残积土水稳性差,强度参数随饱和度和应变水平变化而变化.为了研究深厚残积土层中的基坑变形特性受降雨的影响,依托厦门某残积土深基坑工程开展围护桩变形和坑外地面沉降的监测;结合开挖工况和降雨数据,探讨降雨条件下残积土结构弱化对基坑支护结构和土层环境变形响应的影响.结果表明:基坑围护结构和土体的变形在连续降雨阶段较小,在雨停后的排水清淤阶段开始缓慢增大;排水清淤后继续开挖,基坑变形急剧增大.开挖结束后,基坑围护桩的最大侧向变形量约为无降雨影响下的1.5倍,坑外地表沉降的影响范围从开挖深度的1.5倍增至2.5倍.研究结果对受降雨影响的残积土基坑的工程应用具有一定的参考意义.

Residual soil has a poor water stability, whose strength varies with the changes of saturation and deformation. To study the deformation response of foundation pit in deep residual soil affected by rainfall, the deformation of retaining pile and ground surface settlement outside the pit was monitored based on a deep residual soil foundation pit project in Xiamen. Combining the excavation steps with rainfall data, the influence of the strength weakness of residual soil caused by rainfall on the deformation of retaining piles and soil was discussed. The results show that the deformation of retaining piles and soil settlements remains stable during rainfall, and increases slowly in the stage of drainage. However, as the excavation continues after drainage, the deformation increases significantly. The maximum lateral deformation affected by rainfall is about 1.5 times of that without rainfall. The influence range of the ground surface settlement on excavation depth increases from 1.5 to 2.5 times due to rainfall. The results have a certain reference significance for the engineering application of residual soil foundation pit affected by rainfall.