基坑大开口逆作环板支撑体系刚度效应分析

Stiffness Effect Analysis on Support System of Beam and Slab Structure with Large Opening in Top-down Excavation Foundation Pit

将有限元法与结构力学理论相结合,提出基坑大开口逆作环板支撑体系的刚度计算方法,分析了逆作环板开口形式、尺寸及开挖深度对支撑体系刚度的影响,以及围护墙的侧移及内力随支撑刚度变化的情况,并通过工程实例及监测数据验证了该计算方法的可行性.结果表明:对于开口形式为圆形、方形的大开口环板水平支撑体系,其刚度与开口尺寸比的关系分别为上凸、下凹形式的二次曲线;而2种开口形式的结构刚度与开口面积比的关系均呈现出下凹的二次曲线形式,开口面积比可作为优化工程设计的控制指标.

The FEM method and theory of structure mechanics were adopted to analyze the relationship be- tween the shape or the size of the opening and the support system stiffness of the beam and slab structure. The response of the lateral displacement and inner force of diaphragm wall with the variation of support stiffness in different depth were studied. The results show that the relation curves of the structure stiff- ness and opening size are different between the circular shaped opening and square-shaped opening; howev er, the relation curves of the structure stiffness and opening area are similar between different opening shapes, and the opening area ratio can be used to determine the minimum structure stiffness and the maxi- mum opening size of the beam and slab structure in engineering design. The lateral displacement of enclo- sure structure increases with the decrease of the support system stiffness, but no adverse impacts are noted to the inner force of the enclose structure. The inner force of the enclosure structure can be optimized by adjusting the opening size and shape of the beam and slab structure.