【作者】 李鹏；

【导师】 刘建； 贺怀建；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2010， 博士

【摘要】 水是影响岩体工程安全性的重要因素之一,水与岩体之间不仅存在力学作用,还存在复杂的水-岩物理化学作用,许多岩体工程的破坏和失稳均与水-岩作用密切相关。随着我国大规模的岩体工程建设,岩体工程在荷载和水-岩作用下的应力-渗流-化学(M-H-C)耦合问题日趋重要。因此,开展岩体剪切特性的水-岩作用效应、岩石M-H-C耦合本构模型以及M-H-C耦合数值模拟的研究,对于受水-岩作用影响的岩体工程如边坡、坝基、地下洞室及核废料地下储存、溶浸采矿、油气田开采等问题,均具有重要的理论意义与应用价值。本文围绕存在水-岩作用的岩体工程稳定性问题,采用试验研究、理论分析与数值模拟相结合的方法,就水-岩作用对岩体剪切特性的影响效应开展了系统的试验研究,分析了水-岩作用对岩体剪切特性的影响规律,探讨了其作用机理；建立了岩石水化学损伤动态演化数学模型,开展了岩石水化学损伤动态演化的数值模拟研究；探讨了岩石M-H-C耦合的基本理论与相关问题；提出了岩石M-H-C耦合弹性本构模型和M-H-C耦合弹塑性本构模型,分别编制了其数值模拟程序,建立了相应的数值模拟方法,同时进行了工程算例分析。论文的主要研究内容如下：1.开展了不同水化学溶液侵蚀条件下砂岩的抗剪强度试验,分析了水化学作用对砂岩微细观结构的影响效应,探讨了砂岩的水化学损伤机理。在此基础上,分析了水化学作用对砂岩抗剪强度的影响规律,同时通过引入岩石水化学损伤度,定量表达了砂岩抗剪强度参数随水化学损伤的变化过程。2.开展了具不同含水率的砂岩软弱结构面剪切蠕变试验,分析并探讨了含水率对砂岩软弱结构面剪切蠕变特性及长期抗剪强度的影响规律与机理。研究表明,在相同应力水平下,随着含水率增大,其蠕变变形和蠕变速率显著增大,达到稳态阶段所需时间明显延长,初始蠕变强度和长期抗剪强度逐渐降低,且长期抗剪强度随含水率变化符合指数函数关系。3.根据试验结果,对黏弹塑性元件组合蠕变模型进行了改进,建立了能考虑含水率影响效应的砂岩软弱结构面剪切蠕变模型,同时采用进化优化算法对该蠕变模型中的多参数进行了反演。4.采用化学动力学方法建立了岩石水化学损伤动态演化数学模型。在此基础上,对工程时间尺度内重庆砂岩在水化学环境下的损伤演化过程进行了数值模拟,分析了水溶液酸碱度、离子种类与离子浓度对重庆砂岩损伤演化的影响效应与规律。5.提出了由水化学损伤动态演化模型、岩石固相基质本构方程、渗流方程、孔隙压力变化方程等构成的岩石M-H-C耦合弹性本构模型。6.基于所提出的M-H-C耦合弹性本构模型和模块化思想,利用多物理场耦合分析软件COMSOL的流-固耦合模块和水文地球化学分析软件Phreeqc,分别对其进行二次开发,编制相关的接口程序,并通过岩石水化学损伤度将Phreeqc的水化学损伤计算过程与COMSOL的应力-水力耦合计算过程有机融合,构建起岩石M-H-C耦合的弹性数值模拟程序与方法。7.通过引入化学软化概念,在D-P屈服准则中加入化学软化力,提出了考虑水化学作用效应的岩石屈服准则及加卸载准则,采用关联流动法则,建立了相应的弹塑性本构模型,进而构建起包括水化学损伤动态演化模型、渗流方程、弹性常数和渗透系数的水化学损伤演化方程等的岩石M-H-C耦合弹塑性本构模型。8.基于所提出的岩石M-H-C耦合弹性数值模拟方法,通过嵌入上述M-H-C耦合弹塑性本构模型,构建了岩石M-H-C耦合弹塑性数值模拟程序与方法。9.采用所提出的M-H-C耦合弹性和弹塑性数值模拟方法,对某一存在水-岩化学作用的隧道稳定性分别开展了弹性和弹塑性计算分析,模拟了隧道在不同酸碱度、不同离子种类与离子浓度水环境下的损伤演化过程,分析了水环境酸碱度、离子种类与离子浓度对其稳定性的影响效应,并就弹性和弹塑性结果进行了比较分析。更多还原

【Abstract】 Water is one of the most active components in geological environment. Its interactions with geo-materials are not only the hydraulic effect which is correlated with the concept of effective stress, but also the effect of complicated water-rock effects. Previous studies have shown that the water-rock interactions play an important role in the geotechnical instability or failure. Moreover, with the advance of engineering technology and the scope of the deepening development of rock engineering, the coupled mechanical-hydraulic-chemical problem becomes more and more prominent. Therefore, the studies on mechanical characters of rock mass under water-rock interactions and the coupled problem of M-H-C have important theoretical significance and practical value to evaluate the long-term stability of rock engineering, such as slope, dam foundation, tunnel, underground cavern and waste disposal in environment engineering, etc.To study the stability problem in geotechnical engineerning, shear strength tests of sandstone under different hydro-chemical environments were carried out. The mechanism of hydro-chemical corrosion of sandstone was discussed. The effect of hydro-chemical action on shear strength of sandstone was analyzed and a variable was introduced to quantitatively express the hydro-chemical damage evolution of shear strength parameters. Moreover, shear rheology tests on weak structural plane of sandstone with different water contents were conducted. The effects of water content on the shear rheology behavior and long-term shear strength of weak structural plane of sandstone were analyzed, and then a modified viscoelastoplastic model was identified to describe the effects of water content on the rheology behavior of weak structural plane. A numerical model was proposed to predict the hydro-chemical damage evolution of rock. Following that, the coupled mechanical-hydro-chemical elastic and elastoplastic model were proposed respectively and the corresponding numerical simulation programs were developed. Then the stability evolution processes of a tunnel under different hydro-chemical circumstances were analyzed by both the coupled M-H-C elastic and elastoplastic methods. The main contents of the thesis are represented as follows:(1) Shear strength tests of sandstone under different hydro-chemical environments were carried out. The effect of hydro-chemical action on sandstone structure was analyzed from the viewpoint of meso-mechanism, and the mechanism of hydro-chemical damage of sandstone was discussed. On this basis, the effect of hydro-chemical action on shear strength of sandstone was analyzed, and a variable was introduced to quantitatively express the hydro-chemical damage evolution of shear strength parameters.(2) Shear rheology tests on weak structural plane of sandstone with different water contents were conducted. The curves of the shear rheology deformation vs. time under different water contents of the fillings were derived. The effects of water content on shear rheology behavior and long-term shear strength of weak structural plane of sandstone were analyzed. Moreover, the influence mechanism of water content effects on the rheological characteristics and long-term shear strength were discussed.(3) A modified viscoelastoplastic model, which based on the test results and analysis, was identified to describe the effects of water content on the rheology behavior of weak structural plane. Meanwhile, the parameters of the model were identified through back analysis by genetic algorithm.(4) A hydro-chemical damage evolution model was proposed by chemical kinetics method. Based on the model, the hydro-chemical damage evolution processes of Chongqing sandstone under different circumstances, which considered the variations of pH values, ions species and ions concentrations, were simulated. Moreover, the sensitivity of the influencing environmental factors was discussed.(5) A coupled M-H-C elastic model was proposed, which was composed by hydro-chemical damage evolution model, rock matrix constitutive model, seepage equation and pore pressure equation.(6) With modular software development method, a new program was developed to simulate the coupled M-H-C elastic model based on COMSOL and Phreeqc.(7) By introducing the concept of chemical softening, a coupled M-H-C elastoplastic model was established.(8) Based on the numerical simulation program of the coupled M-H-C elastic model, by embedding the coupled M-H-C elastoplastic constitutive model, a new program was developed to simulate the coupled M-H-C elastoplastic model.(9) The stability evolution processes of a tunnel under different hydro-chemical circumstances were predicted by both the coupled M-H-C elastic and elastoplastic methods. Then the environmental impact factors to the stability of the tunnel were analyzed.更多还原