颗粒材料黏滑运动特征与颗粒黏结试验研究

 为了研究饱和颗粒材料的黏滑运动特征与颗粒表面黏结机制，采用钠钙玻璃珠，开展颗粒材料的固结排水三轴试验、单颗粒压缩试验、固结试验和热熔试验。三轴试验结果表明：饱和、密实的颗粒材料在高围压条件下具有黏滑运动特征，并且随着有效围压的增大，平均偏应力降幅呈指数增长。试样在滑动瞬间，偏应力骤降，体积突然收缩。试样在黏滞阶段，偏应力逐渐增长，表现为应变硬化；试样体积首先收缩到最小点，然后才开始膨胀。黏滑运动过程中，偏应力变化与围压变化的一致性要好于与孔隙水压力变化的一致性，说明围压监测精度较高。单颗粒压缩试验、固结试验和热熔试验表明，在常温条件下颗粒表面黏结形态与高温条件下的热熔黏结形态完全不同。这是因为常温条件下，颗粒在压力作用下互相接触、压缩，在水的作用下表面逐渐溶解，并在颗粒表面再沉淀导致颗粒黏结，其黏结强度较低且颗粒表面形态变化较小。

Experimental study on stick-slip behaviour and sintering phenomenon of glass beads

In order to investigate the stick-slip phenomenon and surface sintering of saturated granular materials，spherical soda lime glass beads were used to perform consolidated drained triaxial compression，single particle compression，oedometer and thermal melting tests. The triaxial compression experiment results showed that the stick-slip events of saturated and dense glass beads always appeared under higher confining stress. As increasing the confining stress，the mean amplitude drop of the deviatoric stress shows an exponential growth. At the slip phase，the abrupt drop of the deviatoric stress corresponds to the jump of volumetric strain. At the stick phase，the deviatoric stress increases gradually，showing strain strengthening characteristic. The sample volume contracts first and then dilates until the next slip phase. The consistency of the deviatoric stress and cell pressure is better than the pore water pressure because the cell pressure was more accurately measured. The single compression test，the oedometer test and the thermal melting test results show that in the ambient temperature condition，the sintering form of particles is totally different from the thermal melting in the high temperature condition. In the ambient temperature condition，due to the action of contacting and compressing，the surface of particles gradually dissolve and then re-precipitate on surrounding surface of glass beads，but with lower sintering strength and small morphologic change of glass beads.