叠加采动影响下保留巷道围岩破坏机理及其控制技术

Surrounding rock failure mechanism of reserved roadway under superimposed mining and its control technology

以布尔台煤矿上下煤层叠加采动影响下保留巷道严重变形破坏为工程背景,采用理论分析、现场监测、实验室试验、数值模拟和工业性试验等综合研究方法,从巷道围岩塑性区形成和发展的角度,对巷道围岩破坏特征、采动应力时空演化规律、保留巷道塑性区恶性扩展破坏机理、应力调控围岩控制技术方面进行系统研究。结果表明:上下煤层叠加采动后,保留巷道处于高应力比值带,主应力比值为1.84~2.22,最大主应力与竖直方向夹角为39.7°~41.9°,导致巷道围岩塑性区恶性扩展,顶板破坏深度7.5 m,底板破坏深度4.5m,煤柱帮破坏深度3m,煤壁帮破坏深度2.25m。基于塑性区破坏机理提出应力调控技术,通过改变煤柱尺寸或上下工作面开采布局等手段调控围岩应力,减小围岩塑性破坏范围,并进行工业性试验,取得良好的应用效果。

This study focuses on the serious deformation and failure of reserved roadway affected by superimposed mining of upper and lower coal seams in Buertai coalmine.Comprehensive research methods including theoretical analysis,field monitoring,laboratory test,numerical simulation and industrial test were adopted.From the perspective of formation and development of plastic zone in roadway surrounding rock,the failure characteristics of surrounding rock,the temporal and spatial evolution of mining stress,the failure mechanism of plastic zone malignant extension around reserved roadway,and the surrounding rock control technology by changing stress were systematically investigated.Results showed that:after superimposed mining of upper and lower coal seams,the reserved roadway is in the zone with high stress ratio.The ratio of principal stress is 1.84-2.22.The angle between maximum principal stress and vertical direction is 39.7°-41.9°,which results in plastic zone vicious expansion in the roadway surrounding rock.The depth of roof failure is 7.5 meters.While the depth of floor failure is4.5 meters,the depth of pillar failure is 3 meters,and the depth of wall failure is 2.25 meters,respectively.Stress control technology is put forward based on plastic zone failure mechanism.By changing the size of coal pillar or mining layout of upper and lower working faces,the surrounding rock stress is controlled.Meanwhile,the plastic failure range of surrounding rock reduces.Finally,industrial tests are carried out and shows good application results.