胡麻岭隧道水敏性砂岩地下水渗流场模拟研究

Research on the Seepage Field Simulation of Water- sensitive Sandstone in Humaling Tunnel

研究目的:兰渝铁路胡麻岭隧道中部的第三系砂岩,施工中出现涌水涌砂现象,进度缓慢,安全风险高。根据勘探试验及现场开挖揭示的文地质特征开展科研攻关,深入分析含水砂岩段的水文地质条件及富水性,建立相应的水文地质数学模型进行模拟计算,指导隧道施工,加快工程进度。研究结论:(1)第三系砂岩具有复杂的水敏特性,在地下水的作用下,围岩易发生塑性变形或流变,施工难度大;(2)概化计算单元的边界条件,建立了水文地质概念模型及数学模型,运用MODFLOW软件对第三系水敏砂岩地下水渗流场进行了模拟,计算了最大流速及水量;(3)渗流场模拟计算与常用公式计算的涌水量经施工开挖检验,模拟成果更接近实际发生的涌水量;(4)本文提出的地下水渗流场模拟及涌水量计算方法,对均质含水地层水文地质条件分析具有一定的参考意义。

Research purposes： The Tertiary sandstone lies in the middle of Humaling Tunnel. Water and sand inflow appeared during construction, which caused the slow process and the high security risk. According to the field survey, we analyzed the hydrogeological characteristics and water abundance of the water - bearing sandstone and established related hydrogeological mathematical model to simulate the groundwater seepage field, in order to speed up the job progress. Research conclusions： （1） The Tertiary sandstone has complex water - sensitivity. Under groundwater condition, plastic deformation or flowing deformation occurring in the rock mass caused high difficulty during construction. （2） By conceptualization of the computing cell boundary conditions, we set up the hydrogeological conceptual and mathematical models by using the MODFLOW, and simulated the seepage field of Tertiary water - bearing sandstone and calculated the maximum velocity and water inflow of the tunnel. （3） Compared with the conditional water inflow calculation methods in excavation, the numerical simulation method did more tally with the actual situation of water- inflow. （4） The methods of seepage field simulation and water - inflow calculation in this study has certain reference significa nce for hydrogeological condition analysis in homogeneous water- bearing strata.