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SHEET PILE WALLS. generally used for retaining shallow heights of soil wharfs, key walls temporary structures for excavation (eg. dredging). From McCarthy, 6 th Edition. Cantilever Sheet Pile Walls. stability depends on passive resistance developed below the lower soil surface
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SHEET PILE WALLS generally used for retaining shallow heights of soil wharfs, key walls temporary structures for excavation (eg. dredging)
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
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
Danish Rules • a factor of safety, FPis 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 tie rod T da A b • 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 >½da Passive E.P. 45° - f/2 Active E.P. anchor wall d 45° + f/2 no fixity