| 原地电阻率变化的实验 |
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| 引用本文： | 赵玉林,钱复业,杨体成,刘建毅.原地电阻率变化的实验[J].地震学报,1983,5(2):217-225. |
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| 作者姓名： | 赵玉林 钱复业 杨体成 刘建毅 |
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| 作者单位： | 1. 国家地震局地球物理研究所
2. 河北省地震局
3. 国家地震局兰州地震研究所 |
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| 摘 要： | 在野外原地对某些自然状态非饱和的土层及含裂隙矽化灰岩电阻率随应变的变化进行了实验.主要结果有:1)低应力下,随体积的压缩电阻率下降;体积膨胀时电阻率上升;2)所测岩、土层电阻率相对变化(/)对微小应变()的变化响应甚为敏感,裂隙岩层比土层更甚.放大系数(/)/与应变量有关,对10-4应变通常有一、二百倍,对10-5应变可达数百乃至上千倍;3)电阻率相对变化幅度随力源强度和尺度的增加而增加,随力源距离的增加而衰减.电阻率变化起始时间随距离的增加显示出滞后现象;4)水平各向同性土层,在应力作用下,不同方向电阻率变化不同,呈现出方向性.通常垂直最大压缩方向的电阻率 下降较多,平行方向的∥下降较小或略有上升,与压力呈45的45下降幅度介于中等.含裂隙矽化灰岩则不同,不同方向电阻率的变化不仅与压缩方向有关,而且还与裂隙方向有关.通常是∥下降较多.当压应力平行裂隙时, 也下降,但当压应力垂直裂隙时, 则明显上升.
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EXPERIMENTS IN SITU OF ELECTRICAL RESISTIVITY CHANGES |
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| Affiliation: | 1. Institute of Geophysics. State Seismological Bureau;
2. Seimnological Bureau of Hebei Province;
3. Seismological Institute of Lanzhou, State Seismological Bureau |
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| Abstract: | Under natural conditions in the field some experiments have been done for electrical resistivity changes with strain in partially saturated soil layers and siliceous limestone layers containing cracks. The major results are as follows:(1) At very low stresses, the resistivity drops (or rises) when rock (or soil) layers are compressed (or extended).(2) The relative change in resistivity of the rock or soil layers, /, is sensitive to strain changes (); this is particularly true for the rock containing cracks. Amplification factor, (/)/, changes with strain, and generally ranges from 100-200 at a strain of 10-4 up to about 103 at a strain of 10-5.(3) With increasing intensity and dimension of the force, the resistivity change increases. When the distance between the point of measurement and the force is increased, the resistivity change decreases and shows a delay.(4) For horizontally isotropic soil layers, resistivity changes due to stress variation exhibit directivity, that is, the changes measured along different profiles are not identical., measured along the profile perpendicular to the pressure, usually has a larger drop. As for ∥, parallel with the pressure, a much smaller drop, or sometimes a little rise, occurs. For 45, the drops are moderate. In contrast, the resistivity change of the siliceous limestone layer containing cracks is not only related to the directions of the pressure but also to that of the cracks.The drop of ∥ usually is larger. has a smaller drop when the pressure is parallel to the cracks, and rises distinctly when the pressure is perpendicular to them. |
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