【作者】 康小兵；

【导师】 许模；

【作者基本信息】 成都理工大学 ， 地质工程， 2009， 博士

【摘要】 瓦斯灾害是隧道建设中的重大灾害之一,主要表现为中毒、窒息、燃烧、爆炸、煤与瓦斯突出五种情况,其中以瓦斯爆炸最易发生,一旦发生瓦斯灾害,后果往往十分严重。随着我国基础交通的建设和发展,穿越煤系地层的隧道越来越多,隧道施工瓦斯灾害事故也在不断的增加。因此,人们越来越认识到防范和减轻瓦斯灾害的重要性,迫切需要寻求有效的隧道瓦斯灾害危险性评价方法与手段。本文在研究我国大量已有瓦斯隧道的基础上,归纳分析各瓦斯隧道所处的地质环境条件及施工中瓦斯状况,通过对影响隧道瓦斯灾害危险性的地质因素、瓦斯因素和施工时人为因素等研究,遵循定性分析与定量评价相结合的基本学术思想,建立了一套较为完善的隧道工程瓦斯灾害危险性评价技术方法体系。研究成果既达到了瓦斯灾害危险性评价的目标,又在隧道工程瓦斯灾害调查技术和危险性评价方法方面取得了一定进展,在系统的研究工作中取得了以下主要成果:(1)从瓦斯的生成、赋存条件和分布规律三个方面入手,通过统计分析我国瓦斯隧道所处地质环境条件,得出隧道瓦斯状况与我国区域性瓦斯分布密切相关,高瓦斯隧道多位于区域性高瓦斯区、高瓦斯带,低瓦斯隧道多位于区域性低瓦斯区、低瓦斯带。(2)针对隧道工程规划选线阶段资料储备不足的情况,结合影响瓦斯赋存分布的影响因素,用地质工程理论的原理和方法,建立以地质宏观判断为主的简洁的瓦斯隧道分级评价方法。分级评价以隧道所处区域性瓦斯区带、隧道埋深以及隧址区地质构造、煤层厚度、地下水出露程度为评价指标,采取影响因素综合评判法进行瓦斯隧道分级评价。(3)针对设计施工阶段对工程条件了解要求较高以及此时基础资料相对丰富的情况,在瓦斯隧道分级评价方法的基础上,同时参照2002版《铁路瓦斯隧道技术规范》,建立隧道工程施工瓦斯灾害危险性评价方法。瓦斯隧道施工危险性评价包含两个部分,首先是瓦斯隧道的分区评价,然后是叠加施工因素进行修正。分区评价以隧道瓦斯涌出量、瓦斯压力、地质构造、煤体结构类型、地下水状况和工区距煤层距离六个指标组成评价指标,分区评价是自然地质条件下隧道各区段危险性评价,同时也是施工危险性评价的基础和本底值。施工时由于瓦斯防治措施、瓦斯管理、施工经验和技术水平的不同瓦斯灾害危险性也不同,因而在分区评价基础上考虑这四个修正因素进行瓦斯隧道施工危险性评价。评价方法采用影响因素综合评判法、模糊综合评判法、可拓评判法三种方法。(4)针对有瓦斯突出危险区掌子面可能出现的瓦斯突出危险,建立起瓦斯隧道施工掌子面突出危险性评价方法。以最大埋深、地质构造、超前钻探时动力现象、最大瓦斯压力、最大钻孔瓦斯涌出初速度和煤体结构类型为突出危险性评价指标,对指标逐个判别进行预测评价。(5)瓦斯隧道分级评价、瓦斯隧道施工危险性评价、瓦斯隧道施工掌子面突出危险性评价三个层次构成了隧道工程的瓦斯灾害危险性评价体系,从而在隧道选线、设计、施工阶段均能对瓦斯灾害进行快速准确的评价,进而采取相应的工程防治措施。在评价方法的建立过程中,对各层次评价指标的权重采取主观(层次分析法)和客观(关系矩阵法、灰色关联法)的计算方法,结果表明各主客观方法计算出指标重要性相同,在指标权重计算方面是可行的,为了同时体现主观信息和客观信息,本文最后用综合集成赋权法对瓦斯灾害危险性评价指标权重赋值。(6)以紫坪铺隧道为例对隧道工程瓦斯灾害危险性评价方法进行了具体应用,取得了较好的应用效果。通过紫坪铺瓦斯隧道地质环境条件描述,研究评价指标的实际状态,根据评价指标量化标准赋值,在此基础上,采用定性分析与定量评价相结合的隧道工程瓦斯灾害危险性评价方法对紫坪铺隧道瓦斯灾害危险性进行评价,评价结果与隧道实际状况达到了较好的一致性,并根据隧道危险性等级结合地质条件提出相应的防治措施。更多还原

【Abstract】 Gas disaster is one of the major disasters during the tunnel construction. Gas disasters are in the forms of poisoning, asphyxia, combustion, explosion, and outburst of coal and gas, among which gas explosion is most likely to happen with serious consequences. Since more and more tunnels passing through coal-bearing strata, gas accidents are on the rise accompanying the construction and development of basic communication in our country. Therefore, it is so urgent to realize the significance of preventing and mitigating gas disaster that a effective risk assessment method of gas disaster should be established.Based on the research of gas tunnel in our country, a relatively perfect gas disaster risk assessment medhod and system of tunnel has been set up through the following measures. Above all, geo-environmental conditions and gas situation in the construction have been analyzed; combining qualitative analysis and quantitative evaluation, the influencing factors of gas disaster also have been studied, including geological factors, gas factors and human factors. The results not only reach the goal of risk assessment, also make a progress in investigative techniques and assessment method in tunnel engineering. The main achievements of this work are shown below:(1) Analyzing the geo-environmental conditions of gas tunnel in our country, based on the gas formation, distribution and occurrence, the conclusion that gas situation has closely related to China’s regional gas distribution can be made: that is high gas tunnels always locate in regional high gas zone or high gas belt, vice verse.(2) According to the principles and methods of geological engineering theory, a concise gas tunnel classification evaluation method has been set up, mainly based on geological macroscopical estimation. The method takes distributed gas zone, buried depth of tunnel, and geological structure, seam thickness, the degree of exposed groundwater in tunnel site areas as evaluation indexes, and adheres to general evaluation method factors to carry out the classification.(3) Considering relatively numerous materials in design and relatively more demanding of projects, meanwhile, due to classification evaluation method, and referring to gas tunnel railway technical specifications of 2002 version, a suitable gas disaster engineering risk assessment method should be established. Gas tunnel engineering risk assessment is composed of two parts: division evaluation and risk assessment, and amend by superposition construction factors. Division evaluation is a risk assessment of each division under natural geological conditions, meanwhile, the background value and basis of construction risk assessment, which includes six evaluation indexes: gas emission, pressure, geological structure, the type of coal structure, groundwater conditions, and depth between working zone and the coal. Different prevention and control measures, gas management, construction experience, and technical level may bring out different level of risk. Those four factors can be taken as amending factor; methods of assessment can be divided into comprehensive evaluation method of general factors, fuzzy comprehensive evaluation method, and extension evaluation method.(4) Tunnel face risk assessment method of gas tunnel engineering has been set up for the potential risk of gas outburst in dangerous area of outbursting (dangerous zone). Taking the maximum buried depth, geological structure, dynamic phenomenon in advance borehole drilling, maximum gas pressure, maximum initial velocity of gas emission in borehole, and coal structure as the outburst risk evaluation indexed, by discriminating each of them to conduct the predictive assessment.(5)The complete gas disaster risk assessment system, applicable to tunnel engineering, is composed of three parts described above: gas tunnel classification evaluation, gas tunnel engineering risk assessment, and tunnel face risk assessment. Therefore, it can make a prompt and accurate assessment of gas disaster in any phase, such as route selection, designation, construction, and take appropriate engineering control measures. At the process of establishing the system, both subjective (analytic hierarchy process) and objective (interactive matrix method, grey correlation method) methods are resorted to calculate the of index in each phase. The identical significance of each index demonstrates the justifiability of calculating weight using subjective and objective methods. In order to reflect the subjective and objective information simultaneously, this paper adopts mestasynthesis weight approach to assign the indexes.(6) This paper has applied the Zipingpu tunnel to perform the gas disaster risk assessment of tunnel engineering, and achieved a relatively good results. By means of geo-environmental conditions of Zipingpu tunnel, research has been done on the actual status of evaluation indexes, the values of which been assigned according to quantitative criteria. On this basis, adopting gas disaster risk assessment system, combining qualitative analysis and quantitative evaluation, to assess the risk of Zipingpu tunnel. The results are accordance with the actual situation of tunnel, correspondingly, prevention and control measures has been put forward in light of risk level integrated with geological conditions.更多还原