二元岩土基坑支护中强度折减法的研究及应用

Research and Application of Finite Element Strength Reduction Method in the Support of Dualistic Foundation Pit

采用吊脚桩支护结构的二元岩土基坑侧土压力分布复杂,岩肩嵌固作用不明确,难以确定支护结构内力和失稳模式。本文利用有限元强度折减法考虑支护结构和岩土体共同作用,分析了吊脚桩支护结构的侧土压力分布,以及岩土体破坏模式和对应的安全系数。分析结果表明,强度折减法以安全系数定量评价了吊脚桩支护二元基坑的稳定性,在确定基坑破坏模式的同时,也确定了侧土压力分布。支护桩弯矩随工况的变化趋势表明在基岩垂直开挖后,需重点关注锁脚锚杆轴力和预留岩肩的完整程度对二元岩土基坑稳定性的控制作用。

Due to the formation of suspending pile supporting structure in the dualistic foundation pit,the earth pressure distribution form is complicated,and the rock shoulder embedding effect is not clear,so it is difficult to determine the internal force and failure mode of the supporting structure.In this paper,the finite element strength reduction method,considering the joint effect of structure and the rock and soil mass,was used to analyze the earth pressure distribution,and accordingly the shear failure form and the corresponding safety factor of the dualistic foundation pit supported by the suspending pile,is obtained.The analysis results show that the finite element strength reduction method can not only quantitatively evaluate the stability of the dualistic foundation through the safety factor,but also determine the potential failure modes of multiple sliding surfaces of the binary foundation pit,which directly determined the earth pressure distribution on the supporting structure.The variation trend of the bending moment of pile with the working conditions indicates that after the excavation of the bedrock,the control effect of the axial force of the feet-lock foot bolt and the integrity of the reserved rock shoulder on the stability of the dualistic foundation should be focused on.