刚性桩复合地基的主动土压力分析

桩足够长、桩间距不大于6倍桩径的刚性桩复合地基中，在桩间土内部的剪切力和桩土间摩擦力共同作用下，桩顶段桩间土压力仅在一定深度范围内有所增加，且随深度迅速衰减，而桩顶段桩身轴力随深度增加。基于刚性桩复合地基的这一特点，紧邻刚性桩复合地基开挖基坑且基坑底高于刚性桩桩底时，得出刚性桩复合地基上的附加荷载作用在支护结构上的主动土压力可以简化为倒三角形，最大主动土压力作用在刚性桩桩顶平面与支护结构相交处，随深度增加，主动土压力迅速衰减至0。实践表明该计算方法比较符合工程实际。

Analysis of active earth pressure of rigid pile composite foundation

In the rigid pile composite foundation that pile is long enough and is not more than 6 times the pile diameter,the internal shear force between pile and soil and under friction of the pile-soil interaction,the soil pressure in the top section of the pile only increased at a certain depth range,it decays rapidly with depth and axial force of top pile increases with depth in soil shear stress and friction.Based on this characteristic of the rigid piles composite foundation,when there is rigid pile composite foundation surrounding excavation and the excavation bottom is higher than rigid pile bottom,soil pressure on the retaining structure which is caused by the additional vertical stress of rigid pile composite foundation can be simplified as an inverted triangle;and the maximum earth pressure effect on intersection of the rigid pile top plane and supporting structure,as the depth increasing,the active earth pressure attenuates to zero.It is shown that the calculation method is consistent with the engineering reality.