热-流-固耦合作用下铀尾矿库坝体稳定性数值模拟

Numerical simulation of dam stability of a uranium tailings pond under thermal-fluid-solid coupling

为可靠评估铀尾矿坝的稳定性,以我国南方某铀尾矿坝为例,采用基于COMSOL软件的数值模拟方法,对坝体内温度、渗流和应力耦合进行建模分析,分别研究了自重应力、流-固耦合及热-流-固耦合作用下铀尾矿坝的稳定性,分析比较了安全系数、等效塑性及位移。结果表明,耦合降雨会使尾矿坝的安全系数下降4.7%,耦合温度后则进一步降低5.9%;单独改变降雨强度和温度,安全系数都会随之增大而减小,等效塑性应变随之增大而增大。总体而言,在强降雨和高温耦合天气下,该铀尾矿坝处于安全稳定状态,但长时间的强降雨和高温会降低铀尾矿库的安全系数。

Rainfall and evaporation are important factors affecting the stability of uranium tailings dams.To reliably evaluate and predict the stability of the uranium tailings dam,taking a uranium tailings dam in southern China as an example,COMSOL numerical simulation method is adopted to analyze and evaluate the safety and stability of the dam under heavy rainfall and high temperature.Firstly,three physical fields,namely solid mechanics,Richards equation,and heat transfer in porous media,are selected to build models of uranium tailings dam under gravity,fluid-solid coupling,and thermal-fluid-solid coupling,and the safety factor,maximum equivalent plastic strain,and displacement changes under three different coupling conditions are compared and analyzed.Then the effects of rainfall intensity and temperature on safety factors,maximum equivalent plastic strain and displacement are studied.The results show that:under the action of dead weight stress,the safety factor of the uranium tailings dam is 1.595.After coupled rainfall,the safety factor of the uranium tailings dam is 1.52,reduced by 4.7%.After coupled temperature,the safety factor becomes 1.435,further reduces by 5.9%.When the rainfall intensity is changed separately(90 mm/d,150 mm/d,200 mm/d,400 mm/d),the safety factor decreases from 1.550 to 1.290,decreasing by 16.8%.The maximum equivalent plastic strain increases from 0.11 to 0.26,and the displacement increased from 0.52 m to 1.33 m.When the temperature changes separately(298.15 K,308.15 K.318.15 K,328.15 K),the safety factor decreases from 1.47 to 1.37,a total decrease of 6.8%,the maximum equivalent plastic strain increases from 0.14 to 0.26,and the maximum displacement increases from 0.67 m to 1.32 m.Under the coupled weather conditions of heavy rainfall and high temperature,the uranium tailings dam is generally in a safe and stable state,but long-term heavy rainfall and high temperature may increase the risk of dam failure of the uranium tailings dam.The modeling results can also contribute to a better understanding of slope failure induced by the thermal-fluid-solid couplings.