为研究土工格栅加筋尾矿坝剪切带影响范围,提升尾矿坝整体稳定性,通过对不同含水率和上覆荷载的尾矿砂进行室内直剪试验,从宏细观2种不同角度分析剪切应变带的影响规律。试验结果表明:试验曲线近似呈线性增长,峰值位移出现在20~25 mm之间,上覆荷载与峰值剪切位移呈正比例关系,增长速度逐渐减缓;尾矿砂含水率为3%、7%、11%和15%,尾矿的密度等幅递减2.2%,随着含水率增大,表观黏聚力逐渐增大,界面摩擦角先增大后减小;建立颗粒流程序(PFC)模型精准定位试验箱中位移变化较大区域并进行细观无标点量测分析,剪切应变带影响距离随尾矿砂含水率增加而减小,减少量缓慢降低。
Abstract
The aim of this research is to enhance the overall stability of tailings dam by identifying the influence range of shear zone of geogrid-reinforced tailings dam. The influence law of shear strain zone was analyzed from macro-and-microscopic perspectives via indoor direct shear tests of tailings sand with varied moisture contents under different overlying loads. Results unveiled that: the test displacement of geogrid-reinforced tailings increased approximately linearly with the peak displacement ranging between 20 mm and 25 mm; overlying load presented a positive proportional relationship with peak shear displacement, and the growth rate of shear displacement gradually attenuated. The water content of tailings sand was 3%, 7%, 11% and 15%, respectively, and the density of tailings declined by 2.2%. With the growth of water content, the apparent cohesion gradually strengthened, and the interfacial friction angle first climbed and then dropped. Furthermore, partical flow code(PFC) model was established to accurately locate the area with large displacement change in the test chamber for meso-scale non-punctuation measurement analysis. The influence distance of shear strain zone reduced with the increase of water content of tailings sand, and such reduction alleviated gradually.
关键词
土工格栅 /
加筋尾矿坝 /
直剪试验 /
PFC离散元 /
剪切应变带
Key words
geogrid /
reinforced tailings dam /
direct shear test /
PFC discrete element /
shear strain zone
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基金
国家自然科学基金项目(51774163);鞍钢科研项目(2018-科A19)
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