【作者】 汪斌；

【导师】 李新平；

【作者基本信息】 武汉理工大学 ， 岩土工程， 2011， 硕士

【摘要】 深埋地下工程岩体由于所处的特殊的“三高”复杂力学环境,即高地应力、高地温、高岩溶水压,使得其与浅部岩体相比具有明显不同的工程响应特征。深埋上千米的工程,在开挖、施工与运营的过程中,往往带来很多难以预测的问题,如岩爆、瓦斯突出、突水等一系列灾害性事故频频发生。为了避免突发性地质灾害对人民生命和财产造成危害,同时也为了尽量减少重大灾害的发生,必须对深埋岩体在开挖时引起力学特征进行深入细致的研究,分析研究深部岩石复杂的赋存地质环境,在高围压下的加卸载力学特性以及多场耦合模型。这样使得深部岩体工程面临着严峻的挑战,同时也是许多学者和工程技术人员进行科学研究的热点问题之一论文在研究“深部”及“深部工程”概念的基础上,收集大量国内深部工程的资料文献,参照Hoek-Brown的方法对深部岩体地应力特征进行了初步的分析,回归分析了深部岩体垂直应力随埋深的分布规律；最大和最小水平主应力随埋深的分布规律以及侧压力系数随埋深的分布规律等。分析了深部岩体结构面及二次应力分布的主要特征,并制定了相应的室内试验计划。从位于雅砻江上的锦屏二级水电站引水隧洞现场取得了白山组大理岩,岩石被加工成了标准的圆柱形试件(直径50mm,长100mm)。采用MTS815.03型岩石力学试验机系统对大理岩试样进行了一系列的常规三轴加载试验和卸围压试验。首先,进行了常规单轴试验和高围压下的三轴压缩试验,试验结果为后续的三轴卸荷试验的设计提供了指导和依据。其次,进行了不同初始卸荷围压下的三轴峰前、峰后卸荷试验。试验的卸荷方式采取恒定轴压、卸围压的方式。对三轴压缩试验和三轴卸荷试验的全应力应变曲线以及岩样破坏特征的进行了对比分析。在多场耦合理论方面,从应力和应变的角度研究了岩石渗透性演化规律,考虑岩石损伤对渗流场和应力场的影响,以弹性多孔介质孔隙度与体积应变的关系式为桥梁,建立深部岩石破裂过程的应力场、渗透场、损伤场相耦合的力学模型。根据锦屏二级水电站深埋引水隧洞地质条件以及室内试验相关结果,运用有限元分析方法研究了白山组大理岩地段引水隧洞的开挖及围岩的受力变形特征,计算主要考虑了常规的隧洞开挖支护计算工况以及考虑渗流应力耦合的隧洞开挖支护计算工况,进行了对比分析并得到了相关结论和工程建议。更多还原

【Abstract】 The engineering response characters of the deep rock masses are obviously distinct from that of the shallow part because of its complicated mechanical environment, that mean high in-situ geostress, high temperature and extra-high hydraulic pressure. There are a lot of doubtful questions, such as rock burst, water inrush and gas burst, in the process of construction, excavation and operation in deep rock engineering. In order to avoid the burst geological disaster and reduce the harm to the people’s life and the property, we have to do meticulous research in the mechanical characteristics of deep rock mass in the process of excavation. It is also essential to study the occurrence regularity of geological environment in deep rock, the load-unload mechanical behaviors of deep rock mass under the effect of high confining pressure, and the multi-filed coupling model. Deep rock mass has become one of the most important issues for many scholars and engineers, that is also a rigorous challenge for the current scientific research.Based on the research of the concept of "deep stratum" and "deep project", a large number of domestic document literatures about deep engineering have been gathered. Based on this, a preliminary analysis about the characteristics of geostress in deep stratum has been made referring the method of Hoek-Brown. Some regression analysis of the geostress in deep rock has been done, such as the distribution of the vertical geostress varying with depth, the distribution of maximum and minimum horizontal geostress varying with the depth and the distribution of the lateral pressure coefficient with the depth, etc. In addition, the distribution characteristics of the structural surface and the quadratic stress field in deep rock have been studied. The corresponding laboratory test plan has been designed for the paper.The typical Baishan marble rocks were obtained from headrace tunnel in Jinping II Hydropower Station lying on Yalong River and they were prepared as standard columniform specimens of 50mm in diameter and 100mm in length. A series of tri-axial tests under loading and unloading conditions are carried out by MTS815.03 rock mechanics test system for the marble samples. First, both conventional uniaxial and tri-axial tests under high confining pressure are conducted. The experimental results can provide scientific evidence for the design of tri-axial unloading tests. Second, tri-axial pre-peak and post-peak unloading tests are conducted under different initial confining pressure. The unloading mode is keeping axial stress and unloading confining pressure. The complete stress-strain curves and the rock sample failure characteristics are studied and compared between tri-axial compression and unloading confining pressure tests.In the theory of multi-filed coupling aspect, the permeability evolvement law of rock is studied from the point of stress and strain. The connection of the damage of rock mass with stress and seepage were analyzed. Take the relationship of the porosity and volumetric strain in elastic porous medium as a bridge, the stress-seepage-damage coupling model in the fracture process of deep rock was obtained. According to the geological condition of the deep-lying headrace tunnel in JinpingⅡHydropower Station and the related results from the laboratory tests, the excavation of the headrace tunnel in Baishan marble and the stress and deformation performance of the adjoining rock are analyzed by the finite element method. The conventional condition of the excavation process with support and the stress-seepage coupling condition are considered in the calculation. Some conclusions and engineering proposals are put forward through the comparative analysis in the last.更多还原