SHEET PILE WALLS
 generally used for retaining shallow
heights of soil
 wharfs, key walls
 temporary structures for excavation (eg.
dredging)
From McCarthy, 6th Edition
Cantilever Sheet Pile Walls
 stability depends on passive resistance
developed below the lower soil surface
 failure is by rotation about a point O near
bottom of wall
Active E.P.
Depth of
embedment, d
d
O
fixity
Passive E.P.
 a fixing moment is provided by the extra depth
below point O to prevent rotation
 Generally, design is based on a simplified but
equivalent approach: the fixity provided
previously is replaced by a resisting force, R at
point C which is just below point O
Active E.P.
Passive E.P.
d
C
R
Danish Rules
 a factor of safety, FP is applied to the
passive resistance in front of the wall
 take moments about C to calculate d
 then, increase d by 20% (empirical)
 finally, check that the passive resistance
provided by the extra 20% is > R, where
R = SPH
Free Earth Support
Passive E.P.
A
T
tie rod
45° - f/2
b
da
Active E.P.
anchor wall
d
45° + f/2
no fixity
 Determine the depth of embedment, d by taking
moments about A (SMA = 0, apply FP)
 Find tension, T from SFH = 0 (don’t apply FP)
 Constraints: failure wedges must not overlap
b > ½ da