近距离双洞单线地铁隧道开挖变形规律分析

Analysis of Deformation Law of Short-distance Double-hole Single Line Subway Tunnel Excavation

地下工程的建设,不可避免地会造成地层的沉降变形以及地面塌陷等现象,如何有效降低地铁隧道开挖造成的变形,是地铁隧道建设一直以来工作的重点和难点.以天津地铁6号线双洞单线段为例,采用MIDAS数值模拟软件建立三维隧道开挖地质模型,分析不同隧道截面对围岩变形的影响,在此基础上分析不同双洞间距对隧道开挖的影响.结果表明:圆形断面隧道相比其他三种断面变形量相对最小,其次为拱形断面隧道,次之为三心圆断面隧道效果最差,且圆形断面隧道剪应力变化偏转情况相对幅度和偏转范围也最小,最有利于隧道施工;双洞隧道间土层变形受双洞间距的影响,双洞间距越小,围岩变形程度越大,当双洞距离大于25 m后,围岩变形程度受双洞间距的影响程度逐渐减缓.

The construction of underground engineering will inevitably cause the phenomenon of ground settlement deformation and ground collapse.How to effectively reduce the deformation caused by subway tunnel excavation has always been the focus and difficulty of work.Taking Tianjin Metro Line 6 double-hole single line section as an example,the MIDAS numerical simulation software is used to establish a three-dimensional tunnel excavation geological model to analyze the impact of different tunnel sections on the deformation of surrounding rock,On this basis,the influence of different double tunnel spacing on tunnel excavation is analyzed.The results show that compared with the other three types of tunnel,the circular section tunnel has the smallest deformation,followed by the arch section tunnel,and the three-center section tunnel has the worst effect,and the circular section tunnel has the smallest shear stress deflection relative amplitude and deflection range,which is the most conducive to tunnel construction.The soil deformation between double holes is affected by the distance between double holes.The smaller the distance between double holes,the greater the deformation degree of surrounding rock.When the distance between double holes is larger than 25m,the influence degree of surrounding rock deformation gradually decreases.