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综放开采过程中顶煤和覆岩由连续向非连续和散体介质状态转变,描述矿压在断裂覆岩和碎裂顶煤中的形成、传递方式和作用机理是综放开采矿压理论研究的难点.基于光弹试验原理,借助散体介质双轴加载双向流动光弹试验装置,对综放开采过程中散体顶煤与非连续覆岩关键层中力链网络结构及演化特征进行研究.研究发现:地层载荷在煤岩体中构成了错综复杂的弱-强力链网络.综放开采打破了初始力链网络结构的平衡,顶煤与覆岩中形成梁-拱复合力链拱结构,覆岩荷载以强力链形式传递到工作面前方煤体.随着工作面推进和顶煤放出,覆岩梁-拱力链网络不断扩展和演化,形成更大规模的力链拱结构.关键层弯曲、断裂和失稳运动,使工作面前方的强力链拱脚出现回缩现象,力链分布密度和强度增加,导致工作面来压现象.地层内水平力作用使顶煤与覆岩内的梁-拱力链结构效应较更加明显,整体拱结构形态愈加完整,强力链网络结构更加紧致,关键层断裂失稳时力链拱对工作面煤层的作用力更加显著.
During the process of fully mechanized top coal caving, top coal and overburden change from continuous to discontinuous and bulk media state to describe the formation of rock pressure in the overburden and fractured top coal. The transmission mechanism and mechanism are the pressure theory of fully mechanized caving mining Based on the theory of photoelastic test, the structure and evolution characteristics of the chain network in the critical layers of top-coal and non-continuous overburden strata during the process of fully mechanized top-coal caving mining are studied by means of biaxial loading biaxial flow photoelastic testing device in bulk medium Research shows that the strata load forms a complex network of weak-strong chain in coal and rock mass.The fully mechanized top-coal caving has broken the balance of the initial force chain network structure, and the top coal and overlying strata form the beam-arch complex chain arch structure , The load of overburden rock is transmitted to the coal body in front of working face by the form of strong chain.With the expansion of caving face and the release of top coal, the network of overlying beam-arch chain expands and evolves to form larger-scale force chain arch structure. Bending, breaking and destabilizing movement of the working face make the arch of the power chain arch retract in front of the working face and the distribution density and strength of the power chain increase, resulting in the phenomenon of pressure on the working face. Beam - Arch power Structure effect is more obvious than the overall morphology even more complete arches, strong chain network structure more compact, when the interlaminar fracture key chain destabilizing forces Arch more significant force on the coal face.