远场和超远场前兆的模拟实验研究

在岩石试件、传压块体（包括岩石和钢块）和压机架上布设应变观测点，观测研究它们在岩石试样破裂孕育过程中的变化特征。结果发现，岩样临破坏前除岩样上各个测点都出现异常变化外，同时较远处的测力元件、传压块体和压机架上的应变也出现了突变或扰动前兆异常。岩石试样外部测点的应变特征变化在极临近主破裂时才有反映。而岩样上的测点除极临近主破裂时有突变和扰动外在离主破裂较早时已有反映。岩石试样外的测点距岩样约25－90cm，约为破裂尺度的3－10（多）倍。这表明在孕震区以外很远的地方都可能出现前兆异常。并初步探讨了形成远场前兆的原因。

Experimental Study of the Precursor in Far and Ultra-far Field

The strain gauges are arranged in the sample, the block of transferring pressure and the machine frame. When sample is compressed the variation of stress and strain occurred in and out the sample is observed and studied. The results show that there appears mutation or disturbance precursor of strain in the force-measuring sensor, on the block of transferring pressure and the machine frame before rock fracture beside anomaly variation appearing in all observing points on sample. These precursory variations out the sample occur only before main fracture of rock, but it in the sample appear early and have long trend character. The observing points on the block of transferring pressure are 25-90cm away from sample, which are 3-10 times of fracture sizes. It is explained that precursor anomaly is possible appearing in far places from fracture area. The reason forming far field precursor is primarily studied.