四柱支撑掩护式支架空间承载特性研究

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为极限承载体,其外形与“三角曲面锥”体类似,呈现四周低、中心高的特点。通过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。

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

Because the theory of load-bearing area based on the plane force system fails to reflect the full-range load-bearing characteristics of four-pillar chock-shield support top beam, the theory of load-bearing body is proposed to analyze the characteristics. By constructing the space mechanics model of the four-pillar support top beam separation body, the spatial force system expression is obtained and the analytical expression of the load-bearing surface is also derived. The load-bearing body is the ultimate load-bearing body when the support is at the maximum support height according to the surface judgment principle. The shape is similar to the triangular 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 performed to obtain the longitudinal and transverse load-bearing area and the load-bearing capacity contour surface. Above analysis shows that the support resultant force and the area of the longitudinal load-bearing area in the middle of the top beam are the largest, and attenuate along both sides of the area, which is the same as the theoretical research results of the plane load-bearing area. The morphological characteristics of different positions in the transverse load-bearing area differ significantly when the limit load-bearing point m₀ is boundary. The area of the load-bearing area is the largest at m₀, and decreases from front to back; the shape of contour surface of load-bearing capacity is triangular distribution, and the larger the load-bearing capacity is, the smaller the triangle will be. A volume calculation method for quantifying the load-bearing capacity of support is proposed; the key influencing factors for the ultimate load-bearing volume are the working resistance of single pillar and the positioning dimensions of the pillar. The results show that the abnormal decrease of the working resistance of single pillar will affect the rated working resistance of the support, reduce the load capacity, affect the overall load-bearing capacity of the support, and weaken the adaptability of support to the roof. Increasing the spacing of the pillars appropriately can increase the load-bearing capacity of the support, expand the effective support area of the support, enhance the adaptability of support to the change of roof load, and improve the roof control effect of support, while the overall support efficiency of support does not change.