不同应力下剪切速率对尾矿砂强度特性影响研究

发布时间：2018-04-16 13:05

本文选题：尾矿砂 + 围压　；参考：《地下空间与工程学报》2016年S2期

【摘要】：尾矿库的运行稳定性很大程度上取决于尾矿砂的强度特性。为了分析应力及剪切速率对尾矿砂抗剪强度的影响,利用室内三轴仪对云南某铁矿尾矿库内原尾矿砂进行了不同围压及剪切速率条件下的固结不排水(CU)试验,并对试验后的颗粒破碎进行分析。试验结果表明:尾矿砂的抗剪强度在低应力下(小于500 k Pa)基本符合线性摩尔库伦准则,但在高应力下(大于500 k Pa)符合幂函数强度准则。尾矿砂的抗剪强度及内摩擦角在各围压下均随着剪切速率的增加而减小,其减小速率在剪切速率0.08~2 mm/min范围内先增加后减小。试验尾矿砂在各围压下剪切后颗粒均有破碎,且在高应力下固结过程也会造成颗粒破碎,但相对整过剪切过程中的破碎量比值很小。颗粒破碎主要集中在构成骨架结构的粗颗粒段(粒径大于0.25 mm),粒径小于0.074 mm的细颗粒基本不破碎,且颗粒破碎与剪切速率成负相关,但颗粒破碎在围压低于400 k Pa时很少受剪切速率的影响。
[Abstract]:The stability of tailing reservoir depends to a great extent on the strength of tailings.In order to analyze the effect of stress and shear rate on the shear strength of tailings, the undrained undrained cud tests were carried out under different confining pressures and shear rates of the original tailings in a tailings reservoir of a certain iron mine in Yunnan by using an indoor triaxial apparatus.The particle breakage after the test was analyzed.The experimental results show that the shear strength of tailings conforms to the linear Moore Coulomb criterion at low stress (less than 500 KPA), but the power function strength criterion at high stress (> 500 KPA).The shear strength and the internal friction angle of tailings decrease with the increase of shear rate under each confining pressure, and the decreasing rate increases first and then decreases in the range of 0.08 ~ 2 mm/min.The particles of the test tailings are broken after shearing under various confining pressures, and the consolidation process also results in the breakage of the particles under high stress, but the ratio of breakage is very small in the shear process of the test tailings.Particle breakage is mainly concentrated in the coarse grain segment of skeleton structure (particle size > 0. 25 mm, fine particle size less than 0.074 mm), and particle breakage is negatively correlated with shear rate.However, particle breakage is rarely affected by shear rate at a circumferential depression of 400 KPA.
【作者单位】：重庆大学资源及环境科学学院;重庆大学煤矿灾害动力学与控制国家重点实验室;
【基金】：国家自然科学基金(51404049)
【分类号】：TU411

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