多空隙组合介质隧道渗透物理模型试验

Physical Model Test for the Seepage of the Tunnel Excavated in a Combinational Fractured-vuggy-porous Combination Media

跃龙门隧道工程施工期出现严重的涌突水问题,不仅制约隧道开挖安全,而且会因地下水位降低而触发该区植被生态健康问题。结合该隧道的水文地质条件,并基于相似模型原理,选用普通砖钻孔填砂模拟具有多空隙组合特征的岩体,设计研制了隧道渗透物理模型。物理模型考虑了岩体主要裂隙倾角分别为0°和60°两种情况。对两个倾角8种工况进行了渗透试验,测试分析表明:(1)主要裂隙方向会对渗流产生较大的影响,当倾角与水流方向夹角较小时涌水现象较为突出;(2)隧道正上方的地下水位下降最快,离隧道轴线越远的水位下降越慢,稳定渗流时的水位也越高,连接相同高程测点在同一时刻的水位形成的水面线均呈现降落漏斗形状;(3)试验获得的稳定渗流时间与原型观测结果一致;(4)模型影响范围与数值计算隧道开挖影响范围较为接近。

A serious inrush water problem occurred during the construction period of Yuelongmen Tunnel. It not only restricts security tunnel excavation, but also triggers vegetation ecological health problem of the area due to the decrease of groundwater level. This paper makes use of the treated common brick to simulate the field rock mass with a combinational fractured-vuggy-porous feature, designs and builds a physical model of tunnel seepage according to the hydro-geological conditions of the tunnel and on the basis of the principle of similar model. The physical model considers both cases in which the angles between the main crack of rockmass and horizontal direction are 0° and 60 ° respec- tively. The seepage test is carried out on 8 working conditions. The test results are analyzed and some conclusions have been drawn ： （ 1 ） The direction of the main crack has a great impact on seepage. The water gushing phenomenon is more prominent when the main crack and flow direction angle is smaller. （2） The decline of the water level above tunnel is fastest, and the water level away from the tunnel axis decreases more slowly, the stable water level is higher. The connecting line of water level of these measured points located in the same height presents landing funnel shape. （3） The stable seepage time obtained from the experiment is consistent with the prototype observation results. （4） The influenced range of model tests and the numerical calculation of tunnel excavation is relatively close.