基坑近接地铁车站主动土压力合力算法研究

Algorithm for resultant force of active soil pressure of excavations adjacent to underground subway stations

针对有限土体主动土压力合力计算公式复杂的问题,以既有地铁车站邻域内新建基坑工程为依托,根据既有地铁车站与基坑的位置关系提出多种有限土体破坏模式,采用薄层微元法,考虑土体与结构界面摩擦作用,建立主动土压力合力计算方法。通过调整新建与既有结构空间位置关系,得到了主动土压力合力等值图,并对其开展了参数分析,提出了主动土压力简便计算方法。研究结果表明:①提出了5种有限土体破坏模式,建立了相应的主动土压力计算公式;②随着近接距离的增加,主动土压力逐渐增大;随着既有地铁车站覆土厚度的增加,靠近基坑的时候主动土压力逐渐增大,远离基坑侧的主动土压力先增大后减小最后增大;③基坑深度对主动土压力影响大,内摩擦角有影响,墙土摩擦角基本上没有影响;④给出了有限土体主动土压力合力空间位置关系系数建议取值情况。通过以上研究,提出了一种简便的有限土体主动土压力合力计算方法,可以为近接工程设计与施工提供参考。

Aiming at the problem of complex formula for calculating the resultant force of active soil pressure of limited soil,based on the newly built excavations in the vicinity of subway stations,multiple limited soil failure modes are proposed based on the positional relationship between the existing subway stations and the excavations.The thin-layer microelement method is used to consider the frictional effects between the soil and the structural interface,and a method for calculating the combined force of active soil pressure is established.By adjusting the spatial position relationship between the newly built and existing structures,an active soil pressure contour map is obtained,and the parameter analysis is conducted.Furthermore,a simple calculation method for active soil pressure is put forward.The research results indicate that:(1)Five finite soil failure modes are proposed,and the corresponding formulas for calculating the active soil pressure are established.(2)As the proximity distance increases,the active soil pressure gradually increases.As the thickness of the existing subway station cover increases,the active soil pressure gradually increases when approaching the excavation,and the active soil pressure on the side far from the excavation pit first increases,then decreases,and finally increases.(3)The depth of the excavation has a significant impact on the active soil pressure,the internal friction angle has an impact on the active soil pressure,and the wall-soil friction angle has basically no effect on the active soil pressure.(4)The value of the spatial position relationship coefficient of the combined force of active soil pressure is given.Through the above research,a simple method for the combined force of active pressure of limited soil is proposed to provide reference for the design and construction of adjacent projects.