基坑工程有限土体主动土压力计算分析研究

Analytical Study on Active Soil Pressure from Finite Soil Body in Construction Pit

在深基坑工程中,拟开挖基坑距已有建筑物地下部分较近时,基坑支护体系承受的是有限土体的土压力,若根据Rankine理论计算,常导致计算土压力偏大,造成浪费。针对基坑工程中有限粘性土体的土压力计算问题,基于滑楔体平衡理论,本文推导了考虑土体变形情况的有限土体土压力计算模式,通过工程实例计算进行对比分析,提出了基坑工程中有限粘性土体土压力的计算方法,结果表明有限土体土压力分布模式及其量值与半无限土体土压力分布模式及其量值间存在显著差异,当有限土体宽度不大于坑深的0.75倍时,宜按有限土体土压力计算模式进行计算。

In construction pit, the retaining structure is loaded with the lateral active soil pressure derived from the finite soil body between the pit wall and the underground structures of existing surrounding buildings. Traditionally, the active soil pressure is determined by Rankine＇s Theory, and its result greatly deviates and causes waste. Based on Wedge Theory, various active soil pressure modes, existing in deep foundation pit, are suggested taking certain finite soil body deformation patterns, such as sliding and cracking into consideration. Finally, a moderate case study is given to validate the calculation and analysis by a real engineering example and a developed software. It revealed that the active clay pressure mode and its outcomes of finite clay body are quite different from those of semi-infinite clay body. When the breadth of finite clay body is 0.75 or less of the height of pit wall, the active soil pressure of pit wall should be estimated in accordance with the calculation modes of finite soil body.