Chapter11:Pile Foundations

Ex11.1:Pg-532

In [3]:
#example 11.1
import math

#parta
phi=30.0; # angle in degree
pa=2000.0; 
q=100*50/1000.0;
Nq=55.0;
Ap=16*16/16/12; # area in ft^2
Qp=Ap*q*Nq; # in kip
qp=0.4*pa*Nq*math.tan(phi*math.pi/180)*Ap; # in lb
print round(Qp,2),"ultimate load in lb"
print round(qp/1000,2),"ultimate load in kip"
print "there is change in answer because of calculation mistake in the book"

#partb
Nsigma=36;
Ap=16*16.0/12.0/12;
q=110*50.0/1000;
Qp=Ap*q*Nsigma*((1+2.0*(1-math.sin(phi*math.pi/180)))/3); # in kip
print round(Qp,2),"ultimate load in kip"
#partc
Nq=18.4;
Qp=Ap*q*Nq; # in kip
print round(Qp,2),"ultimate load in kip"

# ANSWER IN THE BOOK IS WRONG
275.0 ultimate load in lb
25.4 ultimate load in kip
there is change in answer because of calculation mistake in the book
234.67 ultimate load in kip
179.91 ultimate load in kip

Ex11.2:Pg-533

In [5]:
#example 11.2

import math
#parta
K=1.3;
f0=0;
Delta=0.8*30; # in ft
D=16.0/12; # in ft
L1=50.0;
p=4*16/12.0; # in ft
Gamma=110/1000.0; # in lb/ft^3
L=15*D; # in ft
sigma=Gamma*L; # in kip/ft^2
f20=K*sigma*math.tan(Delta*math.pi/180); # kip/ft^2
Qs=(f0+f20)/2*(p*L)+f20*p*(L1-L);
print round(Qs,2),"ultimate load in kip"
#partb
FS=4; # factor of safety
Qp=56.45/3+234.7/3+179.9/3; # in kip
Qu=Qs+Qp; # in kip
Qall=Qu/FS; # in kip
print round(Qall,2),"is allowed load in kip"
271.65 ultimate load in kip
107.17 is allowed load in kip

Ex11.3:Pg-534

In [7]:
#example 11.3
import math
K=0.25;
Ap=16*16.0/12/12; # area in ft^2
phi=30*math.pi/180;
Nq=25;
q=110*50.0/1000; # in kip
sigmao=q/2; # in kip/ft^2
p=4*16.0/12; # in ft
L=50; # in ft
FS=4; # factor of safety
Qu=q*Nq*Ap+K*sigmao*math.tan(0.8*phi)*p*L; # in kip
Qall=Qu/FS; # in kip
print round(Qall,1),"allowed load in kip"
81.5 allowed load in kip

Ex11.4:Pg-535

In [9]:
#example 11.4

import math
import numpy
FS=4; # factor of safety
Ap=0.1295; # area in m^2
Nc=9;
cu2=100;
Qp=Ap*Nc*cu2; # in kN
D=[5, 10, 30]; # depth in m
avgD=[2.5, 7.5,20.0]; # average depth in m
sigma=[45.0, 110.5, 228.5]; # in KN/m^2
cu=[30, 30, 100]; # in kN/m^2
alpha=[0.6, 0.9, 0.725];
L=[5, 5, 20]; # in m
p=math.pi*0.406;
Qs=0; # in kN
cusig=numpy.zeros(3)
print round(Qp,2),"bearing capacity in kN"
print  "depth (m)\t avg Depth(m)\t avgVerticalStress(kN/m**2)\t cu(kN/m**2)\t cu/sigma\t alpha\n"
for i in range(0,3):
    cusig[i]=cu[i]/sigma[i];
    Qs=Qs+alpha[i]*cu[i]*L[i]*p;
    print round(D[i],2),"\t \t \t",round(avgD[i],2),"\t \t",round(sigma[i],2),"\t\t\t   ",round(cu[i],2),"\t  ",round(cusig[i],2),"\t\t ",round(alpha[i],2),"\n"
print round(Qs,2),"bearing capacity in kN"
#part2
Lambda=0.136;
L=30;
fav=Lambda*(178.48+2*76.7);
Qs2=p*L*fav; # in kN
#part3
fav1=13;
fav2=31.9;
fav3=93.43;
Qs3=p*(fav1*5+fav2*5+fav3*20); # in kN
print round(Qs3,1),"bearing capacity in kN"
Qsavg=Qs/3+Qs2/3+Qs3/3; # in kN
Qu=Qp+Qsavg # in kN
Qall=Qu/FS; # in kN
print round(Qall,1),"allowed bearing capacity in kN"
116.55 bearing capacity in kN
depth (m)	 avg Depth(m)	 avgVerticalStress(kN/m**2)	 cu(kN/m**2)	 cu/sigma	 alpha

5.0 	 	 	2.5 	 	45.0 			    30.0 	   0.67 		  0.6 

10.0 	 	 	7.5 	 	110.5 			    30.0 	   0.27 		  0.9 

30.0 	 	 	20.0 	 	228.5 			    100.0 	   0.44 		  0.72 

2136.44 bearing capacity in kN
2669.7 bearing capacity in kN
573.6 allowed bearing capacity in kN

Ex11.5:Pg-538

In [17]:
#example 11.5

import numpy
D=[6, 12, 20]; # depth in m
fc=[34.34, 54.94, 70.63]; # in kN/m**2
alpha=[0.84, 0.71, 0.63];
dL=[6, 6, 8]; # in m
p=4*0.305;
Qs=0;
Q=numpy.zeros(3)
print "  depth(m)\t fc(kN/m**2)\t alpha \t \t deltaL(m)\t Q(kN)\n"
for i in range (0,3):
    Q[i]=alpha[i]*fc[i]*p*dL[i];
    Qs=Q[i]+Qs;
    print D[i],"\t\t   ",fc[i],"\t  ",alpha[i],"\t   ",dL[i],"\t\t ",round(Q[i],2)

print round(Qs),"bearing force in kN"
  depth(m)	 fc(kN/m**2)	 alpha 	 	 deltaL(m)	 Q(kN)

6 		    34.34 	   0.84 	    6 		  211.15
12 		    54.94 	   0.71 	    6 		  285.53
20 		    70.63 	   0.63 	    8 		  434.29
931.0 bearing force in kN

Ex5.6:Pg-545

In [21]:
#example 11.6

import math
L=21; # in m
Qwp=502-350; # in kN
Qws=350; # in kN
Ap=0.1045; # area in m^2
Ep=21e6; # in kN/m^2
epsilon=0.62;
Se1=(Qwp+epsilon*Qws)*L/Ap/Ep; # in m
#part2
Iwp=0.85;
qwp=152/Ap;
Es=25e3; # in kN/m^2
D=0.356; # in m
mus=0.35;
Se2=qwp*D/Es*Iwp*(1-mus**2); # in m
#part3
p=1.168;
Iws=2+0.35*math.sqrt(L/D);
Se3=Qws/p/L*D/Es*Iws*(1-mus**2); # in m
Se=Se1+Se2+Se3; # in m
print round(Se*1000,1),"settlement in mm"
19.8 settlement in mm

Ex11.7:Pg-560

In [25]:
#example 11.7

Ep=207e6; # in kN/m^2
Ip=123e-6; # in m^4
nh=12000; # in  kN/m^3
#from table 11.13
xz=0.008;
Ax=2.435;
T=(Ep*Ip/nh)**0.2;
Qg1=xz*Ep*Ip/Ax/T**3;
#part2
Fy=248000;
d1=0.254;
Am=0.772;
Mzmax=Fy*Ip*2/d1; # in Kn-m
Qg2=Mzmax/Am/T; # in kN
if Qg2>Qg1 :
    Qg=Qg1;
    print round(Qg,2),"lateral load in kN"
# there is slight variation in answer in textbook due to approximation
53.27 lateral load in kN

Ex11.8:Pg-561

In [28]:
#example 11.8

import math
#part1
Ep=207e6; # in kN/m^2
Ip=123e-6; # in m^4
nh=12000; # in kN/m^3
#from table 11.1a
xo=0.008; # in m
L=25;
Fy=248000; # yield stress in kN/m^2
D=0.254;
Am=0.772;
Gamma=18.0; # in kN/m^3
phi=35; # in angle
Kp=(math.tan(math.pi/4+phi*math.pi/360))**2;
My=Fy*Ip*2/D; # in kN-m
Qug=140*Kp*D**3*Gamma; # in kN

#part2
Qg1=xo*(Ep*Ip)**0.6*nh**0.4/0.15/L; # in kN

if Qug>Qg1:
    Qg=Qg1;
    print round(Qg,2),"lateral load in kN"
40.2 lateral load in kN

Ex11.9:Pg-567

In [35]:
#example 11.9

import math
Wrh=30*12; # in kip-ft
E=0.8;
Wr=7.5; # in kip
S=1/8.0; 
C=0.1;
FS=6; # in factor of safety
n=0.4; # Coefficient of restitution
Wp=12/12.0*12/12.0*80*150+550; # in lb
Wp=Wp/1000.0;
Qu=E*Wrh/(S+C)*(Wr+n**2.0*Wp)/(Wr+Wp); # in kip
Qall=Qu/FS; # in kip
print round(Qall),"allowed bearing capacity in kip"
#part2
He=30*12.0;
L=80*12.0;
Ap=12*12.0; # area in in^2
Ep=3e6/1000.0; # in kip/in^2
FS=4; # factor of safety
Qu=E*He/(S+math.sqrt(E*He*L/2.0/Ap/Ep)); # in kip
Qall2=Qu/FS; # in kip
print round(Qall2),"allowed bearing capacity in kip"

#partc
a=27;
b=1;
He=30;
FS=3; # factor of safety
Qu=a*math.sqrt(E*He)*(b-math.log10(S)); # in kip
Qall3=Qu/FS; # in kip
print round(Qall3),"allowed bearing capacity in kip"
101.0 allowed bearing capacity in kip
104.0 allowed bearing capacity in kip
84.0 allowed bearing capacity in kip

Ex11.10:Pg-570

In [38]:
#example 11.10

Hp=350; # in HP
vp=0.0016; #  in m/s
Sl=0.762e-3; # in m/cycle
f=115; # in Hz
Qu=(0.746*Hp+98*vp)/(vp+Sl*f); # in kN
print round(Qu),"pile load capacity in kN"
2928.0 pile load capacity in kN

Ex11.11:Pg-578

In [42]:
#example 11.11

Lg=9.92; # in ft
Bg=7.0; # in ft
n1=3.0;
Nc=8.75;
n2=4.0/1000;
Ap=14.0**2.0/12.0**2;
cup=1775.0;
a1=0.4;#alpha1
p=4*14.0/12.0;
cu1=1050.0; # in lb/ft^2
L1=15.0;
a2=0.54;#alpha2
cu2=1775.0; # in lb/ft^2
L2=45.0;
FS=4; # factor of safety
Qu=n1*n2*(9*Ap*cup+a1*p*cu1*L1+a2*p*cu2*L2); # in kip
Qu2=Lg*Bg*cup*Nc+2*(Lg+Bg)*(cu1*L1+cu2*L2); # in kip
print round(Qu2/1000),"load in kip"
Qall=Qu/FS; # in kip
print round(Qall),"allowed load in kip"
4314.0 load in kip
757.0 allowed load in kip

Ex11.12:Pg-583

In [45]:
#example 11.12

import math
z1=21/2.0; # in ft
Lg=9.0; # in ft
Bg=6.0;# in ft
Qg=500*1000.0; # in kip
Cc1=0.3;
Cc2=0.2;
Cc3=0.25;
H2=12;
H3=6;
H1=21;
e1=0.82;
e2=0.7;
e3=0.75;
s1=Qg/(Lg+z1)/(Bg+z1); #sigma1 in lb/ft^3
s2=500*1000/(9+27)/(6+27);#sigma2 in lb/ft^3
s3=500*1000/(9+36)/(6+36);#sigma3 in lb/ft^3
ss1=6*105+(27+21/2)*(115-62.4);#sigmadash1 in lb/ft^3
ss2=6*105+(27+21)*(115-62.4)+(120-62.4)*6;#sigmadash2 in lb/ft^3
ss3=6*105+48*(115-62.4)+12*(120-62.4)+3*(122-62.4);#sigmadash3 in lb/ft^3
sc1=Cc1*H1/(1+e1)*math.log10((ss1+s1)/ss1); # in inch
sc2=Cc2*H2/(1+e2)*math.log10((ss2+s2)/ss2); # in inch
sc3=Cc3*H3/(1+e3)*math.log10((ss3+s3)/ss3); # in inch
sc=sc1+sc2+sc3; # in inch
print round(sc*12,1),"total settlement in inch"
9.6 total settlement in inch