Geotechnical Engineering

DHARM

SETTLEMENT ANALYSIS 397

Immediate Settlement of a Thin Clay Layer

The coefficients of Tables 11.2 and 11.3 apply only to foundations on deep soil layers. A draw-
back of the method is that it can be applied only to a layer immediately below a foundation and
extending to a great depth.

For cases when the thickness of the layer is less than 4B, Steinbrenner (1934) prepared
coefficients. His procedure was to determine the immediate settlement at the top of the layer
(assuming infinite depth) and to calculate the settlement at the bottom of the layer (again
assuming infinite depth below it). The difference between these two values is the actual settle-
ment of the layer.

The immediate settlement at the corners of a rectangular foundation on an infinite
layer is given by:

Si = q. B

F 1 −^2

HG

I

KJ

ν

E

I

s

. s ...(Eq. 11.6)

The values of the influence coefficients Is (assuming ν = 0.5) are given in Fig. 11.3.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Influence coefficientIs

2

4

6

8

10

H/B

L/B=1

2

¥

10

5

Df

H

G.S.

B

Df

H 1

G.S.

B

H 2

(c) Values ofIsfor different values of H/B

(a) Layer immediately below

foundation

(b) Layer at a certain depth

below foundation

Fig. 11.3 Immediate settlement of a thin clay layer (After Steinbrenner, 1934)