考虑孔压消散的静压单桩挤土位移场研究

STUDY OF COMPACTING SOIL DISPLACEMENTS AROUND JACKED SINGLE PILE BASED ON EXCESS PORE PRESSURE DISSIPATION

静压桩挤土位移会随压桩过程中产生的超孔隙水压力的消散而变化,但由于压桩过程的复杂性,这一问题尚没有得到很好的解决。基于应变路径法及源汇法理论,根据土体的固结度理论推导小应变条件下考虑孔压消散的静压单桩周围土体位移场的解析解,该解析解可以考虑如下问题:地表面的自由边界条件问题,土体中孔隙水压力的消散问题,并能给出整个压桩深度内土体的水平及竖向位移场。根据压桩过程中近桩身土体变形特性对大变形条件下近桩周土体位移场做出相应的理论推导,并分析大小应变条件下挤土位移场的差别。利用所获得的挤土位移理论解分析超孔压消隙对土体位移场的影响,与现场测试结果进行对比,结果表明:静压单桩水平挤土位移和地表面隆起量均随孔隙水压力的消散而减小;考虑孔压消散的静压单桩挤土位移场的理论解和实测值变化规律相一致,且数值上基本吻合,能够满足工程需要。

Compacting soil displacements vary with the dissipation of excess pore water pressure produced by the installed pile,and this problem is still not well resolved because of the piling process complexity. According to strain path method and source-sink method,the closed-form analytical expressions of displacement fields caused by the installation of jacked pile due to the dissipation of excess pore water pressure were obtained in small strain condition. The solution taking into consideration stress-free ground surface and dissipation of excess pore water pressure was in accordance with the practical engineering,and the solution could provide the whole-depth compacting soil displacements. Based on soil deformation characteristics near the installed pile,the integrate expressions of compacting soil displacements in large strain condition were also deduced,and the differences of compacting soil displacements in small and large strain conditions were analyzed. The influences of excess pore water pressure dissipation on compacting soil displacements were analyzed by use of the theoretical solution and the analytical results of compacting soil displacement were compared with field tests. The results show that the horizontal and vertical compaction soil displacements of the installed pile reduce with the dissipation of excess pore water pressure. Theoretical solution variation trends of compacting soil displacements based on the dissipation of excess pore water pressure were in accord with measured results,and the calculating values of soil displacements were agree well with experimental results.