Load-settlement behaviour of bored piles with loose sediments at the pile tip: Experimental, numerical and analytical study

An elevated raft technique is proposed for cast-in-place bored piles, where loose sediments and excavation debris at the pile tip can be compressed by the applied load from the superstructure. The axial load-settlement (i.e., P-S curve) behaviour of bored piles with debris is evaluated by a series of model-scale laboratory experiments. Numerical simulation is conducted using a two-dimensional axisymmetric model for comparison. An analytical model is then proposed to capture the whole P-S curve in three segments: (a) the contribution of skin friction, (b) increased settlement associated with the compression of debris, and (c) the development of tip resistance.