【作者】 钟金先；

【导师】 许模；

【作者基本信息】 成都理工大学 ， 环境地质， 2010， 硕士

【摘要】 随着国内交通基础设施的建设和发展,复杂地质环境条件下的基岩裂隙型隧道的涌水量预测和危险性评价愈来愈受到重视。拟建的巴朗山隧道位于小金、汶川、宝兴三县交界处的巴朗山,是省道S303线的一段,是连接九环线和卧龙大熊猫自然保护区及东方圣山四姑娘山的唯一道路。由于越岭段地势十分险峻,气候恶劣,海拔高,拟建巴朗山隧道工程是为改善越岭公路的行车条件,提高行车安全,提升卧龙大熊猫自然保护区及东方圣山四姑娘山旅游资源而设计的。本文从隧址区岩性构造出发,查明地下水系统的补、径、排条件和运移规律及其水动力特征,分析地下含水介质类型,评价岩体渗透性,在此基础上选取隧道涌水危险性指标,分析隧道施工过程中可能出现的集中涌水段与突水点,再通过隧道涌水计算分析,验证危险性指标选取的合理性,从而进一步评价隧道涌水对工程与环境的影响。论文主要的研究内容和成果如下:(1)含水层岩性组合特征。本区地下水分为第四系松散岩类孔隙水和基岩裂隙水两种类型。其中松散孔隙水因地形起伏大,切割深,无法形成大片的补给径流区,主要以潜水或上层滞水形式存在,其富水性弱-中等,且受季节和气候的影响显著;基岩裂隙水主要由大气降水补给,其次接受高山地区的冰雪融化水的补给,动态季节变化明显,一般在沟底或低洼的地方出露。(2)岩体渗透性研究。通过深孔的压水试验以及岩芯室内渗透率测试,结果显示了砂岩的渗透系数比板岩的大;渗透系数随着深度的增加呈逐渐减小的趋势,到达一定深度后趋于稳定。(3)地下水水动力场、水化学场的研究。通过泉点调查追踪以及深孔揭示的地下水信息、水化学组分和氢氧稳定同位素分析,研究地下水补径排条件和循环交替规律。巴朗山南坡地下水循环以浅循环为主,岩石介质对于地下水化学类型的改造作用不明显,矿化程度普遍不高;巴朗山北坡以深部循环为主,主要原因是北坡“U”型谷更加发育、斜坡坡度较缓的缘故。(4)水系统研究分析。根据隧址区地下水的补径排特征划分地下水一级系统,即巴朗山北坡地下水系统和巴朗山南坡地下水系统,进而依据含、隔水层组的空间展布进一步划分次级地下水系统,初步判断海子沟口和高店子沟地下水系统对隧道的危险性较大。(5)隧道涌突水危险性指标的选取。本文主要通过收集整理关于隧道涌水量危险性分级的相关资料以及已有的研究成果,结合隧道的地质构造、水文地质条件等相关因素,初步选取了基岩裂隙型隧道的危险性评价指标,推测了隧址区的危险段。(6)隧道涌水量计算。利用传统的、经典的隧道涌水量计算公式(如降雨入渗法、水动力学法等),对已分段的巴朗山隧道进行典型地段涌水量计算,同时结合Visual ModFlow数值模拟计算,初步获得隧址区典型地段涌水量的范围。(7)隧道涌突水危险性综合评价。通过评价指标推测出巴朗山隧道危险段,利用涌水量计算结果进行校核,得出隧道危险段与该段隧道涌水量的值较为匹配。隧道整体涌水量较小,危险性小;仅在褶皱转折端和破碎带危险性相对较大,在施工和运营阶段需要特别注意。隧道开挖后将影响松散层孔隙水的径流、排泄条件,但隧道涌水漏失的主要为基岩裂隙水,对土壤含水、储水功能影响较小,对地表生态植被造的破坏较小。更多还原

【Abstract】 With the construction and development of domestic transportation infrastructure, people pay more attention to water inflow forecasting and risk assessment of the tunnel in the fissured bedrock in complex geological environment conditions. The proposed Balang Mountain tunnel will be built in Balang Mountain which is at the junction of Xiaojin, Wenchuan and Baoxing counties. The tunnel is a section of Provincial highway line S303 and it is the only way to connect nine ring lines, Giant Panda Nature Reserve of the Wolong, and the East Sacred mountain --Siguniang Mountain. For the steep terrain, bad weather and high altitude, the proposed tunnel project is to improve the conditions of road crossing the mountain, improve the traffic safety and enhance Giant Panda Nature Reserve of Wolong and the travel resources of East Sacred mountain --Siguniang Mountain.This paper first introduces the rock structure in the tunnel site areas, identifies the recharge, runoff and discharge conditions, the rule of migration and hydrodynamic characteristics of the groundwater system, analyses water-bearing media types of the underground water, evaluates the rock permeability, on this basis, the risk indicators of water inflow into the Tunnel is selected. Then analyses the probable water inflow sections and points during the tunnel construction, calculates and analyses water inflow in the tunnel for checking on rationality of the risk indicators, the influence of water inflow into the Tunnel on the project and the environment is further evaluated.The main research contents and results are as follows:(1) Characteristics of lithological association in the aquifer. The groundwater in this area can be divided into pore water in the loose rocks of Quaternary and fissured water in the bedrock. Due to the large topographic relief and deep cut which make recharge and runoff areas not large, Pore water in the loose rocks is mainly in the form of phreatic or perched water, whose ability of containing water is weak - medium, and effected by seasons and climate significantly; fissure water in the bedrock is mainly recharged by rain, then supplied by water from ice and snow melting in the mountain areas, whose dynamic seasonal change is remarkable and exposure is generally in the ditches or low-lying areas.(2) Study the permeability of rock mass. Through the packer permeability test in the deep holes and the indoor core permeability test, the results of two tests show that the permeability coefficient in sandstone is larger than in slate, and the permeability coefficient is decreased with the depth gradually increased, when it reaches a certain depth, the permeability coefficient will be stable.(3)Study on dynamic field of the groundwater and field of water chemistry. Through survey and tracing spring points and analysis the information of underground water, chemical compositions and Hydrogen and Oxygen stable isotopes revealed by deep holes, we study the recharge, runoff and discharge conditions and the cyclic-alternating rule of the groundwater. The groundwater circulation in the southern slope of Balang Mountain is mainly shallow. The effect of the rock medium on hydrochemical type of the groundwater is not very clear, and the mineralization is generally not high; the groundwater circulation in the northern slope of Balang Mountain is mainly deep, mainly due to "U" shaped valleys in the northern slope are more developed, and the slope is gentle.(4) Analysis of water system. According to the recharge, runoff and discharge characteristics of groundwater in tunnel site areas, class 1 systems of the groundwater are divided: groundwater system in the northern slope of Balang Mountain and groundwater system in the southern slope of Balang Mountain. Then sub-groundwater systems of the groundwater are further divided, due to the spatial distribution of the confining layer groups. The groundwater systems of Haizi ditch and Gaodianzi ditch are risk for the tunnel by the initial judgement.(5) Risk indicators select of the water inflow. This article initially establishes the risk evaluation indexes of the fissured bedrock tunnel mainly by collecting and tidying related data on the risk classification of the water inflow and former research results, combined with the geological structure, hydrogeological conditions and other relevant factors of the tunnel, meanwhile, presume the risk segment of the tunnel site areas.(6) Calculation of the water inflow. The water inflow of typical sections of the Balang Mountain tunnel which has been segmented is calculated by traditional, classic formulas of the tunnel water inflow (such as rainfall infiltration method, hydrodynamics method, etc.), and combined with Visual ModFlow numerical simulation, the ranges of the water inflow in typical sections of the tunnel site areas are initially got.(7) Comprehensive evaluation of Tunnel water-busting risk. High-risk sections of Balang Mountain tunnel are obtained though risk indicators, then verified by water inflow calculations. It proves that the risk sections of the tunnel are matched with the values of water inflow. The water inflow of the tunnel is small, and the risk is small; only in the transitions of the foldings and in the broken belts, is the risk relatively large, which needs special attention during the construction and operation phases. Tunnel excavation will affect runoff and discharge conditions of the pore water in loose layers .But the leakage of the water inflow in the tunnel is main from the water in bedrock fissures, which affects little in the ability of soil containing and storing water and in the damage of surface vegetation.更多还原