Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
Print version ISSN 0038-223X
MA, L.Q. et al. Support stability mechanism in a coal face with large angles in both strike and dip. J. S. Afr. Inst. Min. Metall. [online]. 2015, vol.115, n.7, pp.599-606. ISSN 2411-9717. http://dx.doi.org/10.17159/2411-9717/2015/V115N7A6.
To solve the support stability control problem for a coal face with large angles along both strike and dip (CLSD), the 'support-surrounding rock' mechanical model has been developed, which takes into account the impact of the dip angle of the seam on the stability of the support in the strike direction. The mechanical relationships of the critical topple angle and critical slip angle of the support along the strike of the coal face with large dip angle and the support height, support resistance, friction coefficient, and other factors have been derived through the mechanical analysis of support stability in the strike direction of CLSDs in the free state, the operating state, and the special state. The research findings were applied to a fully mechanized CLSD in Xinji Coal Mine. The maximum underhand angle and overhand angle in strike are 42° and 25° respectively, and the maximum dip is 39°. It is calculated that during underhand mining and overhand mining, the critical support resistances for avoiding support toppling are 3723 kN and 1714 kN respectively, and the critical support resistances for avoiding slipping of the support are 7405 kN and 6606 kN respectively. Thus, the selection of type ZZ7600/18/38 hydraulic roof support for the coal face is justified. Measures to prevent sliding of the support and the installation of a limiting stop maintain the support runs in good condition and ensure safe and efficient mining of CLSD.
Keywords : coal mining; support stability; dip angle; strike angle; critical topple; critical slip.