深部岩石应变型岩爆的能量驱动机理与倾向性判据研究

The strain rockburst is one of the major geologic disasters that often encountered in the process of excavation of deep underground engineering, which seriously threatens the safety of on-site personnel and equipment. Making the occurrence mechanism of rockburst clear is one of the scientific difficulties in the research field of rock mechanics. The strain-type rockburst is essentially a violent energy releasing phenomenon induced by excavation unloading and external disturbance in high stress surrounding rocks. Its mechanism is closely related to the stress states as well as the internal elastic strain energy of rock, the external unloading speed, and the dynamic disturbance modes, which is relatively complex. This project will focus on two main strain-type rockbursts, namely the pillar rockburst and the carven wall rockburst that occurred in deep stress environments. Four experimental schemes for rockburst simulations which can meet the stress condition of “high stress + unloading + external disturbance” are designed in this project. By using the modified rock true triaxial electro-hydraulic servo testing machine and the three-dimensional coupled static-dynamic loading system, we would achieve the laboratory simulation of rockburst and record the rockburst process in real time. In the theoretical analysis, taking the energy-driven mechanism of strain-type rockburst as the guidance, three key scientific problems, the classification standard of indoor rockburst tendency, the quantitative method of elastic strain energy in rocks before rockburst occurrence, and the energy mechanism of rockburst occurring under the three factors of “high stress + unloading + external disturbance”, are going to be emphatically investigated. Meanwhile, a new discriminant criterion for strain-type rockburst proneness based on the remaining energy density index would also be proposed.

应变型岩爆是深部地下工程开挖中经常遇到的主要工程地质灾害之一，严重威胁现场人员和设备的安全，明确其发生机理是岩石力学研究领域的科学难题之一。应变型岩爆本质上是高应力岩石在开挖卸荷和外力扰动下发生的动能释放现象，其发生机理与岩石受力模式、内部弹性应变能、外部卸荷速度和动力扰动方式密切相关，相对比较复杂。本项目针对深部受力环境下岩柱式和洞壁式两种主要的应变型岩爆，分别设计四种满足“高应力+卸荷+外力扰动”受力条件的岩爆模拟试验方案，然后采用改进后的岩石真三轴电液伺服试验机和三维动静组合加载试验机，实现岩爆室内试验模拟和发生过程的实时纪录；在理论分析方面，以应变型岩爆的能量驱动机理作为主线，重点突破室内岩爆冲击倾向性等级划分标准、岩爆发生前内部弹性应变能的量化方法和“高应力+卸荷+外力扰动”三因素下岩爆发生的能量作用机制等三个关键科学问题，并提出以剩余能量密度参数为指标的应变型岩爆倾向性判据。

本项目围绕矿柱型岩爆和洞壁型岩爆的受力特点，通过室内试验和理论分析，对两者发生的能量驱动机理与倾向性判据进行了系统深入的研究。首先分别设计了满足“高应力+卸荷+外力扰动”组合受力条件的岩爆模拟试验方案，先后开展了一维高应力扰动作用下矿柱型岩爆模拟试验、二维高应力卸一维情况下矿柱型岩爆模拟试验、三维高应力卸二维情况下矿柱型岩爆模拟试验、高应力内部卸荷&扰动作用下洞壁型岩爆模拟试验，再现了各种工况下岩爆发生过程和特点；进而以岩石线性储能规律为基础，围绕岩爆发生前内部弹性应变能的量化方法，分别开展了单轴压缩、双轴压缩&卸荷、三轴压缩&卸荷下岩样弹性应变能计算方法的研究，并提出了各种工况下以剩余弹性能指数为核心的岩爆倾向性判据，可以科学衡量岩爆发生的激烈程度。针对高应力卸荷&扰动作用下诱发岩爆的能量作用机制，分别开展了预制钻孔岩石和高应力实时钻孔岩石储能能力及岩爆倾向性特征的研究，确认了钻孔卸压防治岩爆的能量机理。