【作者】 郭富利；

【导师】 张顶立；

【作者基本信息】 北京交通大学 ， 岩土工程， 2010， 博士

【摘要】 摘要：复杂条件下地下洞室及其围岩的稳定性历来受到关注,尤其是高地应力、地下水发育和较为破碎的围岩,变形破坏非常严重且持续时间长,同时又表现出时间上和空间上不均匀、不对称等诸多特性,开挖、支护和维护难度大。由于这类围岩显示出显著的时间特性,因此,以前的研究者多基于岩石流变观点,用连续介质流变理论来研究围岩的流变性及巷道变形破坏的时间相关性,而对其岩体结构,则认为是确定的和固定不变的。工程实践表明,这些研究尚未能揭示层状围岩大变形本质,基于这些研究而采取的支护措施,效果不甚理想。堡镇隧道地质条件复杂,局部地段处于高应力区,围岩变形具有变形速度快、变形量大且破坏严重、持续时间长的特征,同时又表现出变形不对称和不均匀的特征。本文依托堡镇隧道工程实践进行了大量的室内试验研究：(1)考虑围岩赋存环境,对不同岩性岩石的物理力学性质参数进行测定,得到了围压和饱水时间对软岩峰值强度、残余强度和峰后体积变化的影响规律；(2)根据大变形段掌子面围岩分布有软弱夹层的岩层组合结构,利用常规三轴压缩试验研究夹层厚度对岩石强度的影响规律,根据试件破坏形态,提出夹层破坏前后与围岩的相互作用关系,分析了夹层引起围岩结构变形失稳的动态过程,建立了含软弱夹层层状岩体结构系统力学模型,研究了变形失稳机理；(3)根据饱水试验结果和现场支护结构应力的监测数据,进行了低围压条件下的三轴压缩试验,探求支护阻力对软岩强度和体积应变的影响规律,在控制围岩大变形方面,指出了“强支硬顶”的支护方式在理论上不合理、实践中不可行,提出了峰后软化阶段末尾和残余阶段开始作为二衬的最佳施作时机。根据试验结论及大量的现场调研及丰富的测试和监测资料,同时查阅并参考了国内外较多类似地下工程实例,发现这类高应力区的层状软弱围岩的流变性及其它相关特征,不是由岩石变形引起,而是由地层结构的时间相关性变形所致。据此,提出堡镇隧道围岩变形的3种模式：①围岩岩性控制类,②层状岩层结构控制类,③围岩赋存环境控制类。岩层结构控制类大变形是堡镇隧道围岩大变形的主要形式,是指在高应力区完整性差的软弱围岩体内,由于岩体开挖,岩层结构依应力状态而发生一系列复杂的时间相关性的力学行为和力学响应,使工程岩体表现出显著流变的现象或过程。利用多种实测资料,从围岩位移和变形破坏的时间和空间分布特征,论证了层状围岩动态过程,分析了地层结构随时间而变化的演化机理,探讨了导致围岩产生大变形及其它相关特性的原因,在此基础上,总结了围岩的动态特征、变形机制和模式,建立了不同岩性、不同地层结构围岩变形的力学模型,解释了围岩变形具有不对称性的原因,为不对称支护和不对称预留变形量提供了理论依据。在二衬的实践中,认为“当初期支护变形量达到总变形量的70%时尽快施作二衬”比较符合现场实践,提出了控制软岩隧道大变形的原理和方法和高地应力大变形段围岩支护的6条原则,形成了系统的关键技术。层状地层结构变形失稳引起围岩大变形的观点从动态上和本质上认识岩体演化过程及其变形破坏机理,突破了关于岩体结构及其特征的静态认识,研究成果在堡镇隧道应用后可以做到措施超前、到位,确保了软岩地段的快速、安全施工该研究成果也可为同类型复杂条件下的地下工程研究及支护提供借鉴和参考。更多还原

【Abstract】 ABSTRACT: It has been greatly concerned to study the stability of underground caverns and theirs surrounding rock masses under very complex geological environments. High earth stress, deep-buried, rich groundwater and very weak and cracked rock masses make self-stability of the tunnel be unfavorable, it is difficult to excavate, support, and maintain. During construction, The high deformation rate, intense and long-time deformation are the basic characteristics; At the same time, the deformation shows asymmetrical features and uniformities. Surrounding rock masses mentioned as above have remarkable rheological property, but previous researchers consider that the rheology of rock masses resulted from rocks and that structure of rock masses is determinate and static and does not change in spite of any condition, so their researches had been carried out by rheology theory of continua. Engineering practices show that these studies do not reveal the key of deformation and failure of surrounding rock masses with above-mentioned properties and those supports adopted on the basis of their research results can not be take effects.Baozhen tunnel is the only soft rock tunnel and the key project in the Yi-wan railway. The very complex geological environments, such as high earth stress, deep-buried, rich groundwater, very weak and cracked rock masses and bias pressure along the rock seam, make self-stability of the tunnel be unfavorable. During construction, The high deformation rate, intense and long-time deformation are the basic characteristics; At the same time, the deformation shows asymmetrical features and uniformities. Carrying out a series r of laboratory testing research on Buzhen tunnel engineering practice:(1) According to the environment of surrounding rock occurrence, different physical and mechanical parameters of rock were measured, the Impact law of confining pressure and saturated time on peak strength, residual strength and post-peak volume change was obtained;(2) According to the rock laminated composite structures which tunnel face section distribute weak interlayer in large deformation sector, the law between interlayer thickness and rock strength was researched through conventional triaxial compression tests, the relation between interlayer and surrounding rock was put up before and after the interlayer damaged according to the specimen failure mode, the dynamic process of surrounding rock damaged caused by interlayer failure was studied, mechanical model of structural system was established to study the mechanism of deformation and yield;(3) According to test results and monitoring data of stress on supporting structure, a series of triaxial compression tests were conducted under conditions of low confining pressure, and explore the influence law of support resistance to the soft rock strength and the volumetric strain, in controlling aspects of large deformation of surrounding rock pointed out that the "strong support" was unreasonable support method in theory, in practice not feasible, put forward the best reasonable time for lining was at the end stage of post-peak softening and residual phase begins.Take Baozhen tunnel as an example, on the basis of detail site investigation and lots of data tested, measured and monitored in laboratory and on site, it is found that rheology and other characteristics of jointed and soft surrounding rock in high stress area resulted from not rocks but strata structure. It is complicated time-dependent deformation of structural distortion that results in large deformation of rock masses. Based on calculation and analysis by these data, three kinds of types of deformation were put forward:rock property controlling type, strata structure controlling type and environment in which surrounding rocks existed controlling type, pointed out that the second type was the key type which provoking large deformation. The large deformation of strata structure controlling type is defined as the phenomena or process in which surrounding rocks put up rheology feature due to the complex time-dependent behaviors and response of strata structure in the course of stress redistribution by excavation of soft jointed rock mass in high stress area.By analyzing spatial and temporal characteristics of displacements and failure of surrounding rock, the strong rheology and other correlated properties during dynamic evolutionary process of surrounding rocks are discussed. The mechanism and its characteristics and pattern of deformation were also discussed. On this basis, the dynamic characteristics of the surrounding rock and deformation types were summed up, the mechanical models of deformation were given respectively according to different strata structures, the principles and methods of controlling large deformation in soft tunnel were put up. At last, systemic technologies for building the tunnel in high earth stress and soft rock area were formed.From the viewpoint of large deformation provoked by strata structure failure, the dynamic evolutionary process and deformation mechanism were understood, which modifies the classic knowledge completely. The research results obtained form the author of this dissertation applied to Baozhen tunnel ensure various measures of controlling large deformation done in advance, and can also be used and referred for other similar underground works under complicated conditions.更多还原