Study on mechanics model of overburden large structure of fully-mechanized sublevel coal caving face

Fully-mechanized sublevel coal caving face full-seam mining thickness is increasing; the movement range of overburden stratum also increasing, most obvious character is the more capacious range and more large span overburden large structure that formed in the higher position. This paper analyzed the formation of fully-mecchanized sublevel coal caving face overburden large structure by using the new research production of underground pressure theory Key stratum theory, elasticity mechanics and structure mechanics theory, brought forward its conception and model, and carried through mechanics analysis on the model, and presented the two possible movement patterns mechanics criterion of overburden large structure, presented the directional distributing of normal stress, shearing stress and extrusion & compression stress along the span and height of overburden large structure. Based on two type of basic form of the overburden stratum movement brought forwards by Academician Song Zhen-qi, analyzing the possible movement tendency of overburden large structure: (1) It was ripped in the pedestal negative bending moment stratum, and two end embed beam model translate into simple supported beam model, moreover rupture in the middle part; (2) shear destroy, and get the ultimate span of the two circs separately.