干模式下颗粒粘滑震动试验研究

为了研究浅源地震的诱发机制，基于室内三轴试验，对颗粒材料的粘滑震动特性进行了分析. 采用颗粒直径为0.6～0.8 mm的玻璃珠，在围压为30、60、100、200、400 kPa和600 kPa的条件下，以0.02 mm/min的轴向应变速率，开展干燥、密实玻璃珠的固结不排水三轴压缩试验，结果表明:试样偏应力主震和偏应力应变间距随着围压的增大而增大；除了初始压密阶段外，体变-应变曲线中所有体积的突然收缩均与粘滑震动有关；在30、60、100 kPa围压条件下，围压-应变曲线中出现较多尖而窄的波峰和波谷；在200、400 kPa和600 kPa围压条件下，围压-应变曲线中只有尖而窄的波谷；玻璃珠类颗粒材料发生粘滑震动过程中既有静摩擦也有转动摩擦；颗粒之间应力链的连续变形和破坏是引起颗粒粘滑震动的根本原因. 

Experimental Study of Stick-Slip Behaviour of Dry Granular Materials

The stick-slip characteristics of glass beads were analysed based on an indoor triaxial test to investigate the mechanism of shallow vibration. Glass beads with diameters of 0.6–0.8 mm were used to conduct consolidated and undrained triaxial tests under cell pressures of 30, 60, 100, 200, 400, and 600 kPa at an axial strain rate of 0.02 mm/min. The results show that the deviator drop and the interval strain between the maximum deviator drops increase with cell pressure. In addition to the first compaction, the volumetric strain drops in the volumetric curve are related to the stick-slip. Under confining stresses of 30, 60, and 100 kPa, a large number of sharp and narrow peaks and valleys appear in the curve of cell pressure versus strain. Only sharp and narrow valleys are observed under confining stresses of 200, 400, and 600 kPa. It is found that static friction and sliding friction affect the stick-slip characteristics of the glass beads by observing the surface of the glass beads before and after the triaxial compression test. Finally, the continuous deformation and destruction of the force chain between the glass beads are the causes of stick-slip in the glass beads.