Bearing Capacity Examples 1 Solutions
-
Upload
sujani-maarasinghe -
Category
Documents
-
view
221 -
download
0
Transcript of Bearing Capacity Examples 1 Solutions
-
8/21/2019 Bearing Capacity Examples 1 Solutions
1/13
Bearing Capacity – Examples 1
In all these questions use partial factor set 'A1' + 'M1' + 'R1' from
the Tables below.
1. A shallow strip footing of breadth 3.5 m is to be founded at a depth of
2.0 m in a soil which has the following (drained) properties ck' 12
k!"m2 # φκ ' 25$ # γ κ 1% k!"m3. &etermine the design bearing
resistance of the soil at this depth.
2. A strip tpe footing will be reuired to transmit a total design load of
1.1 !"m (includes self*weight of foundation) in a saturated cohesi+esoil ha+ing the following (drained) properties ck' 1, k!"m2# φκ '
2-$# γ κ 1% k!"m3. &etermine the breadth of footing reuired at a
depth of 1.0 m. Assume &"/1.
3. A footing# 2.25 m suare# is located at a depth of 1.5 m in a sand
soil# the shear strength parameter φκ ' 3,$. &etermine the design
bearing resistance of the soil at this depth (a) if the water table is
well below foundation le+el and (b) if the water table is at groundsurface. he characteristic unit weight of the soil abo+e the water
table is 1, k!"m3 and the saturated unit weight is 20 k!"m3 .
. A strip footing is to be designed to carr a total design load of 2#000
k!"m at a depth of 0. m in a gra+ell sand (φ'k ' 0$). &etermine
the width of the assuming the water table ma rise to foundation
le+el. or the sand γ k.sat
20 k!"m3 and abo+e the water table γ k.bulk
1 k!"m3. Assume &"/1.
5. A column is supported on a reinforced concrete pad footing 2.0 m
suare and located at a depth of .0 m in a sti4 cla (γ k.sat
21 k!"m3
). he undrained shear strength of the cla is cu.k
120 k!"m2.
&etermine the design load the column can transmit. Assume the
following the water table is at founding depth6 the soil abo+e the
water table is in a full saturated state# and the unit weight of the
concrete and back7ll material is eual to that of the cla remo+ed
from the e8ca+ation.
1
-
8/21/2019 Bearing Capacity Examples 1 Solutions
2/13
2
-
8/21/2019 Bearing Capacity Examples 1 Solutions
3/13
The following should be used:
General Bearing Capacity equations (strip footing)
&rained condition Bearing Resistance/unit area (R'/A) c'!c 9 '! 9 0.5γ !γ
:ndrained condition Bearing Resistance/unit area (R/A) (29π)cu 9
Bearing capacity factors
!c (!*1)cotφ' 6 ! eπtanφ' tan2(5$ 9 φ'"2) 6 !γ 2(!*1)tanφ'
Shape factors
;ondition sc s sγ
?ectangle
&rained
−−1
1
q
qq
N
N s
1 9
L
B
@inφ'
1 0.3
L
B
:ndrained
19 0.2
L
B 1 *
>ircle"
@uare
&rained As rectangle 1 9 @inφ' 0.
:ndrained 1.2 1 *
Depth factors
Condition dc dq dγ
D/B ≤ 1 1 + 0.4(D/B) 1 + 2tanφ'(1-inφ')2(D/B) 1.0
D/B > 1 1 + 0.4tan-1 (D/B) 1 + 2tanφ'(1-inφ')2 tan-1(D/B) 1.0
ote: the factor tan*1(&") must be e8pressed in radians not degrees
3
-
8/21/2019 Bearing Capacity Examples 1 Solutions
4/13
Partial Factors for Soil Properties (BS EN 1997-1!""#)
Partial $esistance Factors (BS EN 1997-1!""#)
Partial Factors for %ctions (N% to BS EN 1997-1 !""#)
Soil Parameter
Set
M1 M2
Ang!e o" s#earing resistance$ 1.0 1.2%
&""ectie co#esion 1.0 1.2%
ndrained s#ear strengt# 1.0 1.4
eig#t Densit* 1.0 1.0
$ #is "actor a,,!ied on tanφ'
Resistance
Set
R1 R2 R3
Bearing 1.0 1.4 1.0
!iding 1.0 1.1 1.0
Action Set
A1 A2
eranent n"aourae 1.% 1.0
aoura!e 1.0 1.0
aria!e n"aoura!e 1.% 1.
aoura!e 0 0
-
8/21/2019 Bearing Capacity Examples 1 Solutions
5/13
SOLU!O"S
5
-
8/21/2019 Bearing Capacity Examples 1 Solutions
6/13
-
-
8/21/2019 Bearing Capacity Examples 1 Solutions
7/13
-
8/21/2019 Bearing Capacity Examples 1 Solutions
8/13
,
-
8/21/2019 Bearing Capacity Examples 1 Solutions
9/13
%
-
8/21/2019 Bearing Capacity Examples 1 Solutions
10/13
10
-
8/21/2019 Bearing Capacity Examples 1 Solutions
11/13
11
-
8/21/2019 Bearing Capacity Examples 1 Solutions
12/13
12
-
8/21/2019 Bearing Capacity Examples 1 Solutions
13/13
13