Pile Design and Construction Practice, Fifth edition

sustained horizontal load which can be applied at a point 4 m above ground level. Also find
the maximum working load if the lateral deflection of the pile at ground level is limited to
not more than 25 mm.
Consider first the ultimate horizontal load. For conditions of immediate application, that
is, using the undrained shearing strength, from Table 6.5 for cu � 120 kN/m , the soil mod-
2
ulus k is 7.5 mN/m 2 . If the elastic modulus of concrete is 26 � 10 3 MN/m 2 and the moment
of inertia of the pile is 0.0491 � (900) 4 mm 4 , from equation 6.11:
R �� 4 26 � 103 � 0.0490 � 0.9 4
7.5 � 0.9
� 3.3 m
Piles to resist uplift and lateral loading 363
L is 6 m which is less than 2R, therefore the pile will behave as a short rigid unit, and Brinch
Hansen’s method can be used. Brinch Hansen’s coefficients, as shown in Figure 6.22 with
c � c u � 120 kN/m 2 and � � 0 are as tabulated below:
z (m) 0 1 2 3 4 5 6
z
B
0 1.1 2.2 3.3 4.4 5.5 6.6
Kc 2.2 5.5 6.2 6.7 7.0 7.2 7.3
cuKc 264 660 744 804 840 864 876
The soil resistance of each element 1 m wide by 1 m deep is plotted in Figure 6.44a. As a
trial assume the point of rotation X is at 4.0 m below ground level. Then taking moments
about point of application of H u:
�M � (462 � 1 � 4.5) � (702 � 1 � 5.5)�(774 � 1 � 6.5) �(822 �1 � 7.5)
� [(852�1�8.5) � (870�1�9.5)] ��16 291 Nm per metre width of pile
(a) (b)
Hu 4.00
0.900 pile
4.00
0.900 pile
0 264
0 58
Ground
level
1
2
3
4
5
6
X
462
660
702
744
774
804
822
840
852
864
870
876
1
2
3
4
5
6
151
244
324
416
496
577
666
X 755
842
928
1011
1094
Depth in m
Figure 6.44
Depth in m
H u