不同应力状态下北山花岗岩岩爆倾向性研究

Investigation on the Rockburst Proneness of Beishan Granite Under Different Stress State

为研究不同应力状态下北山花岗岩岩爆倾向性,对北山花岗岩试件进行不同围压下的三轴试验,通过轴向压力和横向变形协调控制加载,获得不同围压下岩石全应力应变曲线,研究岩石破坏前能量聚集及破坏后能量释放特征。结果表明:破坏时弹性能、总能量随着围压增加而增大,且破坏后的总能量变化量及弹性能释放量也随着围压增加而增大。分析岩石储能系数和能量释放指数对岩石破坏的影响,发现岩石储能系数和能量释放指数随围压增加而增大;综合能量储存系数和能量释放指数建立新的岩爆倾向性评价指标,该指标不仅表述了岩石破坏前后各能量的综合变化特征,且能研究不同应力状态下岩石岩爆倾向性;使用该指标研究不同应力状态对北山花岗岩的岩爆倾向性,结果表明:北山花岗岩具有较强的岩爆倾向性,且随着围压增大,岩爆倾向性增加;当围压低于10 MPa时,围压对北山花岗岩岩爆倾向性影响较小,当围压超过10 MPa时,围压对岩爆倾向性的影响突然增加,但随着围压进一步增加,其对岩爆倾向性影响逐渐减弱。

For researching the rockburst proneness of Beishan granite under different stress state,servo Test System was used in this study.The stress-strain curves of Beishan granite under different confining pressures were obtained,and the loading process was controlled by axial pres- sures and circumferential deformation.It was mainly focused on the energy evolution of rocks in the process of failure,and the results proved that both the total energy and elastic energy increased with increasing confining pressure when rock failure.Variable quantity of total energy and elast- ic energy from peak stress to residual stress increased with increasing confining pressure.The effect of the energy storage coefficient and the en- ergy releasing coefficient on the rock failue were analysed,and a new rock burst proneness index was performed based on the energy storage and releasing coefficient,which not only represented energy change characteristics but also expresses the rockburst proneness under different stress states.It was thusused to research the rockburst proneness under different stress states,and the result showed that the rockburst proneness in- creased with increasing confining pressure.Specifically,when the confining was less than 10 MPa,the effect of confining on rockburst proneness was weakened;when the confining pressure exceeded 10 MPa,the effect on rockburst proneness sharply increased;thereafter, as the confining con- tinues to increase,the effect was gradually decreased.