Pile Design and Construction Practice, Fifth edition

348 Piles to resist uplift and lateral loading
where
E m � mean value of the pressuremeter modulus over the characteristic length of
the pile
B 0 � pile width
� � rheological factor varying from 1.0 to 0.5 for clays, 0.67 and 0.33 for silts, and
0.5 to 0.33 for sands
Between the ground surface and the critical depth, Xc, the value of km should be reduced by
the coefficient �z, given by
(6.44)
A simplified procedure in a homogeneous soil is to assume that there will be no lateral soil
reaction between the ground surface and a depth equivalent to 0.5 to 0.75B then to use the
full reaction given by the upper curve in Figure 6.34b.
Baguelin et al. (6.22) 1 �
�z �
give the following equations for calculating deflections, bending
moments and shears at any depth z below the ground surface for conditions of a constant
value of the pressuremeter modulus with depth:
X
Xc 2
Deflection y(z) � (6.45a)
2H
RkmB · F1 � 2Mt R2kmB · F4 Moment (6.45b)
Shear T(z) � HF4 � (6.45c)
2Mt R F M(z) �
3
H.R. F3 R
� MtF2 where
R � stiffness coefficient given by equation 6.11 (Baguelin refers to this as the transfer
length, l 0)
H � horizontal load applied to the pile head
M t � bending moment at the pile head
z � dimensionless coefficient equal to
Values of the coefficients F 1 to F 4 are given in Figure 6.35.
At the ground surface the deflection becomes
and slope � y0 � � �2H
R2kmB � 4Mt R1kmB radians
y0 � 2H
RkmB � 2Mt R2kmB (6.46)
(6.47)
If the head of the pile is fixed so that it does not rotate ( y 0 � 0) equations 6.45 to 6.47
become
y(z) � H
Rk mB F 2
X
R
(6.48a)