富水软弱破碎带大断面隧道施工渗流影响及控制效果分析

依托某大断面隧道工程为背景,通过数值模拟并结合现场实测方法研究了隧道不同埋深条件下拱顶沉降、水平收敛、整体围岩应力和塑性区分布规律,并在此基础上,又对隧道在富水条件下的孔隙水压力进行了探讨。结果表明:拱顶沉降、水平收敛位移与水位高度呈正相关,埋深对水平位移影响较小,但影响范围增大;且随着隧道埋深的增加,拱顶沉降和水平收敛位移将在与破碎带间隔10m左右开始呈“瀑布式”增长;围岩应力随埋深和水位高度呈线性增长,其最大值集中在在拱腰处,最大达到1.34MPa,增长速率受水位高度影响更大;塑性区主要分布在隧道两侧,但随着埋深增加,拱顶也出现少量塑性区,这对拱顶的稳定是十分有利的;隧道周围孔隙水压力与埋深和地下水位高度呈正相关。该项研究可为提升大断面隧道穿越断层破碎带施工提供有益的借鉴和参考。

Analysis on Seepage Influence and Control Effect of Large Section Tunnel Construction in Water Rich Weak Fracture Zone

Based on the background of a large section tunnel project, through numerical simulation and field measurement, the settlement of vault, horizontal convergence, overall surrounding rock stress and plastic zone distribution of tunnel under different buried depths are studied. On this basis, the pore water pressure of tunnel under water rich conditions is discussed. The results show that the vault settlement and horizontal convergence displacement are positively correlated with the height of water level, and the buried depth has little effect on the horizontal displacement, but the influence range increases; With the increase of the buried depth of the tunnel, the vault settlement and horizontal convergence displacement will begin to increase in a "waterfall" at an interval of about 10 m from the fracture zone; The stress increases linearly with the height of the arch, and the maximum stress increases at the waist height of the arch and reaches 1.34 MPa; The plastic zone is mainly distributed on both sides of the tunnel, but with the increase of buried depth, a small amount of plastic zone also appears on the vault, which is very beneficial to the stability of the vault; The pore water pressure around the tunnel is positively correlated with the buried depth and the height of groundwater level. This study can provide useful reference and reference for the construction of large section tunnel crossing fault fracture zone.