Undisturbed Slope Analysis for Section 4

8/2/2019 Undisturbed Slope Analysis for Section 4

1/27


2/27

Undisturbed Slope Analysis for Section D-D ( Before Cut and Fill )

Slope analysis 1

The Contour View shows the possible slip surface and the safety factor of 1.576 indicates it

is safe from slipping

Slice information

Slice 1 - Morgenstern-Price Method

2.1372

0.86163

2.0915

0.84606

0.039251


3/27

Critical slice - Morgenstern-Price Method

Factor of Safety 1.5764

Phi Angle 33

C (Strength) 0 kPa

C (Force) 0 kN

Pore Water Pressure 0 kPa

Pore Water Force 0 kN

Pore Air Pressure 0 kPa

Pore Air Force 0 kN

Phi B Angle 0

Slice Width 0.62806 m

Mid-Height 0.21268 m

Base Length 0.8783 m

Base Angle -44.35

Anisotropic Strength Mod. 1

Applied Lambda 0.5344

Weight (incl. Vert. Seismic) 2.1372 kN

Base Normal Force 2.0915 kN

Base Normal Stress 2.3813 kPa

Base Shear Res. Force -1.3582 kN

Base Shear Res. Stress -1.5464 kPa

Base Shear Mob. Force -0.86163 kN

Base Shear Mob. Stress -0.98102 kPa

Left Side Normal Force 0 kNLeft Side Shear Force 0 kN

Right Side Normal Force 0.84606 kN

Right Side Shear Force 0.039251 kN

Horizontal Seismic Force 0 kN

Point Load 0 kN

Reinforcement Load Used 0 kN

Reinf. Shear Load Used 0 kN

Surface Pressure Load 0 kN

Polygon Closure 0.032058 kN

Top Left Coordinate 63.114m, 34.377m

Top Right Coordinate 63.742m, 34.189m

Bottom Left Coordinate 63.114m, 34.377m

Bottom Right Coordinate 63.742m, 33.763m


4/27

Cohesive vs Distance

Co

hes

ive

(k

Pa

)

Distance (m)

-1

0

1

0 5 10 15 20 25

Frictional vs Distance

Fr

ic

tiona

l(

kPa

)

Distance (m)

0

5

10

15

20

25

0 5 10 15 20 25

Shear Strengthl vs

Distance

Shear

Streng

th

(kPa

)

Distance (m)

0

5

10

15

20

25

0 5 10 15 20 25

Shear Mobilized vs

Distance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

2

4

6

8

10

12

14

0 5 10 15 20 25


5/27

Slope analysis 2

The Contour View shows the possible slip surface and the safety factor of1.541 indicates it is

safe from slipping

Slice Information


6/27



Phi Angle 33

C (Strength) 0 kPa

C (Force) 0 kN




Pore Air Force 0 kN

Phi B Angle 0

Slice Width 0.4771 mMid-Height 0.21863 m


Base Angle -53.199










Left Side Normal Force 0 kN

Left Side Shear Force 0 kN




Point Load 0 kN










7/27


Co

hes

ive

(kPa

)

Distance (m)

-1

0

1

0 5 10 15


Fr

ic

tiona

l

(kPa

)

Distance (m)

0

5

10

15

20

25

0 5 10 15

Shear strength vsDistance

Shear

Streng

th

(kPa

)

Distance (m)

0

5

10

15

20

25

0 5 10 15

Shear mobilized vsDistance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

5

10

15

0 5 10 15


8/27

Slope Analysis for Section D-D ( After Cut, Fill and Loading )

The loadings of 5 storeys apartment, double storeys terrace house, car park and roads was

then key in. 6 critical locations has been chosen to carried out the slope analysis, where only

2 locations past the required factor of safety.

Location 1


safe from slipping


9/27

Critical slice information


Phi Angle 37

C (Strength) 0 kPa

C (Force) 0 kN




Pore Air Force 0 kN

Phi B Angle 0



Base Length 0.43044 mBase Angle -66.575















Point Load 0 kN










10/27


Co

hes

ive

(kPa

)

Distance (m)

-1

0

1

0 1 2 3 4 5 6 7


Fr

ic

tiona

l

(kPa

)

Distance (m)

0

2

4

6

8

10

12

14

0 1 2 3 4 5 6 7

Shear strengthl vs

Distance

Shear

Streng

th

(kPa

)

Distance (m)

0

2

4

6

8

10

12

14

0 1 2 3 4 5 6 7

Shear Mobilizedl vs

Distance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7


11/27

Location 2


not safe and will slip.

Slice information


12/27



Phi Angle 37

C (Strength) 0 kPa

C (Force) 0 kN




Pore Air Force 0 kN

Phi B Angle 0




Base Angle -62.78 Anisotropic Strength Mod. 1














Point Load 0 kN





Top Left Coordinate 12.325m, 43m

Top Right Coordinate 12.493m, 43m

Bottom Left Coordinate 12.325m, 43m



13/27


Co

hes

ive

(k

Pa

)

Distance (m)

-1

0

1

0 1 2 3 4 5 6 7 8


Fr

ic

tiona

l(

kPa

)

Distance (m)

0

2

4

6

8

10

12

14

16

0 1 2 3 4 5 6 7 8

Shear Strenglth vsDistance

Shear

Streng

th

(kPa

)

Distance (m)

0

2

4

6

8

10

12

14

16

0 1 2 3 4 5 6 7 8

Shear Mobilized vsDistance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

2

4

6

8

10

12

14

0 1 2 3 4 5 6 7 8


14/27

Location 3


safe from slipping

Slice information


15/27

Critical Slice - Morgenstern-Price Method


Phi Angle 37

C (Strength) 0 kPa

C (Force) 0 kN




Pore Air Force 0 kN

Phi B Angle 0


















Point Load 0 kN










16/27


Co

hes

ive

(k

Pa

)

Distance (m)

-1

0

1

0 2 4 6 8 10 12 14


Fr

ic

tiona

l(

kPa

)

Distance (m)

0

10

20

30

0 2 4 6 8 10 12 14

Shear strength vsDistance

Shear

Streng

th

(kPa

)

Distance (m)

0

10

20

30

0 2 4 6 8 10 12 14

Shear Mobilized vsDistance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8 10 12 14


17/27

Location 4



Slice information


18/27



Phi Angle 45

C (Strength) 0 kPa

C (Force) 0 kN




Pore Air Force 0 kN

Phi B Angle 0


















Point Load 0 kN



Surface Pressure Load 0.08897 kN


Top Left Coordinate 105.88m, 11m

Top Right Coordinate 105.89m, 11m

Bottom Left Coordinate 105.88m, 11m



19/27


Co

hes

ive

(k

Pa

)

Distance (m)

-1

0

1

0 0.1 0.20.3 0.4 0.5 0.6 0.70.8 0.9


Fr

ic

tiona

l(

kPa

)

Distance (m)

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Shear strength vs

Distance

Shear

Streng

th

(kPa

)

Distance (m)

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Shear moblilized vs

Distance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

1

2

3

4

5

6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9


20/27

Location 5



Slice information

Slice 1 - Morgenstern-Price Method

0.0002267

0.00021591

6e-005

5.9071e-005

8.3089e-006


21/27



Phi Angle 37

C (Strength) 0 kPa

C (Force) 0 kN




Pore Air Force 0 kN

Phi B Angle 0







Base Normal Force 7.1496e-005 kN


Base Shear Res. Force -5.3876e-005 kN






Right Side Normal Force 5.9071e-005 kN

Right Side Shear Force 8.3089e-006 kN


Point Load 0 kN




Polygon Closure 1.1335e-006 kN






22/27


Co

hes

ive

(k

Pa

)

Distance (m)

-1

0

1

0 0.5 1 1.5


Fr

ic

tiona

l(

kPa

)

Distance (m)

0

1

2

3

0 0.5 1 1.5

Shear strengthl vs

Distance

Shear

Streng

th

(kPa

)

Distance (m)

0

1

2

3

0 0.5 1 1.5

Shear mobilized vs

Distance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

2

4

6

8

10

0 0.5 1 1.5


23/27

Location 6



Slice information


24/27



Phi Angle 29

C (Strength) 5 kPa

C (Force) 1.519 kN




Pore Air Force 0 kN

Phi B Angle 0
















Right Side Shear Force 7.2132e-005 kN


Point Load 0 kN



Surface Pressure Load 0.71777 kN







25/27


Co

hes

ive

(k

Pa

)

Distance (m)

4.5

5

5.5

0 1 2 3 4 5


Fr

ic

tiona

l(

kPa

)

Distance (m)

-5

0

5

10

15

20

0 1 2 3 4 5

Shear strength vs

Distance

Shear

Streng

th

(kPa

)

Distance (m)

0

5

10

15

20

25

0 1 2 3 4 5

Shear Mobilized vs

Distance

Shear

Mo

bilize

d

(kPa

)

Distance (m)

0

10

20

30

40

0 1 2 3 4 5


26/27

Comments on slope analyses section D-D :

Location 1, 2, 3 :

Local soil failure occurs when the shear strength is mobilized in a limited zone of the subsoil.

General slope failure occurs when kinematic conditions are such that the soil mass can

experiencelarge displacements. Slopes are generally characterized by non-uniform stress field.Additional stresses induced by changes in boundary conditions can emphasize local

differences in the stress level. As a consequence, every failure process is, at first, local, with

formation of plastic zones, then general.

Our analyses on these 3 locations justified what is explained. Location 1 and 2 are the local

analyses and we get the value factor of safety of 1.58 and 1.241, which are safe and unsafe

respectively. However, location 3 is the global analyse and the factor of safety is 1.653 which

is safe from slipping. This mean that location 2 will have a possibility of local failure first and

cause the general failure at location 3 although location 3 is show safe during analyse.

i) Apply man made surface drainange and control water infiltration.As rain water infiltrates a slope, it definitely increase the moisture content, causing a

lowring of the soil suction in unsaturested zone and making the pore pressures less

negative, hence lowering the shear strengths of the soil. In addition, sufficient

rainfall and infiltration uphill of a slope can raise the water table in the slope.

Furthermore, the wetting of the soil mass makes it heavier and causing destabilizing

forces to increase. Thus, we can cover the slope surface by some thin gabion with

siemen or install geotextile to act as man made surface drainage in order to prevent

the infiltration of rainfall water. Besides that, it can be added man made concretegullies to properly drain down the surface water. These surface structure must be

free of cracs and be well maintained.

ii) Soil nailing

Soil nailing is a technique in which soil slopes, excavations or retaining walls are

reinforced by the insertion of relatively slender elements - normally steel reinforcing

bars. The bars are usually installed into a pre-drilled hole and then grouted into

place or drilled and grouted simultaneously. They are usually installed untensioned

at a slight downward inclination. A rigid or flexible facing (often sprayed concrete) or

isolated soil nail heads may be used at the surface.

Location 4 :

Since the reduce level was already attained from the planning location map, the cut was

planned in a way to suit the best angle in order to allow the structure to maintain the

architectural requirements. At location 4 and 5 , the slope is cut straight at 90 degree and isside by side with the structure of buildings.
http://en.wikipedia.org/wiki/Earthworks_%28engineering%29http://en.wikipedia.org/wiki/Grouthttp://en.wikipedia.org/wiki/Grouthttp://en.wikipedia.org/wiki/Earthworks_%28engineering%29


27/27

Hence, the slope will be straight forward supported by the structure of builidngs with

ground anchored inserted.

Location 6 :

In location 6, we will assigned a retaining wall next to the road. A retaining wall is astructure designed and constructed to resist the lateral pressure of soil when there is a

desired change in ground elevation that exceeds the angle of repose of the soil. The active

pressure increases on the retaining wall proportionally from zero at the upper grade level to

a maximum value at the lowest depth of the wall. After installation of retaining wall, our

slope factor of safety is apparently increase from 0.644 to 2.027

Undisturbed Slope Analysis for Section 4

Documents

Transcript of Undisturbed Slope Analysis for Section 4