岩溶地区基坑开挖桩锚支护结构变形与稳定性影响研究

Study on the Influence of Deformation and Stability of Pile-anchor Support Structure for Foundation Pit Excavation in Karst Area

为了探究溶洞对超长锚索支护基坑开挖与稳定性的影响,以广州市白云站二期基坑为研究对象,采用有限元软件Plaxis 3D建立了三维模型,分别从溶洞宽度、溶洞距锚固段始端和溶洞距地连墙的距离进行了模拟,并以地连墙沿深度方向的水平位移为指标进行了分析。研究结果表明:当溶洞宽度增加或溶洞距锚固段始端和溶洞距地连墙的距离减小时,对基坑变形的影响较大,且变形幅度较大,需对溶洞进行加固处理并及时监测基坑变形;当溶洞宽度减小或溶洞距锚固段始端和溶洞距地连墙的距离增加时,对基坑变形的影响减弱;当溶洞宽度减小或溶洞距锚固段始端和溶洞距地连墙的距离增加至一定程度后,几乎对基坑变形无影响。因此,在溶洞较发达地区进行基坑开挖,施工前对周围溶洞进行研究分析和预处理,有利于基坑稳定性。

In order to study the influence of the cavern on the excavation and stability of extra-long anchor cable supported foundation pit,the foundation pit of Phase II of Baiyun Station in Guangzhou was taken as the research object.A 3D model was established by the finite element software Plaxis 3D to simulate the width of the cavern,the distance of the cavern from the beginning of the anchorage section,and the distance of the cavern from the diaphragm wall.Being the indexes,the horizontal displacement along the depth of diaphragm wall was analyzed.The results show that when the width of the cavern increases or the distance of the cavern from the beginning of the anchoring section and the distance of the cavern from the diaphragm wall decreases,it has a greater influence on the deformation of the foundation pit and the deformation amplitude is larger so it is necessary to carry out the reinforcement for the cavern and monitor the deformation of the pit in time;Under the opposite conditions,the influence on the deformation of the pit is weakened;When the width decreases or the distances increases to a certain degree,it almost has no influence on the deformation of the foundation pit.Therefore,that study and analysis of the surrounding caverns and pre-treatment before construction will be beneficial to the stability of foundation pit to carry out foundation pitexcavation in the more developed cavern areas.