# Chapter9-In Situ Stresses¶

## Ex1-pg230¶

In [1]:
import math
#calculate total pressure and pore water pressure and effective stress at point
##initialisation of variables
Ds= 16.5 ##kN/m**3
S= 19.25 ##kN/m**3
g= 9.8 ##kN/m**3
h1= 6. ##m
h2= 13. ##m
##at point A
Sa= 0.
Ua= 0.
Sa1= 0.
##at point B
Sb= h1*Ds
Ub= 0.
Sb1= Sb-Ub
##at point C
Sc= h1*Ds+h2*S
Uc= h2*g
Sc1= Sc-Uc
##results
print'%s %.2f %s'% ('total pressure at C= ',Sc,' kN/m^3 ')
print'%s %.2f %s'% ('pore water pressure at C = ',Uc,' kN/m^3 ')
print'%s %.2f %s'% ('effective stress at point C=',Sc1,' kN/m^3 ')

total pressure at C=  349.25  kN/m^3
pore water pressure at C =  127.40  kN/m^3
effective stress at point C= 221.85  kN/m^3


## Ex2-pg233¶

In [8]:
#calculate maximu depth that can be made in clay
##initialisation of variables
h= 20. ##ft
g= 120. ##kg/ft**3
h1= 12. ##ft
w= 62.4 ##kg/ft**3
##calculations
H= h-(h1*w/g)
##results
print'%s %.2f %s'% ('maximu depth that can be made in clay = ',H,' ft ')

maximu depth that can be made in clay =  13.76  ft


## Ex3-pg236¶

In [9]:
#calculate effective stress at point a and b and see page force per unit voume
##initialisation of variables
G= 2.68
e= 0.52
g= 9.81 ##kN/m^3
h1= 0.7 ##m
h2= 1 ##m
h3= 1.5 ##m
h4= 2 ##m
##calculations
##for soil A
sa= (G+e)*g/(1.+e)
##point a
Sa= h1*g+h2*sa
u= (h2+h1+h3/2.)*g
Es= Sa-u
##point b
sb= h1*g+h4*sa
ub= (h4+h1+h3)*g
Eb= sb-ub
i= h3/2.
s= i*g
##results
print'%s %.2f %s'% ('effective stress at point a=',Es,' kN/m^2 ')
print'%s %.2f %s'% ('effective stress at point b= ',Eb,'kN/m^2 ')
print'%s %.2f %s'% ('seepage force per unit voume = ',s,' kN/m^3 ')

effective stress at point a= 3.49  kN/m^2
effective stress at point b=  6.97 kN/m^2
seepage force per unit voume =  7.36  kN/m^3


## Ex4-pg239¶

In [5]:
#calculate safety factor
##initialisation of variables
C0= 0.357
H1= 30.5 ##ft
H2= 5. ##ft
w= 62.4 ## lb/ft^3
D= 20.
g= 112. ## lb/ft^3
##calculations
G= g-w
FS= D*G/(C0*w*(H1-H2))
##results
print'%s %.1f %s'% ('safety factor =',FS,' ')

safety factor = 1.7