Coupling bearing mechanism of roof arch-beam of roadway in deep and extra-thick and soft coal seam

Due to the serious development of cleavage and fracture, low cohesion and low strength in the top coal of the extra thick and soft coal seam roadway, in order to solve the technical problemsof difficult control of crushing and deformation of surrounding rock of such roadway and the instability of supporting structure, theoretical analysis and similar material simulation tests and numerical simulation analysis were adopted comprehensively, an arch-beam coupling active bearing structure support system for extra-thick coal roof roadways was proposed, The formation and function of composite beams and load-bearing arches and the mechanism of arch-beam coupling were elaborated. The mining roadway of Jindi Coal Industry was used as the object, the influence of key parameters of anchor cable (length, pre-tightening force and row spacing) on the stability of arch-beam bearing structure was studied in detail by numerical simulation. At the same time, the stability evaluation system of the arch-beam bearing structure was established, and the influence factors of key parameters were calculated by weighted average method. The results show that the arch-beam coupling bearing structure is the main part of the roadway supporting structure, which effectively improves the strength and stability of the surrounding rock in extra-thick soft seam roadway, improves the crushing deformation of surrounding rock and prevents the instability of roadway. Applying morphological parameters to evaluate the stability of the arch-beam bearing structure has certain degree of objectivity, and the contribution coefficients of structural morpho logical parameters are as follows: arch volume 0.3, arch core compressive stress 0.3, arc length 0.2, beam volume 0.1 and beam core compressive stress 0.1. The contribution rates of key parameters of anchor cables to the stability of arch-beam bearing structure are as follows: the row spacing contributes 365.21%, the pre-tightening force contributes 80.34%, and the length contributes 30.98%. That is, the effect of the inter-row distance > the effect of the pre-tightening force > the effect of the length. For the mining roadway in Jindi Coal Industry, the support parameters are optimized (the row spacing between anchor cables is 1 m×1.6 m, the pre-tightening force is 150 kN, the length is 8 m and the row spacing between anchors is 0.8 m×0.8 m), which can maintain the stability of the roadway and meet the production requirements.