【作者】 刘钦；

【导师】 李术才；

【作者基本信息】 山东大学 ， 岩土工程， 2011， 博士

【摘要】 交通隧道、水工隧道及其它地下工程在穿越高地应力、较大残余构造应力、浅埋偏压区域及软弱破碎围岩体时,围岩大变形是一种常见的、危害极大的施工地质灾害。我国基础建设事业的蓬勃发展,公路、铁路以及地下工程迅猛发展,穿越软弱破碎岩体或相对高地应力条件下,围岩产生具有累进性扩展和时间效应的塑性变形,常规支护难以抑制该变形,给施工处理带来极大的困难,处理不当将造成塌方、侵限等,进而造成施工机具毁坏、工期延误、施工成本增加等问题。本文以在建的贵广铁路天平山隧道为依托工程,综合运用室内试验、粘弹塑性理论、地质力学模型试验和三维数值仿真等手段,深入研究了软弱破碎围岩隧道的大变形机理,分析了软弱破碎岩体的大变形机制以及软弱破碎围岩隧道的施工力学性态,提出了大变形控制综合技术体系,取得了一系列有意义的研究成果。(1)系统地调查研究了国内外大变形隧道的变形特征及支护对策,分析了现场软弱破碎围岩大变形段的地质勘察及施工等实际情况,采集了典型软弱破碎围岩岩样,在室内开展了三轴常规压缩和三轴压缩流变试验,依据试验结果曲线,分析炭质页岩的流变力学特性,建立了可以描述依托工程炭质页岩蠕变全过程的粘弹塑性应变软化蠕变力学模型,基于模型的一维本构方程,推导了该蠕变力学模型的三维本构方程,确定了模型的4个参数。借助MATLAB程序对模型的参数进行了辨识,为软弱破碎围岩隧道大变形的时间效应研究奠定了试验基础。(2)通过对软弱破碎围岩大变形新定义的探讨,发现了软弱破碎围岩的累进性扩展和时间效应两大特征；为充分考虑岩体的流变特性,在5项合理假设前提条件下,推导了隧道表面位移及表面位移速率的解析解,实现了对大变形理论的拓展,对比发现解析解与数值解基本吻合。结合依托工程超大断面开挖和软弱破碎围岩的流变特性,开展了现场炭质页岩大变形段施工过程的三维数值仿真,针对隧道施工过程中掌子面前方的先行位移、掌子面位移及掌子面后方位移分别进行了分析和探讨,并考虑了流变时效特征。结果表明,掌子面位于隧道纵深方向某一位置时,受开挖卸荷的影响,掌子面前方1倍洞径左右的岩体将产生较大先行位移,掌子面处位移约占最终位移量量的36%；对于倾斜地层,岩层倾向与掘进方向成钝角时掘进引起的掌子面挤出变形比岩层倾向与掘进方向成锐角时掌子面的挤出变形大。隧道贯通后流变计算的结果表明,流变变形占开挖变形的25%左右,并且主要发生在初期,变形速率达到4.76mm/d,趋于稳定的时间约为60天。(3)基于地质力学模型试验相似理论和现场岩样力学特性的测试结果,研制了软弱破碎岩体隧道施工过程及超载渐近破坏过程的地质力学模型试验系统。该系统包括相似材料、三维组合式模型试验台架、非均匀梯度加载系统和多元信息监测系统等。设计研制了新型低强度单轴压缩蠕变装置,对所研制的软弱围岩相似材料开展了单轴压缩蠕变特性试验研究。研制了大型三维组合式模型试验钢结构台架、非均匀梯度加载液压控制系统。基于光纤光栅传感技术,构建了以全自动信息采集的光纤监测系统为核心的多元信息并行实时监测方法,并辅以自主研发和改进的高精度机械式和光栅尺型微型多点位移计,配合电阻应变采集系统,能够全面捕捉开挖和超载过程中试验材料的位移场、应力场等多场信息的微小变化信号和大幅度波动值,解决了监测方法、仪器和数据处理软件对采集信息造成差异性的难题。经校核计算,模型试验系统主要构件满足强度、刚度要求,可实现同埋深和岩层产状条件下隧道施工过程及围岩渐进性破坏试验。(4)开展了软弱破碎围岩隧道的施工过程及超载渐近性破坏试验,首次从试验角度分析了隧道施工过程中的掌子面挤出变形规律,以及掌子面前方的先行位移变化规律,针对不同支护条件,开展了隧道周围位移的影响范围及其最终沿径向分布规律研究。根据固定断面位移随开挖推进的变化规律,给出了软弱破碎围岩隧道施工过程中纵深影响范围以及掌子面前方径向位移变化规律,分析了隧道施工过程中掌子面挤出变形规律,试验结果与数值仿真结果吻合较好,分析结果对实际工程的施工和设计起到了一定的指导作用。(5)基于软弱破碎围岩隧道大变形的理论分析、模型试验与数值仿真所揭示的规律,通过对软弱破碎围岩的变形特征进行总结,分析了大变形的原因,建立了软弱破碎围岩隧道施工期大变形的综合防治技术体系。该体系对软弱破碎围岩隧道施工期所产生的掌子面前方先行位移、挤出变形以及掌子面后方位移分别提出了针对性控制对策。基于该技术体系,将相应的控制对策在依托工程贵广线天平山隧道和沪蓉西高速公路龙潭隧道进行应用,成功穿越了天平山隧道DK372+535～DK372+335段和龙潭隧道YK70+969～YK70+800段,取得了良好的效果,证实了该体系的有效性和实用性。更多还原

【Abstract】 With the rapid development of the highway, railway and other underground engineering, the situation that the tunnels have to pass through surrounding rocks with high geo-stress, high residual tectonic stress, shallow bias, and fractured weak zone, will follows. Large deformation of surrounding rocks is a commonly encountered and high harmful geological hazard in this situation. As the tunnels pass through surrounding rocks with high geo-stress, high residual tectonic stress, shallow bias, and fractured weak zone, cumulative extension and plastic deformation with time-dependence is likely to occur. Conventional support techniques cannot effectively control the deformation, which may result into great difficulties in the tunnel construction. Collapse and intrude limit may happen if the treatment measures are not suitable. And then a lot of additional problems may occur such as damage of construction equipment, schedule delays, cost increase, etc.This paper is based on the Tianpingshan tunnel which lies in Guiguang railway and the Longtan tunnel which lies in Hurongxi highway. During the research, various means, such as laboratory test, theoretical analysis, and 3D numerical simulation, are used. In this paper the mechanisms of large deformation in tunnels with fractured weak zone are studied and mechanisms and mechanics behaviors during construction are analyzed. A comprehensive technology system for controlling large deformation is presented and a serious of useful research results are obtained.(1) Geological survey data in areas of large deformation with fractured weak zone are collected and analyzed systematically. Typical rock samples are collected and the triaxial compression and triaxial compression rheological tests are also carried out. According to the test curves, rheological characteristics of carbonaceous shale are summarized. And the viscoelastic plasticity strain softening creep mechanical model which can describe the overall creep process of black cat of the based engineering is established. Based on the one-dimensional constitutive equations, the three-dimensional constitutive equations of the model are deduced and 4 parameters of the model are decided. Parameters are identified using MATLAB, which is the experimental fundamental of the research of large deformation of surrounding rocks in tunnels with time effect.(2) By discussing the new definition of soft fracture rock mass, two characteristics, namely cumulative extension and time-dependence, are proposed. Five reasonable assumptions have been made on the large deformation theory and geometric field theory, Considering MR effect, the characteristic theory of large deformation has been expended. The analytical solutions of the tunnel surface displacement and the surface displacement rate have been obtained. Based on the project, three dimensional numerical simulation of large section tunnel construction process with soft fracture rock conditions, Considering rheological aging characteristics, targeted antecedent displacement, tunnel face displacement and the displacement behind tunnel face respectively, have been analyzed and discussed. The result shows that large antecedent displacement is likely to occure in front of the tunnel face, where double tunnel diameter away from tunnel face. The displacement of tunnel face accounted for 36% of the final total settlement. The extracted deformation of tunnel face caused by tunnel excavation is larger as the rock tendencies direction at an obtuse angle with driving directions than as the rock tendencies direction at an acute angle with driving directions. Calculated based on the results rheological, rheological deformation mainly concentrated at preliminary stage. The max deformation rate is 4.76mm/d, and the stable time is 60 days, which accounts for 25% of the excavation deformation(3) Based on the similar principal analysis of the goemechanical model test and the mechanical character test results of in-situ rock specimen, the geomechanical model test system is developed, which is used in the construction process of soften broken rock mass tunnel and the overload asymptotic process. The system is consist of similar material, triaxial combined model test-bed, non-uniform gradient loading system and multielement massage monitoring system. The newly low intensity axial compress creep equipment is developed and based on this, the axial compress creep character research on the developed similar material for soften rock mass is carried out. The large scale 3D combined model test steel structural rack and non uniform gradient loading hydraulic control system are developed. Based on the optical grating sensor technology, the multielement message parallel real time monitoring method which the nuclear is the optical grating system of full automatic information collection is established. With the self-developed high precision mechanical and grating ruler micro multiple points meters and the resistance strain collection system, the micro change signal and substantially fluctuate data of displacement and stress in the model can be monitored fully during the excavation and over load process, which solve the problem of information diversity made by monitoring method, apparatus and data processing software. By the check and computing, the main member of the model test system can fulfill the demand of intensity and stiffness, it can be used in the model test of construction process and progressive failure of rock mass in the condition of the same embedded depth and stratum.(4) The model test on construction process of soft fractured surrounding rock mass surrounding tunnel and overload asymmatic damage was carried out. During the test, the displacement changing law before the tunnel face is analyzed and the affecting range of radical displacement surrounding tunnel and the ultimate radical distribution laws were carried out according to the different anchoring condition. Based on the changing law of fixed section displacement with the excavation steps, the affecting range in depth during the construction process of soft fractured surrounding rock mass and the radical displacement changing laws of tunnel face were got. The squeeze deformation law of tunnel face is analyzed, and the test results and numerical simulation results are coincident well. The results can be guidance to the construction and design of the actual engineering.(5) Based on the laws got by theoretical analysis, model test and numerical simulations on the large deformation of soft fractured surrounding rock mass, through the summary of the deformation character of the soft fractured rock mass, the reason of large deformation is analyzed and the comprehensive technical on the large deformation during the construction of soft fractured rock is established. Based on the technical system, the control method is applied in the Tianpingshan tunnel which lies in Guiguang railway and Longtan tunnel which lies in the Hurongxi Highway and the well effect was got, which proved the practicability of the system.更多还原