软岩边坡陡帮开采破坏机理及数值研究

Study on Failure Mechanism and Numerical Simulation of Steep Slope Mining in Soft Rock Slope

露天矿开采边坡角是资源回收率的重要标志,而陡帮开采可以提高采矿边坡角但会加剧边坡的变形,因此陡帮开采中需要控制应力释放及位移变形。通过摩尔库伦准则研究地应力与软岩强度关系,确定了应力重分布与应力释放的判别条件;选取某矿典型软岩矿山边坡模型、地下水富存状况,及岩土体力学指标,通过研究确定:边坡滑动模式为“坐落-滑移式”,沿软弱泥岩层滑动;陡帮开采前边坡沿煤层顶底板滑动稳定性为1.142和1.150,底板控制下稳定性大于顶板控制稳定性;陡帮开采后在558水平以下台阶形成大位移和塑性变形区域,该区域处于极限平衡状态,整体沿煤层底板滑动稳定性为1.033,稳定性与数值模拟中陡帮开采位移破坏模式相符合。

Slope angle of open pit mining is an important indicator of resource recovery rate,and steep slope mining can improve the mining slope angle,but it will aggravate the slope deformation,so it is necessary to control stress release and displacement deformation in steep slope mining.The relationship between in-situ stress and strength of soft rock is studied by Mohr-Coulomb criterion,and the criterion of stress redistribution and stress release is determined.The slope model of typical soft rock mine,the condition of groundwater and the mechanical index of rock and soil are selected.Through research,it is determined that the sliding mode of slope is“sitting-sliding”and slides along weak mudstone stratum.Before steep slope mining,the sliding stability of the slope along the roof and floor of the coal seam is 1.142 and 1.150,and the stability under the control of the floor is greater than that under the control of the roof.After steep slope mining,a large displacement and plastic deformation area is formed on the bench below 558 level,which is in the limit equilibrium state.The overall sliding stability along the coal seam floor is 1.033,which is consistent with the displacement failure mode of steep mining in numerical simulation.