长边采空(煤柱)弹性基础边界基本顶薄板破断规律

Fracture rule of main roof thin plate with the elastic foundation boundary and long side coal pillar

建立长边为煤柱支撑、实体煤区为弹性基础边界的基本顶板结构力学模型,运用有限差分方法计算了煤柱宽度Lp1及支撑系数kp、基本顶厚度h、弹性模量E、实体煤区的弹性基础系数ks及跨距L对基本顶破断规律的影响。得到:(1) Lp1与kp既可改变实体煤区及中部区主弯矩大小且可显著影响煤柱区基本顶的破断形式及整体破断形态;(2)基本顶初次破断位置为长边实体煤侧深入煤壁上表面(E,h较小,L较大时),反之为中部区偏长边煤柱侧下表面;(3) Lp1,kp较大,E,h较小,L较大时,基本顶在煤柱区产生平行于煤柱轴向的断裂线,破断顺序为:长边实体煤区超前煤壁上表面→采空区中部偏煤柱侧下表面→长边煤柱区上表面→短边超前煤壁上表面,最终破断形态为非对称"O-X"型;(4)Lp1,kp较小,E,h较大,L较小时,基本顶在煤柱区不产生平行于煤柱轴向的断裂线,破断顺序为:采空区中部偏煤柱侧下表面→长边实体煤区超前煤壁上表面→短边超前煤壁上表面,最终破断形态为非对称"C-X"型;(5)比值ks/h^3或者ks/(Eh^3)不变时破断规律不变。

By establishing the mechanical model of main roof thin plate with long side as coal pillar supports and the solid coal area as the elastic foundation boundary, using the finite difference method,the effects of the coal pillar width Lp1 and support coefficient kp, main roof thickness h, elastic modulus E, elastic foundation coefficient ks of solid coal area and span L on the fracture rule of main roof are studied.(1) The Lp1 and kp can change the main bending moment of the solid coal area and the central region, and also significantly affect the fracture forms and the overall fracture shape of the main roof in the coal pillar area.(2) The initial fracture location of the main roof is the upper surface of advance coal wall(When the E and h are small and the L is large). Conversely, the initial fracture location is the lower surface of the middle region.(3) When the Lp1 and kp are large, the E and h are small and the L islarge, the main roof in the coal pillar area produces a fracture line parallel to the axial direction of the coal pillar;the main roof fracture order is: the surface area of long side advance coal wall area→the lower surface of the middle part deviates from the coal pillar→the surface area of short side advance coal wall area. Finally,the type of "O-X" fracture pattern is formed.(4) When the Lp1 and kp are small, the E and h are large, and the L is small, the main roof in the coal pillar area doesn’t produce the fracture line parallel to the axial direction of the coal pillar;the main roof fracture order is: the lower surface of the middle part deviates from the coal pillar→the surface area of long side advance coal wall area→the surface area of short side advance coal wall area. Finally,the type of"C-X"fracture pattern is formed.(5) If the ratio ks/h^3, or ks/(Eh^3) is unchanged, the fracture rule is constant.