【作者】 禹朝群；

【导师】 甘德清；

【作者基本信息】 河北理工大学 ， 采矿工程， 2010， 硕士

【摘要】 在露天转地下开采的过程中,采用无底柱崩落法的矿山,需要在露天坑底预先铺设合理结构的覆盖层,以起到较好的滞水效果及满足防冲击地压等要求。由于覆盖层在地下采矿活动下发生移动变化,进而影响覆盖层的厚度及结构的改变,因此研究覆盖层的移动规律,对于确定合理的覆盖层结构和厚度以满足其功用具有重要意义。以首钢杏山铁矿露天转地下工程为背景,根据相似定律确立了实验的相似条件,设计并制作了露天转地下覆盖层相似物理模型,按不同粒度组成、不同厚度、不同含水量和不同放矿制度条件分别进行了覆盖层移动特性物理模拟试验,同时运用PFC2D软件建立数值模拟模型,再现了覆盖层散体的运移过程。通过物理模拟和数值模拟的结果对比分析,得出了覆盖层在地下开采过程中的移动变化规律。通过模拟研究得出,覆盖层随着地下采矿活动而改变。覆盖层的移动规律受放矿松动椭球体的影响,其影响范围取决于放矿过程中松动椭球体的高度,一般覆盖层的影响高度约为放出椭球体高度的1.5倍;覆盖层下移的过程中,在松动椭球体内的岩石沿轴线方向移动速度最大,细粒覆盖岩的下移速度大于粗粒覆盖岩的下移速度,若矿岩交界面部位岩石块度过细会引起矿石的超前贫化,建议矿岩交界面上(一定厚度)覆盖层块度和地下采场矿石的平均块度相近为宜。根据对不同厚度覆盖层的试验研究,厚度较小时,覆盖层上表面凸凹不平,形成波浪形,不利于覆盖层实现滞水、防风和缓冲冲击地压等功能,建议首钢杏山铁矿覆盖层的厚度不小于40m。更多还原

【Abstract】 In the process of open pit to underground, in order to attain a better effect of stagnant water and to prevent rock burst, a rational structure covering layer is necessarily paved on the bottom of open pit before mining in mines which utilize sublevel caving method without sill pillar. The covering layer will change underground mining activities happen, simultaneously, it will affect the layer thickness and structure. So it has a great significance to investigate movement features of covering layer for identifying a rational structure and thickness of covering layer.Take Xingshan iron mine from open pit to underground Shougang an example, a similar experimental conditions is established accoring to the similarity law, a similar physical model of covering layer from open pit to underground was designed and constructed. According to the different combinations of granulometric composition, thickness, humidity and ore drawing condition, mobile physical simulation experiments of covering layer were finished, at the same time, the establishment and use of numerical simulation software PFC2D model reproduced the moving process of loose layer. Through the comparative analysis of results of physical simulation and numerical simulation, the movement rule of covering layer in the process of underground mining was obtained.From the study of model, the covering layer was changed with the underground mining activity. The movement rule of covering layer was affected by the ellipsoid of ore drawing, its affect limitation range was depended on the height of loose ellipsoid, the general height of covering layer is close to 1.5 times of drawing ellipsoid’s. In the process of the downward covering layer, the movement speed along the axis of loose ellipsoid is fastest. The downward speed of fine-grained covering rock is faster than the one of coarse-grained covering rock. If the rock lumpiness between the border of ore and rock is too thin, it will cause over early ore dilution, it is suggested that the rock lumpiness of the border should be as near as the average limpiness of underground mining. According to the experimental study of thickness of different covering layers, when the thickness is small, the surface of covering layer is rugged to be waved and disadvantaged of the function realization of stagnant water, wind-prevention and rock burst, so it is suggested that the covering layer thickness of Xingshan iron mine should be better more than 40m.更多还原