变形过程中岩石P波速度场的空间变化
SPATIAL VELOCITY VARIATIONS OF P WAVES DURING ROCK DEFORMATIONS
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摘要: 在一次地震之前,在不同观测点测量岩石中弹性波速度,经常得到不同的结果.这一现象提示我们:岩石破坏前,其物理性质的变化在空间上的分布是不均匀的,破坏前兆的获得应该建立在对岩石性质的空间分布,即对物理场分析的基础上. 本实验观测了岩石样品在单轴压缩下,P波走时空间分布变化的全过程.实验表明:在岩石的破坏过程中,岩性的空间分布具有同步性变化的中长期前兆和差异性变化的短期前兆的特点.在岩石接近破坏时,岩性的变化表现出严重的不均匀性.岩石的整个破坏过程可以看成岩石的物性分布是由无序向有序的演化,即是一个熵减小的过程.Abstract: Before an earthquake,the velocities of elastic waves observed at different stations usually have different values. This phenomenon suggests that the spatial distribution of the variations of rock properties is inhomogeneous before the failure of rocks. The precursors to failure in rocks should come from the changes of the spatial distributions (physical fields) of the rocks.The process of spatial variations in the travel times of P-wave in the rock under uniaxial stress is studied. The experimental results show that the long-term precursor of failure of rocks is characterized by synchronism in variations of the P-wave velocities,and the short-term precursor by nonuniformity. The process of the rupture in rocks is the evolution process from disorder to order in the spatial distributions of the vairations of physical properties of rocks,or the process of the decrease in entropy.
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[1] Aggarwal, Y. P.,Sykes, L. R., Simpson, D. W. and Richards, P.G.,I975. Spatial and temporal variations in TS/TP and in P Wave residuals at Blue Mountain Lake. New York: Application to earthquake prediction. J. Gcophys. Res., 80, 718——732.
[2] Anderson, D. L. and Whitcomb, J. H. 1973. The dilatancy——diffusion model of earthquake prediction, in Proceedings of the Conference on Tectonic Problems of the San Andrews Fault System, 417——426. Stanford University Press, Palo Alto, Calif.
[3] Kondratenko, A. M. and Netsesov, I. L.,1962. Some results of the study on change in the velocities of longitudinal and transverse waves in a focal zone (in Russian), Tr.lnst. Fiz. Zemli Akad. Nauk SSR, 25, 130——150.
[4] 陈颗、郑捷、郭继光、阎虹,1984.脉冲激光全息干涉术在岩石力学研究中的应用.科学通报,l0,609——611,
[5] 陈濒、阎虹,1989,实验室中岩石破裂的变形前兆.地球物理学报专辑.
[6] 许征宇,1986.辉长岩破坏过程b值的测定.国家地震局地球物理研究所研究生论文.
[7] 郑捷、姚孝新、陈颜,1983,岩石变形局部化的实验研究.地球物理学报,26, 554——563,
[8] Lockner, D. A., Walsh, J. B. and Byerlee, J. D. 1977. Changes in seismic velocity and attenua.tion during deformation of granite. J. Geophys. Res.,82, 5374——5378.
[9] 许昭永、李忠富、李佩林、华培忠、张万普,1982.大理石板中心受压至断裂时P波速度变化的实验研究.地震学报,4,404——411,
[10] Sobolev, D.,Spetzler, H, and Salov, B., 1978. Precursor to failure Rocks While undergoing an elastic deformations.J.Geophys. Res.,B4, 1775——1784.[1] Aggarwal, Y. P.,Sykes, L. R., Simpson, D. W. and Richards, P.G.,I975. Spatial and temporal variations in TS/TP and in P Wave residuals at Blue Mountain Lake. New York: Application to earthquake prediction. J. Gcophys. Res., 80, 718——732.
[2] Anderson, D. L. and Whitcomb, J. H. 1973. The dilatancy——diffusion model of earthquake prediction, in Proceedings of the Conference on Tectonic Problems of the San Andrews Fault System, 417——426. Stanford University Press, Palo Alto, Calif.
[3] Kondratenko, A. M. and Netsesov, I. L.,1962. Some results of the study on change in the velocities of longitudinal and transverse waves in a focal zone (in Russian), Tr.lnst. Fiz. Zemli Akad. Nauk SSR, 25, 130——150.
[4] 陈颗、郑捷、郭继光、阎虹,1984.脉冲激光全息干涉术在岩石力学研究中的应用.科学通报,l0,609——611,
[5] 陈濒、阎虹,1989,实验室中岩石破裂的变形前兆.地球物理学报专辑.
[6] 许征宇,1986.辉长岩破坏过程b值的测定.国家地震局地球物理研究所研究生论文.
[7] 郑捷、姚孝新、陈颜,1983,岩石变形局部化的实验研究.地球物理学报,26, 554——563,
[8] Lockner, D. A., Walsh, J. B. and Byerlee, J. D. 1977. Changes in seismic velocity and attenua.tion during deformation of granite. J. Geophys. Res.,82, 5374——5378.
[9] 许昭永、李忠富、李佩林、华培忠、张万普,1982.大理石板中心受压至断裂时P波速度变化的实验研究.地震学报,4,404——411,
[10] Sobolev, D.,Spetzler, H, and Salov, B., 1978. Precursor to failure Rocks While undergoing an elastic deformations.J.Geophys. Res.,B4, 1775——1784.
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