抛掷型岩爆机制与模拟试验技术

MECHANISM OF EJECTIVE ROCKBURST AND MODEL TESTING TECHNOLOGY

为探讨高地应力隧洞岩爆机制，在岩爆试件试验的基础上，对抛掷型岩爆机制提出4点新的认识，即围岩中要发生抛掷型岩爆，单靠岩爆体本身积蓄的能量还不够，必须要有周围岩体对其破坏过程进行能量补充；工程中发生岩爆时，洞壁围岩会对岩爆体产生能量汇聚，这是抛掷型岩爆发生的重要前提；在抛掷型岩爆发生过程中，动、静状态转化是由洞壁围岩对岩爆体释放的能量有剩余造成的；在岩爆应力判据中，围岩在σθ／RC=0-3～0．7的条件下就可能发生岩爆，甚至可能发生强烈岩爆，这是因为围岩不是均质体，围岩内存在应力集中区和软弱结构区。现有的岩爆模拟试验采用油压控制系统加载无法实现抛掷型岩爆，这是因为油路供油速度缓慢所致。对抛掷型岩爆模拟试验技术，提出新的试验方案，研发新的试验装置，开展新的岩爆模拟试验。实践证明提出的试验技术和试验装置均能较好地模拟抛掷型岩爆现象，可供岩爆机制研究、教学及相关工程建设参考。

New understandings about the mechanism of rockburst of high stress tunnel are presented on the basis of rockburst model tests. Energy accumulated within the rock mass of rockburst alone is insufficient to generate ejective rockburst, extra energy must be transmitted from the surrounding rock to rockburst mass when rockburst happens. Energy convergence from surrounding rock to burst rock is a significant premise of ejective rockburst. In the process of ejective rockburst, the transformation from static to dynamic state is caused by the surplus energy released from the surrounding rock to rockburst body. Rockburst, even intense rockburst may happen when σθ/RC= 0.3 - 0.7, because of the existence of regions with weak structures and stress concentrations in the surrounding rock. Ejective rockburst could not be realized in the existing model tests under the slow loading with the ordinary hydraulic control system of slow oil supply. New model test devices were thus developed. Test results show that the developed devices can simulate ejective rockburst phenomenon well.