膨胀土地层地铁车站基坑围护结构受力与变形分析

Analysis of stress and deformation in enclosure structure of metro foundation pit in expensive soil stratum

成都地铁天回镇南站位于膨胀土地层,基坑周边膨胀土在上层滞水浸泡下产生膨胀力作用于车站基坑围护结构上,在基坑开挖过程中围护桩体变形过大,桩端出现踢脚现象,极易导致围护结构体系失稳。针对这种情况,采用FLAC差分软件对车站围护结构及基坑开挖进行模拟计算,分析该膨胀土地层围护桩的合理插入深度及横撑轴力增量、桩体最大位移、桩端位移随膨胀力变化的规律,并提出确保围护结构稳定的应对措施。

Chengdutianhui town south metro station is located in the expansive soil layer. The expansive soil surrounding foundation pit and soaking by the upper perched water produced expansion force applied to the station foundation pit retaining structure. During the excavation, the supporting pile deformation is too large and kicking phenomenon occurs in pile ends, which are easy to result in the enclosure structure system instability. Aimed at this situation, conducting the simulation calculation for the station enclosure structure and excavation by finite difference software-FLAC. Analysis the expansive soil layer supporting piles reasonable insert depth, the lateral brace axial force increment, the pile maximum displacement, and displacement laws of pile end changed with the expansion force to put forward the control measures.