The effect on river and earth dam caused by large height mining in underground coal mine - a case in Inner Mongolia

Abstract

Some coal seams located in the shallow area belong to Jurassic system strata in Inner Mongolia, China. There may be some effect on the rivers and earth dam on the earth surface of coal field after large height mining. Hydraulic connection was analyzed according to the hydrogeological condition and additional exploration results in Wotugou coal mine. Empirical formulas were used to predict overburden failure height after analyzing the strength type of overlying rocks. The deformation of earth dam was predicted through probability integral method under large height mining. The final research results include: (1) Quaternary system aquifer belongs to the type of weak to strong watery property and has an intimate hydraulic connection with the Youfang River. (2) The overlying rocks of 2-2 coal seam belong to medium hard type for the average uniaxial compressive strength of 25.52 MPa. The maximum height of fissure zone is 92.40 m, there was no effect on Youfang River after large height mining under the depth of 251.46 m. (3) The maximum surface subsidence reached 1.7 m and the horizontal deformation reached the allowable maximum value 4.0mm/m, there would be some effect on the earth dam, so some safety measures were put forward and needed to be done.