基于LBM-DEM耦合方法的突水溃砂运移规律研究

Study on laws of water inrush and sand burst migration based on LBM-DEM coupling method

我国西部矿区因其特殊的地质赋存条件及高强度开采方式易诱发突水溃砂灾害,迫切需要对灾害机理进行研究。为了解突水溃砂下水砂运移规律及致灾的关键原因,借助LBM-DEM耦合模拟方法对单裂隙开口通道模型中水砂两相运移问题进行了初步探究,通过对比截面流量及溃砂速率变化情况,分析了其受不同边界压力、裂隙开口宽度及砂层厚度的影响,基于Bulsara式拟合了不同边界压力时最大单位质量流量数值计算结果。研究结果表明:随边界压力增加,截面流量及最大溃砂速率单调增加,高压力下砂粒更容易在裂隙开口处堆积形成临时性密实结构阻碍水砂运移,截面流量及最大溃砂速率增幅逐渐降低,在Bulsara式基础上给出的修正式能较好的拟合最大单位质量流量曲线;随开口宽度增加,截面流量、最大溃砂速率和砂粒在开口处形成的密实结构体积均单调增加,但增幅逐渐降低,发现灾害的关键影响因素之一为砂粒密实结构体积;随砂层厚度增加,砂粒密实结构持续时间增长造成阻碍效果逐渐增加,截面流量及最大溃砂速率逐渐减小且降幅逐渐降低,灾害发生点由初始水驱动砂快速流出裂隙孔口阶段转变为砂粒密实结构失稳造成砂粒倾泻阶段。

Due to the special geological conditions and high-intensity mining methods in the western mining areas,it is easy to induce wa⁃ter inrush and sand burst disasters,so it is urgent to study the mechanism of the disaster.In order to understand the law of water and sand migration under water burst and sand burst and the key causes of disasters,the problem of water and sand two-phase migration in the sin⁃gle-fracture open channel model was preliminarily explored with the aid of LBM-DEM coupling simulation method.Compared with the change of section flow rate and the sand break rate per unit time,the influence of different boundary pressure,crack opening width and sand layer thickness were analyzed and the numerical calculation results of maximum unit mass flow rate at different boundary pressures were fitted based on the Bulsara formula.The results show that with the increase of boundary pressure,the cross-sectional flow rate and the maximum sand bursting rate increase monotonously.Under high pressure,sand particles are more likely to accumulate at the crack o⁃pening and form a temporary compact structure to hinder the migration of water and sand.The cross-sectional flow rate and maximum sand break rate decrease gradually.As the opening width increases,the cross-sectional flow rate,the maximum sand break rate and the volume of the compact structure formed by sand particles at the opening all increase monotonically,but but the increase decreases gradually.The modified formula based on Bulsara equation can fit the maximum unit mass flow curve well.It is found that one of the key factors affecting the disaster is the volume of dense sand structure;as the thickness of the sand layer increases,the duration of sand dense structure increa⁃ses and the hindering effect gradually increases.The cross-sectional flow rate and the maximum sand break rate gradually decrease and the decline gradually decreases.The disaster occurred from the initial water-driven sand flowing out of the crack orifice stage to the stage of sand-grain compact structure instability caused by sand-grain dumping.