土工织物加筋尾矿砂界面力学特性试验研究

Experimental Study on Interfacial Mechanical Properties ofGeotextile-reinforced Tailings Sand

为研究土工织物加筋尾矿砂界面力学特性,在不同的尾矿砂含水率、试验拉拔速率和竖向压强下开展一系列土工布及土工格栅的拉拔试验。比较相同条件下的土工格栅与土工布拉拔试验结果可知:土工布对细粒尾矿砂的加筋效果优于土工格栅的加筋效果,竖向压强较大时两者的拉拔力峰值差值增大;随尾矿砂含水率增加,界面剪应力峰值明显减小,界面剪应力峰值在含水率1.2%时比含水率8.4%时增加50%以上,表观黏聚力先增加后减小,在最优含水率附近时达到最大,界面摩擦角先快速减小后缓慢减小;随试验拉拔速率增加,界面剪应力峰值缓慢增加,表观黏聚力先增加后减小,界面摩擦角先减小后增加;各工况下剪应力峰值均随竖向压强的增大而增大。研究结果可为土工织物加筋尾矿坝工程设计提供参考。

In order to study the mechanical properties of the reinforced interface between geotextile and fine tailings sand,we carried out pull-out tests on geogrid and geotextile under different test pull-out rates and different vertical pressures with varying moisture content of tailings sand.By comparing the pull-out test results of geogrid and geotextile under the same conditions,we conclude that geotextile has stronger reinforcement effect on fine tailings sand,and when vertical pressure is higher,the difference between the reinforcement effect on geotextile and geogrid is larger.With the rising of moisture content of tailings sand,the peak value of interfacial shear stress drops obviously:the interfacial shear stress at a moisture content of 1.2%is 1.5 times that when moisture content is 8.4%.Apparent cohesion increases at first but then decreases,with the peak value appearing near the optimal moisture content,whereas interfacial friction angle reduces rapidly at first and then declines slowly afterwards.With the augment of pull-out rate,the peak value of interfacial shear stress climbs slowly,and the apparent cohesion increases at first and then decreases,while the interfacial friction angle decreases at first and then increases.Under all working conditions,the peak value of shear stress increases linearly with the rising of vertical pressure.