The Influence of a Thin Weak Clay Layer on the Close-Ended Pile Behaviors in Sand

This work studies the uncertainties in the bearing capacity of axially loaded close-ended piles. The focus is on the impact of the location of a thin weak clay on the behaviours of the piles in sand. Simulations have been conducted in Plaxis 3D by varying the position of the weak layer relative to the pile tips. The thickness of the weak layer equals one diameter of the pile (1D). It is found that the effect of the thin weak layer on the pile behaviour varies with its location. The influence zone of the weak layer is found to be 1D above and 4D below the pile tip under the 0.1D settlement criteria. The relative distance between the weak layer and pile tip is one of the critical factors that affect the failure mechanism of the piles. The weak clay layer may increase, decrease or has no impact on the bearing capacity of the piles depending on the location of the weak layer. A probabilistic analysis is performed to study the variation of the pile bearing capacity with the location of the weak layer.

Keywords: Thin weak clay layer, pile capacity, FEM simulation, influence zone.