陡倾岩层深埋地铁车站3台阶开挖可行性分析

Feasibility Analysis of 3 Benches Excavation of Deep Buried Subway Station in Steep Dip Rock Stratum

岩石地层中的地铁车站施工多采用双侧壁导坑法,工程实践中发现深埋地铁车站局部地段有采用3台阶法施工的案例。以陡倾岩层某深埋地铁车站为例,采用三维有限元数值模拟方法,从围岩变形、应力特征及塑性区分布特征三个方面,对车站采用3台阶开挖过程中的车站围岩应力应变特征随时间和空间的变化规律进行研究。有限元分析表明:岩石地层深埋地铁车站围岩的位移、应力大小及塑性区范围可以满足稳定和安全要求,且表现出明显的非对称性,在砂质泥岩–砂岩接触面两侧出现明显的位移错动;对研究断面影响较大的位置,基本上位于断面前后3个施工步(6.0 m)内。在车站施工过程中要注意岩层层面对围岩稳定性的影响,加强顺倾侧的监测和支护。

The subway station construction in the rock stratum mostly adopts the double side wall guide method.In the engineering practice,it is found that the 3 benches method is used in the local sec-tion of the deep buried subway station.Taking a deep-buried metro station in steep inclined rock stratum as an example,the variation of stress-strain characteristics of surrounding rock with time and space in the process of three-bench excavation of the station is studied by using three-dimensional finite element numerical simulation method from three aspects of deformation,stress characteristics and plastic zone distribution characteristics of surrounding rock.Finite element analysis shows that the displacement,stress and plastic zone of surrounding rock of deep-buried metro station in rock stratum can meet the requirements of stability and safety.It also shows obvious asymmetry and displacement dislocation on both sides of sandy mud-stone-sandstone interface.The excavation location which has great influence on the study section is basically located in three construction steps(6 m)before and after the section.During the con-struction of the station,attention should be paid to the influence of the rock layer on the stability of the surrounding rock,and the monitoring and support of the inclined side should be strengthened.