Page 53 - Handbook GEOTEKNIK_Final_Neat

Soil Bearing Capacity Soil Bearing Capacity

• There are three essential components for computing soil bearing capacity: • For strip footing
 Ultimate soil bearing capacity, q (kN/m )
2
u
 Factor of safety, FOS = 3 S = S = S = 1.0

q

c
2
 Allowable soil bearing capacity, q (kN/m ) = Q / FOS → q = CN + DN + 1/2BN 
all
u
u
c
q

• Ultimate soil bearing capacity, qu • For square & circular footing
 According to Terzaghi, ultimate soil bearing capacity
q = CN S + DN S + 0.5BN S  S = 1.3 S = 1.0 S = 0.8
c
q
γ

c
c
u
q
q
→ q = 1.3CN + DN + 0.4BN 
q
u
c

• Effect of water table
2
Where q = ultimate soil bearing capacity (kN/m ) If water table rises above foundation level, submerged density ( ) should be used
u
2
C = cohesion of soil (kN/m ) sub
D = depth of footing (m)  =  –  ( = 10 kN/m )
= least lateral dimension of footing (width) (m)
2
B

3
 = unit weight of soil (kN/m ) sub sat water water
N , N ,N = bearing capacity factor
c q 
S , S , S  = shape factor
c
q
Note:
Formula to computing ultimate soil bearing capacity is not limited to Terzaghi
formula only

36 PUBLIC WORKS DEPARTMENT MALAYSIA GEOTECHNICAL ENGINEERING HANDBOOK 37