单轴应力作用下两种不同方法研究岩石磁化率变化的结果
THE EXPERIMENTAL RESULTS OF VARIATIONS IN THE SUSCEPTIBILITY OF ROCK SAMPLES UNDER UNIAXIAL STRESS BY TWO DIFFERENT APPROACHES
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摘要: 本文介绍了对北京——唐山地区八种强磁性岩石标本的压磁实验结果,观察了它们在高压应力下,直至破坏前后的磁化率变化特征。发现磁化率的变化只是其应力值的函数,与体积变化过程、微裂膨胀过程关系甚微。磁化率的压力系数取值范围为——(0.4——3.0)10-3MPa-1。同时,本文还得到了标本中出现破裂后岩石的压磁曲线。 运用铁磁学理论,对上述压磁实验结果作了初步的分析解释。Abstract: This paper shows the results of piezomagnetic experiments on eight kinds of strong magnetic rocks collected in the Beijing-Tangshan area of China under uniaxial pressure. The features of variation in magnetic susceptibility with increasing stress until fracture and even after fracture have been observed. It is shown that the variation in magnetic susceptibility is mainly a function of stress but not of strain,volume change,or relaxation. The large volume change marked by strong acoustic emission under a stable stress didn't cause any obvious,excessive change in susceptibility. Thus,this puts a negative factor on the possible dilatancy-magnetic precursor of earthquakes.Comparing the experimental results from two different approaches,this paper shows that the results are quite consistent. Thus it is shown that a simple detector attached to.the surface of the sample will provide a powerful tool in studying the variation in susceptibility. This makes the synchronous measurements of susceptibility,bulk strain,accoustic emission etc. easier.This paper also discusses the two types of piezomagnetic curves and their possible physical meaning.The measured coefficients of piezomagnetic variation versus stress range around -(0.4-3.0)10-3 MPa-1 for the rocks tested.
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[1] Nagata, T., Tectonomagnetism, IAGA Bulletin, No`. 27, 12——42, Madrid, Spain, 1969.
[2] Lapma, IvI. Yi., Geomagnetism and seismological phenomena, Izv. Akad. Nauk. USSR Fix. Zemli,No. 5, 1, 1953.
[3] Kean, W. F., R. Day, M. Fuller, and V. A. Schmidt, The effect of uniaxial compression on the initial Susceptibility of rocks as a function of grain size and composition of their constituent titanomagnetites, J. Geophys. Res., 81, 861——872, 1976.
[4] Martin III, R. J., R. E. Habermann, and M. Wyss, The effect of stresses cycling and inelastic volumettic strain on remanent magnetization, J. Geophy. Rc"r,84, 3485——3496, 1978.
[5] 祁贵仲,“膨胀”磁效应,地球物理学报,21, 18——33,1978,
[6] 徐世浙、关于压磁效应和膨胀磁效应,地震学报,1, 81——89,1979.
[7] Rikitake, T., Geomagnetism and earthquake prediction, Tectonophysics, 6, 59——68, 1968
[8] Smith, B. E. and M. J. 5. Johnston, A tectonomagnetic effect observed before a magnitude 5.2 earthquake near HoIlister, California,J.Geophys. Res., 81, 3556——3560, 1976.
[9] 范国华、侯作中、詹志佳、黄平章,唐山地震对北京地区地磁场总强度的影响,地震学报,1, 1,39——49, 1979.
[10] Kalashnikov, A. G. and S. P. Kapitsa, Magnetic susceptibility of volcanic rocks under elastic streses, Dokl. Akad. Nauk USSR, 86, 521, 1952.
[11] Kapitsa, S. P., Magnetic properties of eruptive rocks exposed to mechanical stresses, Izv. Akad.Nauk USSR Fiz. Zemli, No, 6, 489, 1955.
[12] Nagata, T., Magnetic susptibiIity of compressed rocks,].Geomag. Geoelectr., 18, 73——80, 1966.
[13] Ohnaka, M., and H. Kinoshita, Effect of axial stress upon initial susceptibility,J.Geomag. Geoelectr., 20, 107——109, 1968.
[14] Stacey, F. D., Theory of magnetic susceptibility of stressed rocks Phil. Mag., 7, 551——556, 1962.
[15] 北京大学物理系《铁磁学》编写组编,铁磁学131——133,科学出版社,1,,6,
[16] Na,ata, T., Basic magnetic properties of rocks under the effects of mechanical stresses, Tectonophysics, 9, 167——195, 1970.
[17] Nersesov, I. L., A. N. Semionov, and I. G. 5imbireva, Space time distribution of ratios of traveltimes of transverse and Longitudinal wares in Garm region, Exp. Seismology, Sbornik, 334, 1971.
[18] Johnston, A. C., Max Wyss and R. E. Habetmann, Robert koyanagi, Stability and change of p——wave, travel times in the crust (abstract), EOS, 62, 964, 1981.
[19] hijachkin, V. L, W. F.Brace G. A. SoboIev, and J. H. Dieterich, Two models for earthquake forerunners, Pageoph, 113 169——181. 1975.
[20] Mizutani, H. and T. Ishido, A new interpretation of magnetic field variation associated with the Matsushito earthquakes, j. Geomag. Geoelectr., 28 179——188 1976.[1] Nagata, T., Tectonomagnetism, IAGA Bulletin, No`. 27, 12——42, Madrid, Spain, 1969.
[2] Lapma, IvI. Yi., Geomagnetism and seismological phenomena, Izv. Akad. Nauk. USSR Fix. Zemli,No. 5, 1, 1953.
[3] Kean, W. F., R. Day, M. Fuller, and V. A. Schmidt, The effect of uniaxial compression on the initial Susceptibility of rocks as a function of grain size and composition of their constituent titanomagnetites, J. Geophys. Res., 81, 861——872, 1976.
[4] Martin III, R. J., R. E. Habermann, and M. Wyss, The effect of stresses cycling and inelastic volumettic strain on remanent magnetization, J. Geophy. Rc"r,84, 3485——3496, 1978.
[5] 祁贵仲,“膨胀”磁效应,地球物理学报,21, 18——33,1978,
[6] 徐世浙、关于压磁效应和膨胀磁效应,地震学报,1, 81——89,1979.
[7] Rikitake, T., Geomagnetism and earthquake prediction, Tectonophysics, 6, 59——68, 1968
[8] Smith, B. E. and M. J. 5. Johnston, A tectonomagnetic effect observed before a magnitude 5.2 earthquake near HoIlister, California,J.Geophys. Res., 81, 3556——3560, 1976.
[9] 范国华、侯作中、詹志佳、黄平章,唐山地震对北京地区地磁场总强度的影响,地震学报,1, 1,39——49, 1979.
[10] Kalashnikov, A. G. and S. P. Kapitsa, Magnetic susceptibility of volcanic rocks under elastic streses, Dokl. Akad. Nauk USSR, 86, 521, 1952.
[11] Kapitsa, S. P., Magnetic properties of eruptive rocks exposed to mechanical stresses, Izv. Akad.Nauk USSR Fiz. Zemli, No, 6, 489, 1955.
[12] Nagata, T., Magnetic susptibiIity of compressed rocks,].Geomag. Geoelectr., 18, 73——80, 1966.
[13] Ohnaka, M., and H. Kinoshita, Effect of axial stress upon initial susceptibility,J.Geomag. Geoelectr., 20, 107——109, 1968.
[14] Stacey, F. D., Theory of magnetic susceptibility of stressed rocks Phil. Mag., 7, 551——556, 1962.
[15] 北京大学物理系《铁磁学》编写组编,铁磁学131——133,科学出版社,1,,6,
[16] Na,ata, T., Basic magnetic properties of rocks under the effects of mechanical stresses, Tectonophysics, 9, 167——195, 1970.
[17] Nersesov, I. L., A. N. Semionov, and I. G. 5imbireva, Space time distribution of ratios of traveltimes of transverse and Longitudinal wares in Garm region, Exp. Seismology, Sbornik, 334, 1971.
[18] Johnston, A. C., Max Wyss and R. E. Habetmann, Robert koyanagi, Stability and change of p——wave, travel times in the crust (abstract), EOS, 62, 964, 1981.
[19] hijachkin, V. L, W. F.Brace G. A. SoboIev, and J. H. Dieterich, Two models for earthquake forerunners, Pageoph, 113 169——181. 1975.
[20] Mizutani, H. and T. Ishido, A new interpretation of magnetic field variation associated with the Matsushito earthquakes, j. Geomag. Geoelectr., 28 179——188 1976.
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