I

CLAY (125 PCF)

-

GRAVEL, SAND, BOULDERS (135PCF)

-

BEDROCK

POISSON'S RAT I 0 0 . 4 0

PLATE 6

S H E A R WAVE V E L O C I T Y , FT/SEC

SHEAR WAVE VELOCITY PROFILE FOR THE FOUNDATION

VIE RATORY T E S T DATA

00 1000

Q

9

n "

0

800 700 800 0

1100

-

0

0

20

40

F LL

C

6 0 - F Q W 0

80

100

120

P c - -

0

PLATE 7

-

I800 0

2 0

4 0 .

6 0 , I- LL - I + n W n

8 0

100

I 2 0

140

SHEAR WAVE VELOCITY PROFILE FOR THE

FOUNDATION RAY LE IGH WAVE DISPERSION

DATA

S H E A R WAVE VE L O C I T Y , FT/SEC 6 0 0

*

R - l FROM R - 2 FROM S E I S M I C L l N E 5 - 2, S E E A P P E N D I X 0

-

1 2 0 0 800

&

S E I S M I C

1000

L I N E S - I , SEE

1400

2 7 2 0 rA

R - 2

1 6 0 0

- -

R-l

A P P E N D I X D %?a

S H E A R MODULUS, K S F I

LEGEND

- V I B R A T O R Y D A T A --- RAY L E I G H D I S P E R S I O N D A T A

/ / IN / RANGE FOR e = 0.9 e = 0.4, O C R K = I, - MATERIAL PROPERTIES IN PLATE 5

FOUNDATION S H E A R MODULUS COMPARISONS

PLATE 8

PLATE 9

J

SHEAR MODULUS, KSF

0

2 0

4 0 I- LL - I C Q W 0

6 0

80

100

SHEAR MODULUS VS DEPTH OF F O U N D A T I O N AT CENTER LINE OF D A M

8 3 4 5

\

6 7

.

b

SHEAR WAVE VELOCITY , FT/SEC 2 0 0 0

0 0

20 -

40 LL

I-- m W a U

6 0 0 J W rn

x C a W

80

100

1 2 0

SHEAR WAVE VELOCITY PROFILE FOR

THE EMBANKMENT VIBRATORY TEST DATA

PLATE 10

4 0 0 800 1200 I 6 0 0

\

\

1

/

1 .o

* I- z - 2 ,

a 0.8 a u z a a 0 a ' W 0 I 11 0 . 6 "'F

.a 2 V)

D L " : 0.4

a n 0 0 1 1 a a a 4 0 . 2 W W I I IJl v,

0 10-4 10-3 10-2 10-1 I

S H E A R S T R A I N 7 , . PERCENT

VARIATION OF SHEAR MODULUS WITH SHEAR STRAIN FOR SANDS

A F T E R R E F 4

28- /

/ /'

2 4

2 0

z W U

F a

a I a 0

I 0-4 10-3 1 0 - 2 10-1 I SHEAR STRAIN, PERCENT

DAMPING RATIOS FOR SANDS AFTER REF 4

0 10 - 4 10-3 10-2 1 0 - 1 I 10

S H E A R S T R A I N Y , P E R C E N T

TYPICAL REDUCTION OF SHEAR MODULUS WITH SHEAR STRAIN

FOR SATURATED CLAYS AFTER REF 4

b

I

35

3 0

25

I- z W U K

2 2 0 . 0 I- < E

0 15

Z 0 x 4 0

10

5

0

.

/ . /

, /'I . , /

----- 1 0 - 4 1 0 - 3 10-2 10-1 I I' o

SHEAR STRAIN, PERCENT

DAMPING RATIOS FOR SATURATED CLAYS

AFTER REF 4

UPSTREAM + I 1

0 DOWNSTREAM

FINITE ELEMENT MESH FOR 20 ANALYSIS AND LOCATIONS OF

MEASUREMENT STATIONS

I PLATE I5

PLATE 16

I

0 3 5

0 30

0 2 5 0,

2' 0 - k Q a W J 0 20 W U U 4 W V) Z 0 a y, 0.15. I W CK

L u W a

0 10-

I 0 05 - I

I

0 0 0 2 0 4 0 6 0 8 10

PERIOD, SEC

RESPONSE SPECTRA FOR I D LUMPED-MASS ANALYSIS

CASES I AND 5

y*CASE /

7

I CASZ 5

I \ I I

PLATE 17

2

0 3 5 r

0 30

0 2 5 [r,

2' 0 - I- u [I W 1 020. W U U 4 W m z 0 a m 0 15. W &

K u W a

0.10 \

'y CASE 2

/ - OBSERVED

I

I f\ \ 1 I

4 0 6 0 8 10

1 ' I I \ I /

f

0 05

0 ,

PERIOD, SEC

OBSERVED AND COMPUTED I D RESPONSE SPECTRA

C A S E 2

w

\ \ f I v l \ I

\$J

0 0.2 0

PLATE 18

I

_ . I . . . . = . . . . . _ . _ . - 7 = -7- 7 7 - - ..=--:- -7' - i-- . = _ . C : - - = > - -z-;. . %. .: z-- i .... .- i__- .;

- - - - - - - . . - . _ _ - . - - A. A - A - A 4

10

PERIOD, SEC

COMPUTED I D RESPONSE SPECTRA,

CASES 3 A N D 6

- 0 35

0 30

0 25 0,

z' 0 - 4 a W J 0 20 W U U a W V) z 0 0. y, 0.15 n W I \ (t y-CASE 6 s u W 0.

0. I 0

0 0 5 . /

\ -- -- -- 0 -

0 0.2 0.4 0 8 0 8

-

,CASE 3

. 0 35

0 30

0 25 0,

2' 0 - C a a W A 0 20 W V U Q --OBSERVED W V) z 0 a , / C A S E 6 y, 0 15' W a s a W a

0 I 0

0 05 J

\ .- -- * -\, 0

0 0 2 0 4 0 8 0 8 10

PERIOD, SEC

OBSERVED AND COMPUTED I D RESPONSE SPECTRA

C A S E 6

PLATE 19

0 35

0 3 0 -

0 25 IJ)

z' 0 - F 4 (I W J 0 20 W u u 4 W v, Z 0 a. y, 0 15, n W a f -2 W n

0 I0

0 05 -

0 0 0 2 0 4 0 8 0 8 10

PERIOD, SEC

COMPUTED I D RESPONSE SPECTRA

CASES 6 AND 8

LEGEND

SHEAR MODULUS, KSF

-- CASE' 3 -- - CASE 6 - CASE 8

NOTE: MODULUS MODIFIED' FOR SHEAR STRAIN.

5

PLATE 21

- 1

SHEAR MODULUS PROFILE MODIFIED FOR SHEAR STRAIN

0 -

2 0 .

4 0

LL

L

x l- a. W 0

6 0 ,

80

I OD L.

0 I 2

\ 1

I I

3

-- -4-

4

PLATE 22

i s

0 35.

0 30

0 2 5 m

2' 0 - I- u a W J 0 2 0 , W u V Q. W cn z 0 0. y, 0 1 5 , W LL

f 4 W a.

0 10,

O B S E R V E D

I

I

:y ! \,

I j \ v t 1,

I

\

0

'.

I /

I-' I

0 05 I

0 0 2 0 4 0 6 0 8 10

PERIOD, SEC

OBSERVED AND COMPUTED I D RESPONSE SPECTRA

CASE 8

0.

1

PLATE 23

3 - 0 35

0 30

0 2 5 . m

2' 0 - I- a a W _t 0 20 W U U Q W m z 0 a y, 0 1 5 . W

i l ,

' 1 I I

I I

' I I I I l 1 1 1 1 ! I I I ' I I I I I ' I I I I t ! !

lx L a w - OBSERVED a

0 I0

0 05

0 0 0 2 0 4 0 6 0 8 10

PERIOD, SEC

OBSERVED AND COMPUTED I D RESPONSE SPECTRA

C A S E 14

PLATE 24

PLATE 25

-

-

.O

0.3 5

0.30

0.25

rn

9 0 . - I- 4 [I W J 0.20 W u V u W ul '. Z ,CASE 2 0 a y, 0 . 1 5 - W ( t .

e . u W CL -CASE 20

0 . 1 0 .

0.05 -

\ -- 0

0 0.2 0.4 . 0.8

COMPUTED I D RESPONSE SPECTRA

CASES 2 AND 20

7

---- 0.8 I

PERIOD, SEC

L

0 35

0 30

0.25 D

2' 0 - I- u a W J 0 2 0 W U V u W V) z 0 a cn 0 15 W Q

f a W Q

0. I 0

0 0 5

0 0 0.2 0 4 0 6 0 8 1 0

PERIOD, SEC

COMPARISON OF I D AND 2 D RESPONSE SPECTRA

LOCATION 5 RADIAL COMPONENT

CASES 4 AND 2 2

. 0.35

0.30

0.2 5 m

2- 0 - + a a W J 0.20 W 0 U a W i n . z 0 0. y, 0.15 W a L a W a.

0. I 0

0.0 5

0 0 0.2 0.4 0 .8 ' 0.8 1 .O

PERIOD, SEC

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCATION I RADIAL C O M P O N E N T

CASE 23

PLATE 27

PLATE 28

4

0 35

0 30

0 2 5 m I I

I \

2' I I 0 - I + a a

W V

W m OBSERVED z

W a s 4 W a

0 - 0 0 2 0 4 0 8 0 8 10

PERIOD, SEC

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCATION I VERTICAL COMPONENT

CASE 23

- I,

I

p, I' 'I I I

' I I I I \ I \ I I

2

/'

PLATE 29

h

0 . 3 5

0.30

0.2 5 0,

z' 0 - +

I u a W J 0.20 I

W v

V 4 W ul Z 0 a y, 0 . 1 5 I 1 ' W 1 a I z I u I \ W- 0. \

\ \ \

0.1 0' \ &--0BSf RVED

\ n

0 . 0 5

0 0 0.2 0.4 0 . 8 0 .8 1 .O

PERIOD, S E C

. OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCAT ION 2 ' RADIAL C O M P O N E N T

CASE 2 3 C

r. A

PLATE 30

0 3 5 1

0 3 0 ,

0 2 5

n,

2' 0 - I- a a W J 0 2 0 W w U a W

'\ , ' \ I \

I \ I I

. I \

I m z 0 I a 1 m 0 1 5 , W (r

s a W a -OBSERVED

0 10

0 05

0 0 0 2 0 4 0 8 0 8 10

PERIOD, SEC

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCAT ION 2 VERT ICAL COMPONENT

CASE 23 ,

I \ / -CASE 23

0 35

0 30

0 2 5 0,

2' 0 - C u a W J 0 20 W U U u W V) z 0 a. y, 0 15 W a z a W a

0 I 0

0 0 5

0 0 0.2 0 4 0 . 8 0 8 10

PERIOD, SEC I

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCATION 3 RADIAL COMPONENT.

C A S E 23 >

PLATE 31

. -

10

0 35*

0 3 0

0 2 5 0)

2' 0 - C 4 a W J 0 2 0

PLATE 32

^ . _ _ _ _ _ _ _. _ . _. . -- _ _ _ _ _ . . - . _ _-- - -.- -. -. - . .- . - . - - --. .._--. - _/ -._ .... . -..- - _. - - - - - - - & L A - - & - & &

1111111111111111111llllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllmlllllllllllttttttttmttttttttttt~~~~~~~~w"~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCAT l O N 3 VE RT I C A L COMPONENT

CASE 23

- ,'l

1 l I I I I

I Ij,;

W V U 4 W V) z -CASE 23 0 n V) 0 1 5 , W (L:

< a W (1 -OBSERVED

0. I 0

0 .05 ;J

0 0 0 .2 0 4 0 6 0 8

P E R I O D , S E C

PLATE 33

4

0.35

0.30

0.2 5

-

0

2' 0 OBSERVED - I- < a W _r 0.20 W U U < W ln z 0 P cn 0.15 W a * a W a .

0. I0

0.05 \ \

-- 0 ' 0 0.2 0.4 0.8 0.8 I .O

PERIOD, SEC

OBSERVED ANDCOMPUTED 2 D RESPONSE SPECTRA

L O C A T I O N 5 RADIAL C O M P O N E N T

C A S E 23

PLATE 34

- _ . __ . _ _ _ _ _ _ _ . __ _ . - - ..I _ I . _ . _----- - <. - _ .- . . ._- __ _ _:_ _ _. - - ..C - . .- .. - - - - - -L - 4 - - . - - -. A & - -

10

0 3 5

PERIOD, SEC

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCAT ION 5 VERTICAL COMPONENT

CASE 23 L

3

0 30 I

0 2 5 m

z' 0 - l- a a W J 0 20 W U U a W m Z I 0 I a Y, 0 15

I I

W a I

s a W a

0 I 0

0 0 5

0 0 0.2 0 4 0 8 0

)

-.------- 8

PLATE 35

L

0.35.

0.30

0.2 5 (T,

z' 0 - I-

.

-

d a W J 0.20 1

W u u d

W m z 0 n m 0.15 W I\ 1 a I I

I I ' s Q

I . I W

I I a 9,' +-CASE 26

I !! I

0. I 0 I 6' I /

1

; I

b

/ 1

. \(\, , 0.05

\ \ '..

-- ----, 0' 0 0.2 0.4 0.6 0.8 1

PERIOD, SEC :O

OBSERVED. AND COMPUTED 2 D RESPONSE SPECTRA

L O C A T ION 3 RADIAL C O M P O N E N T

C A S E 26

PLATE 36

4

0 35

0 3 0 ,

025 0,

2' 0 - k a n W J 0 2 0

-

-

f-'\ I' ! ', I I

W U

I I U a W -CASE 26

W a. - OBSERVED

\ \ \

0.05 /! \ \

0 0 0 2 0 4 0 8 0 8 10

PERIOD, SEC

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCAT ION 3 VERTICAL COMPONENT

CASE 26 6

PLATE 37

h

0 35

0 30

0 2 5 . 0,

z' 0 - I- < a W J 0 2 0 , W U U < W ul Z 0 [L y, 0 15 W a z 4 W a

0. I 0

0.05

0 0

-

I' I \

1 I I

I L' I I N '"'

-

0.2 0.4 0 8 0 8 10 PERIOD, SEC

COMPUTED 2 D RESPONSE SPECTRA

LOCATION 5 RADIAL COMPONENT

CASES 23 AND 27

PLATE 38

2

0 3 5 r

0 30

CASE 27

0 2 5 , [T,

z' 0 - I- 4 a W _J 0 2 0 W U U a W m Z 0 Q. m 0 15 W

1

(t

YZ a W a

0 1 0 ,

0 05

0'

PERIOD, SEC

COMPUTED 2 D RESPONSE SPECTRA

LOCATION 5 VE R T I C A L COMPONENT

CASES 23 AND 27 L

I I

10

- 8 0 0 0 2 0 4 0

- 8

0.35

0.30

0.25

cn

2' 0 - I- 4 a . W

0.20 W V U a W V) z 0 (L y, 0.15 W a ' L a W Q

0. I 0

0.05

0 0 0.2 0.4 0 .6 0.8 1 .O

P E R I O D , SEC

OBSERVED AND COMPUTED 2 0 RESPONSE SPECTRA

L O C A T I O N 2 '

R A D I A L COMPONENT C A S E 27

2

17 \

-- OBSERVED

PLATE 39

r

0 3 5

0 30

0 2 5 m

2' 0 - I- 4 a W _1 0 2 0 - W U U ?

- OBSER YE D Q W cn z 0 0. I y, 0 15 W a s Q W (L

0 -

0 0 2 0 4 0 6 0 8 10

PEBIOD, SEC

OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA

LOCATION 2 VERTICAL COMPONENT

CASE 27 &

PLATE 40

This page intentionally left blank

This page intentionally left blank

1. The f i r s t 6 sec o f motion h i s t o r y f o r t h e r a d i a l and v e r t i c a l

, components are shown i n p l a t e s A l through A10 f o r l o c a t i o n s 1 through 5 ,

respect ively; acce le ra t ion response s p e c t r a a r e a l s o shown i n these

p l a t e s . Pla tes A l l and A12 show t h e observed r a d i a l and v e r t i c a l motion

h i s t o r i e s from PVT l oca t ions 6 and 7. The r a d i a l components were mea-

sured hor izontal ly and perpendicular t o t h e a x i s of t h e dam; t r ansve r se

. motion components were measured ho r i zon ta l l y and p a r a l l e l t o t h e axis of

the dam and are reported i n re fe rence 2. The a c c e l e r a t i o n h i s t o r i e s

have been modified f o r base- l ine s h i f t wi th a parabol ic cor rec t ion .

They have a lso been i n t e g r a t e d t o produce ve loc i ty and displacement

h i s t o r i e s .

2. A response spectrum is t h e maximum response of a single-degree-

of-freedom system t o an acce l e r a t i on h i s t o r y , a s i l l u s t r a t e d i n f i g . A l .

In t h i s case, the spec t r a a r e p l o t t e d as curves of maximum acce l e r a t i on

versus na tura l period T f o r a value of damping D . By varying t h e

values of T and D , a complete s e t of curves is developed. A re-

sponse spectrum can be used a s a veh ic l e t o compare t he frequency con-

t e n t of various motion h i s t o r i e s . The r e l a t i v e ve loc i ty and r e l a t i v e

displacement response s p e c t r a have been computed and a r e ava i l ab l e from

WES bu t a re not presented he re in .

w CIRCULAR FREQUENCY CURVES FOR VARIOUS D K STIFFNESS M MASS D DAMPING

U U T PERIOD <

RESPONSE SPECTRA

Fig. A l . Response spec t r a

-

0 . I I .O

0,

2' 0 + 2 0 0 . 0

J W U

< m 2 0 C .

- 0 . I < 0 . 6 u 2 . 0

w J

;I 4 9b C R I T I C A L DAMPING W

$ 0 . 4 0

I .O '0 w . u

- U

m '. E 0 2

*' 0 t t: w > 0

0.2 0.4 0.6 0.0 I .O - 1 .O .PERIOD, SEC

b. ACCELERATION RESPONSE SPECTRUM

- 2 . 0

0 . 1 NOTE: LOCATION I WAS ON THE SURFACE Of THE DAM AT THE CREST.

c I-- 2 . W

5 0

4

- a !?

- 0 . 1 MOTION HISTORY

L I I 1 I I 1 0 I .O 2 .O 3 . 0 4 . 0 5 . 0 8 . 0

AND ACCELERATION TIME, SEC RESPONSE SPECTRUM

a. MOTION HISTORY RADIAL. COMPONENT LOCATION I .

0 . 8

0)

2.

0 ; 0 . 8 LI W

J Y

U U .

6

w % CRITICAL DAMPING

":. 4 0

. n u a

0 2

0

PERIOD, SEC

b. ACCELERATION RESPONSE SPECTRUM

N O T E : LOCATION I WAS ON THE SURFACE OF THE DAM AT THE CREST.

z I-'

w

D -

6 -1

Ul - 0

- 0 . 1

6

v-

- MOTION HISTORY 1 I I I I J

5 0 8 . 0

AND ACCELERATION 0 ' I .o 2 0 3 0 4 . o

TIME, SEC RESPONSE SPECTRUM

a . ' M O T I O N HISTORY . . VERTICAL COMPONENT LOCATION I

- ~

0 I * 0 4 5

m 2'

0 t

2 O 0 38 _I w U u m

i 0

- 0 I 2 0 2 7

2 0 w J u u u % CRITICAL DAMPING < w

$ 0 1 8

1 0 L "7 w

u a

u Ln , r o 09

> 0 t - u 0, >

0 0 0 2 0 4 0 6 0 8

- I 0 I 0

PERIOD, SEC

b ACCELERATION RESPONSE SPECTRUM

- 2 0

0 1 -

z I-'

$' w o u 6 _I

"l - a

- 0 I

NOTE LOCATION 2 WAS ON THE DOWNSTREAM FACE OF DAM

- MOTION HISTORY I I I I I

0 J

I 0 2 0 3 0 4 0 5 0 6 0 AND ACCELERATION

TIME, sEc RESPONSE SPECTRUM a MOTION HISTORY RADIAL COMPONENT

LOCATION 2

. 1 . 0 -

0 . 8 -

m 2'

0 'i o . e - u

0.2 0.4 0.6 . 0.8 I .o

PERIOD. SEC

b. ACCELERATION RESPONSE SPECTRUM

NOTE: LOCATION 2 WAS ON THC DOWNSTREAM FACE OF DAM. 0 . I r

E . I--

w . 5 0 ,

Q

a I? 0

- 0 . 1

MOTION HISTORY - I I I I I I

0 I . O 3 0 4 . 0 .5 0 6 . 0

AND ACCELERATION * O .

TIME, SEC RESPONSE SPECTRUM

a. MOTION HISTORY VERTICAL COMPONENT LOCATION 2

r 0 1 I 0

m 2 0 b

, l o 0 8

J W U

U <

m

i 0

- 0 I 2 0 6

2 0 W J Y U U 6

u Ln

2 0 4 0 a % CRIT ICAL DAMPING

1 0 'n u

u u

W

, 0 2 Z

> 0 C u 0

w > 0

0 0 2 0 1 0 6 0 8 1 0

- I 0 PERIOD, SEC

b ACCELERATION RESPONSE SPECTRUM

- 2 0

0 1 - NOTE LOCATION 3 WAS NEAR TOE OF DAM

z

6 J

'n - a

- 0 I

MOT1 ON HISTORY -

I I I I I I AND ACCELERATION 0 1 0 2 0 3 0 4 0 5 0 6 0

TIME, SEC RESPONSE SPECTRUM

a MOTION HISTORY RADIAL COMPONENT LOCATION 3

. 0 . I I . O

0

1' 0 b-

2 O 0 . 8

J u U U m

2 0

- 0 . 1 t 0 . 8 Q

2 . 0 u J u U U

u 0 . 4

I . O 0

LA W

U a

u 96 CRITICAL DAMPING

' z 0 . 2

>' 0 t

0, >

0 0.2 0 .4 , 0.6 0 . 8 I .O

- I 0 t PERIOD. SEC

b. ACCELERATION RESPONSE SPECTRUM

- 2 . 0 NOTE: LOCATION 3 WAS NEAR TOE oc DAM.

0 . I

3

I-'

u

J

"l - 0

- 0 . 1 , - MOTION HISTORY

I I I I I 1 0 1.0 2 . 0 3 0 4 . 0 5 . 0 8 . 0

AND ACCELERATION TIME, SEC RESPONSE SPECTRUM

a. MOTION HISTORY. VERTICAL COMPONENT LOCATION 3

I 0 1

0

2'

0 + 2 0

J w

U U

- 0 I

2 0

1 0 % C R I T I C A L D A M P I N G

U W "7 , z > 0 .+ - u

2 W

> 0 0 2 0 4 0.8 0 8 1 0

- I 0 P E R I O D . SEC

b ACCELERATION RESPONSE SPECTRUM

- 2 0 N O T E L O C A T I O N 4 WAS IN THE GATE CHAMBER

0 l r

I

*- w Z w 0 . U

J

"7 - 0

- 0 I

- - MOTION HISTORY L 1 I I I I I 0 1 0 2 0 3 0 4 0 5 0 6 0

AND ACCELERATION TIME, SEC

RESPONSE SPECTRUM a MOTION HISTORY RADIAL COMPONENT

LOCATION 4

0 1 0 35

0

2' 0 $ O 0 28

J Y

u U m

2 0

- 0 I 2 0 2 1 I

2 0 Y J Y

U d

Y r 0 1 4 0

1 0 a ul Y

U

a % CRITICAL DAMPING

"l

2 0 07

2' 0 E U

J Y >

0 0 2 D d 0 I 0 8 1 0

- I 0 PERIOD. SEC

b ACCELERATION RESPONSE SPECTRUM

- 2 0 NOTE LOCATION 4 WAS IN THE GATE CHAMBER

0 1 -

z I--

: Id o 4 J a "l - 0

- 0 I

-- AA-- V

- MOTION HISTORY L I 1 I I I I 0 1 0 2 0 3 0 4 0 5 0 6 0

AND ACCELERATION T IUC, SCC RESPONSE SPECTRUM

a MOTION HISTORY VERTICAL COMPONENT LOCATION 4

- 0 0.2 0.4 0.6 0 .0 1.0 . PERIOD, SEC

b. ACCELERATION RESPONSE SPECTRUM

- 0 . l L I 1 1 I I 1 I 0 1.0 2 . 0 3.0 4 . O 5 .0 0 . 0

TIME, SEC

a. MOTION HISTORY

MOTION HISTORY AND ACCELERATION

RESPONSE SPECTRUM RADIAL COMPONENT

LOCATION 5

0 1 1 . 0

111

2'

0 k

d 0 0 . 8

J Y

U u m

2 0

- 0 . 1 : 0 . 6 u

2 . 0 u J

Y 4 u

0 . 4

I . O 0 n In W

U a

Y % CRITICAL DAMPING "7 " Z 0 2

> 0 t 0

Y >

0 0.2 0.4 0 .6 0 . 8 I .O - 1 . o PERIOD. SEC

b. ACCELERATION RESPONSE SPECTRUM

- 2 . 0

0 . I

z e'

W

I u 0 U 6 J n "l - 0

- 0 . 1 MOTION HISTORY

I I I I I I I 0 1.0 2 0 3 0 4 . 0 5 0 6 .O

AND ACCELERATION TIME, scc RESPONSE SPECTRUM

a. MOTION HISTORY VERTICAL COMPONENT LOCATION 5

NOTE: LOCATION 5 WAS ON THE SURFACE OF THE ALLUVIAL VALLEY.

PLATE All

I

0

- I

2 U) ' - 2 z D-‘ RADIAL COMPONENT !z 0

S 2 W >

I

I 1 I I I

- -

0 -A- . v

- l o I I I I I I 2 3 4 5 6

T IME, SEC

VERTICAL COMPONENT

N O T E : L O C A T I O N 6 W A S ADJACENT TO L O C A T I O N 5 (ON T H E SURFACE O F T H E A L L U V I A L V A L L E Y A P P R O X I M A T E L Y 5 0 0 F T D O W N S T R E A M F R O M L O C A T I O N 3 )

MOTION HISTORIES LOCATION 6

L

I

0

- I

U W V)

' - 2 z >- RADIAL COMPONENT k U

9 W >

0

- I

-2 0 I 2 3 . 4 5 6

T I ME, SEC

VERTICAL COMPONENT

NOTE : L O C A T I O N 7 WAS AT A S E T T L E M E N T MARKER, 2OOFT WEST OF LOCATION I, O N T H E SURFACE' OF T H E D A M AT THE CREST.

MOTION HISTORIES LOCATION 7

,

PLATE A12

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Response spec t ra as defined i n Appendix A a r e shown i n p l a t e B 1

for t h e observed motion a t loca t ion 5 R , which i s t h e r a d i a l component of

acce lera t ion on the alluvium over 500 f t downstream from Ri f l e Gap Dam.

Acceleration response spec t r a computed from the 1D analyses fo r t h e var-

ious cases invest igated a r e shown i n p l a t e s ~ 2 - ~ 6 . Spect ra l damping i n * .

a l l p l a t e s i s 5 percent.

I

0 . 2 5

0 2 0

0 15

0 . 1 0

0 0 5

0

CASE 1, 8 0 F T TO BEDROCK CASE 2, 85 FT T O BEDROCK

0 2 5

0 2 0 m i 0 2 0 I S W J w LJ

. Y 0 l o

Z 0 L VI w a

0 0 5

0

CASE 3. 9 0 F T TO BEDROCK 0 0 2 0 4 0 6 0 8 1 0

PERIOD. T, SEC

CASE 4, 100 FT TO BEDROCK

LEGEND -- OBSERVED AT LOCATION 5 - COMPUTED NOTE' MATERIAL ASSUMED TO BE SAND.

SHEAR MODULUS C FROM VIBRATORY FIELD METHOD WAS USED I N COMPUTATIONS. SIX SEC OF HORIZONTAL INPUT MOTION.

ACCELERATION RESPONSE PERIOD, T, SEC SPECTRA FROM 10

CASE 5, 110 F T TO BEDROCK LUMPED-MASS ANALYSES CASES 1, 2, 3, 4, A N D 5

PLATE 81

J

0 0 . 2 0 . 4 0 . 6 0 . 8 "%bl PERIOD, 1.0 T, 0 SEC 0 . 2 0 . 4 0 .8 0 . 8 1 . 0

CASE 6, 9 0 F T TO BEDROCK CASE 7, 110 FT TO BEDROCK

LEGEND -- OBSERVED AT LOCATION L)

COMPUTED ACCELERATION RESPONSE NOTE: MATERIAL ASSUMED TO BE CLAY. SPECTRA FROM I D

SHEAR MODULUS C USED IN COMPUTATIONS SIX SEC OF HORIZONTAL INPUT MOTION.

LUMPED-MASS ANALYSES CASES 6 AND 7

A

I 4 r l \ ! \

I I I ' * , I

Y 4, I I

0 . 2 5

z 0 Q V) W a

0 0 5

1- -- 0

0 . 2 0

rn

z 0 2 0 . 1 5 a W 2 W U U 4

W a 0 . 1 0 I 11

\

* I I

1 I

+

#

0 2 5

0 20

0 I 5

0 10

0 0 5 m

i 2 I- : 0 W

A W U U

CASE 8, 80 FT TO BEDROCK CASE 9, 9 0 FT TO BEDROCK

1 0 0 0.2 0.4 0.8 0.8 1.0 PERIOD, 1, SEC

CASE 10, 100 FT TO BEDROCK CASE 1 1 , 110 FT TO BEDROCK

LEGEND -- OBSERVED AT LOCATION 5 COMPUTED

NOTE MATERIAL ASSUMED T O BE SAND AND CLAY MIXED. CLAY MODULUS C MULTIPLIED BY 1875 . SIX SEC OF HORIZONTAL INPUT USED.

ACCELERATION RESPONSE SPECTRA FROM I D

LUMPED-MASS ANALYSES CASES 8, 9, 10, AND I I

b

PLATE 83

0 0. Z 0.4 '0.6 0.8 1.0 PERIOO, T. SEC

CASE 12, SIX SECONDS OF INPUT

LEGEND --- OBSERVED AT LOCATION 5

- COMPUTED

NOTE: MATERIAL ASSUMED TO BE SAND AND CLAY MIXED. CLAY SHEAR MODULUS G MULTIPLIED BY 1.875. DEPTH TO BEDROCK IS 110 FT.

ACCELERATION RESPONSE SPECTRA FROM ID LUMPED

PERIOD, T, SEC MASS ANALYSES CASE 13. TWELVE SECONDS OF INPUT CASES 1 1 , 12, AND 13 ' ,

PLATE 85

0.2 5

0 . 2 0

0 . 1 5

0 . 1 0

0 . 0 5 - z P 5 : O J CASE 19, 80 FT OF LAYERED W U PERIOD, T, SEC U 4 SAND A N D CLAY CASE 20, 85 FT OF SAND w 0 . 2 5 In z 0 P VI

W a

0 2 0

0 . 1 5 L E G E N D

--- OBSERVED AT LOCATION 5 - COMPUTED

0 . 1 0 NOTE: SHEAR MODULUS C FROM VIBRATORY FIELD METHOD WAS USED IN COMPUTATIONS. o.05sj

OO 0 . 2 0 . 4 0 . 6 0.8 1 .O PERIOD, T, SEC

CASE 2 1, 85 F T OF SAND

ACCELERATION RESPONSE SPECTRA FROM ID FOURIER

ANALYSIS METHOD CASES 19, 20, AND 2 1

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The response spec t r a , as defined i n Appendix A , are given i n t h e

. p la t e s l i s t e d below f o r t h e computed and observed responses of t h e mea-

surement. loca t ions a t R i f l e Gap Dam. The computed spec t r a a re from the

2D analyses, and spec t r a l damping i n a l l p l a t e s i s 5 percent.

Location

1R

1 V

2R

2v

3R

3v

5R

5v .

Pla te

C 1

C 2

C 3

c 4

c 5

c 6

c7 c8

PLATE C1

PLATE C2

I

n

MOOULI=l.5 C

I I I! ,], I

CASE 22 CASE 23 CASE 2 4 w u 100-FT FOUNDATION 100-FT FOUNDATION 100 - F T FOUNDATION u ( 0.50 W "l j DAMPING RE-

/ ' DUCEO TO $ 0 f w . a 0.45 - ...-&loF

i ! 20.40---i W a i l i ! I 0 35 - I .

I

I

!

0

0 '

PERIOD, SEC

CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDAT ION 1 0 0 - F T FOUNDATION

LEGEND ---- OBSERVED

ACCELERATION RESPONSE COMPUTED SPECTRA FROM .

NOTE: SHEAR MODULUS C F R O M VIBRATORY F I E L D TECHNIQUE. SAND FOUNDATION

2 D ANALYSIS WITH 120-FT CLAY EMBANKMENT. VERTICAL COMPONENT

LOCATION I *

! MODUL1=0.5 G

! j I --

1 i

.J -. I I I

. I --TT, I I

J CASE 22 CASE 23 CASE 24 W U u 100-FT FOUNDATION 100-FT FOUNDATION 100-FT FOUNDATION

0.50- I W "7 i DAMPING RE- DAM MOOUL I = 2 . 5 C z ; DUCED TO $ ! 1 ' FOUNDATION MODULI = 1.5 G 0

0.45---.+ . - ,OF CASE 22 . i I i W

a 1 I j 1 I I ! 5 0 . 4 0 - --t

W i P

I ! , 0 3 5 . - 1 I --+-I

! . .

I i

I I ' 0 30--- L -

0 . 2 5 . - -. -. : - - - - . . . -- -- -. - - - -

. . . - . . . - - - - -

PERIOD, SEC

CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDATION 109 - FT FOUNDAT ION

LEGEND ---- OBSERVED ACCELERATION RESPONSE

COMPUTED SPECTRA FROM NOTE: SHEAR MODULUS C FROM VIBRATORY

FIELD TECHNIQUE. SAND FOUNDATION 2 D ANALYSIS

WITH 120-FT CLAY EMBANKMENT. RADIAL COMPONENT LOCATION 2

PLATE C3

CASE 22 100-FT FOUNDATION

PERIOD, SEC

CASE 25 100-FT FOUNDATION

LEGEND ---- OBSERVED

COMPUTED

NOTE: SHEAR M O D U L U S G F R O M VIBRATORY F I E L D TECHNIQUE. SAND FOUNDATION WITH 120-FT CLAY EMBANKMENT.

CASE 26 8 0 - F T FOUNDATION

CASE 27 100-FT FOUNDATION

ACCELERATION RESPONSE SPECTRA FROM 2 D ANALYSIS

VERTICAL COMPONENT LOCATION 2 .

PLATE c4

0 . 4 5

0 :40

-' 0 . 3 5

0 . 3 0

0 . 2 5 3 -.t- . - ' - ! 1 i

0 . 2 0

0 . I 5

0 . 1 0

b

Z-0.05 2 l-

a u o J W CASE 22 CASE 23 CASE 2 4 u u 100-FT FOUNDATION 100-FT FOUNDATION 1 0 0 - F T FOUNDATION ( 0.50" Y I I VI z i i 1 DAMP&G RE- I

i I DAM MODULI = 2 . 5 G'

, DUCED TO $ , FOUNDATION MOOULI = 1.5 G 0 % 0 . 4 5 -- -OF CASE. 2 2

! I I I

Y I a

x i j 0 . 4 0

W a.

---- --- . 7--

PERIOD, SEC

CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDATION 100-FT FOUNDAT ION

L E G E N D

---- OBSERVED ACCELERATION RESPONSE COMPUTED SPECTRA FROM

NOTE: SHEAR MODULUS G FROM VIBRATORY FIELD TECHNIQUE. SAND FOUNDATION

2 D ANALYSIS WITH 120-FT CLAY CM~ANBMENT. RADIAL COMPONENT

LOCATION 3 ,

PERIOD, SEC

CASE 25 100-FT FOUNDATION

LEGEND ---- OBSERVED

COMPUTED

NOTE: SHEAR MODULUS C FROM VIBRATORY FIELD TECHNIQUE. SAND FOUNDATION WITH 120-FT CLAY EMBANKMENT.

CASE 26 8 0 - F T FOUNDATION

CASE 27 100-FT FOUNDATION

ACCELERATION RESPONSE SPECTRA FROM 2 D ANALYSIS

RADIAL COMPONENT LOCATION 5

I I

PLATE C7

4

CASE 24

'0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 0 0 . 2 0 . 1 0.6 0 . 8 1.0

PERIOD, SEC

CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDATION 100 - F T FOUNDAT ION

LEGEND ---- OBSERVED

COMPUTED ACCELERATION RESPONSE

SPECTRA FROM NOTE: SHEAR M O D U L U S C F R O M VIBRATORY

FIELD TECHNIQUE. SAND FOUNDATION 2 D ANALYSIS WITH 120-FT CLAY EMBANKMENT. VERTICAL COMPONENT

LOCAT ION 5

PLATE ~8

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APPENDIX D: SEISMIC FIELD STUDY \

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DEPARTMENT OF THE ARMY WATERWAYS EXPERIMENT STAT ION. CORPS OF ENGINEERS

P. 0. BOX 631

VICKSBURG. MISSISSIPPI 39180

IN RCCLV ~ c r s n TO, WESSD 31 March 1971

MEMORANDUM FOR RECORD

SUBJECT: Seismic Fie ld Study, R i f l e Gap Dam, R i f l e , Colorado,, 16-28 November ,1970

1. A seismic f i e l d study was conducted a t R i f l e Gap Dam n e a r R i f l e , Colorado, during the pe r iod 16-28 November 1970. This f i e l d s t u d y con- s i s t e d of conventional s u r f a c e v i b r a t o r y and r e f r a c t i o n seismic t e s t s . I n add i t ion t o these t e s t s , a n o t h e r seismic t e s t was conducted i n which t h e Rayleigh wave t r a i n w a s recorded. f i e purpose of t h e s e tests w a s t o provide seismic information r e l a t i v e t o s o i l c o n d i t i o n s and e l a s t i c p roper t i e s wi th in t h e Rifle Gap Dam and o f t h e foundat ion on t h e down- stream s i d e of t h e dam. S p e c i f i c a l l y , - compress i o n w a v e v e l o c i t i e s , depth t o in te r faces , bedrock c o n f i g u r a t i o n , and s h e a r wave v e l o c i t i e s a s a function of depth were t o b e determined from t h e f i e l d s tudy. An- o ther purpose of t h e se ismic tests, i n which t h e Rayleigh wave t r a i n was recorded was t o determine Rayleigh wave v e l o c i t i e s wi th depth (Rayleigh wave d i spers ion method) s o t h a t a' comparison and e v a l u a t i o n o f d a t a could be m d e between t h e Rayleigh wave d i s p e r s i o n method and t h e sur-- face v ibra tory method.

2 . Messrs. F. K. Chang, M. M. Carlson, and J. R. Curro, Jr., v i s i t e d t h e s i t e t o perform the s u b j e c t s t u d y . P r i o r t o a r r i v i n g a t t h e test s i t e , mechanical d i f f i c u l t i e s were encountered wi th t h e ins t rumenta t ion vehic le i n Denver and Fr isco , Colorado. These mechanical breakdowns caused a time l o s s of some f o u r days. When t h e ins t rumenta t ion v e h i c l e was repaired, Messrs. Chang and Curro .proceeded t o Grand Junct ion, Colorado, t o meet with o u r con tac t , M r . B i l l McCleneghan, Bureau o f Reclamation. M r . Carlson drove t h e ins t rumenta t ion v e h i c l e t o t h e Rifle Gap Dam test s i t e . M r . McCleneghan was presenTed wi th a p l a n o f t e s t s which were t o be performed a t t h e test s i t e . He approved t h e p l a n of t e s t s , bu t s t i p u l a t e d t h a t charge s i z e s be l i m i t e d t o 2 l b and deto- nated i n shotholes l e s s t h a n 5 f t deep. He a l s o r e q u e s t e d t h a t any ho les caused by t h e de tona t ion o f exp los ives b e b a c k f i l l e d . During t h e course of conversation, M r . Curro asked about w a t e r l e v e l s in piezom- e t e r s t h a t were located on t h e downstream s i d e o f t h e dam abou t 100 ft from the toe . M r . McCleneghan s t a t e d t h a t approximately s i x weeks p r i o r t o 20 November, a l l piezometer p i p e s were overflowing. At t h e present time (20 ~ovember) , water l e v e l s i n t h e p iezometers were a b o u t 2-3 ft above t h e ground s u r f a c e toward t h e west end o f t h e dam and 2-3 ft below t h e ground surface toward t h e e a s t end o f t h e dam.

WES SD 3 1 March 1971 SUBJECT: Seismic F i e l d Study, R i f l e Gap Dam, R i f l e , Colorado,

16-28 November 1970

M r . McCleneghan a l s o obta ined. permiss i o n from t h e Colorado S t a t e ' High- way Department f o r t h e conduct o f a ' v i b r a t o r y t e s t on S t a t e Highway 325 which t r a v e r s e s t h e c r e s t o f t h e dam.

3. A f t e r meeting w i t h M r . McCleneghan, t h e WES c o n t i n g e n t went t o t h e R i f l e Gap Dam t e s t site, m e t M r . C a r l s o q and made a v i s u a l reconnais- s a n c e o f t h e s i t e . No seepage from t h e embankment and no p i p i n g o r sand b o i l s from t h e founda t ion were observed. M r . S. W. GUY, Instrumen- t a t i o n Branch, WES; jo ined t h e f i e l d p a r t y 20 November f o r t h e conduct of t h e v i b r a t o r y tests and r e t u r n e d t o WES on 23 November.

4 . Seven r e f r a c t i o n s e i s m i c t r a v e r s e s , seven seismic t r a v e r s e s f o r t h e Rayleigh wave d i s p e r s i o n method, and t h r e e v i b r a t o r y t r a v e r s e s were run a t t h e R i f l e Gap D a m site'. R e f r a c t i o n se ismic . t r a v e r s e s S-1 through S-6 are shown i n I n c l 1 and S-7 is shown i n I n c l 2. The se i smic t r a - v e r s e s f o r t h e Rayleigh wave d i s p e r s i o n method were l o c a t e d i n t h e same p o s i t i o n as t h e r e f r a c t i o n seismic t r a v e r s e s . The v i b r a t o r y t r a v e r s e s (V-1 through V-3). were l o c a t e d as shown i n I n c l 3.

5. The d a t a obta ined from t h e r e f r a c t i o n s e i s m i c tests ( t r a v e r s e s S-1 through S-7) are shown i n t h e t i m e ve r sus d i s t a n c e p l o t s , I n c l s 4-7. The t i m e ve r sus d i s t a n c e p l o t s were used t o c o n s t r u c t subsur face p r o f i l e s f o r t h e s e i s m i c d a t a . The subsur face p r o f i l e is shown in I n c l 8 f o r t r a v e r s e s S-1 and S-2, i n I n c l 9 f o r t r a v e r s e s . S - 3 and S-4, and i n I n c l 10 f o r t r a v e r s e s S-5 and S-6. A s u b s u r f a c e p r o f i l e f o r t r a v e r s e S-7 cou ld n o t be c o n s t r u c t e d because it was s h o t i n on ly one d i r e c t i o n .

6. The seismic d a t a ( I n c l s 7-10) i n d i c a t e d one minor and t h r e e major v e l o c i t y zones. The minor v e l o c i t y zone was n e a r t h e s u r f a c e of t h e ground w i t h a maximum t h i c k n e s s o f 4 f t and had v e l o c i t i e s t h a t ranged from 1000 t o 1200 f p s . The thre; major v e l o c i t y zones were, 1400 t o 2500 f p s w i t h a maximum t h i c k n e s s o f abou t 37 f t , 4800 t o 8600 fps with a maximum t h i c k n e s s of about 116 f t , and 10,800 t o 12,500 f p s f o r t h e bedrock v e l o c i t y zone. Bedrock w a s encountered a t a maximum depth of 130 f t below t h e ground surface.

7. Data ob ta ined from t h e v i b r a t o r y t r a v e r s e s are p l o t t e d a s number of waves ve r sus d i s t a n c e from which s h e a r (Rayleigh) wave v e l o c i t i e s a r e determined. These p l o t s a r e shown f o r t r a v e r s e s V-1 through V-3 i n I n c l s 11-13, r e s p e c t i v e l y . From t h e d a t a t a k e n from t h e number of waves ve r sus d i s t a n c e p l o t s , surface wave v e l o c i t y is simply ca lcu la ted a s wavelength times frequency. Assuming t h a t t h e surface wave ve loc i ty is e q u a l t o t h e s h e a r wave v e l o c i t y and is a p p l i c a b l e a t . a depth equal t o one-hal f t h e wavelength, p l o t s o f s h e a r wave v e l o c i t y v e r s u s depth were prepared f o r t r a v e r s e s V-1 through V-3, as shown i n I n c l s 14-16, r e s p e c t i v e l y . For t r a v e r s e V-1, t h e s h e a r wave v e l o c i t y g e n e r a l l y

, WESSD 3 1 March 1 9 7 1 SUBJECT: Seismic F i e l d Study, R i f l e Gap Dam, R i f l e , Colorado,

16-28 November 1970

increased from 560 f p s a t a depth o f 7 f t t o 750 f p s a t 93.5 ft. A s l i g h t l y lower v e l o c i t y o f 495 fps a t a depth of 11 ft was noted. The shear wave v e l o c i t y f o r t r a v e r s e V-2 i n c r e a s e d from 625 fps a t a depth of 6.5 f t t o 1085 f p s a t 108.5 ft. The s h e a r wave v e l o c i t y f o r t r a v e r s e

.V-3 increased from 700 f p s a t a depth o f 7 f t t o 960 f p s a t 32 ft, t h e n showed a s h a r p decrease i n v e l o c i t y t o 805 f p s a t 33.5 f t . The s h e a r wave v e l o c i t y inc reased a g a i n t o 1090 f p s a t 90 f t . The d a t a p o i n t s a t 97 f t and 117.5 ft are q u e s t i o n a b l e because o f s i g n a l q u a l i t y . .

8. The p l o t s of s h e a r modulus, .G , v e r s u s depth f o r t r a v e r s e s V-1 through V-3 a r e shown in I n c l s 17-19, r e s p e c t i v e l y . Shear modulus is equal t o t h e s h e a r wave v e l o c i t y squared t i m e s t h e mass d e n s i t y . For t r a v e r s e s V - 1 and V-2, a wet u n i t weight o f 120 p c f w a s used above 50 ft and 130 pcf below 50 ft. For t r a v e r s e V-3, a w e t u n i t weight o f 135 pcf was used f o r a l l depths. The s h e a r modulus ranged from 63,50 p s i t o 33,800 p s i a s shown i n I n c l s 17-19.

9. Only t h e r e s u l t s of t h e Rayle igh wave v e l o c i t y s e i s m i c tests con- ducted a long t r a v e r s e s S-1 and S-2 and a l o n g t r a v e r s e S-7 are p r e s e n t e d i n t h i s memorandum. The o t h e r two se i smic tests c rossed over a c r e e k about 1 0 f t deep and t h e Rayleigh wave energy was n o t w e l l d e t e c t e d which may i n d i c a t e t h a t a t r e n c h could be d e t r i m e n t a l t o t h e normal propagation o f Rayleigh wave energy. There were a l s o o t h e r problems encountered i n ob ta in ing good d a t a from t h e Rayleigh wave d i s p e r s i o n seismic t e s t s . The most d i f f i c u l t problem was o b t a i n i n g usab le ampli- tudes o f t h e Rayleigh wave t r a i n . Ampl i f i e r g a i n s a r e c r i t c a l and must be ad jus ted f o r a p a r t i c u l a r charge s i z e . If t h e g a i n s a r e t o o high, t h e d a t a traces w i l l exceed t h e osc i l logram width and b e l o s t . Con- versely, i f t h e g a i n s are t o o low, t h e Rayleigh wave train w i l l n o t b e detec ted . This procedure caused a number o f s h o t s t o b e repea ted . Another problem is t h e e r r o r in t roduced i n t h e d a t a caused by s h o o t i n g i n or n e a r t h e o r i g i n a l d i s t u r b e d shothole . When t h e i n i t i a l charge is detonated, it produces a c a v i t y i n t h e s3i1, thus caus ing a n o t h e r charge detonated i n t h e same sho tho le t o produce d a t a somewhat d i f f e r e n t from t h e o r i g i n a l sho t .

10 . The r e s u l t s o f t h e Rayleigh wave seismic t e s t a long t r a v e r s e s S-1 and S-2 a r e shown i n I n c l 20 a l o n g wi th t h e d a t a from v i b r a t o r y tra- verse V-1. . The Rayleigh wave v e l o c i t y from t h i s t e s t is determined a s t h e d i s t a n c e between two geophones d ivided b y t h e , t i m e r e q u i r e d t o t r a v e l between t h e same two geophones. The Rayleigh wave v e l o c i t i e s a r e abou t two t o t h r e e t imes h i g h e r t h a n t h e s h e a r wave v e l o c i t i e s determined from t h e v i b r a t o r y d a t a . It should b e no ted t h a t d a t a from two bor ing l o g s have been included i n I n c l 20. Data from bor ing DH21, which i n d i c a t e s two d i s t . i n c t boundar ies a t depths of 56 and 84 ft,

' WESSD 3 1 March 1970 SUBJECT: Seismic F i e l d Study, R i f l e Gap Dam, R i f l e , Colorado,

16-28 November 1970

c o r r e l a t e w e l l w i t h t h e Rayleigh wave v e l o c i t y p r o f i l e . However, o t h e r b o r i n g s i n t h e a r e a , such as bor ing DH22 ( I n c l 20), i n d i c a t e a d i f f e r ence as r e g a r d s dep ths a t which certain materials a r e encountered. The r e s u l t s of t h e Rayleigh wave seismic test a l o n g t r a v e r s e S-7, which w a s s h o t up t h e f a c e o f t h e dam, i n d i c a t e d t h a t t h e d i r e c t compression and s h e a r wave v e l o c i t i e s ob ta ined were 4000 and 1900 fps, r e s p e c t i v e l y , f o r t h e embankment as shown in I n c l 21. The average s h e a r wave v e l o c i t y determined from t h e v i b r a t o r y d a t a ( t r a v e r s e V-3) was a b o u t 900 fps and t h e compression-wave v e l o c i t y was 4800 f p s from t r a v e r s e S-7.

' 11. Thus f a r , r easons f o r d i f f e r e n c e s between s u r f a c e , v i b r a t o r y , and Rayleigh wave d i s p e r s i o n d a t a have n o t been determined. It is suggested t h a t t h e v i b r a t o r y s h e a r wave v e l o c i t y d a t a b e used as a lower bound .

and t h e maximum Rayle igh wave v e l o c i t y d a t a b e used as t h e upper bound ' f o r t h e m a t e r i a l p r o p e r t y d e s c r i p t i o n .

2 1 I n c l as

CF w/ i n c l : M r . S. J. Johnson

J. R. CURRO, JR. Geophys ic is t Vibra to ry Loads S e c t i o n

S R I O Shotpoint

Seismic traverse no. and d i rec t ion 1" = 2 00 '

SEISMIC T!ST LAYOUT Rifle Gap Dam, Colorado

Inclosure 1

o Shotpoint X Geophones

1"= 100 f t . S5ISP;IC TEST WYOiJT Traverse 5-7 (up face of d m ) Rifle Gap Dam, Colorado

1 Inclosure 2

8 Vibrator l oca t ion VIBRATCISY mT LAYOUT Vibration t r ave r se no. and d i r ec t ion Z f l e Gap Dam, Colorado

1" = 200 f t .

Inc losure 3

H

2 t-' 0

F ID

Traverses S-1 and S-2 I

.STANCZ and S-4

0 Traverse S-5 X Traverse S-6

Distance, ft. TIMIX versus DISTANCE Traverses S-5 and S-6

H : t-' 0

; iD , . . . . , .

1,; , , , / > ,- .;I.:: ijl~;~:~?~~''~: 'Ti ' ..::::.i.: ;-7 (up face of dam)

Zast , Distance . f t .

APPR0XC;AT:I PROFILE OF SUBSURFACE !~IATUIIAIS Traverses S-1 and S-2

North, Distance, ft.

APPROXS34ATE PROFILE OF SUBSURFACE NATERIALS Traverses S-3 and S-4

I .' H s 0

I I-' 0

I :

E m I-' 0

I '

APPltOl!llihTiS PROl"'CL2 31: SUElmI?AC:< ilATXR1I;LS Traverses S-5 and S-6

Inclosure 11

Inclosure 12

Inclosure 13

Velocity, f p s

SHZAR dAVZ VZLOCITY versus DEPTH

Traverse V-1 Yest 6

Velocity, fps

SHEAR HAVE VEI.OCITY versus DSPTH

Traverse V-2 North

Inclosure 16

3 Shear Moduli. 10 psi

10 '15 29 25 3,O Shear doduli, ld kips/sq. d. I 2.L 1 3.2 1 L.0 I

SHEAR MODULI versus DEPTH Traverse V-1

3 Shear Moduli, 10 osi 20 I

30

SHEllR MODULI versus DEPTH Traverse V-2

3 Shear Moduli, 10 psi

SHEAR I*IODULI versus DEPTH Traverse V-3

Comparison Of Kayleigh Wave Velocities versus Depth(along Traverses ,S-1 and S-2) and Shear Wave Velocities versus Depth(Traverse V-1)

TDU versus 'DISTANCE Rayleigh Wave Seismic ~ e s t ( u p face of dam)

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Unclass i f ied . . security C l a s s i f i c a t i o n

I DOCUMENT CONTROL DATA - R 6 D . 1 (S.~,,,I~~ c ~ r ~ ~ r l l c = t r o n of tltl*. body 01 =barrrct and Ind.xln# .nnot=t lm muat & .nt.r*d when the o.~~.II r.por~ 1, clm..lllrd,

' I . OR0,GlNATlNG A C T I V I T V fCO)PO.*t* *"thol) Ir. R E P O R T SKCURITV CLASSICICATION

U. S. Army Engineer Waterways Experiment S ta t ion ~ n c l a s s ' i f i ed Vicksburg, Miss iss ippi ~ b . GIOUP

I 3 . R E P O R T T I T L E EARTHQUAKE: RESISTANCE OF EARTH AND ROCK-FILL DAMS; Report 2, ANALYSIS OF RESPONSE OF RIFLE GAP DAM TO PROJECT RULISON UNDERGROUND NUCLEAR DETONATION

m. OESCIIPTIVL NOTES f f lp . 01 t*pcat a d I n c l u ~ l ~ * d.t*o)

Report 2 of a s e r i e s 5 . ~ u ~ u o R t l 1 (F1t.1 nome. middle Inltl*l. 1a.t n*m*J

James E. Ahlberg Jack Fowler Lyman W. Heller

8. R E P O R T O A T E 7.. T O T A L ' W O . O F P A C K S 7b. NO. O C R L C S

June 1972 132 10 or. C O N T R A C T 01 G R A N T NO. 9.. ORIOINATOR.S R E P O R T NUMLIISI

b. P R O J E C T N O . I, Miscellaneous Paper S-71-17, Report 2

C. ob. O T u L R n L P o l l T NOIS I (Any other numb.- h.t .ur & r**I@.d thl* npon)

d.

10. D I S T R I B U T I O N S T A T E Y C N T

Approved fo r pub l ic r e l e a s e ; d i s t r i b u t i o n unlimited.

I I S U P P L E Y L N T A R V N O T E S II. S P O N S O R I N G Y I L I T A R V A C T I V I T V

Office , Chief of Engineers, U. S. Amy Washington, D. C .

The motion of R i f l e Gap Dam w a s measured i n September 1969 during the Project RULISON underground nuclear explosion. The observed response w a s then compared with t h e re- sponse computed i n a mathematical model. Observed and computed responses were s i m i l a r . From t h i s study it appears t h a t t h e mathematical models used a re applicable t o t h e de- s ign and analysis of s o i l s t r u c t u r e s , a t l e a s t f o r ground motion in tens i t i e s comparable t o those observed a t R i f l e Gap D m .

I I m C L A C C m 00 C O I Y 1.7.. I J A N S1. W W I C I I. DD ,'27,,1473 o m s o L m y m .om Am-* urn.. Unclassified

Security C l ~ ~ ~ i f i c ~ t i o n . .

Unclassified

Unclassified Security CIsaaification .

Security Classification

I a. K C V W 0 1 1 0 S

'

Earth dams

Earthquake-resistant structures

Ground motion

Mathematical models

Nuclear explosion effects

Rifle Gap Dam

Rock-fill dams

Rulison (h-o ject )

Underground explosions

*

L I N K

ROLE

A

WT

LINK

ROLE

I)

I T

LINK

ROLL

- C

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