Research on mechanism and control technology of cooperative load-bearing of backfill-gangue in gob-side entry retaining by roof cutting

In view of the problems such as large displacement of the roof to floor, large deformation, failure and instability of the backfilll in deep gob-side entry retaining, the stress evolution law and deformation characteristics of surrounding rock of gob-side entry retaining under collaborative load-bearing of traditional gob-side entry retaining by roof cutting and pressure relief were analyzed by combining numerical simulation and field practice.On this basis, with the gob-side entry retaining in Ⅲ635 working face of Zhuzhuang Coal Mine as the engineering background, a technology of gob-side entry retaining by roof cutting with cooperative load-bearing of side backfill-gangue combined structure was proposed.The roof deflection equation was derived by establishing the mechanical model of the co-supporting roof of backfill-gangue, and the engineering application of backfill-gangue was carried out.The numerical simulation results show that after the adoption of the technology of gob-side entry retaining by roof cutting with cooperative load-bearing, the vertical stress peaks of solid coal wall and backfill are reduced by 28.3% and 44.4%, respectively.The deformation of the roof to floor of the roadway is reduced by 58.2%.The field application results show that after using this technology, the roof and floor convergence and the deformation of the two sides are 382.9 mm and 253.6 mm respectively.The average support force of the working face support is reduced by 45.3%, which effectively controls the roadway deformation, and provides a reference for the control of surrounding rock of gob-side entry retaining under similar conditions.