SHEET PILE WALLS

1
SHEET PILE WALLS

• generally used for retaining shallow heights of
  soil
• wharfs, key walls
• temporary structures for excavation (eg.
  dredging)

2

• From McCarthy, 6th Edition

3
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
Passive E.P.
fixity
4

• 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
R
C
5
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 gt R, where R SPH

6
Free Earth Support
tie rod
T
da
A
b
Passive E.P.
45 - f/2
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 (dont apply FP)
• Constraints failure wedges must not overlap
• b gt ½da