基于漏风特性的覆盖层合理级配与厚度研究

Study on reasonable gradation and thickness of overburden based on air leakage characteristics

针对露天转地下矿山覆盖层漏风难以有效控制的问题,研究覆盖层碎岩级配与厚度和漏风量的关系,提出确定覆盖层合理级配与合理厚度的方法。基于多孔介质漏风理论,搭建覆盖层下放矿的相似物理实验平台;采用6种级配的碎石开展覆盖层漏风特性实验,分析覆盖层碎石d60/d30、-0.5mm细颗粒含量t(-0.5mm)、-5mm细颗粒含量t(-5mm)与孔隙率的量化关系,研究孔隙率与厚度对漏风量的协同影响,确定覆盖层不漏风的合理级配与厚度。结果表明,覆盖层的孔隙率与级配指标呈单调递减的函数关系,降低孔隙率或增大厚度可显著控制覆盖层漏风,孔隙率降低到21.5%以下时有利于控制漏风。通过建立覆盖层漏风量与孔隙率、厚度的关系模型,得出孔隙率为20.0%~21.5%时覆盖层不漏风的合理级配与合理厚度。研究结果为露天转地下矿山覆盖层提供了理论指导。

Aiming at the problem of air leakage control in overburden of mines transiting from open-pit to underground,the relationship between the gradation and thickness of overburden rock and air leakage is studied,and the method to determine the reasonable gradation and thickness of overburden is put forward.Based on the theory of air leakage in porous media,a physical similar experimental platform for ore drawing under overburden is built.Experiments on air leakage characteristics of overburden are carried out with 6 kinds of gradation to analyze the relationship between d 60/d 30,-0.5 mm fine particle content(t(-0.5 mm)),-5 mm fine particle content(t(-5 mm))and air leakage respectively.Synergistic effect of porosity and thickness on air leakage is researched,and the reasonable gradation and thickness of overburden are determined.The results show that the relationship between porosity and grading index of overburden is monotonically decreasing,reducing porosity or increasing thickness can significantly reduce the air leakage of overburden,and air leakage is easier to be controlled when porosity is reduced to below 21.5%.The relationship model of air leakage with porosity and thickness is established,and then the reasonable gradation and thickness of the overburden without air leakage are obtained when the porosity is 20.0%-21.5%.The research provides theoretical guidance for the formation of overburden in mines transiting from open-pit to underground.