Seismic effort of blasting wave transmitted in coal-rock mass associated with mining operation

Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Australia,by using spread velocities,amplitudes and frequency contents as the main analysis parameters.The results show that the average P-wave velocity,mean values of combined maximal amplitudes and frequencies of the first arrivals are all reduced significantly along with goaf expanding and intensity weakening of overlying strata during mining process.A full roof fracturing can make the average P-wave velocities,combined maximal amplitudes and frequencies of first arrivals reduce to about 69.8%,92.2% and 60.0%,respectively.The reduction of the above seismic parameters reveals dynamic effects of the variation of strata structure and property to the wave transmission and energy dissipation of blasting wave.The research greatly benefits further study on stability of surrounding rock under the destructive effort by mine tremor,blasting,etc,and provides experimental basis for source relocation and parameter optimization of seismic monitoring as well.

岩爆条件和岩爆支护

首先介绍应变岩爆和矿震岩爆的发生条件,提出解释岩爆的球–崖概念模型,然后介绍2个金属矿山应变岩爆和矿震岩爆的案例。应变岩爆由应力集中引起,通常量级较小,在围岩中爆深比较浅。应变岩爆一般在埋深超过1000m初次开挖的岩体中。在已经经受过扰动的岩体中开挖,应变岩爆明显减少,甚至完全消失。矿震岩爆与旧断层滑移或者新断层形成有关。矿震岩爆量级分布宽,高量级矿震岩爆对围岩的破坏范围比应变岩爆大得多。还对岩爆支护方法的历史做了简要回顾,介绍了从软支护、硬支护到高能支护的演变过程和这些方法的理论根据。目前广泛采用的岩爆支护方法是使用高能屈服锚杆和高强临空面约束构件金属网和金属网带。理想的岩爆支护应该能够有效地把岩爆能转化为岩体支护构件变形能和围岩破坏能。