Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 7 RETAINING WALL
Thus the
factor of safety against sliding is given
by:
F = =
= 1.1 ≤ 1.5
not OK, need to increase resistance against sliding either
by increasing
the width of the base
slab, introduce shear key
or using raked pile.
7.6
7.6.1
FLEXIBLE WALL SYSTEM
General
Unlike rigid retaining wall, the stability of the flexible wall depends mainly on the embedded length
of the wall element. Some of the common types of flexible wall are sheet
pile wall, soldier pile wall,
contiguous bored pile wall and diaphragm wall. Sometimes due to stability requirement, tie backs or
anchors to deadman and strut system are used to increase the overall stability of the wall.
The common failure modes of a flexible retaining wall are:
a) Rotational failure (at strut/ /tie back or at
toe of the wall)
b) Deep seated/global stability failure
c) Hydraulic failure due to piping and uplift (in case of high differential hydrostatic head)
d) Structural failure (tie back failure or wall element failure)
(a) Deep-seated failure
(b) Rotation about the anchor/prop
(c) Rotation near base
(d) Failure of
(e) Failure by bending
Figure 7.20 Typical Failure Mode of a Flexible Wall
March 2009
7-25