Pile Design and Construction Practice, Fifth edition

Baguelin et al.(6.22)give two sets of curves relating the response of the soil to lateral loading
for the two stages in the pressuremeter tests as shown in Figure 6.34b. The upper curve is
for depths below the ground surface equal to or greater than the critical depth, xc, at which
surface heave affects the validity of the calculation method. In fine-grained soils xcis taken
as twice the pile width and in coarse soils it is four times the width. Where there is a pile
cap there is no surface heave, xcis zero and the lower curve in Figure 6.34b applies. The
value of the coefficient of subgrade reaction, kmin Figure 6.34b, is given by

for pile widths greater than 600 mm

(6.43a)

for pile widths less than 600 mm

(^1) (6.43b)
km

B

Em

4(2.65)^  3

18 

1

km

2

9 Em

B (^0) B
B 0
·2.65
^ B
6 Em
Piles to resist uplift and lateral loading 347
Pseudo
elastic
(a)
(b)
Pressure
Soil reaction
p
Deflection y
Plastic
Limit pressure pl
Creep pressure pf
Volume change
Vf
VO
pu 5 pl
pu 5 pl
x > xc
kp 5 0.5km
pf
km
l
l
x 50
2
pl^2
Figure 6.34Obtaining soil reaction values from pressuremeter test (a) pressure/volume change
curve (b) design reaction curve (after Baguelin et al.(6.22)).