基坑外卸载对连续墙主动土压力的影响及计算

基坑外卸载对连续墙主动土压力的影响到目前为止很少有人问津.以上海铁路南站3.5万伏变电所基坑为工程背景,利用有限元及现场实测资料对基坑外卸载情况下的连续墙主动土压力进行了研究,并推导了其计算公式.研究认为,基坑外卸载主要对连续墙顶、底部土压力产生影响;当卸载边缘离开挖基坑边缘距离大于1～1.5倍的基坑开挖深度时,可不考虑其对基坑连续墙土压力的影响;随着土体强度的降低,卸载对连续墙土压力的影响增大.

Study on Active Earth Pressure behind the Retaining Wall of a Foundation Pit Influenced by Neighboring Unloading

To study the active earth pressure behind the Retaining Wall under the condition of an unloading or negative overload existing near the foundation pit, finite element and in - situ data were used based on the foundation pit work of Shanghai Railway South Station Electric Substation. Equations of active earth pressure considering of neighboring unloading were also given in this paper. It was found that soil pressures of the upper and under part of the retaining wall will be influenced by neighboring unloading, and could not be taken into account when the distance between unloading and retaining wall are more than 1 - 1.5 times of excavation depth, The influence will be bigger with the angle of internal friction decreases.