【作者】 刘业科；

【导师】 曹平；

【作者基本信息】 中南大学 ， 土木工程， 2012， 博士

【摘要】 地下深部岩体处于高地应力、高温和地下水的多场耦合复杂环境中,其岩体的变形破坏特征呈现出明显的流变性,岩体变形具有时间相依性,变形量随时间延长而不断增加,从而导致岩体抗破坏能力下降。同时,地下水通过物理化学作用和水压作用使岩体组分改变、微孔隙生成、微裂隙扩展,损伤程度加剧,粘聚力和摩擦系数变小,使其宏观上的强度和刚度等力学性能下降,岩体更易变形且变形量更大。深部岩体所处的特殊地质力学环境是造成深部岩体工程毁坏和人员财产损失自然原因。因此,开展水岩作用下深部岩体的损伤演化和流变特性研究,其成果能为地下深部井巷工程和硐室开挖、支护以及稳定性分析提供科学依据,对深部岩体工程的安全建设、营运及其长期稳定性具有重要的指导意义和良好的工程应用价值。本文研究内容依托国家自然科学基金资助项目(50774093：水岩作用下裂隙岩体流变—损伤—断裂耦合理论及应用)、中南大学研究生创新基金项目(134377237：高应力下极软弱岩体变形机理及巷道断面大规模收敛成因研究)和金川有色公司重大科技攻关课题：“金川矿山深部高强度采掘条件下的岩石力学研究”。采用流变力学与损伤力学理论,从现场调查、采样加工到室内试验、理论分析与计算机仿真模拟等多方面深入研究了水岩作用下深部岩体的损伤演化规律和流变特性。主要研究工作及成果包括以下几个方面：(1)通过资料整理、现场地质调查和现场监测等手段探明金川二矿区深部岩体的地质环境和节理裂隙的赋存情况；对金川二矿区深部850m、978m和1098m三个分段的典型岩性进行采样-加工-室内物理力学试验,得到了各岩性岩样的基本物理力学参数；对各岩性岩样的试验结果进行对比分析发现：二辉橄榄岩和含辉橄榄岩的力学强度指标较高,大理岩和斜长角闪岩的力学强度指标较低,且斜长角闪岩饱水后的力学性能下降最为明显,以此确定各岩性中岩石强度较低、饱水后力学指标下降最多的斜长角闪岩作为后阶段水损伤演化试验和流变试验的研究对象。(2)以斜长角闪岩为代表岩性,开展了水岩作用下岩样的膨胀损伤演化试验、离子浓度测定试验、电子显微镜微观结构成像试验、基于核磁共振技术的水岩作用下岩样内部结构的细观试验和水物理化学损伤下岩体节理表面形貌特征的细观试验。试验成果表明：岩样遇水发生水损伤的机理就是岩样中的亲水性矿物成分蒙脱石与水发生一系列的物理化学反应,改变岩体组分和内部结构,岩样的自由膨胀率、内部孔隙度、节理表面特征参数和宏观力学参数都随浸水时间的延长而呈指数衰减函数关系,并运用岩石损伤力学理论建立了分别以膨胀率、孔隙度和浸水时间为损伤变量的金川二矿区深部岩体—斜长角闪岩的水损伤演化方程和本构关系。(3)使用RYL-600岩石剪切流变仪在自然状态下和饱水状态下对含蒙脱石的斜长角闪岩开展了的室内单轴分级增量循环加卸载蠕变试验,得到了各应力水平下岩样的应变-时间曲线。试验结果分析表明：岩样同时具有瞬弹性、瞬塑性、粘弹性和粘塑性的非线性粘弹塑特性；岩石的变形量随时间的延长而不断增大,具有明显的流变性,地下水对深部岩体内部组构的改变与力学性能的损伤弱化降低了初始蠕变强度和岩石长期强度,增大了蠕变变形量和蠕变速率,加剧了深部岩体流变性。(4)采用无损高效的核磁共振技术,对蠕变试验过程中不同应力加卸载状态中的岩样进行了核磁共振成像和横向弛豫时间T2谱面积的反演分析,得到了对应蠕变试验阶段中岩样的核磁共振孔隙度。由试验结果可知：饱水状态下的岩样在相同的蠕变试验过程阶段中具有更大T2谱面积以及核磁共振孔隙度,反映出水与岩样发生水岩物理化学反应,岩样内部结构变松散,损伤程度加剧,蠕变变形量更大；自然状态下和饱水状态下岩样的T2谱面积和核磁共振孔隙度随着蠕变加载荷载的增加而减小,说明在岩样未破坏的衰减蠕变阶段,随着外载荷的增加,岩样内部的微裂隙和孔隙被压密闭合的程度越来越高；饱水状态下的岩样的相邻荷载等级的T2谱面积和孔隙度变化率更高,说明饱水状态下的岩样内部细小缺陷更多,压密闭合的空间更大,而且其抵抗压力的力学能力较弱,对于相同外荷载变化的情况内部响应更加明显。(5)根据室内蠕变试验所获得的试验数据,本文基于岩石流变力学理论引入非线性元件,建立了一个能同时模拟衰减蠕变、定常蠕变和加速蠕变特征的新的岩石非线性粘弹塑蠕变模型。通过对模型参数的辨识,对各应力水平下岩样单轴蠕变试验数据进行处理,确定了该模型本构方程各参数的量值。从试验曲线和模型曲线的高吻合程度可知,新建立的模型能很好的描述深部工程岩石的蠕变特性。(6)通过蒙特卡洛法建立随机分布的二维岩体裂隙网络,结合Visual C++的编程功能产生能够描述节理裂隙各种分布特征的随机数,在ANSYS平台上建立有限元模型,然后根据已建立的力学模型,利用FLAC3D的蠕变计算模块,应用fish语言完成本构模型的二次开发设计,对水岩损伤作用和岩石流变作用下金川二矿区深部岩体在不同支护条件下井巷围岩塑性屈服状态和围岩松动圈的动态扩展进行了FLAC3D数值仿真分析。围岩采用锚杆支护系统的巷道收敛变形量大幅降低；岩体中裂隙水的存在会进一步恶化围岩环境,使得相同条件下巷道收敛变形量更大；锚杆长度是影响支护效果的主因,而锚固力对锚杆支护系统的锚固效果作用有限,锚杆长度以自由端略大于松动圈厚度为最佳,这样既能保证锚固端处于稳定围岩内,又由于锚固端与松动区有一定的距离而减缓松动圈外扩速度,从锚固效果、施工难易程度和经济效益等三方面因素来综合分析比较,本文建议金川二矿区深部井巷围岩选择3.0米长的锚杆来进行支护。更多还原

【Abstract】 Underground deep rock mass is in the complex environment of high in-situ stress, high temperature and underground water. Its deformation and failure characteristics have shown a significant rheological behavior. The deformation quantity of rock mass is increasing with time, causing the rock mass anti-destruction capability decline. At the same time, its components are changed by underground water through physical and chemical effects and hydraulic pressure. Besides, its microporosity generate, micro-crack propagating, damage aggravating, the cohesion and the friction coefficient smaller, macro-mechanical properties such as strength and stiffness declining and deform easier and the amount of deformation greater. The complex and specific environment resulted in the destruction of the rock engineering and personnel property damage.Therefore, the research of damage evolution and rheological behavior of the deep rock mass under water-rock interaction could provide scientific proof for the excavation,support and stability analysis of deep rock mass engineering, and had important guiding significance and good engineering value in the aspects of production safety, operation and engineering lond-term stability.This doctoral dissertation has been supported by National Natural Science Foundation of China (NO.50774093), Graduate Degree Thesis Innovation Fundation of Central South University (NO.134377237) and Jinchuan mining company significant science and technology project. Rock mass mechanics, rheology and damage mechanics theory has adopted to study damage evolution and rheological behavior of deep rock mass under the water-rock interaction from the field survey, the experimental research, the theoretical analysis and the computer simulation. The research work and achievement include the following aspects:(1) The geologic environment of deep rock mass at Jinchuan2#Mine had been known though the summary of data, the field work and on-the-spot measure. A mass of rock smples of different lithology were gained from850m、978m and1098m level of deep rock mass at Jinchuan2#Mine. A series of rock physical mechanics lab tests had been carried out in order to get fundamental physical mechanics parameter of rock samples. The result of tests showed that the mechanical property of the iherzolite and the clinopyroxene-peridotite exceeded in the Amphibolite’s and the marble’s, and the Amphibolite’s declined most obviously with the increase of the moisture content. So the amphibolite had been determined as the research object of water damage tests and rheological behavior in the later stage.(2) Several tests aiming at the amphibolite were done for damage evolution research with soak time on deep rock mass under water-rock interaction, including swelling test,ionic concentration measure test, microcosmic test of rock mass internal structure damage by electron microscope(EMS), mesoscopic test of rock mass internal structure damage based on nuclear magnetic resonance (NMR) technology and mesoscopic test of rock mass joint surface topography using advanced TalysurfCLI20003d laser surface topography measure instrument. The results of tests showed that the montmorillonite of rock samples occurred a series of physical and chemical reaction with water and led to rock mass damage.Besides,the free swell ratio,the NMR porosity,the joint surface topography characteristic parameter and the macro mechanical parameter had exponential decay function relation with soak time. And then damage evolution equation and constitutive relation of the amphibolite under water-rock interaction were established respectively by different damage variable according to the rock damage mechanics theory(3) The uniaxial multi-step incremental cycling loading and unloading creep tests of the amphibolite had been conducted with using the RYL-600shear rheometer both in nature drying condition and saturated water phase. And the strain-time curves of the rock samples under different stress were got from the creep tests. The experiment results showed that the rock samples had nonlinear viscoelastoplastic characteristics, including instantaneous elasticity, instantaneous plasticity, viscoelasticity and visco-plasticity.The deformation amount of rock increased continually with loading level and loading time. The rock samples showed obvious rheology. The underground water by water-rock interaction changed rock composition and structure, resulted in rock damage and reduced rock mechanic property, which dropt the creep threshold,increased the creep deformation amount, the creep rate and the stability time and aggravated the rheology of deep rock mass.(4) The T2relaxation time spectrum area and NMR porosity of rock samples at creep test could obtain with high effective and non-damage NMR technology.The results of the NMR image analyzing system indicated that the rock sample at saturated state had greater T2relaxation time spectrum area and NMR porosity, proved that water-rock interaction resulted in rock mass internal structure looser,rock damage aggravation and creep amount geater.The micropores and microcracks were consolidated with the increase of the external loading when the samples were at decay creep stage both in the natural state and in the saturated state,and the more the external loading,the less the T2relaxation time spectrum area and NMR porosity. The change rate of the T2relaxation time spectrum area and NMR porosity at different external loading in the saturation state was bigger.Because the rock sample had more micro defects,greater consolidation space and respond more strongly on the change of the external loading.(5) On the base of the results from the creep test and rock rheological mechanics theory, a new rock creep model had been put forward in this paper. The new model adopted the series and parallels of different linear elements of elasticity, viscosity and plasticity and the introduced nonlinear elements. It could simulate the behavior of decay creep, steady creep and accelerating creep at the same time. The parameters of constitutive equation of the new model had been confirmed though recognizing model parameters and processing the uniaxial creep tests results of rock samples under different stress. From the high consistency between the test and model curves, it could be known that the new model was suitable to describe the creep characteristics of the deep engineering rock.(6) The joint cracks random distribution network of rock mass was established by the monte carlo method.The random number had been produced with Visual c++programming,which could describe all kinds of distribution characteristics of the joint cracks. The finite element model was established, using ANSYS.And then, based on the established rock rheological model, to use the FLAC3D creep calculation module completed constitutive model of secondary development design through the application of fish language.The computer numerical modeling was done by FLAC3D to simulate the plastic yield state and loose circle dynamic expansion of deep surrounding rock at Jinchuan2#Mine under the water rock damage effect and rock creep in different supporting conditions. The results showed that the bolting system could decrease the deformation amount of the surrounding rock obviously.The underground water had an adverse effect to the tunnel’s long-term stability and increased its deformation amount.The length of the bolt had major influence on the supporting and was the best when the bolt’s free end was slightly greater than the thickness of the loosen zone According to the computer simulation analysis,the paper advised that the length of th bolt was3.0meter.更多还原