【作者】 郭佳奇；

【导师】 乔春生；

【作者基本信息】 北京交通大学 ， 地下工程， 2011， 博士

【摘要】 摘要：随着我国西部大开发战略的快速推进,西部地区交通等基础建设迅猛发展,长大岩溶隧道建设越来越多。岩溶隧道修建过程中,经常遇到突水、涌泥等大型地质灾害,轻则冲毁器具,贻误工期,重则造成人员伤亡和重大经济损失。本文以岩溶区隧道施工中防突层突水灾变为研究对象,通过工程实例调查、室内试验、理论分析以及数值模拟等手段,分析山岭隧道—岩溶系统概化模型及岩溶隧道突水机理,建立隧道与周边隐伏溶腔间岩层最小防突厚度及掌子面前方岩墙安全厚度的计算方法,并总结和概括岩溶隧道突水防治对策,取得了一系列具有重要理论意义和工程应用价值的研究成果：(1)以最具代表性的宜万线岩溶隧道为例分析了山岭隧道岩溶发育特征、分布规律及形态,阐明了隧址区的地层岩性、岩层构造、地下水渗流途径等因素是深部大型岩溶形态及空间分布的主控因素,总结了不同岩溶形态的地质灾害及风险,并进一步分析了其与岩溶隧道的位置关系。基于此,将隧道—岩溶系统概化为弹性梁板模型、双孔洞模型、裂隙导通模型等四种力学模型,为采用定量手段研究岩溶隧道灾害机理提供基础；(2)通过室内单轴压缩试验、三轴压缩试验以巴西劈裂试验对岩溶区灰岩的基本力学性质和强度特征进行了深入研究,发现自然状态和饱和状态的岩溶区灰岩力学性质差别显著。结合现场调查得出的岩体结构特征和主要结构面的表面状况,确定了地质强度指标GSI和岩体的霍克—布朗岩体强度参数及变形模量；(3)通过实际岩溶隧道突涌水实例的调查与分析,将岩溶突水划分为高压裂隙突水、富水溶腔突水、地下暗河或岩溶管道突水及断层突水,并从微、宏观层面分析了岩溶隧道突水机理,指出围岩二次应力重分布和高水头岩溶水压力共同作用下的综合破坏型突水是岩溶隧道突水的主要类型,并通过离散元数值模拟对隧道与水压充填溶腔间防突岩层破坏突水灾变过程进行了验证；(4)针对大尺度隐伏溶腔,将防突岩层简化为两端固定梁模型,采用弹性理论,基于岩体抗弯、抗剪强度准则建立岩层最小防突厚度计算方法；针对中小尺度隐伏溶腔,采用Schwarz交替法结合格里菲斯强度准则计算岩层最小防突厚度,并编制基于该方法的计算程序,同时讨论了埋深、侧压力系数、溶腔尺度等因素对防突厚度的影响,特别是岩溶水压力的影响；针对裂隙导通突水模式,采用最小拉应力理论研究了隐伏断层活化突水方向,根据裂纹扩展准则建立了该突水模式下的最小防突厚度计算公式；(5)从断裂力学角度分析了高压岩溶水作用下裂隙的扩展机理,发现自然营造力作用下的水压劈裂多属压剪破坏模式。运用断裂力学和水力学理论分析了隧道掌子面突水的滞后效应和扩径效应,指出裂纹扩展的跳跃性在宏观上表现为隧道掌子面突水的滞后性；掌子面突水通道的最终形成需经过多个阶段,其最终尺寸受岩溶水压力、掌子面岩体工程质量等因素的控制。在综合分析基础上,认为隧道掌子面突水是由于开挖扰动降低了水压劈裂的临界水压力导致的,基于此观点,建立了基于临界水压力的掌子面岩墙安全厚度计算公式；(6)根据防突厚度及突水机理的研究成果,结合岩溶隧道灾害治理的工程实践及前人在此方面的研究结论,总结、概括了岩溶隧道突水防治的基本原则、突水治理对策,重点讨论了防治高压富水充填溶腔突水突泥灾害的新技术—释能降压法。更多还原

【Abstract】 Accompanying the enforcement of strategy to develop western regions, transport and other infrastructures of western China expand substantially and long tunnel in karst zone increases dramatically. Geological hazard of water inrush and mud outburst often occur in the process of karst tunnel construction, which often lead to equipment destroyed and construction period bungled, even serious casualty and economic loss. This article is a subject which studies the disater-induced waterinrush of against-inrush rock in construction. Generalized model of mountain tunnel-Karst system and mechanism of water inrush of karst tunnel are studied in a deep-going way, and Against-inrush thickness of rock pillar between tunnel and concealed karst cave with high-pressure and rich water, safe thickness of rock wall in front of tunnel face are eatablished by engineering cases investigation, laboratory experiment, theoretical analysis and numerical simulation, Meantime, prevention measures of water-inrush of karst tunnel are summarized, consequently, series of meaningful research achievements has been obtained:(1) The property of karst development and underground karst of mountain tunnel are summarized through analysis the most representative karst tunnel on Yiwan railway, meantime, based on the practical example of karst tunnel, the location relationship between tunnel and karst structure is classified and the major geological hazards of karst tunnel are discussed. Finally, the system of tunnel and karst is generalized into four mechanics models, which supply support for analyzing the mechanism of water and mud inrush or mid-stratum collapse by quantitative analysis;(2) Mechanical behaviors and strength properties of limestone from karst region are studied intensively through uniaxial compression test, triaxial compression test, brazilian test and mechanical behaviors under natural an saturated condition are different remarkably. Combined with rock mass structural features and surface characteristics of discontinuitity obtained from field investigation, the geological strength index(GSI), Hoek-brown strength parameters and deform modulous are determined;(3) According to engineering cases of water inrush and mud outburst of karst tunnel, water-inrush is divided into high-pressure fissure water-inrush, water-inrush of karst cave with rich water, water-inrush of underground river, karst channel or fault. From micro and macro view, mechanism of water-inrush is analyzed and studied, and, it is pointed that comprehensive failure waterbust under secondary stress distribution and karst water pressure is the main type of karst tunnel waterinrush, process of disater-induced waterinrush of against-inrush rock under geostress and high water pressure is testified by means of discrete element numerical simulation;(4) As far as concealed karst cave at circumference is concerned, different mechanical models are established according to concrete situation. on account of large scale, the destabilization mechanism mid-rock is analyzed and simplified into restrained beam. The theoretical formula for the against-inrush thickness are deduced according to the elastic theory, based on anti-bending and anti-shear criterion; aiming at small and medium sized concealed cave, the against-inrush thickness is calculated by the mechanical model solved by Schwarz alternating methods with Griffith strength theory, moreover, base on this method, the program is designed on Maple platform, subsequently, each influential factor of against-inrush thickness is discussed, especially, water pressure in karst cave. As for model of water inrush along the activation fault, water-inrush orientation of activated concealed fault by use of minimum tensile stress theory, analytical formula of against-inrush thickness is deduced based on crack propagation criterion;(5) The frequent occurrence of water and mud inrush caused by karst cave with high pressurized water ahead of tunnel face has been the critical problem to be researched and resolved in tunnel construction in kasrt area. From view of fracture mechanics, the mechanism of crack extension is analyzed under high karst water pressure, as a result, the outcomes show that hydraulic fracturing under natural pressure mostly belongs to compression-shear(type 11) failure mode. The hysteresis effect and diameter-expanding effect of water-inrush of tunnel face have been studied by use of fracture mechanics and hydromechanics. It is illustrated that the hysteresis effect of water-inrush is macro-view property of the skip of crack extension, meantime, the results also demonstrate that the final formation of water-inrush passage need experience some stages and its final size is controlled by karst water pressure and the quality rock mass of tunnel face and so on and so forth. On the basis of comprehensive analysis, the reason why water-inrush occurs in the vicinity of tunnel face is that the critical water pressure of hydraulic fracturing decreases induced by excavation and disturbance. Accordingly, based on the critical water pressure, the calculating formula of safe thickness of rock wall has been established: (6) Finally, in the light of research achievements about against-inrush thickness and waterburst mechanism, the basic principles and prevention measures of against-inrush are summed up combined with cases of hazards management of many karst tunnel and research conclusions by other scholar. A new technical method to prevent water inrush-energies-release and depressurization technology is emphatically discussed.更多还原