软土地区基坑开挖超静孔隙水压力分布的有限元分析

Finite element analysis of excess pore water pressure during the excavation of soft soil foundation pit

依托某基坑工程案例,利用ABAQUS有限元软件对软土基坑开挖时的超静孔隙水压力进行有限元分析,研究超静孔隙水压力的分布规律及其对围护结构土压力的影响,结果表明:基坑开挖卸荷会在坑底及周围土体中产生负的超静孔隙水压力,坑底以下区域负的超静孔隙水压力分布较为集中且数值较大,坑外区域数值较小;负超静孔隙水压力的消散会引起挡墙前后有效土压力的减少,墙前减少更快,这对基坑工程是不利的,实际工程中应尽量缩短施工工期;邻近超载作用下会引起基坑负超静孔隙水压力绝对值的减少,这对基坑工程也是不利的。

Based on a foundation pit engineering case,the finite element software ABAQUS was used to conduct finite element analysis on the excess static pore water pressure during the excavation of soft soil foundation pit,and the distribution law of the excess static pore water pressure and its influence on the soil pressure of the enclosure structure were studied.The results showed that:The unloading of foundation pit excavation will produce negative excess pore water pressure in the pit bottom and surrounding soil.The distribution of negative excess pore water pressure below the pit bottom is more concentrated and its value is larger,while the value outside the pit is smaller.The dissipation of negative excess pore water pressure will lead to the reduction of effective earth pressure in front and back of the retaining wall,and the reduction in front of the wall is faster,which is unfavorable to the foundation pit engineering.In the actual project,the construction period should be shortened as far as possible.Adjacent overload will cause the reduction of the absolute value of negative excess pore water pressure of foundation pit,which is unfavorable to foundation pit engineering.