预钻孔孔径对沉桩挤土效应的影响分析

为研究预钻孔孔径大小对沉桩挤土效应的影响,基于修正剑桥模型的圆孔扩张理论解答,把沉桩过程看作不排水的圆柱形孔扩张的过程,把桩周土体分为塑性区与弹性区,对比分析不同预钻孔孔径下沉桩产生的塑性区半径、桩土接触压力、桩周土体位移、孔隙水压力.分析表明土体性质及修正剑桥模型中的参数对挤土效应均有影响,其中各向同性超固结比对挤土效应的影响最大,当预钻孔孔径小于一定值时,孔径大小变化对挤土效应影响不明显.本文分析可以为沉桩工程提供理论参考.

Analysis on the Influence of Diameter of Preboredhole on Pile Driving Effect

Based on the modified Cam -clay model and the cavity expansion method , the process of pile driving was considered as cylindrical cavity expansion along the pile .Soil around the pile was divided into two zones：plastic zone and elastic zone .This paper analyzed the influence of different preboredhole diameters on ra-dius of plastic zone , contact pressure between pile and soil , soil displacement and pore water pressure around the pile when driving piles .Analysis showed that both soil properties and modified Cam -clay model parameters can influence the driving effect , whose isotropic over consolidation ratio is the most important factor .When the pre-boredhole diameter is smaller than a critical one , it has a little impact on the driving effect .This paper aims to provide a theoretical analysis reference for pile driving practice .