深埋弱胶结薄基岩厚煤层开采顶板动载冲击效应产生机制试验研究  

Experimental study on mining-induced dynamic impact effect of main roofs in deeply buried thick coal seams with weakly consolidated thin bed rock

作　　者：王家臣[1,2] 王兆会 唐岳松[1] 李猛 常坤林 弓昊[1] 徐国梁 WANG Jiachen;WANG Zhaohui;TANG Yuesong;LI Meng;CHANG Kunlin;GONG Hao;XU Guoliang(School of Energy and Mining Engineering,China University of Mining and Technology,Beijing 100083,China;Top-coal Caving Mining Research of Coal Mining Industry,Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)能源与矿业学院,北京100083 [2]放顶煤开采煤炭行业工程研究中心,北京100083

出　　处：《岩石力学与工程学报》2021年第12期2377-2391,共15页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51934008,51904304)。

摘　　要：深埋弱胶结薄基岩厚煤层采场动压显现强烈,顶板动载冲击作用下液压支架压死、损坏现象时有发生。为提高该类采场围岩控制效果,采用室内试验、理论分析和现场实测等手段研究厚冲积层作用下深埋弱胶结薄基岩顶板动载冲击效应产生机制,探究动载冲击力确定方法。结果表明:深埋弱胶结薄基岩厚煤层采场覆岩采动裂隙萌生于高位厚冲积层,上行扩展导致冲积层垮落,下行扩展导致基本顶断裂,形成覆岩冒落拱;冒落拱局部失稳,则新生冒落拱呈非对称形态,基本顶发生拉伸破断,支架承受静载作用;冒落拱整体失稳,则新生冒落拱呈对称形态,基本顶发生剪切破断,支架承受动载作用;快速下行扩展的采动裂隙在惯性作用下穿越岩层交界面进入基本顶,使其成为上表面含惯性裂纹的悬臂梁,极大劣化基本顶承载能力;采动裂隙扩展至冒落拱顶部和拱脚的时间一致,冒落体脱离冲积层母体前,裂隙萌生位置处应变集中程度最高,拱脚次之,拱顶最低;冒落拱整体失稳导致大范围冲积层自重载荷迅速传递至劣化基本顶悬臂梁,惯性裂纹尖端出现剪应力集中现象,基本顶发生剪切破断,存储于其中的弹性应变能转化为破断岩块动能,非静态启动的破断岩块冲击下位直接顶和液压支架,引发采场动压;采用上限定理确定了厚冲积层冒落拱边界方程,得到作用于基本顶之上的冲积层载荷和存储于基本顶中的弹性应变能,基于动能、动量守恒原理分别确定了基本顶破断岩块启动速度、顶板动载冲击力计算方法;最后提出采用预裂爆破方法释放赵固二矿14030工作面基本顶应变能,预防顶板动载冲击现象的发生。Mining pressure occurrence is strong in longwall faces of deep-buried thick coal seams with weakly consolidated thin bed rock.The compression and damage of hydraulic supports happen frequently due to dynamic loads resulted from roof failure.In order to improve surrounding rock control of such longwall faces,adopting laboratory experiment,theoretical analysis and in situ measurement,the occurrence mechanism of the dynamic impact effect is analyzed and the determination method of the dynamic load is discussed.The results show that mining-induced fractures initiate within upper alluvium in the referred longwall face,and that upward and downward propagations of the fractures respectively lead to collapse of the alluvium and rupture of the main roof,leading to the development of a caving arc in the overburden.If the caving arc undergoes local instability,the new caving arc presents an asymmetric shape.In this case,the main roof fails in tension,exerting a static load on the hydraulic support.If the caving arc shows integral instability,the new caving arc presents a symmetric shape.The main roof fails in shear,exerting a dynamic load on the hydraulic support.Downward propagation speed of the fractures is so fast that it penetrates the interface between the alluvium and the bed rock inertially.The main roof becomes a cantilever beam with inertial cracks at the top edge,seriously deteriorating the load-bearing capacity.The times required for the fracture propagating to the vault and the foot of the caving arc are consistent.Before caving of the alluvium,strain localization is highest at the initiation position of the fracture,followed by the arc foot and the arc vault.Instability of the caving arc leads to quick transition of the gravity load of the caving alluvium to the deteriorated cantilever beam,resulting in shear stress concentration at the inertial crack tip.Accordingly,shear failure happens to the main roof,and the strain energy stored in the main roof is transformed to be kinetic energy of the broken block.Non-s

关 键 词：采矿工程 弱胶结薄基岩 采动裂隙 冒落拱 应变能 动载冲击力 

分 类 号：TD32[矿业工程—矿井建设]