细粒含量对饱和钨钼尾砂剪切变形及稳态特性影响的试验研究

Experimental Study on the Effect of Fine Particle Content on Shear Deformation and Steady-State Characteristics of Saturated Tungsten and Molybdenum Tailings

通过对赣南地区某矿山的钨钼尾砂进行等向固结不排水三轴剪切试验,研究细粒含量对饱和钨钼尾砂剪切变形及稳态特性的影响。试验结果表明:不同细粒含量的钨钼尾砂在同一固结围压下的应力应变曲线可以分为三类:应变硬化型、应变稳定型、应变软化型。在相同的有效固结围压下,当轴向应变达到20%,孔压保持稳定。细粒含量虽然改变了试样颗粒级配,但是各稳态线的变化范围仍然很窄:ess-qss空间内的稳态线线性拟合的截距在0.9左右,当细粒含量低于30%时,斜率在0.000 6左右变动;当细粒含量高于30%时,斜率则在0.000 8左右波动。细粒含量为15%时,饱和钨钼尾砂的稳态内摩擦角为30.62°,细粒含量45%时饱和钨钼尾砂的稳态内摩擦角为27.85°,表明饱和钨钼尾砂的稳态内摩擦角与颗粒的平均粒径呈正相关。

The triaxial shear test of the saturated molybdenum tailings in a mine in southern Jiangxi province was carried out to study the shear properties and steady strength characteristics. The results show that the stress-strain curve of tungsten and molybdenum tailings with different fine content can be divided into three types: strain hardening, strain stabilization and strain softening. When fine content of tail sample increases from 15 % to 22 %,the stress-strain curve of tungsten and molybdenum tailings transition from strain hardening to strain stability. When fine content is higher than 30 %, the stress-strain curve under different confining pressures becomes strain softening. Under the same effective confining pressure, the pore water pressure increases with the increase of the fine grain content. When the axial strain is about 20 %, the pore pressure is stable and the sample reaches steady state.The change of fine grain content had a significant effect on the steady-state line. With the increase of fine grain content, the steady-state line gradually shifted down. Although the change of fine particle content changes the grading of the sample particles, the steady-state lines still change in a relatively narrow range: the intercept of the linear fitting curve changes around 0.9, and when the fines content is less than 30 %. The slope is about 0.000 6, and the slope is above 0.000 8 when the fines content is higher than 30 %.With the increase of fine particle content, the steady state friction angle of tungsten and molybdenum tailings decreases. When the fine grain content of tail sample is 15 %, the steady state friction angle is 30.62°.When the fine grain content of tail sample is 45 %. The steady state friction angle is 27.85°. This indicates that the steady-state friction angle is positively correlated with the average particle size of the particles.