采场厚硬顶板破断失稳与能量聚散演化研究

Study on fracture instability and energy accumulation-release evolution of thick-hard roof in stope

针对采场厚硬顶板强矿压问题,在采场厚硬顶板采动失稳影响特征分析基础上,运用力学理论构建采场厚硬顶板采动承载力学模型,分析采场厚硬顶板采动承载状态及能量积聚演化发布规律,从能量转化角度分析采场厚硬顶板破断致积聚能量释放与强动压显现关系,推导出工作面液压支架动载响应估算方程,揭示厚硬顶板破断失稳强矿压显现影响特征。研究结果表明,1)厚硬顶板在破断失稳前处于覆岩承载状态和自身弹性势能积聚,在破断瞬间显现略高于重力作用的加速运动失稳,加之悬伸跨度较大,导致厚硬顶板条件工作面动压显现尤为强烈;2)悬伸跨度、上覆岩层荷载是厚硬顶板采动承载和能量聚散演化的关键影响因素,上覆岩层荷载、自身厚度和强度是厚硬顶板极限悬伸跨度的关键影响因素;3)在工作面液压支架动态阻力响应的力源构成中,厚硬顶板破断积聚能量释放所形成的动态阻力占比最高,上覆岩层荷载做功转化所形成的动态阻力占比次之;4)在工作面液压支架动态阻力响应的影响因素中,厚硬顶板的悬伸跨度、上覆岩层荷载起直接加剧影响,岩层厚度增加厚硬顶板极限悬伸跨度,进而间接加剧动态阻力响应,直接顶厚度可对动态阻力响应起缓冲降低作用,支架控顶距的加剧影响程度不明显。

In order to address the strong mining pressure of thick-hard roof,in this paper,the mining-induced bearing mechanical model was established based on the instability influence analysis of thick-hard roof.The evolution law of the mining bearing state and energy accumulation of thick-hard roof was investigated.From such energy transfer perspective,the mechanical relationship between the accumulated energy release caused by the thick-hard roof breakage and the associated strong dynamic pressure appearance was analyzed.On this basis,the dynamic load response estimation equation of hydraulic support in the working face was derived to reveal the characteristics of impact from the strong mining pressure caused by the thick-hard roof breakage.The conclusions drawn from this paper are as follows.Firstly,the thick-hard roof is in the state of bearing the overburden,with its own elastic potential energy accumulating before the fracture instability.In case of fracture instability,the thick-hard roof shows a slightly higher level of accelerated motion instability compared to gravity,and the overhang span of the broken block is large,which leads to the high dynamic pressure on the working face due to the instability of thick-hard roof.Secondly,overhanging span and overburden load are the significant influencing factors for the evolution of mining bearing capacity,as well as the energy accumulation and release in the thick-hard roof,where the overburden load,thickness and strength are the crucial influencing factors in the ultimate overhanging span of thick-hard roof.Thirdly,as for the composition of the strong dynamic pressure behavior in the working face for thick-hard roof,the dynamic resistance caused by the cumulative energy release accounts for the largest proportion,followed by the dynamic resistance caused by the work of the overlying rock load.Lastly,among the influencing factors of dynamic resistance response of hydraulic support in working face,the overhanging span and the load of the overlying strata play a direct role in causing aggravation,and the rock thickness plays an indirect role in causing aggravation by increasing the limit on overhanging span of the thick-hard roof,where the direct roof thickness can buffer and reduce the dynamic resistance response,and the roof control distance of the support plays a role in causing aggravation,but not to a significant extent.