基于灾害链效应的小秦岭乱石沟矿渣堆危险性评价

矿产开采过程中,大规模不合理的矿渣堆弃以及高强度降雨等所引发的矿渣碎屑流,对矿山的正常生产和人员安全带来了巨大的风险。由于矿渣堆普遍沿沟谷呈串珠状分布,若下级渣堆受到上级矿渣碎屑流的冲击、加载作用,其失稳起动概率及渣流量将明显增加,这种空间逐级影响所表现出的灾害链效应是矿渣碎屑流灾害作用的重要特征。以小秦岭乱石沟为例,在对研究区内矿渣堆详细调查的基础上,首先以矿渣堆高度、坡度、方量、是否堆载振动、底床坡度以及降雨汇流累积量6项指标对矿渣堆的危险性进行评价。其次,采用UBCDFLOW方法,考虑碎屑流的路径宽度、平均坡角及流动类型,估算碎屑流的滑移距离。最后,在此基础上从风险评价与预测的角度出发,综合考虑矿渣堆碎屑流的链状逐级影响,以及下级渣堆位于上级渣堆碎屑流冲击范围内的相对位置,得到灾害链效应下的矿渣堆危险性评价。计算结果表明考虑灾害链效应后,乱石沟内受碎屑流影响的矿渣堆的破坏概率明显增加,研究结果也为矿山沟谷流域矿渣堆灾害的风险评价及防治规划设计提供依据。

HAZARD EVALUATION OF SLAG HEAPS IN XIAOQINLING LUANSHI GULLY USING DISASTER CHAIN EFFECT

During the process of mineral exploitation, extensive unreasonable slag discharge and mine debris flow induced by high intensity rainfall can cause tremendous risks to the normal production and personnel safety. Meanwhile, massive slag heaps are distributed along the gully. The slag heap at lower elevation can be impacted by the debris flow caused by the failure of slag heap at higher elevation. Its failure probability can greatly increase. The disaster chain effect, shown with the spatial successive influence, is an important formation character of mine debris flow. The Luanshi gully is taken as study area. It is at Xiaoqinling, China. The study is based on the detailed investigation of slag heaps. The height, slope angle and volume of slag heaps, continuing heaping or not, original terrain slope and rainfall confluence cumulant are selected as indexes to evaluate the stability of slag heaps. The travel distances of mine debris flow are estimated using an empirical-statistical model(UBCDFLOW)considering width of path, slope angle and the type of flow behavior. Subsequently, the chain effect of the mine debris flow and the relative position between the slag heaps at higher and lower elevation are considered. The slag heap hazard assessment under disaster chain effect is obtained. It is concluded that the failure probabilities of slag heaps influenced by debris flow are increased distinctly. The results can provide useful advices for risk assessment and treatment design of slag heaps in Xiaoqinling Luanshi gully.