Shaft resistance characteristics of steel pipe prebored and precast piles based on field loading tests

Prebored and precast piles (here and after, PPP) are being frequently used for various structures to reduce nuisance caused by vibration and noise, substituting driven piles. In PPP design, skin friction is the most critical factor affecting bearing capacity and settlement behavior. Main focus of this paper is set to establish an analysis model considering the interface behavior at the pile-cement milk-surrounding soil interface during the installation and in-use of PPP. A case of single pile was analyzed through a three-dimensional finite element approach and field load tests. In the analysis, t-z curve allowing a slip along the interfaces were proposed, designed with a certain length of slip for each soil layers. A series of numerical analysis on the interface of pile-cement milk-soil was conducted based on a proposed t-z curve. It is shown that the complex elements around the pile increases the skin friction to some extent and reduces the pile settlement.