金佳旭 李世旺

摘 要：寒区冻融环境条件下，尾矿砂的冻融、缩胀、损伤破坏给寒区尾矿坝工程造成极大的危害。为探究冻融循环作用下尾矿坝变形规律，揭示其变形机制。采用自主设计的尾矿坝相似模型试验装置，开展不同冻结温度（-5、-25、-45 ℃）条件下，尾矿坝的变形规律模型试验。借助土压力、激光位移、孔隙水压力传感器，采用动态数据采集仪采集相关数据，分析冻融循环过程中尾矿坝各关键位置应力、变形、孔隙水压力的动态变化规律。试验结果表明：坝体内应力随冻结温度的降低而增大;在冻融循环前期，尾矿坝各关键位置应力增长速度明显高于冻融循环其他阶段。坝体内孔隙水压力随冻结温度的降低而减小;坝体越深，孔隙水压力的变化幅度越大，周期性更强，也更具有规律性。冻结温度具有明显的位置效应，越靠近尾矿坝边缘，坝体变形量越大，变形速度越快。

关键词： 岩土工程;尾矿坝;冻融循环;力学响应特性;变形机制

中图分类号：TU431    文献标志码：A

Abstract：The freezing and thawing， shrinkage， expansion and damage of tailings sand cause great damage to the project of tailing dam in cold regions. In order to explore the deformation law of tailing dam and reveal the deformation mechanism under freeze-thaw cycle，tailings dam of similar model test device was designed and carried out different freezing temperature （5， 25， - 45 ℃） under the condition of the deformation law. By means of soil pressure， laser displacement and pore water pressure sensor， the dynamic data acquisition instrument was used to collect relevant data and analyzed the dynamic change law of stress， deformation and pore water pressure at each key position of tailing dam during the freeze-thaw cycle. The test results show that： The internal stress of dam increases with the decrease of freezing temperature; In the early stage of freeze-thaw cycle， the stress growth rate at each key position of tailing dam is higher than that at other stages of freeze-thaw cycle.The pore water pressure in the dam decreases with the decrease of freezing temperature; the deeper in the dam， the larger the change range of pore water pressure， and the stronger periodicity and more regular.The freezing temperature has obvious position effect. The closer to the tailings dam edge， the larger the deformation amount of dam body， the deformation speed is faster.

Keywords：geotechnical engineering; tailings dam. freeze-thaw cycle; mechanical response characteristics; deformation mechanism

尾矿坝是金属、非金属矿山的重大危险源[1-8]。它不仅给生态环境的治理带来困难，更会威胁到附近居民的生命财产安全。据统计，中国的季凍区面积约占全国面积的55%，而冻融循环是季冻区尾矿坝稳定性的重要影响因素之一，直接影响尾矿砂物理力学性质的变化[9-10]。同时，会导致坝体内孔隙压力等力学指标发生变化，进而导致尾矿坝坝体变形，即稳定性发生变化。而尾矿坝稳定性是评价项目工程安全是否可靠的关键指标，故研究冻融条件下尾矿坝力学响应特性具有重大意义。……