考虑地表边界效应的静压沉桩挤土位移解析

Analysis of Ground Displacement Caused by Pile Installation Considering Boundary Effects

摘要:

在沉桩挤土位移求解过程中同时考虑了土体弹塑性本构关系以及地表边界效应的影响.假定桩周土体屈服后服从修正剑桥模型，基于圆孔扩张理论推导了桩体无限长时挤土位移的初始解.在此基础上，引入修正函数来考虑地表边界和沉桩深度对挤土位移的影响；经与文献实测结果比较，验证了修正后沉桩挤土位移解析方法的合理性和可靠性.参数分析表明，沉桩挤土位移随桩径的增加呈非线性增长，随预钻孔孔径的增大呈非线性减小；当超固结比增大时，挤土位移也随之增大，分析认为是由于重超固结土颗粒排列紧密，受到的挤压作用明显所致.

Abstract:

In the analytical analysis of the lateral displacement caused by pile installation, an elasticplastic model of soils and the effects of the ground surface boundary were synchronously considered in this study. To be specific, the modified Cam Clay constitutive model was used to capture the soil behavior after yielding. The initial solution of ground displacement induced by installation of pile with infinite was derived based on the theory of cavity expansion. The effects of boundary surface and depth of pile buried in soils were considered by introducing a modified function into the initial solution. The analytical solution was validated using the field measure data first. Then it is exploited to undertaken parameter analysis. The results show that the soil displacement caused by pile installation increases nonlinearly with the increase of pile diameter and the decrease of preboredhole diameter. In addition, the displacement also increases with OCR, which can be attributed to the obvious squeezing effect of the heavily consolidated soils with compact structures.