深部硬岩矿山工程围岩非常规破裂演化与阻断机制

The shallow intact surrounding rock need be not supported. Because the unconventional slabbing or rock burst fracture, which have the similar macroscopic performance and breeding area, frequent concur in the deep intact surrounding rock, so the deep surrounding rock must be supported. At present, the evolution mechanism of unconventional fracture is not clear and it is difficult controlling the support time, area and strength accurately. The safety and efficient of deep resources exploitation are seriously restricted. Based on the knowledge mentioned above, the project focuses on the evolution and interrupt mechanism of the unconventional fracture in deep surrounding rock by reproducing secondary stress and dynamic disturbance. Through the theoretical analysis and numerical simulation, the response of the secondary stress to the boundary initial stress and the engineering layout will be revealed. Based on the true / conventional triaxial perturbation mutation test system and the pore pressure loading-unloading test system, the static compressing fracture test and the disturbance inducing fracture test on thick hollow cylinder and cube hard rock specimens will be carried out under different stress boundaries and stress paths. Through the analysis of Strength and deformation, Acoustic emission localization and Crack scanning, The fracture evolution properties and pore pressure interrupt parameters of unconventional fracture will be explored, and the unconventional fracture criterion will be established. The fracture criteria and interrupt parameters will be tested and optimized by the unconventional fracture examples in deep hard rock engineering. Furthermore, a comprehensive prevention and control theory and technology system of unconventional fracture in deep surrounding rock will be established。The project can provide theoretical basis for the mechanism recognition and prevention technology optimization of deep mining disaster.

由于高次生应力和采掘扰动下深部完整围岩易发生宏观表现和孕育区域类似的非常规板裂或岩爆破坏，浅部无需支护的完整围岩在深部就需要支护。目前，非常规破裂的孕育规律尚不明确，造成支护时机、区域与强度难以精确把握，严重制约了深部矿产资源的安全高效回收。基于上述认识，项目通过再现次生应力和动力扰动，重点研究深部围岩非常规破裂的孕育演化和支护阻断机制。通过理论分析和数值模拟，揭示不同工程布置支护下次生应力对边界原岩应力的响应规律；利用真/假三轴扰动诱变及孔压加卸载系统，开展不同应力边界和加卸载路径下圆筒和方筒硬岩静载压裂和动载诱裂试验，通过强度变形、声发射定位和裂纹扫描探求非常规破裂的时空演化规律和孔压阻断参数，进而构建非常规破裂判据；针对深部工程板裂或岩爆实例，检验并优化上述破裂判据和阻断参数，继而形成非常规破裂的防控理论和技术体系。研究结果可为深部矿山工程灾害灾变机制认识及防治技术优化提供理论依据。

我国浅部矿产资源消耗殆尽，越多的矿山迈入深部开采行列，深部开采已然常态化。岩爆等非常规岩石破裂灾害的频度和烈度会随着开采深度的增加而增加，严重制约了深部资源的安全、高效和绿色开采。高原岩应力、非均匀次生应力和采掘扰动是诱发岩爆等非常规破裂灾害的三个主要因素，基于此，本项目开展了岩石破裂灾变的相关研究，取得的主要研究进展如下：(一) 通过岩石多维静载压裂试验，研究了深部岩石的岩爆和板裂的发生的强度特征和应力条件。单轴抗压、双轴抗压和真三轴抗压强度均表现出明显的非线性规律，主要由尺寸效应和中间主应力效应引起；在“临空面σ3=0+较大的σ2应力水平”、“较小的σ3应力水平+较大的σ2/σ3比值”、“较小的岩样高宽比或较大的岩样宽厚比”等条件下更容易发生板裂或岩爆；(二) 通过室内试验和理论分析，揭示了岩石岩爆或板裂破坏的扰动催化和预应力阻断机制。疲劳或冲击扰动会促进岩石岩爆或板裂灾害的发生，施加扰动前体积应变为零，则岩石会更易扰动破裂；扰动诱裂岩石碎片中的小块含量增加，说明岩石的破裂更加的剧烈且岩爆发生的概率和烈度更大；通过施加预应力，可以减小次生应力场的应力梯度，进而阻断岩石的破裂和提高岩石的承载能力；(三) 基于声发射信号的峰值频率、平均频率和上升角等基本参数，提出了岩石破裂过程中拉、剪裂纹的判别依据。张拉裂纹声发射信号的峰值频率PF主要分布在200-400KHz之间，而剪切裂纹声发射的峰值频率PF主要分布在200KHz以下；在平均频率AF-上升角RA平面内，张拉裂纹与剪切裂纹声发射信号可以用AF=a RA+b (a，b为材料常数)来区分；(四) 结合小厂坝铅锌矿的工程分布和原岩应力情况，从应力转移方面入手开展了高岩爆区域资源开采技术的研究。构建了采场动力扰动及应力集中分析模型，分析了卸压爆破、工程卸压下矿体应力传递路线，为强岩爆区域的安全开采提供了理论基础。上述研究成果对深部工程围岩灾害类型认定、有效预警防治等提供了理论依据。