Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
LIU, X.; SONG, G. and LI, X.. Classification of roof strata and calculation of powered support loads in shallow coal seams of China. J. S. Afr. Inst. Min. Metall. [online]. 2015, vol.115, n.11, pp. 1113-1119. ISSN 2411-9717. http://dx.doi.org/10.17159/2411-9717/2015/v115n11a15.
According to the overlying rock strength and thickness of 10 shallow coal seams in China, the strata are classified into four types: weak and laminated strata (hereinafter referred to as WL), weak and massive strata (WM), strong and laminated strata (SL), and strong and massive strata (SM). The four types of strata, together with longwall panel height (M), panel length (L), and seam depth (H) are factors that influence the loads on hydraulic power supports. Principal component analysis was used to study the seven influencing factors. It turns out that seam depth (H) is multicollinear with WL, WM, SL, and SM. Thus the enumerated seven factors are divided into two models. In Model 1, six factors; panel height, panel length, and layer thickness of the four type strata are involved. In Model 2, three factors; panel height, panel length, and seam depth are included. Using multivariate regression analysis, two equations to calculate loads on supports are obtained for each model. The equations were applied to shallow coal seams. The equation of Model 1 is more accurate than that of Model 2, but Model 2 could be further used in deep coal seams. The equations were coded through VB programming to simplify the calculation.
Keywords : shallow coal seam; panel length; mining height; seam depth; principal component analysis.