深部煤岩体开挖动力响应机制及数值计算方法研究

Aiming at national energy strategy security, the safe and efficient coal exploitation in deep mine is one of significant scientific problems for a long time. The researches concerning mechanical characteristics and excavation response mechanism of coal-rock mass are important parts of national deep mining theory. Stress field of surrounding rock changes abruptly inducing by the coal-rock mass excavation in such a high-stress setting and the loading mode turns from axial and radial-direction unloading into combination of various loading modes including axial and radial-direction unloading and radial-direction unloading with axial-direction loading. Besides, it is difficult for routine specimens to achieve the characterization test for diverse mesoscopic structures and complicated boundary conditions of the coal-rock mass. Taking the engineering coal-rock mass as research object, both mechanical experiment and numerical simulation are adopted for trans-scale analysis of mechanical behavior of the coal-rock mass with the complex stress path. Discrete element models for the coal-rock mass considering intrinsic mesoscopic structure property was obtained in the complicated boundary conditions. The numerical method on dynamic effect of the coal-rock mass excavation was established interactively regarding various intrinsic mesoscopic structure property and loading-unloading control factors. The trans-scale relevance between mesoscopic mechanical parameters and macroscopic mechanical parameters was revealed based on DIP-ISA technology and the mesoscopic mechanical parameters were all evolved. Next, we compiled loading and unloading servo-control function satisfying the surrounding rock moving velocity feedback and confining pressure control accouplement. And nonlinear mechanical characteristics and its response mechanism during the coal-rock mass excavation are possible to uncover successfully in the end. The reasonable theoretic proof would provide a basis to form hazard-induced mechanism inducing by the coal-rock mass excavation in deep coal mine.

深部煤炭资源安全高效开发是保障国家能源战略安全的重大科学问题之一，煤岩体力学特征与开挖动力响应机制是深地采矿理论的重要组成部分。深部煤炭开采诱发煤岩体受荷模式变为轴-径向加卸载与轴向加载、径向卸载的多种组合；借助常规试样，难以进行不同细观结构与复杂边界条件下煤岩体加卸载力学实验。本项目以工程煤岩体为对象，依托室内实验和数值模拟手段，分析复杂应力路径下煤岩体跨尺度力学行为，实现复杂边界条件下考虑既有细观结构属性的煤岩体离散元计算方法，开展不同细观结构属性与加卸载控制因素交互作用下煤岩体开挖动力效应数值方法研究。基于DIP-ISA技术，研究煤岩体细观与宏观力学参数的跨尺度关联性，推绎煤岩体细观力学参数，编写反馈围岩移动速度和匹配围压控制目标的煤岩体加卸载过程伺服控制函数；进而，揭示深部采动煤岩体的非线性力学特征及开挖动力响应机制。研究成果可为深地采矿中煤岩开挖破坏致灾机理研究提供有益理论支撑。

随着国家能源战略安全的逐步推进，深部煤炭资源的高效开发依然是重大科学问题之一。深井环境下，煤炭开采将诱发围岩应力场发生突变，进而煤岩体出现不同形式的宏观破坏，如张拉破坏、剪切破坏、片帮、底臌，并导致冲击地压、煤与瓦斯突出、矿井突水等动力破坏现象频发，亟待研究复杂应力路径下煤岩体非线性力学特征与开挖动力响应机制。深井环境下，煤岩体开挖所诱发的宏观破坏实则是一种“跨尺度”损伤-破裂演变过程。项目采用DIP技术与本征尺度分析（Intrinsic Scale Analysis, ISA）方法，揭示煤岩体开挖过程中细观力学参数与宏观力学参数间的“跨尺度”关联性是解决上述一系列难点问题的关键之所在，也使得准确分析深部煤岩体非线性力学特征与开挖动力响应机制成为可能。本项目凝练两大关键科学问题：（1）煤岩体开挖过程中宏观力学参数与细观力学参数间的“跨尺度”关联性与（2）加卸载过程伺服控制函数，借助于室内煤岩体单轴与三轴压缩实验研究方法，以煤炭开采中的采动煤岩体为研究对象，从分析采动体动力响应突变性出发，形成了不同组合受荷模式下煤岩体加卸载力学特性评价方法，研究了复杂加卸载条件下煤岩体开挖过程细观力学参数确定及数值建模方法，开展了不同细观结构属性与加卸载控制因素的煤岩体开挖动力效应数值计算方法，揭示了采动煤岩体非线性力学特征与开挖动力响应机制，为深地采矿中煤岩体开挖破坏致灾机理提供有益理论支撑，也为不同类型深地资源开发中围岩灾害防治提供科学借鉴。攻关期间，项目负责人先后获省部级科技进步一等奖3项、二等奖1项、陕西省专利一等奖1项，发表论文5篇，其中SCI收录2篇、EI收录3篇，并申请国家发明专利3项，协助指导博士研究生2名、硕士研究生5名，均与本项目研究内容紧密关联，项目负责人入选陕西省科技新星并获批国家自然科学基金面上项目持续资助，圆满完成了预期目标的要求。