山地超深基坑吊脚墙的应用及研究

Application and research of hanging foot wall of deep foundation pit in mountainous area

在山地超深基坑中,通常是上层为土体、下层为岩体的岩土二元结构。此类基坑常用“吊脚墙”进行支护,其可利用下部基岩的稳定性,并可减少围护墙入岩工程量。本文结合大毛坞?仁和大道供水管道工程G1工作井,采用有限元数值模拟“吊脚墙”围护结构在上层土体和下层岩体开挖过程中产生的变形和内力。分析结果表明:上层土体和下层岩体开挖期间,基坑及围护墙的变形和内力均处于可控状态;下层岩体开挖基本不会对围护墙产生附加内力,且土体开挖期间,底部两道支撑对控制围护墙的水平位移具有很好的效果。

In the ultra-deep foundation pits in mountains area,there is usually a geotechnical dual structure with the upper layer of soil and the lower layer of rock masses.This kind of foundation is often supported by"hanging wall",which can make use of the stability of lower bedrock and reduce the depth of the wall invading the rock.In this paper,combined with the G1 working well of Da Maowu?Renhe Avenue water supply pipeline project,the numerical simulation method of finite element is used to simulate the deformation and internal forces of the upper soil layer and the lower rock masses during the process of excavation at the hanging wall structure,the finite element method is used to simulate the deformation and internal forces the lower rock masses of the"hanging wall"enclosure structure under the situation of excavation of the upper soil.The analysis results show that during the excavation of the upper soil and lower rock masses,the deformation and internal forces of the foundation pit and the retaining wall are under control;the excavation of the lower rock masses will not generate additional internal force to the diaphragm wall,and during the excavation of the lower soil layer,the two supports at the bottom have a good effect on controlling the horizontal displacement of the diaphragm wall.