岩石临破坏前波速奇异变化的再研究

Further Study on Strange Variation of Wave Velocity before Rock Rupture

从实验上确证 :岩石在主破裂前一瞬间 ,纵波速度升高甚至超过原最大值的两倍以上 ,纵、横波速比Vp /Vs升高甚至达 2 5～ 3 0 ,之所以造成这种现象 :对前者一个原因是主破裂前有些张裂缝闭合 ,另一个原因是主破裂前微破裂急剧增多 ,在某一时刻同时发生几个小破裂 ,各检波器所记讯息可能不是同一事件。对后者 ,P、S波的走时在破裂孕育过程中的下降———回升 (相对变化量 )

The results of the experiment prove that the P wave velocity increases to the value more than two times of the previous maximum just before the main-rupture. The velocity ration (vp/vs) also increases to 2 5-3 0. For the velocity variation the reason is that the tensile cracks closed and a lot of micro-cracks emerged at the same time before the rock destroyed. At this moment, the different sensor maybe recorded the signal of different crack produced. For the ratio, the decrease and increase of the travel time of P and S wave in preparing process of fracture was not synchronized. In fact, the travel time variation of P wave was earlier or larger than that of S wave.