【摘要】 岩爆孕育过程中所记录的微震事件波形本身就包含着丰富的前兆信息。基于深埋隧洞微震波的衰减特征,修正了最大有效振幅,将相对有效振幅和最大有效频率作为频谱分析参数。TBM和钻爆法不同开挖方式下诱发的即时型岩爆孕育过程的频谱演化特征基本一致,有如下特征:(1)无岩爆发生时,每日最大释放能量微震事件频谱对应的相对有效振幅的量级为10-6m/s及以下,而最大有效频率则多大于300 Hz;(2)中等岩爆发生前,相对有效振幅的量级维持在10-5m/s,最大有效频率则介于200~300 Hz;(3)强烈岩爆发生前,微震事件对应相对有效振幅的量级增长并保持在10-4m/s,最大有效频率则基本在200 Hz以下;(4)对于一个完整的即时型岩爆孕育过程,当岩爆发生时,相对有效振幅增至最大,同时最大有效频率降至最低。微震信号的频谱演化特征可为即时型岩爆发生时间及等级的预警提供参考和依据。更多还原

【Abstract】 The waveforms of microseismic events recorded during rockburst contain abundant precursor information of the rockburst.Based on the attenuation characteristics of microseimic wave in the deep tunnel, the maximum effective amplitude is modified, and the relative effective amplitude and maximum effective frequency are used as analysis parameters of frequency spectrum. Case studies reveal that the evolution characteristics of frequency spectrum during instant rockburst induced by the tunnel boring machine(TBM) and the drilling and blasting(D&B) are similar. As there no rockburst occurs, the magnitude of relative effective amplitude corresponding to the largest radiated microseismic energy for daily event is often at a level of 10-6m/s or even less; and most of the maximum effective frequencies are greater than 300 Hz. Before the medium intensity rockburst happens, the magnitude of relative effective amplitude maintains at a level of 10-5m/s, and the maximum effective frequencies are between 200 Hz and 300 Hz.(3)Before the intense rockbust occurs, the magnitude of relative effective amplitude increases and reaches 10-4 m/s; and the maximum effective frequencies are almost below 200 Hz. For a whole process rockburst, the relative effective amplitude reach its maximum value and the maximum effective frequency become minimum on the occurrence of rockburst. The evolution of frequency spectrum of microseismic signals can provide reference for early warning the occurrence time and degree of instant rockburst.更多还原