【作者】 江权；

【导师】 冯夏庭；

【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， 2007， 博士

【摘要】 一方面,当前的水电开发、战略石油储备、CO2地下隔离、核废料地下处置等一系列国家战略性深部工程的建设与规划使得高地应力背景下大型地下工程的稳定性分析成为亟待解决的关键技术;另一方面,深部高地应力环境下洞室开挖过程中围岩表现出特殊的非线性力学行为使得传统的岩体(石)力学理论与分析方法面临着新的挑战。为满足国家建设需求和推进学科发展需要,本文围绕深埋高地应力条件下硬岩洞室群稳定性这一主题,以黄河上游拉西瓦水电站大型地下发电厂房洞室群和锦屏二级水电站引水隧洞南侧的深埋辅助洞为工程研究背景,在继承现有大型地下工程研究成果基础上,系统地从硬岩本构模型、围岩变形与破坏模式的评价指标、准确的岩体力学参数辨识方法、数值仿真技术的工程实践步骤共四方面形成了一个较完整的深部洞室群围岩稳定性分析方法。概括之,本文主要研究工作与获得的有益认识如下:1.针对传统的弹塑性本构模型在模拟高地应力下硬岩脆性破损的范围和深度方面不理想的问题,提出一种基于岩体力学参数随围岩塑性应变发生动态变化的硬岩劣化本构模型(Rock Deterioration Model,RDM),从而实现了对高地应力下地下工程中硬脆性围岩破损的准确模拟。同时,深入论述了模型的数值计算实现方法、后继屈服面非定常性、塑性区二次划分、模型可蜕化性等特点。室内花岗岩三轴压缩试验曲线拟合和锦屏二级水电站大水沟厂房探洞松动圈(EDZ)的模拟等工程实例验证分析有力地表明该模型可以较好地刻画高应力下硬岩的脆性破损和EDZ内岩体力学参数劣化的现象。2.考虑到洞室开挖后,岩体中主应力在开挖前后发生了大小变化和方向转动的这一应力重分布过程的矢量变化特点,提出了应力松弛系数用以描述平均主应力大小的改变程度,评价围岩的应力松弛范围;提出了主应力转动消散功用以描述主应力大小和方向同时改变的程度,评价洞室围岩破损的时间演化过程和易失稳部位的空间分布特征;并结合岩体内形状改变比能和体积改变比能等指标分析和总结了洞室连续开挖过程中围岩应力、能量、主应力转动消散功调整较剧烈的时段特点和空间分布特征。锦屏二级引水隧洞辅助洞K14～K15段实际开挖过程中岩爆发生的空间位置、岩爆活跃期、大型岩爆发生部位等多方面统计结果分析表明了上述评价指标具有实用性。3.为解决数值仿真计算时参数给不准的难题,提出了同时结合位移增量和实测松动圈两种量测信息,由参数敏感性分析→参数智能反演→反演结果检验三步构成的集成的参数反演分析方法。该集成分析方法较全面地考虑到了不同参数对围岩变形与屈服的敏感程度的差异性、参数辨识的全局搜索能力和反演参数的多角度检验等反分析的基本问题。4.鉴于人们对客观事物的感知是一个渐进式螺旋上升的过程,从认识论的角度出发,提出了大型地下洞室群围岩稳定性数值仿真技术工程应用的PFP(Preparation–Feedback–Prediction, PFP)分析方法,即结合地下工程施工的不同阶段,由第一阶段的工程预研究、第二阶段的前期反馈研究、第三阶段的后期预测研究构成。该方法充分利用了洞群分期开挖过程中信息量不断增多的特点,结合了数值仿真分析的优势,实现了实践到认识、认识再到实践的转化。5.将上述研究成果应用于拉西瓦水电站地下洞室群围岩稳定性研究,系统地从应力场、位移场、弹性应变势能、应力转动消散功和塑性区分布几方面综合分析和揭示了高地应力下洞室群开挖过程中岩体力学行为特点,并在前期反馈分析基础上预测了洞室后续开挖的围岩变形规律和可能的破坏模式与空间部位。同时,其研究成果也较好地应用于该工程的生产建设中。更多还原

【Abstract】 Recent years, stability analysis of large underground caverns has become a urgent key technology with the building and programming of many national strategic deep project and, such as hydropower station, strategic oil reserve, CO2 underground isolation, deep nuclear waste disposal, and so on. At the same time, special nonlinear mechanical behavior of wall rock is showed in the process of excavation under high geo-stress, which challenges the theory and methods of traditional rock mechanics.For the purpose of meeting the demand of national infrastructure and promoting the development of rock mechanics subject, the paper takes high geo-stress and hard rock as the main theme based on the background engineering of LaXiWa Hydropower Station underground caverns and auxiliary tunnel of JinPing II hydropower tunnels. Through roundly study of the rock constitutive model, indicator of rock’s deformation and failure evaluation, obtaining method of rock mass mechanical parameters, steps of numerical simulation for engineering application, the paper forms a relatively integrated stability analysis solution of underground caverns under high geo-stress environment. In sum, the main work and conclusion including:1. Aiming at the problem that the traditional elasto-plastic constitutive models have not been successful in predicting the depth and extent of brittle failed of hard rocks under high geo-stress condition, a new hard rock constitutive model—rock mass deterioration model (RDM) is put forward in which the mechanical parameters can be dynamic update with the plastic strain. The RDM takes the damage of rock as a process of propagating of micro-cracks and the relationship between mechanical parameters deterioration and damage degree represented by general plastic strain of EDZ is established.The model accords with the essential fact that the parameters in EDZ have changed and can describe the elasto-brittle mechanical broken behavior of hard rock. Both fitting of triaxial compression test stress-strain curves of granite and simulation of EDZ of testing tunnel in JinPing II Hydropower Station prove that the model is suitable for numerical calculation of underground hard rock caverns under high geo-stress condition.2. Since it is the vector changing that the principal stress’s direction and magnitude are altered with the redistributing of secondary stress in the process of excavation, a stress loosen coefficient which is used to evaluate the relaxation scope of wall rock is proposed, and a index, named principle stress rotation dissipation work (SRDW), is proposed to predict and judge the caverns’stability and damage spatial characteristics. Including the rock mass elastic strain energy, the paper summarizes the critical period in sequential dig of tunnel. The rock burst statistical analysis in auxiliary tunnel K14– K15 of JinPing II hydropower tunnels implies these indexes are applied.3. In response to the unfaithful value of mechanical parameters in numerical calculation, an integrated analysis method is builded up which is composed of sensitivity identification of mechanical parameters, parameters global optimization algorithm by GA-ANN and verification of displacement sequence gray association. The method absorbs two type measured information including depth of EDZ and deformation of wall rock and considers comprehensively the different effect of parameters related to deformation and plastic zone, the strong global research capability and the necessary of inspection.4. Considering the fact that people’s perception of objective reality is a process of gradual spiral, a new method of numerical simulating application technology for wall rock stability analysis in large caverns, named PFP (preparation–feedback– prediction) is promoted from epistemological perspective. That is composed of preparative study before the construction of engineering, feedback analysis in previous part of construction and prediction of behind part of construction. The method fully utilizes the incremental information in the stepping excavation process, absorbs the advantages of numerical simulation analysis, and realizes the conversion between practice to theory and theory to practice.5. Finally, applying the research fruits mentioned above to the stability analysis of LaXiWa Hydropower Station underground large caverns, the paper summarizes the general rules of hard wall rock mechanical behaviors under high geo-stress condition in stepping excavation from stress field, displacement field, elastic energy, stress rotation dissipation work and plastic zone. The results have provided guidance for rational design and safety construction of the project.更多还原