Soil Bearing Capacity Calculation Passwords Removed
14
FOUNDATION DESIGN Subject: SOIL BEARING CAPACITY BY TERZAGHI Design Code/Ref: Proj. No. Location: Joseph E. Bowles xxxx CODE REF. CALCULATIONS & SKECTHES Compute the allowable bearing pressure using Terzaghi equation for the footing and soil paramete Figure 1. D = 1.20 m footing embedment depth 17.3 kN/m³ soil density Ø = 20 deg angle of internal friction c = 20 kPa cohesion of soil B = 1.5 m footing size Footing Type: square 1.0 Find the bearing capacity. Note that this value is usually the result of geotechnical inves Since: Ø = 20 deg Therefore from Table 4-2: From Table 4-1 17.7 1.3 7.4 0.8 5.0 q = 20.76 ( 613.8 + 34.60 B ) kPa 665.7 kPa Eq. 4-1 SF = 3 Factor of Safety 221.9 kPa allowable bearing capacity g = Nc = sc = Nq = sγ = Nγ = qult = qult = qa = D B Figure 1 qa = qult SF = D * g
-
Upload
maiwand-khan -
Category
Documents
-
view
1.097 -
download
392
description
SBC
Transcript of Soil Bearing Capacity Calculation Passwords Removed
FOUNDATION DESIGN
Subject:
SOIL BEARING CAPACITY BY TERZAGHI
Design Code/Ref: Proj. No. Location: Designer: Date:
Joseph E. Bowles xxxx xxxx 18-Apr-23
CODE REF. CALCULATIONS & SKECTHES
Compute the allowable bearing pressure using Terzaghi equation for the footing and soil parameters shown in
Figure 1.
D = 1.20 m footing embedment depth
17.3 kN/m³ soil density
Ø = 20 deg angle of internal friction
c = 20 kPa cohesion of soil
B = 1.5 m footing size
Footing Type: square
1.0 Find the bearing capacity. Note that this value is usually the result of geotechnical investigation.
Since:
Ø = 20 deg
Therefore from Table 4-2: From Table 4-1
17.7 1.3
7.4 0.8
5.0
q = 20.76
( 613.8 + 34.60 B ) kPa
665.7 kPa
Eq. 4-1
SF = 3 Factor of Safety
221.9 kPa allowable bearing capacity
g =
Nc = sc =
Nq = sγ =
Nγ =
qult =
qult =
qa =
D
B
Figure 1
qa = qult
SF
= D * g
D16
Select the type of footing
H25
Strip = 1.0 round = 1.3 square =1.3
H26
Strip = 1.0 round = 0.6 square = 0.8
FOUNDATION DESIGN
Subject:
SOIL BEARING CAPACITY BY TERZAGHI
Design Code/Ref: Proj. No. Location: Designer: Date:
Joseph E. Bowles xxxx xxxx 18-Apr-23
CODE REF. CALCULATIONS & SKECTHES
FOUNDATION DESIGN
Subject:
SHALLOW FOUNDT'N/SOIL BEARING CAPACITY BY MEYERHOF
Design Code/Ref: Proj. No. Location: Designer: Date:
Shallow Foundation xxxx xxxx 18-Apr-23
CODE/REF. CALCULATIONS & SKECTHES
1.0 Design Parameters
B = 0.60 m
L = 1.20 m
D = 0.60 m
c = 48.0 kPa
25 deg
18 kN/m³
2.0 Determine the ultimate vertical load that the foundation can cary by using Meyerhof's values.
Eq. 2.83
Eq. 2.66
Eq. 2.67
Eq. 2.72
3.0 From Table 2.3 Meyerhof's bearing capacity factor:
Since:
25 deg
20.72
10.66
6.77
3.1 Refer from Table 2.5 Summary of shape and depth factors.
1.246
1.123
1.123
1.314
1.157
1.157
Shallow Foundation, by Braja M. Das
f =
g =
f =
Nc =
Nq =
Ng =
lcs =
lqs =lgs =
lcd =
lqd =lgd =
Df
B
FGL
P
FOUNDATION DESIGN
Subject:
SHALLOW FOUNDT'N/SOIL BEARING CAPACITY BY MEYERHOF
Design Code/Ref: Proj. No. Location: Designer: Date:
Shallow Foundation xxxx xxxx 18-Apr-23
CODE/REF. CALCULATIONS & SKECTHES
Therefore: from Eq. 2.83
q = 10.8 kPa
1825.42 kN/m²
SF = 3
608.47 kN/m²
qu =
qa =
Factor of Safety
= round(cNcl
csl
cd + qNql
qsl
qd + 1 / 2gBNglgslgd , 2)
= round(qu / SF , 2)
FOUNDATION DESIGN
Subject:
SHALLOW FOUNDT'N/SOIL BEARING CAPACITY BY MEYERHOF
Design Code/Ref: Proj. No. Location: Designer: Date:
Shallow Foundation xxxx xxxx 18-Apr-23
CODE/REF. CALCULATIONS & SKECTHES
FOUNDATION DESIGN
Subject:
HANZEN - BEARING CAPACITY
Design Code/Ref: Proj. No. Location: Designer: Date:
Joseph E. Bowles xxxx xxxx 18-Apr-23
CODE REF. CALCULATIONS & SKECTHES
1.0 Design Parameters
Columns: Footing: Loads:
B = 1.80 m 0.40 m P = 1800 kN
L = 1.80 m 0.40 m 450 kN-m
360 kN-m
Soil Parameters:
36 deg 18 kN/m³
c = 20 kPa d = 6.1 m water table depth
D = 1.8 m SF = 3.0
2.0 Required: Allowable soil pressure, if SF = 3.0
0.25
0.20
B/6 = 0.30 m > e
1.4 < B given, Ok.
1.2 < B given, Ok.
c1 =
c2 = Mx =
My =
f = g =
ey =
ex =
Bmin =
Lmin =
= Mx / P
= My / P
= 4ey + 0.4
= 4ex + 0.4
= B - 2ey
Figure 1.0
VMy
L
B
X
y
L'
B'
2ey
2ex
My
ex
ey
D
d
c
FOUNDATION DESIGN
Subject:
HANZEN - BEARING CAPACITY
Design Code/Ref: Proj. No. Location: Designer: Date:
Joseph E. Bowles xxxx xxxx 18-Apr-23
CODE REF. CALCULATIONS & SKECTHES
B' = 1.30 m ( B' < L' )
L' = 1.40 m ( L' > B' )
From: Table 4-4
36 deg
51
38
40
0.745
0.247
D/B = 1.0
1.69
1.40
1.55
1.25
0.63 > 0.60 Ok!
1.0
1.0 not 0.0
1.0 not 0.0
1.0 not 0.0
5081 kPa #ADDIN?
For SF = 3.0
1694 kPa
The actual soil pressure is:
989 kPa
f =
Nc =
Nq =
Ng =
Nq/Nc =
2 tanf(1-sinf)2 =
sc =
dc =
sq =
dq =
sy =
dy = for all f as per Table 4.5a from J. A. Bowles
ii =
gi =
bi =
qult =
the allowable soil pressure qa is
qa =
qact =
= B - 2ey
= L - 2ex
= round(1 + [Nq / Nc][B' / L'] , 2)
= 1 + 0.4D / B
= round(cNcscdc + DgNqsqdq + 0.5gB'Ngsydy , 0)
= round(qult / For SF , 0)
= round(P / [B'L'] , 0)
= 1 + (B' / L')sin(fp / 180)
= 1 + 2tan(fp / 180)(1 - sin[fp / 180])2D / B
at
Note that the allowable pressure qa is very large, and the actual soil pressure qact is also large. Some geotechnical consultants routenly limit the maximum allowable soil pressure to around 500 kPa in recommendations to clients for design wheter settlement is a factor or not. Small footings with large column loads are visually not very confidence-inspiring during construction, and with such a large load involved this in cetainly not the location to be excessively conservative.
