岩溶隧道涌突水灾害危险性评价系统中指标量化及取值方法优化研究

In order to forecast the risk of karst water inrush accurately and effectively during the course of advanced prediction for tunnels, and with cases basic geological factors and conditions investigation, the risk evaluation system of water bursting hazard in karst tunnels has been studied and preliminarily established based on 5 evaluating index, which are solubility of lime rock, geological structure conditions, the water catchment capability of ground surface, karst water circulation rate under the ground, and depth of tunnel relative to the water level. .On the basis of preceding study works, the index value and its quantified method in the founded risk evaluation system is proposed to be further researched..Firstly, basic geological conditions and acting factors of water bursting cases happened in the karst tunnels will be collected and analyzed particularly, and the karst water bursting formation and its actural risk level will be identified. Secondly, the risk of water bursting cases will be evaluated using the established system, and the result will be in comparison with actual disaster level of the cases. Thirdly, the index value and its quantified method will be adjusted and optimized continuously through theoretical analysis and statistical method, which makes the evaluating result match better with the actual level. And then, the established evaluation system is to be modified basing on the study and made more reliable. .The study provides the karst water inrush risk evaluation index system with quantitative method, and it is also much important and instructive to the karst water inrush early-warning and forecast during the course of route selection and tunnel construction.

为了更准确有效地进行岩溶隧道涌突水灾害超前预测预报，基于灾害的形成条件及控制因素研究，选取"岩石的可溶性、地质构造条件、地表汇水条件、地下水循环交替强度、隧道埋深与地下水位的关系"5个评价因子，建立了"岩溶隧道涌突水灾害危险性评价系统"。本项研究拟对评价系统中指标的量化及取值方法进行深入探讨。首先对已建隧道中的岩溶涌突水灾害实例进行收集和分析，确定已发灾害形成的基本地质条件、致灾因素及危险等级；其次，利用评价系统对已发灾害进行分级评价，将评价结果与实际灾害等级进行比对，两者的吻合程度越高，显示评价系统中各指标的量化取值越合理；最终采用理论分析与实例统计相结合的方法，对指标的量化及其取值方法不断进行优化，进一步提高评价系统的可靠性。研究成果将在前期工作的基础上，形成完善的岩溶隧道涌突水灾害危险性定量化评价指标体系，具有一定的创新性，对岩溶隧道选线及施工中的减灾防灾也具有重要的理论指导意义。

通过滇东岩溶高原区新建11座高风险岩溶隧道施工期跟踪调研、资料收集及岩石与水的化学分析测试，系统总结了滇东高原分水岭地带及河谷斜坡地带岩溶发育的控制因素，划分了滇东山原区的主要岩溶水文地质结构类型和含水系统类型，总结了岩溶水流动系统的类型和特点，总结积累已有工程的实践经验基础上，探讨滇东高原区岩溶涌突水灾害的形成机理，基于“岩石的可溶性、地质构造条件、地表汇水条件、地下水循环交替强度、隧道埋深与地下水位的关系”5个评价因子建立的“岩溶隧道涌突水灾害危险性评价系统”（THK），对评价系统中指标的量化及取值方法进行深入探讨，建立了适宜于滇东高原区的岩溶隧道涌突水灾害风险评价系统（修正的评价系统THKDG），并对修正评价系统的可靠性进行了验证。.研究主要完成的工作内容及成果如下：. （1）滇东高原位于金沙江、南盘江、元江流域分水岭地带，地形切割较浅，地理环境差异较大，从前震旦系至二叠系均有出露，岩溶发育强烈，大泉、暗河分布广泛，富水性强；区域位于扬子地台西缘滇东台褶束构造单元中，主要发育北东向、近东西向和南北向构造体系，并伴有多种方式复合，地质条件十分复杂。岩溶隧道涌突水灾害形成控制性因素主要包括岩性、构造、地貌和隧道与地下水位的相对位置关系。. （2）基于西南山区THK评价系统选取的指标，确定了岩石的可溶性（K1）、地质构造（K2）、地表环境特征（K3）和隧洞埋深（K4）四个一级评价指标。选取了岩石成分（K11）、岩石结构（K12）、岩体结构（K21）、地层倾角（K22）、降雨入渗系数（K31）、地形坡度（K32）作为二级评价指标，并对评价指标进行量化取值，利用层次分析法确定各指标权重分配，建立修正的滇东高原岩溶隧道涌突水风险性评价体系。. （3）结合滇东高原牛栏江1#隧道和通海隧道，利用已建（THK）和新建（THKDG）的评价系统对已发岩溶涌突水灾害进行分级评价，将评价结果与实际灾害等级进行比对。结果显示THKDG评价系统可靠程度更高，其评价等级和实际涌水等级相差在一个级别范围以内，吻合程度较THK系统更好，进一步提高了评价系统的可靠性、普适性和易操作性。. 研究成果对岩溶隧道选线及施工中岩溶涌突水减灾防灾具有重要的理论指导意义。

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