大断面小净距城市隧道洞口段穿越散岩堆积体施工技术

Construction Technology of Urban Tunnel Entrance Section with Large Section and Small Net Distance Passing Through Loose Deposits

以曾家岩北延伸段二标段火凤山隧道工程为背景,采用FLAC3D软件研究不同施工工法、开挖顺序对大断面小净距城市隧道围岩变形规律的影响。结果表明:散岩堆积体地层条件下,隧道开挖采用台阶法造成的竖向位移较大,CRD法开挖围岩变形较小。由于左线隧道埋深大于右线隧道,左线隧道各监测点竖向位移均比右线隧道大。隧道开挖顺序对围岩变形有明显影响,右洞先行开挖竖向位移最小,左洞先行开挖次之,同时开挖最大。

Taking Huofengshan Tunnel of Section II of Zengjiayan north extension project as the background, FLAC3 D software was adopted to study the influence of different construction methods and excavation sequence on the deformation law of surrounding rock of urban tunnel with large section but small net distance. The results show that under the condition of loose deposits, the vertical displacement caused by the tunnel excavation is larger when using benching tunneling method, and smaller when using the CRD method. Because the left-line tunnel is deeper than the right-line tunnel, the vertical displacement of each monitoring point of the left-line tunnel is larger than that of the right-line tunnel. And the sequence of tunnel excavation has obvious influence on the deformation of surrounding rock. The vertical displacement is the smallest when first excavating the right hole, then is the excavating of the left, and the largest one is the simultaneous excavation of both the left and the right.