全尾砂-废石混合回填膏体流动特性变化规律

The change laws of flow characteristics of backfill paste mixed by unclassified tailings and waste rock

质量浓度、废石掺量是影响尾砂-废石混合回填体流动特性的主要因素，研究这些因素对膏体流动性的影响规律，对于控制膏体流动性具有重要意义。采用改进的小型直剪装置进行混合回填体直剪试验，以黏聚力、内摩擦角、抗剪强度为依据，综合得出了混合回填膏体流动性变化规律。试验结果表明，膏体在受力变形前期呈较为明显的似弹性性质，随废石掺量增加，位移-剪应力曲线中阶梯状变化趋势增加；回填体黏聚力取决于质量浓度，内摩擦角受质量浓度和废石掺量影响程度基本相同，两者协同作用；质量浓度在80％-88％范围时，黏聚力随质量浓度增大呈非线性增大，内摩擦角与质量浓度呈s型变化趋势；抗剪强度随质量浓度的增大而增加，在82％-84％区间抗剪强度变化显著，流动性出现突变。

Mass fraction and waste rock proportion are main influence factors which affect flow characteristics of backfill paste mixed by unclassified railings and waste rock. To study of the influence law of these factors about paste flow characteristics may have important significance about controlling paste flow characteristics. Shear test of mixed backfilling is conducted with the improved small direct shear device and then get the change law of mixed backfilling. The test results show that paste presents approximate elastic at prophase of force-deformation and the stepladder trend in displacement-shear stress curve increases with the increase of waste rock proportion. Cohesion of paste depends on mass fraction and internal fraction angle is affected by mass fraction and waste rock proportion almost the same, and that is combined effect. When mass fraction in the range of 80%-88%, cohesion pretends as nonlinear growth with the increase of mass fraction, internal fraction angle and mass fraction presents S-type trend, shear strength increases with the increase of mass fraction and varies significantly when in the range of 82%-84%; at the same time, flow characteristics is mutation.