| 不同性质岩块构成的样品破裂前的波速变化 |
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| 引用本文： | 刘晓红.不同性质岩块构成的样品破裂前的波速变化[J].地震学报,1988,10(4):437-443. |
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| 作者姓名： | 刘晓红 |
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| 作者单位： | 国家地震局地球物理研究所 |
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| 摘 要： | 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。
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| 关 键 词： | 岩石破裂 地震模拟实验 地震前兆 波速异常 波速测量 |
THE VARIATION OF WAVE VELOCITY BEFORE RUPTURE OF SAMPLES COMPOSED OF ROCKS WITH DIFFERENT PROPERTIES |
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| Abstract: | The variation of wave velocity before rupture of samples composed of rocks with different properties was studied by the ultrasonic impulse method. The samples were rectangular plates of marble, in whose centre circular disks of marble, gabbro, granite and sandstone were inlaid. The experiments show that when the samples rupture the cracks extend through the rock disks with low strength, but round the rock disks with high strength. For the first group of samples the wave velocity in the inlaid rock disks varies visibly before rupture, while for the second group the wave velocity in the inlaid rock disks does not vary very much. Measurements of wave velocity through the interface between two rocks show that the wave velocity begins to decreas when the compression stress reaches 60% of rupture stress of the sample. The tendency of decrease of wave velocity before rupture of the samples is not monotonous, but it undulates. This makes clear that the heterogeneity of the medium can produce important influence on the law of wave velocity variation before rock rupture. |
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