高应力硬岩卸荷变形破裂机理与模型

This project is practically programmed to study the unloading mechanical behavior of high stressed hard rocks during deep excavation. Firstly, the deformation and failure mechanism, as well as the strength properties of hard rocks under different unloading conditions (e.g. high stress state, unloading rate, stress path and unloading grade) are investigated through real triaxial unloading tests. And also a series of field tests including deformation, elastic wave, borehole camera, acoustic emission and microseism are carried out to recognize the development of excavation damage zone in deep engineering. Then, based on the concept of system recognition and intelligent global optimal analysis, a new and more sufficient model recognition method is designed to establish the strength function and mechanical model accounting for the affects of different high stress state, unloading rates and deterioration of rock properties. This method can perform coupling global optimal search of both model structure and its parameters. Meanwhile an intelligent multi-information back analysis method depending on comprehensive analysis of different field tests is proposed to find the space-time evolution behavior of engineering rock parameters during deep excavation. And finally, based on the new-developed strength function, the deterioration model and the multi-information back analysis method, the stability analysis system of deep engineering rock with high stress under strong unloading conditions is proposed and provides a theory tool for deep rock engineering analysis.

以深埋工程硬岩为研究对象，通过不同高应力状态/路径变化以及不同卸载强度和不同卸载速率下岩石的真三轴卸荷试验以及典型深部工程围岩开挖变形破裂演化过程中变形、弹性波、钻孔摄像、声发射与微震等的综合实时监测，揭示其变形破坏机理及其强度特性；引入系统辨识和全局优化的智能分析思想，研究考虑三向高应力状态变化、卸载速率效应和围岩时空弱化特征的模型结构自组织与参数自适应耦合识别方法，建立新型岩石强度准则和力学模型；提出与深部开挖围岩损伤演化相适应的岩体力学参数多元信息智能反演方法，研究深部开挖卸荷围岩力学参数的时空演化规律；从而建立能够反映开挖卸荷效应和围岩时空劣化特征的深部围岩稳定性分析方法，为资源深部开采以及深部岩石工程建设提供必要的基础理论和分析工具。

我国西部地区山高谷深，地势异常陡峻，随着西部水电开发建设规划的深入开展，一系列在建和将建的水电工程难免遇到超埋深、超高地应力等的特点。深部真三向高应力环境下岩石表现出不同的变形破裂机制，具有显著开挖卸荷效应。现有基于常规三轴试验的岩体强度理论和力学模型计算结果往往与实际不符，给当前岩石力学学科及工程应用研究提出了巨大挑战。为此，本项目依托我国埋深的最大的锦屏地下实验室二期工程(埋深2400m)，开展了不同高应力状态/路径变化以及不同卸载强度和不同卸载速率下锦屏大理岩的真高压三轴加卸荷试验和破裂过程声发射测试，以及实际工程开挖围岩变形破裂演化过程中变形、弹性波、钻孔摄像等的综合实时监测，获得了锦屏大理岩弹、塑、延、脆阶段性变形特性，揭示了高应力诱导的锦屏大理岩脆、延性特性，破坏变形各向异性和以拉为主的破裂机制，以及高压真三轴卸载条件下卸荷起点和卸荷速率对其变形破坏和强度特性的影响机制；提出了系统辨识和智能全局优化与机理认识相结合的建模思想，基于理论分析和模型智能辨识，建立了以拉破坏为主的深部硬岩三维破坏准则和新型力学模型，并嵌入到EPCA3D数值模拟平台，通过对高压真三轴试验过程模拟，验证了模型的准确性；针对深部硬岩从开挖向围岩内部的破裂演化特征和三维应力状态，提出了与深部开挖围岩损伤演化相适应的岩体力学参数多元信息三维智能反演方法。运用上述的理论、模型和算法，对锦屏地下实验室开挖过程进行了模拟验证分析和应用研究，对锦屏大理岩力学参数进行了合理反演，通过数值模拟合理解释了围岩内部变形多模态特征和分区破裂现象，以及典型岩爆孕育过程围压破裂演化和能量积聚释放，从而验证了项目成果的可靠性和实用性，为深部岩石工程建设提供必要的基础理论和分析工具。