大方山隧道岩溶水分带综合分析

Comprehensive Analysis of Karst Water Zone in the Dafang Mountain Tunnel

研究目的:岩溶发育的垂直分带性已得到普遍认同,目前多数研究主要集中在分带现象的描述及如何规避岩溶风险进行选线上,而针对实际工程项目如何进行分带,采用何种方法进行分带的研究则较少。本文通过对大方山岩溶隧道采用工程地质及水文地质调绘、物理勘探、钻探等综合勘察方法,对隧道所在位置地下含水的强弱,泉点、暗河、岩溶洼地之间地下水相互关系,岩溶地下水的补给、径流、排泄条件,雨季、旱季岩溶洼地及隧道洞身地下水位测量等进行综合分析,以确定隧道所处分带。研究结论:(1)岩溶地下水分带应根据岩溶发育情况采用综合手段开展,遵循遥感、地质测绘、物探、钻探、监测、测试等各项工作的程序,循序渐进,相互配合;(2)大方山隧道岩溶段落地下水可划分为季节交替带和水平循环带;(3)根据地下水分带结果结合水文地质单元及选用相应的计算方法预测隧道涌水量,对施工时涌水、突泥风险进行预判;(4)本研究成果可对岩溶地区隧道所处地下水分带、涌水量计算方法的选定以及水量预测提供指导作用。

Research purposes: Vertical zoning of karst development has been generally recognized. At present,most articles mainly study zoning phenomena and how to avoid karst risk to select the line. However,there are few researches about how to zone and which method to use for actual engineering projects. Through comprehensive investigation methods such as engineering geology and hydrogeology mapping,physical exploration and drilling,this paper comprehensively classifies the relationship of groundwater among springs,underground rivers and karst depressions,the conditions of recharge,runoff and discharge of karst groundwater,and the strength of groundwater in the tunnel location,the groundwater table of karst depression and tunnel body in rainy season and dry season,to determine groundwater zoning of tunnel.Research conclusions:( 1) Karst groundwater zoning should be carried out by comprehensive means according to karst development,following the procedures of remote sensing, geological mapping, geophysical prospecting, drilling,monitoring and testing,and cooperating with each other step by step.( 2) Groundwater in karst section of Dafangshan tunnel can be divided into seasonal alternating zone and horizontal cycling zone.( 3) The tunnel water inflow is predicted based on groundwater zoning results combined with literature and geology sheets and corresponding calculation methods,and the risk of water gushing and mud bursting during construction is forecasted.( 4) The research result can provide guidance for determination of groundwater zoning,selection of calculation method of water inflow and prediction of water inflow of tunnel in karst area.