关于震源体物理意义的实验研究
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摘要
运用固体传压介质岩石三轴试验装置模拟震源失稳振动过程,采取多点布设电阻应变片的方法,对试件突发失稳振动行为及其在试件—压机系统中的传播过程进行观测、测试结果为:应力振动的初动半周期平均约为0.11ms,与岩石类型、围压及应力降等因素无关,振幅逐渐衰减;在试件—压机系统中,振动波从试件错动面处向外传播,其速度约为3.30m/ms;在失稳初动半周期内,振动波向试件以上传播的距离为363mm,传播的范围只占试件—压机系统一小部分,即相当于地震的震源体部分。实验研究证实,在地震能量释放过程中,震源体,作为能量的释放源,只是整个系统中对错动失稳有贡献的那一小部分,它可以由错动时间间隔内弹性波的传播范围,或者位移和速度近似大于零的岩体加以定义。
To simulate the hypocentral processes, the sudden instabilities and vibrations of rock specimen-testing machine system and the propagations of elastic waves were investigated by using a triaxial compression apparatus with solid confining medium and the multipoint strain gauging method. The results indicate that the initial semi-period of stress vibration is about 0.11ms on the average, which is independent of rock type, confining pressure stress drop, etc.; the elastic waves propagate from the slip plane of the specimen with a velocity of about 3.30 m / ms; and the wave propagation range within the initial semi-period is about 363mm that is only a small part of the system and corresponde to the range of hypocenter body. The study confirme that hypocenter body, as the source of seimic energy, is such a portion in the whole system that makes contibution to the slip instability and can be defined by the propagation range of elastic wave in the duration of seismic slip or by the rock body with dispalcement and velocity approximately greater than zero.
To simulate the hypocentral processes, the sudden instabilities and vibrations of rock specimen-testing machine system and the propagations of elastic waves were investigated by using a triaxial compression apparatus with solid confining medium and the multipoint strain gauging method. The results indicate that the initial semi-period of stress vibration is about 0.11ms on the average, which is independent of rock type, confining pressure stress drop, etc.; the elastic waves propagate from the slip plane of the specimen with a velocity of about 3.30 m / ms; and the wave propagation range within the initial semi-period is about 363mm that is only a small part of the system and corresponde to the range of hypocenter body. The study confirme that hypocenter body, as the source of seimic energy, is such a portion in the whole system that makes contibution to the slip instability and can be defined by the propagation range of elastic wave in the duration of seismic slip or by the rock body with dispalcement and velocity approximately greater than zero.
引文
[1] 梅世蓉,中国地震活动性,地球物理学报,9,1,1960。
[2] 朱传镇,有关震源体积的理论,地球物理学报,12,2,1963。
[3] 谢原定、杨天锡,震源区内一些宏观现象的讨论一烈度分布与震源体积的关系,西北地震学报,2,3,1970。
[4] Kasahara, K., Earthquake Mechanics, Cambridge University Press, 1981．
[5] Geller, R. J., Scaling relations for earthquake source parameters and magnitudes, B. S. S. A, 66, 5, 1976．
[6] Cao, Tianqing and Aki, K., Seismicity simulation with a mass-spring model and a displacement hardening-softening friction law, Pure and Applied Geophysics, 122, 1984．
[7] 王绳祖。施良骐、张流,环境刚度效应-影响震源应力降的重要因素,地震地质,5,3,1983。
[8] 崔效峰,王威,王绳祖,岩石三轴实验用数据采集系统,第一届高温高压岩石力学学术讨论会论文集,学术期刊出版社,1988。
[9] Johnson, T. L. and Scholz, C. H., Dynamic properties of stick-slip friction of rock, J. G. R, 81, 5, 1976．
[10] Shimamoto, T., Handin, J. and Logan, J. M., Speciman-apparatus interaction during stick-slip in triaxial compression machine: a decoupled two-degree-of-freedom model, Teetonophysics, 67, 175-205, 1980．
[2] 朱传镇,有关震源体积的理论,地球物理学报,12,2,1963。
[3] 谢原定、杨天锡,震源区内一些宏观现象的讨论一烈度分布与震源体积的关系,西北地震学报,2,3,1970。
[4] Kasahara, K., Earthquake Mechanics, Cambridge University Press, 1981．
[5] Geller, R. J., Scaling relations for earthquake source parameters and magnitudes, B. S. S. A, 66, 5, 1976．
[6] Cao, Tianqing and Aki, K., Seismicity simulation with a mass-spring model and a displacement hardening-softening friction law, Pure and Applied Geophysics, 122, 1984．
[7] 王绳祖。施良骐、张流,环境刚度效应-影响震源应力降的重要因素,地震地质,5,3,1983。
[8] 崔效峰,王威,王绳祖,岩石三轴实验用数据采集系统,第一届高温高压岩石力学学术讨论会论文集,学术期刊出版社,1988。
[9] Johnson, T. L. and Scholz, C. H., Dynamic properties of stick-slip friction of rock, J. G. R, 81, 5, 1976．
[10] Shimamoto, T., Handin, J. and Logan, J. M., Speciman-apparatus interaction during stick-slip in triaxial compression machine: a decoupled two-degree-of-freedom model, Teetonophysics, 67, 175-205, 1980．
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