深部高应力硬岩脆性板裂破坏诱发机理与时空演化特征

Slabbing, spalling and strainburst usually occur in deep highly stressed hard rocks. In particular, the slabbing failure may take place when the maximum tangential stress is less or even much less than the corresponding uniaxial compressive strength of the rocks. The induced factors and the occurrence mechanism of slabbing failure are complex and its space - time evolutionary process is not clear. Based on the MTS triaxial testing machine and the true triaxial testing system, a serious of normal triaxial tests and true triaxial compressive tests (including loading and unloading σ3) and coupled highly static stresses and dynamic disturbance tests will be carried out on hard rocks. By using the stress - strain analysis, the acoustic emission monitoring and positioning technology, and the fracture surface microscopic scanning analysis, the failure mode of hard rocks under different stress conditions will be identified. The difference and the relationship between slabbing failure and shear failure can be obtained by the laboratory testing results. The strength criterion will be established and the occurrence mechanism will be revealed for the slabbing failure of highly stressed hard rocks. Meanwhile, the in-site investigations for rock slabbing and spalling will be carried out at some deep hard rock mines in China. The location and the extent of slabbing fractures induced by excavation of hard rock caverns will be determined by using the microseismic monitoring technology and the television borehole camera technology. The stress change induced by the dynamic excavation unloading process will be simulated by numerical modeling. The relationship between the slabbing failure and the stress concentration will be obtained. The space - time evolutionary characteristics of slabbing failure will be verified in this project. The aim of the project is to provide a theoretical basis and technical guidance for the effective control and use of slabbing failure in deep highly stressed hard rock caverns.

板裂、片帮和应变型岩爆是深部高应力硬岩的常见破坏形式，特别是板裂破坏，常在围岩最大切向应力低于甚至远低于岩石单轴抗压强度的情况下发生，其诱发因素和诱发机理复杂，时空演化过程尚不明确。本项目基于MTS三轴试验平台和真三轴扰动试验系统，开展硬岩三轴加卸载及高静应力下的动力扰动试验，通过应力应变分析、声发射监测定位技术和破裂面微观扫描分析确定硬岩在不同应力环境下的裂纹扩展模式，获得硬岩板裂破坏和剪切破坏之间的区别和联系，建立硬岩板裂破坏的强度准则，揭示高应力硬岩开挖板裂破坏的诱发机理。同时，项目结合我国一些深部开采硬岩矿山，开展高应力硬岩板裂破坏现场调研，并利用电视钻孔摄像技术确定深部硬岩硐室开挖板裂破坏的位置与范围，通过三维数值模拟确定板裂破坏与围岩应力和动态开挖卸荷之间的关系，探明板裂破坏的时空演化特征和规律，为深部高应力硬岩板裂破坏的有效防治和利用提供理论基础和技术指导。

随着矿产资源开采逐渐走向深部，深部硬岩硐室在开挖后易发生板裂、片帮、岩爆等工程动力灾害，严重威胁深部资源的安全高效开采。本项目针对深部高应力硬岩板裂破坏诱发因素和诱发机理复杂，时空演化过程不明确等问题，依托中南大学矿业工程“双一流”学科建设平台，基于自主研发的TRW-3000型真三轴扰动试验系统、SHPB动静组合试验系统和MTS815三轴试验系统，开展了大量的硬岩三轴加卸载及高静应力下动力扰动试验、数值模拟与理论研究，深入揭示了深部高应力硬岩开挖诱发板裂破坏机理，获得了加卸荷路径和动力扰动对硬岩强度及破坏模式的影响规律，确定了硬岩板裂破坏和剪切破坏之间的区别和联系，建立了正交各向异性板裂屈曲岩爆力学模型并提出了控制方法，提出了三轴加卸荷下硬岩强度破坏准则，并开发了考虑中间主应力效应的岩石类材料真三轴试验数值软件。结合深部硬岩工程实例，将试验研究结果反馈到深部工程现场，进行了深部高应力硬岩的微震监测、钻孔摄像和三维数值模拟，获得了高应力硬岩硐室开挖卸荷围岩板裂破坏的时空演化特征和规律，形成了深部硬岩板裂破坏的综合防控理论与技术体系，为深部资源的安全高效开采提供了强有力的理论依据与有效的防治措施。本项目超额完成了任务书的预期目标，累计在本领域学术期刊发表标注本基金号论文39篇，其中SCI收录15篇、EI收录14篇，累计申请国家发明专利10项，其中获授权国家发明专利4项、实用新型专利3项，参与制订贵州省地方标准1项，参编教材1部，获中国黄金协会科学技术奖一等奖2项。依托项目支撑，项目负责人先后受邀赴加拿大、新加坡、挪威、北京等地做学术报告13次，2016年项目负责人获澳大利亚“奋进长江研究学者”奖，2017年9月晋升为教授，2018年获湖南省杰出青年基金资助。项目培养毕业博士生1人，硕士生6人，其中3人次获国家研究生奖学金，1人获湖南省优秀毕业研究生，1人获中南大学优秀硕士学位论文。

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