四柱支撑掩护式支架空间承载特性研究

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 pointm₀as the boundary. The area of the load-bearing area is the largest atm₀point, 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.