Abstract: This study takes the north-wing belt transportation roadway of No. 8 coal mine as the engineer-ing context. The key stratum theory is applied to determine the fracture spacing of overlying strata and theheights of the three zonesin upward mining. FLAC3D numerical simulation software is used to analyze themovement law of overlying strata at different mining heights. Orthogonal experiments are conducted to op-limize roadway location selection. The following conclusions are drawn: 1) Due to the influence of keylayers, the height of the fracture zone increases abruptly with the increase of mining height. Each abruptinerease indicates that a key stratum has fractured and formed a voussoir beam structure. 2) The plasticzone of the working face exhibits a saddle-shape distribution (high at both ends and low in the middle).As mining height increases, the difference between the plastic zone above the mining boundary and thatin the middle decreases. The advance stress concentration coefficient and lateral stress concentration coef-ficient increase linearly with mining height, and their peak positions move farther away. 3) The influencing factors, in descending order of weight, are normal distance, horizontal distance, and mining height.The optimal roadway location is at a mining height of 2 meters, with a normal distance of 140 meters fromthe mining face and a horizontal distance exceeding 20 meters from the mining site boundary. Anormaldistance of 60 meters and a horizontal distance of 20 ~ 40 meters define a stress concentration zone,which is unsuitable for roadway placement.

Key words: upstream mining, roadway location selection, key stratum, large mining height, heights of
the three zones