潜埋富水偏压隧道施工稳定控制分析

Analysis of Construction Stable Control of Shallow Bias Water-rich Tunnel

以新疆玉希莫勒盖隧道工程为依托,通过FLAC3D软件对其洞口段施工过程进行模拟,分析施工过程中围岩以及支护结构的变形、应力分布规律,及围岩开挖次序和地下水位对其的影响。研究结果表明:潜埋富水偏压隧道的最大竖向和水平位移位于隧道斜向4个角点位置,同时高压侧的围岩变形明显大于低压侧,且在隧道第1步开挖时差别最为明显;隧道开挖完成后,隧道底部围岩塑性区将会与泄水洞上方围岩塑性区连通成为一个整体,隧道围岩在隧道周边的破裂范围为底部4.2m、顶部5.6m、低压侧4m、高压侧7.6m;对于采用4步CRD法开挖的潜埋富水偏压隧道,应先开挖低压侧隧道上部土体,再开挖低压侧下部土体,最后再开挖高压侧上部和下部土体。

To study the stability control of the shallow-buried,unsymmetrical-loaded and water-rich tunnel,the Yuximolegai Tunnel in Xinjiang province is set as the engineering background,and the FLAC3D software is used to simulate and analyze the variation characteristics of force and deformation of the surrounding rocks and supporting structures of the portal section under construction. The impact of different excavation sequences of the surrounding rocks and the groundwater levels to the deformation of the surrounding rocks and the structural internal force is also studied. The results demonstrate that: the maximum vertical and horizontal displacements of the shallow-buried,unsymmetrical-loaded and water-rich tunnel arise at four oblique corners of the tunnel,and the deformation of the surrounding rocks on the high pressure side is significantly greater than that on the low pressure side,especially in the first step of the tunnel's excavation;after the tunnel excavation is completed,the plastic zones of the surrounding rocks both at the bottom of the tunnel and above the drainage hole will connect as a whole one,and the rupture range of the surrounding rocks around the tunnel is 4. 2 m at the bottom,5. 6 m at the top,4 m at the low pressure side and 7. 6 m at the high pressure side;for the shallow-buried,unsymmetricalloaded and water-rich tunnel excavated with four-step CRD method,the soil at the top of the tunnel's low pressure side should be excavated first,then the bottom of its low pressure side,and finally the top and bottom of its high pressure side.