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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。
In order to study the stick-slip characteristics of saturated granular materials and the bonding mechanism of the surface of the particles, soda-lime glass beads were used to carry out solidified drainage triaxial tests, single-particle compression tests, consolidation tests and hot-melt tests on granular materials. The results of triaxial tests show that the saturated and dense granular materials have the property of stick-slip under high confining pressure, and the average deviatoric stress decreases exponentially with the increase of effective confining pressure. The sample slides at the moment, the partial stress suddenly drops, and the volume suddenly shrinks. In the viscous phase, the deviatoric stress gradually increases and shows strain hardening. The volume of the sample shrinks to the minimum point before it begins to expand. In the process of stick-slip movement, the consistency between the change of deviatoric stress and confining pressure is better than that of the variation of pore water pressure, which indicates that the confining pressure monitoring accuracy is high. Single-particle compression test, consolidation test and hot-melt test show that under the normal temperature conditions, the surface morphology of the particles is totally different from the hot-melt adhesion morphology under the high temperature conditions. This is because under normal temperature conditions, the particles contact with each other under pressure, compressed, under the action of water gradually dissolve the surface and re-precipitation on the particle surface resulting in particle bonding, bonding strength is low and the surface morphology of the smaller changes.