Study on evolution law of overburden morphology in shallow coal seam mining of gully terrain

CHEN Zetao; WANG Feng; LI Ting; HAN Chenghao; LU Lang

doi:10.13347/j.cnki.mkaq.20240780

Abstract：Taking the mining of Ⅱ-3 coal seam in Gongniergaigou area of 231 mining area of Zhuanlongwan Coal Mine as the re-search background,based on the key strata theory of strata control,the similar physical simulation experiment is used to study the failure field,displacement field and mining-induced fissures evolution law of overburden strata in shallow coal seam mining.The results show that the periodic breaking distance of the main key strata decreases with the increase of the thickness of the load layer due to the influence of the valley terrain load distribution.The periodic breaking distance of the main key strata in model 1,model 2 and model 3 is 7-17 cm,12-20 cm and 11-23 cm,respectively.The maximum vertical displacement of the main key strata in model 1,model 2 and model 3 is 22.77 mm,24.42 mm and 20.98 mm,respectively.It is not easy to form a stable"masonry beam"bear-ing structure after the key strata of the missing structure is broken,which is the main reason why the maximum vertical displacement of the main key stratum of model 2 is greater than that of model 1 and model 3.With the advancement of the working face,the influ-ence range of overburden migration gradually increases in the vertical and horizontal directions.The main key stratum is in the stage of periodic breaking,and the development and formation of mining-induced fissures enter the active period.The number and spa-cing of mining-induced fissures are related to the breaking law of the main key stratum.The mining-induced fissures have dynamic change characteristics.The mining-induced fissures at the bottom of the valley and the slope foot on both sides are easily affected by extrusion.The fissures width is small or even closed,and the fissure morphology in the flat surface area is relatively stable.