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用超声脉冲法研究了不同性质岩块构成的样品破裂前的波速变化。样品为长方形大理岩板,中心镶嵌大理岩、辉长岩、花岗岩,砂岩圆块。实验表明,样品破裂时裂纹穿过低强度镶嵌岩块而绕过高强度镶嵌岩块。在第一种场合样品破裂前,镶嵌岩块內波速变化显著,在第二种场合样品破裂前镶嵌岩块內波速变化不大。穿过两种岩石界面的波速测量表明,波速下降的起始点提前到样品破坏应力的60％左右。样品破裂前波速总的变化趋势是下降,但不是单调下降而呈现起伏。这说明介质不均匀性会对岩石破裂前的波速变化规律产生不可忽视的影响。
Ultrasonic pulse method was used to study the change of wave velocity before the rupture of samples composed of different rock masses. Samples for the rectangular marble plate, the center inlaid marble, gabbro, granite, sandstone blocks. Experiments show that the crack passes through the low-strength mosaic rock and breaks the high-strength mosaic rock when the sample is cracked. In the first instance before the sample rupture, the mosaic rock mass velocity changes significantly, in the second instance before the sample rupture mosaic rock mass velocity changes little. Wave velocity measurements across the two rock interfaces show that the onset of the wave velocity drop precedes about 60% of the sample failure stress. The general trend of the wave velocity before the rupture of the sample is declining, but it is not monotonically decreasing and fluctuating. This shows that the media inhomogeneity will have a non-negligible impact on the variation of the wave velocity before rock failure.