四柱支撑掩护式支架空间承载特性研究

Spatial Load-bearing Characteristics of Four-pillar Chock-shield Support

针对基于平面力系建立的承载区理论未能反映四柱支撑掩护式支架顶梁全范围的承载特性问题,提出采用承载体理论分析四柱式支架顶梁全范围的空间承载特性。通过构建四柱式支架顶梁分离体空间力学模型,得到空间力系表达式并推导出承载曲面解析式;根据曲面判定原则进行取舍得到支架处于最大支撑高度时的承载体即极限承载体,其外形与“三角曲面锥”体类似,呈现四周低、中心高的特点。对四柱式支架极限承载体做垂直及水平切面得到纵、横向承载区以及承载力等值面,分析得到纵向承载区在顶梁纵向中部的支架合力以及面积最大,并沿两侧衰减,与平面承载区理论研究结果相同;横向承载区以极限承载点m0为界差异显著,承载区面积在m0处最大,并向前后两侧减小;承载力等值面呈三角形分布,承载力越大三角形越小。提出了量化支架承载能力的体积计算法;分析了极限承载体体积的关键影响因素为支架单立柱工作阻力和立柱定位尺寸,结果表明:单立柱工作阻力异常下降会影响支架的额定工作阻力,减小承载容量,影响支架的整体承载性能,削弱支架对顶板的适应能力;适当增大立柱间距能够增加支架的承载容量,扩大支架的有效支护面积,增强支架对顶板载荷变动的适应性,提高控顶效果,而支架的整体支撑效率并不改变。

The load-bearing body theory is proposed to analyze the full-range spatial load-bearing characteristics of four-pillar chock-shield support top beam,as the traditional load-bearing area theory based on the plane force system fails in this case.The spatial force system expression is obtained and the analytical expression of the load-bearing surface is also derived by constructing the spatial mechanics model of the four-pillar support top beam separation body.The load-bearing body is the ultimate load-bearing body when the support is at the maximum support height via the curved surface judgment principle.The shape is similar to that of the“triangular curved cone”body,which is characterized by low circumference and high center.The vertical and horizontal sections of the ultimate load-bearing body of the four-pillar support are employed to obtain the longitudinal and transverse load-bearing area and the load-bearing capacity contour surface.The above analysis shows that the support resultant force and the area of the longitudinal load-bearing section in the middle of the top beam are the largest,and attenuated along both sides of the area,which is the same as the theoretical results for the plane load-bearing area.The morphological characteristics of different positions in the transverse load-bearing area are significantly distinct with the limit load-bearing point m0 as the boundary.The area of the load-bearing area is the largest at m0 point,and decreases from front to back.Moreover,the shape of the load-bearing capacity contour surface is of triangular distribution,and the larger the load-bearing capacity is,the smaller the triangle will be.A volume calculation method for quantifying the support load-bearing capacity is proposed;the key factors affecting the ultimate load-bearing body volume are the working resistance of the single support pillar and the positioning dimensions of the pillars.The results show that the abnormal decrease of the working resistance of single pillar will affect the rated working resistance of the support.The overall load-bearing capacity of the support is affected and the adaptability of support to the roof is also weakened,while the load capacity is reduced.Increasing the spacing of the pillars appropriately can increase the load-bearing capacity of the support,expand the effective support area,enhance the adaptability of the support to the change of roof load,and improve the roof control effect,but the overall support efficiency of the support does not change.