节理岩体力学性质变异性的多尺度表征及其对地下开挖可靠性的影响

The characteristics of variability and spatial variability in the mechanical properties of the jointed rock mass lead to the uncertainties and design risk in underground rock engineering due to the difficulties in modelling and parameter setting, and consequently become one of the important factors that control the construction safety of the underground engineering. How to quantitatively evaluate the variability in rock mass mechanical properties and its influence on the deformation and stability assessment of underground excavations is one of the difficult and hot problems in both domains of engineering geology and rock mechanics. In this research project, the methods of in-situ geological survey, theoretical analysis, numerical simulation, the indoor and in-situ mechanical testing and the multi-scale geological structure measurement will be comprehensively employed to characterize the variability of the mineral composition, the microscopic geological defects, the roughness and the geometric characteristics of the joint, and so on. The influence mechanism of these multi-scale geological structures on the variability in the mechanical parameters of both the intact rock and the rock mass will be studied. The characteristic of the spatial variability in the rock mass mechanical properties will be investigated based on the qualitative evaluation and quantitative computation of the rock mass mechanical parameters of typical underground engineering. The spatial variability will be modelled using multidimensional correlated random field theory. The reliability assessment model of the underground engineering will be set up and the algorithm to compute the reliability index and its failure probability will be developed. The influence of the spatial variability in rock mass mechanical properties on the reliability of the underground excavations will be investigated. The research achievements of this project will provide theoretical support for uncertainty evaluation of rock mass mechanical parameters, and the safety design and quantitative risk assessment of underground rock engineering.

节理岩体力学性质具有变异性和空间变异性，给地下工程计算建模和参数确定带来不确定性和设计风险，成为影响地下工程建设安全的重要因素。如何定量评价岩体力学参数的变异性及其对地下开挖稳定和变形的影响，是工程地质和岩石力学研究中的热点和难点问题。本项目拟通过野外地质调查、理论分析、数值模拟、室内外力学试验、宏细观地质结构测量等方法，从岩石、结构面和结构面网络三个层次，探索矿物成分，细观地质缺陷，结构面粗糙度，结构面几何特征等宏细观地质结构变异性的表征方法及其对岩石和岩体力学参数变异性的影响机制；通过典型地下工程岩体力学参数的定性评价和定量计算，研究岩体力学参数空间变异性规律和模拟方法；基于多维相关随机场模型，建立地下开挖可靠度分析模型与求解算法，探讨岩体力学参数空间变异性对地下开挖可靠性的影响机制。研究成果将为完善岩体力学参数不确定性评价方法，发展地下工程安全设计和风险定量评价理论提供参考。

节理岩体力学性质具有变异性和空间变异性，给地下工程勘查设计带来不确定性和风险，成为影响地下工程建设安全的重要因素。如何认识并评价岩体力学参数的变异性及其对地下开挖变形和稳定的影响，是工程地质和岩石力学研究中的热点和难点问题。本项目通过野外地质调查、理论分析、数值模拟、室内外力学试验、宏细观地质结构测量等方法，从岩石、结构面和结构面网络三个层次，探讨了矿物成分，细观地质缺陷，结构面粗糙度，结构面几何特征等宏细观地质结构变异性的表征方法及其对岩石和岩体力学参数变异性的影响机制；通过典型地下工程岩体力学参数的定性评价和定量计算，研究了岩体力学参数空间变异性规律和模拟方法；基于多维相关随机场模型，建立了地下开挖可靠度分析模型与求解算法，探讨岩体力学参数空间变异性对地下开挖可靠性的影响机制。主要结果总结如下：. （1）提出了一种基于纳米压痕试验的岩体矿物细观力学参数确定方法，以花岗岩为研究对象，从宏观和细观两个方面研究了花岗岩的力学特性，提出了一种从细观层面研究岩石宏观力学性质变异性的研究方法。. （2）基于三维扫描技术构建了岩石结构面粗糙度精细化表征与评价方法，探讨了采样方法对结构面粗糙度系数尺寸效应和各向异性评价结果的影响。发现结构面粗糙度的空间不均匀性是引起不同区域测量结果变异性的根本原因，提出了全数据采样法和旋转采样法。. （3）建立了考虑支护与围岩相互作用的隧道多失效模式及其功能函数；提出了基于移动最小二乘法的隧道可靠度分析方法；发展了基于条件概率和Excel电子表格中的隧道系统可靠度分析方法；建立了考虑岩体参数空间变异性的隧道可靠度分析方法，揭示了岩体参数空间变异性对隧道失效概率的影响规律；建立了基于响应面法的隧道支护结构概率优化设计发方法。. 研究成果为完善岩体力学参数不确定性评价方法，发展地下工程安全设计和风险定量评价理论提供依据。