注浆加固对近水库隧道裂隙密集带区地下水渗流场的影响性分析

Analysis on Influence of Grouting Reinforcement on Groundwater Seepage Field in Adjacent Reservoir and Tunnel Dense fracture Zone

摘要:

利用Visual-modflow三维可视化渗流软件建模分析了邻近水库裂隙密集带地层，隧道开挖至注浆前后全过程地下水渗流场分布规律。结合隧址区水库、裂隙密集带等水力联系的影响，研究了隧道施工未扰动下渗流场演变过程。结果表明，毛洞开挖后裂隙水垂直补给隧道，影响范围很大，水库方向的反向补给或贯通排泄并不明显；隧道初期支护有利于保持地下水流场稳定，由于密集裂隙带的存在，横断面渗流变化与毛洞状态初期较为接近；随着注浆加固止水效果的提升，地下水向隧道内汇集的趋势减弱且范围减小，当围岩渗透系数折减到90%时，与初始渗流场较为接近，表明良好的防水体系对维持地下水渗流场稳定发挥了较好的作用；密集裂隙带的存在仅对局部渗流场有影响，对隧道和水库之间的水力联系并无显著影响。

Abstract:

The formation in dense fracture zone of adjacent reservoir is analyzed by using Visual-modflow 3D visual seepage software modeling. The distribution law of groundwater seepage field in the whole process from tunnel excavation to grouting is analyzed. Combined with the influence of hydraulic connections such as reservoir and fracture dense zone in tunnel site area, the evolution process of seepage field under the undisturbed tunnel construction is studied. The results show that the fracture water recharges the tunnel vertically after tunnel excavation with large influence range. The reverse recharge or the through discharge in the direction of reservoir is not obvious. The preliminary support of tunnel is helpful to maintain the stability of groundwater flow field. Due to the existence of dense fracture zone, the change of cross-section seepage is close to the preliminary stage of tunnel. With the improvement of grouting reinforcement water-stop effect, the tendency of groundwater to collect into the tunnel is reduced and the range is decreased. When the seepage coefficient of surrounding rock is reduced to 90%, it is close to the initial seepage filed, which indicates that the good waterproof system plays the good role in maintaining the stability of groundwater seepage field. The existence of dense fracture zone has an influence only on the local seepage field, and has no significant influence on the hydraulic connection between tunnel and reservoir.