Stability analysis of inclined coal seam roadway along goaf considering non-uniform filling of gob gangue

After the mining of inclined coal seam, the roof falling gangue of goaf moves downward to fill the goaf due to gravity, which makes the strata behavior law of gob-side entry retaining in inclined coal seam different from that in horizontal coal seam. In order to study the influence of non - uniform filling of gangue on surrounding rock stability of gob - side entry retaining in inclined coal seam, taking No.3131 machine roadway of Longmenxia South Coal Mine in Sichuan as engineering background. The filling zone length of caving rock in goaf was quantified, and the compaction parameters of rock in quantified goaf were obtained by double yield model inversion. On this basis, a numerical calculation model was established to study the evolution characteristics of surrounding rock stress field and the distribution pattern of plastic zone in the whole service cycle of gob-side entry retaining in inclined coal seam, as well as the stress state and support performance of roadside filling body under bearing state. The results showed that the inclined lengths of filling compaction zone, complete filling zone and partial filling zone in goaf of 3131 working face were 57.20 m, 72.18 m and 10.62 m, respectively. For the gob-side entry retaining of inclined coal seam considering the zoning compaction characteristics of goaf, the abutment pressure in front of working face and the residual abutment pressure in goaf increase with the increase of depth. Compared with the first mining, the peak value and influence range of the abutment pressure in front of the working face under the second mining were significantly increased, and the concentration degree of the lateral abutment pressure was also significantly improved. The rock in the caving zone of goaf had a certain supporting effect on the roof strata of roadway, and the lateral abutment pressure had obvious stress concentration. Affected by repeated mining, the failure range of the plastic zone of the two sides extended along the layer, the plastic zone of roadway roof and goaf roof was connected, and the roof near the high sidewall and the surrounding rock of the two sidewalls were seriously broken and the stability was poor. The bearing stress of gob side of roadside backfill used in the mine was significantly greater than that of roadway side, and the horizontal stress was greater than the vertical stress. The roadside filling body can meet the strength requirements, but the anti-tilting performance was weak. On this basis, the control effect of roadway surrounding rock stability under existing support conditions was analyzed, and the reinforcement support scheme of 3131 machine roadway surrounding rock was put forward.