Pile Design and Construction Practice, Fifth edition

348 Piles to resist uplift and lateral loading

where
Em 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 kmshould 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 0.75Bthen to use the
full reaction given by the upper curve in Figure 6.34b.
Baguelin et al.(6.22)give the following equations for calculating deflections, bending
moments and shears at any depth zbelow the ground surface for conditions of a constant
value of the pressuremeter modulus with depth:

Deflection (6.45a)

Moment (6.45b)

Shear (6.45c)

where
R stiffness coefficient given by equation 6.11 (Baguelin refers to this as the trans-
fer length, l 0 )
H horizontal load applied to the pile head
Mt 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

(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 (6.48a)

RkmB

F 2

and slope y 0  ^2 H

R^2 kmB



4 Mt

R^1 kmB

radians

y 0 2 H

RkmB



2 Mt

R^2 kmB

X

R

T(z) HF 4 

2 Mt

R

F 3

M(z)

H.R.F 3

R

MtF 2

y(z) 2 H

RkmB

·F 1 

2 Mt

R^2 kmB

·F 4

z

1 X

Xc

2