巷道近场围岩能量释放规律及诱冲机制

Energy release law of roadway surrounding rock and energy-driven rock burst mechanism

针对冲击地压发生伴随大量能量释放这一特征,通过理论分析和数值模拟建立了巷道近场围岩能量释放模型,分析了巷道近场围岩能量释放规律,揭示了巷道近场围岩动能释放致冲机制,并进行了工程案例验证。结果表明:冲击体破坏释放的动能大小随应力集中系数、冲击体宽度增加呈非线性增大趋势,但随塑性区宽度增加呈非线性减小趋势;当支承压力影响范围一定时,弹性区煤体驱动冲击体动力破坏的能量随塑性区煤体宽度增加呈非线性减小趋势;顶底板驱动冲击体动力破坏的能量随冲击体宽度、顶底板厚度增加而增大,但随塑性区煤体宽度增大而减小;随着顶底板弹性模量增大,其驱动冲击体动力破坏的能量减小并趋于稳定,但此时弹性区煤体的驱动能量呈线性增大趋势;近场围岩能量释放过程中,巷帮煤体各区域的能量调整不协调,造成煤体内部高能量梯度的产生,使煤体更易向巷道临空面释放冲击能量。近场围岩的冲击体宽度增加,不仅冲击体自身释放能量增加,而且弹性区煤体和顶底板的驱动能量均增加,极易使冲击体储存的弹性应变能与弹性区煤体及顶底板的驱动能量之和与冲击体破坏消耗的能量之比大于1,达到冲击地压灾害发生的临界值。

The occurrence of rock burst is accompanied by a large amount of energy release.In this study,the mechanical model of energy release of roadway surrounding rock is established,the law of energy release is analyzed,the rock burst mechanism caused by kinetic energy release is revealed,and a field case study is carried out.Results show that the kinetic energy released by the impact-body(which is defined by the rapid separation part of a certain range of coal mass in coal rib)nonlinearly increases with the increase of stress concentration factor or impact-bodywidth,but decrea-ses nonlinearly with the increase of plastic zone width.As the influencing range of abutment pressure is steady,the released energy of elastic zone acting on the impact-body decreases nonlinearly with the increase of plastic zone width.The energy of dynamic failure driven by the roof and floor increases with the increase of the width of the impact-body and the thickness of the roof and floor,but decreases with the increase of plastic zone width in the coal.With the increase of the elastic modulus of the roof and floor,the energy driven dynamic failure of the impact-body decreases and tends to be stable,but the energy driven by the coal in the elastic zone increases linearly.In the process of energy releasing in near-field surrounding rock,the energy adjustment of roadway wall is inconsistent,resulting in the generation of high energy gradient in the coal body,which makes it easier for the coal body to release impact energy to free face of the roadway.As the impact-body width increases,not only the released energy of impact-body increases,but also the driving energy in the elastic zone and the roof and floor increases.It is easy to make the ratio of the sum of elastic strain energy stored in the impact-body and the released energy of roof and floor and elastic zone to the consumed energy of impact-body failure larger than 1,reaching the critical value of rock burst occurrence.