基于干湿循环的尾矿力学特性试验研究

EXPERIMENTAL RESEARCH ON MECHANICAL BEHAVIORS OF TAILINGS UNDER DRYING-WETTING CYCLES

采用三轴固结不排水试验,测试经历1~6次干湿循环后的尾矿试样的力学特性。通过对经过不同循环次数后试样的应力-应变关系、孔隙水压力和静强度的对比分析,探讨干湿循环作用对尾矿力学特性的影响规律。结果表明:经历不同次数干湿循环后尾矿的应力-应变曲线均呈明显的软化特征,随循环次数的增加,加载初期应力-应变线性增长程度在循环达3~4次后逐渐稳定,峰值应力所对应的应变量在3~4次循环时达到最大值;孔隙水压力峰值分别集中在经1、2、5次循环的试样,尾矿试样的剪缩趋势在此阶段明显加剧;尾矿的静强度在循环达到3次后逐渐稳定且有略微下降的趋势。干湿循环过程中水的反复作用导致了试样内部颗粒间结构状态的变化,致使尾矿在经历不同时期的干湿循环作用时,表现出力学特征的差异。

The consolidated undrained triaxial test was used to measure parameters of mechanical behaviors of tailing specimens after 1 to 6 drying-wetting cycles. The relationship of stress-strain, pore water pressure, static strength after different cycles were contrastively analyzed to discuss the effect of drying-wetting cycles on the mechanical behaviors of tailings specimens. The testing results showed that the relationship of stress-strain of tailings specimens were always in strain softening after the cycles, the linear growth at the initial stage of loading was gradually stabilized after 3 to 4 cycles with the increase of the numbers of drying-wetting cycles. The peak stress value would reach the maximum after 3 to 4 cycles. The values of pore water pressure reached the peak in the 1st, 2nd and 5th cycle. With the increase of the numbers of drying-wetting cycles, the degree of shear-shrinkage of the tailings specimens were significantly increased at the same time. The static strength gradually tended towards stability after 3 times of drying-wetting cycle and then decreased slightly. It was considered that the repeated action of water during the drying-wetting cycles led to the change of the internal particle structure in the specimens, which resulted in the differences in mechanical behaviors of tailings during drying-wetting cycles in different stages.