论文部分内容阅读
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。
The operational stability of tailings ponds depends to a large extent on the strength characteristics of the tailings sand. In order to analyze the influence of stress and shear rate on the shear strength of tailings, the triaxial apparatus was used to analyze the effect of confining undrained (CU) under different confining pressures and shear rates ) Test, and analyze the particle breakage after the test. The results show that the shear strength of tailing sand basically meets the linear molar coulomb criterion under low stress (less than 500 kPa), but meets the power function criterion at high stress (more than 500 kPa). The shear strength and internal friction angle of tailing sand decrease with the increase of shear rate at each confining pressure, and the decrease rate of tailings first increases and then decreases at the shear rate of 0.08 ~ 2 mm / min. After the test tailings were sheared under confining pressure, the particles were crushed, and the consolidation process under high stress would also cause the particles to crumble, but the ratio of the crushing amount during relatively complete shearing was very small. Particle crushing is mainly concentrated in the coarse segment (the particle size is greater than 0.25 mm) which constitutes the skeleton structure. The fine particles with the particle size less than 0.074 mm are basically not broken, and the particle crushing and the shear rate are negatively correlated, but when the confining pressure is lower than At 400 k Pa, it is seldom affected by the shear rate.