Study on mine pressure behavior law of inclined coal seam roadway under great thick and loose sandy conglomerate overburden

CAO Xiaojie; MA Xuezhou; WEN Yingyuan; GUO Wenhao; CAO Anye; WANG Shuai; LYU Zhen; ZHOU Yajing

doi:10.13347/j.cnki.mkaq.20231908

Abstract：Aiming at the abnormal mine pressure behavior of roadway under shallow buried great thick sandy conglomerate overbur-den,the inclined coal seam covered by thick sandy conglomerate in a mine in Wusu City,Xinjiang was selected as the research ob-ject,and the load difference characteristics of roadway surrounding rock under different lithologic overburden conditions were dis-cussed.Through theoretical analysis and numerical simulation,the response mechanism of roadway to the load of thick sandy con-glomerate was revealed.The results show that:the stress of roadway surrounding rock under the cover of extremely thick and loose sandy conglomerate includes the self-weight load of overburden and the additional load of lateral overburden migration area.When the strength of overburden is lower,the internal friction angle is smaller,the migration angle and migration area of overburden are larger,and the additional load applied to roadway surrounding rock is higher;after the excavation of the roadway,the great thick overburden of the roof will form a"funnel-type"stress reduction zone,while the"funnel-type"stress reduction zone shows asym-metry after the inclined coal seam roadway excavation;in the range of 80 m-100 m below the great thick and loose sandy conglomer-ate overburden,the roadway is obviously affected by the stress transfer of the loose layer.There are differences in the stress of sur-rounding rock under different lithologic overburden conditions.The peak stress of the great thick loose conglomerate increased by 1.19 MPa compared with that of the extremely thick sandstone layer,and the plastic zone area and roof displacement are reduced by 86.55%and 97.79%respectively when the roadway is 9 m away from the 80 m relative distance of the great thick sandy conglomer-ate overburden.When the distance between the roadway and the overburden exceeds 80-100 m,the influence of the overburden weight on the stress of the surrounding rock of the roadway begins to appear.The stress of surrounding rock,plastic zone and roof displacement increase gradually with the increase of buried depth.The shallow buried roadway is affected by the superposition of self-weight stress and additional load,in which the additional load is determined by the slip area of the great thick and loose sandy conglomerate layer.It is necessary to control the slip angle and slip area of the great thick and loose sandy conglomerate layer by strengthening the roof support strength of the roadway.After the optimization of the roadway support,the relative displacement of the roof and floor is about 70 mm,and the relative displacement of the two sides is about 130 mm.The overall support effect is bet-ter,and there is no mine pressure appearance.