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本文简要介绍中国压磁应力计的电磁学和力学原理,地壳岩石中水压重复观测实验结果,以及使用它进行地应力测量的地质力学前提条件。在压磁应力计测量地应力相对变化结果中阐述了:“悬空元件”与“受力元件”测值对比;地应力变化与断层微量位移同步波动;压磁应力计与振弦应变计,体积式应变仪测量结果比较;相距十至数百公里的几个台,同期测得相似、相关的地应力变化;少震区地应力测量十分平稳,具有稳定的观测中误差;在多次地应力异常成功预测地震中发现并证实——异常主应力方向指向或转向震中区、异常主应力值较大的台站往往离震中较近,地应力趋势异常时间长短与震级大小呈线性关系。压扭性断裂力学模型解释了地应力异常主应力方向指向震中区,近震中地应力异常值大、远震中地应力异常值小等现象。由此可以证实:我们在数十米至百米钻孔中使用压磁应力计的确可测到震源应力场的变化过程,从而进行地震的时间、地点、震级的预测。
This article briefly introduces the electromagnetics and mechanics principles of China’s piezomagnetic strain gauge, the experimental results of repeated observation of hydraulic pressure in the crustal rocks, and the prerequisite of geomechanics for measuring the geostress using it. In the measurement results of the relative stress change of the piezomagnetic stress meter, the comparison between the measured value of “dangling element” and “force element” is carried out. The variation of geostress and the trace displacement of the fault synchronously fluctuate; Strain gauges, and volumetric strain gauges. Comparisons of measured geostress between the stations from 10 to several hundred kilometers in the same period showed similar and related changes in geostress. The measured geostress in the less earthquake regions was very stable with a stable observed error. Successive earthquakes have been successfully predicted and found in earthquakes and proved that the direction of anomalous principal stress points or turns to the epicenter area. The stations with a larger anomalous principal stress tend to be closer to the epicenter, and the length of the geostress trend anomaly is linear with magnitude relationship. The compressive-torsional fracture mechanics model explains the phenomenon that the principal stress direction of the anomalous earth stress points to the epicentral area, and the anomalies of geostress in the near-epicenter are large and the anomalies of the geostress in the teleseismic are small. From this it can be confirmed that the use of piezomagnetic stress gauges in tens of meters to 100 meters of boreholes can indeed detect the change of source stress field and predict the time, place and magnitude of earthquakes.