DYNAMIC RECOVERY OF CRETACEOUS WATER RESOURCE ABOVE FULLY MECHANIZED CAVING OF JURASSIC ULTRA-THICK COAL SEAM

During the mining of ultra-thick coal seam(12~18m) in Cuimu site of Yonglong mine area, separation water inrush occurred in roof Cretaceous overburden, which and its prevention measures caused a bad influence on the water resources of overlying Luohe formation aquifer. Thus the study on dynamic recovery of Luohe formation water level can provide reference for the influence of water resources caused by the exploitation of coal resources. This paper analyzes the development position and the dynamic process of bed separation using the discriminant formula and discrete element software UDEC, respectively. Based on the water level monitoring, water inrush analysis and theoretical analysis, this paper firstly obtains the hydrogeological parameters of Luohe formation, then establishes the water dynamic recovery model using Theis's equation, finally obtains the time consuming of water recovery. The results show that the bed separation developed in the interface between the sandy conglomerate in the bottom of Luohe formation and the underlying sandy mudstone is relatively closed and largescale. The lowest water level of water inrush point can be regarded as the cone of depression caused by virtual pumping well with discharge Q during the period from 0 to t_p. The water recovery process can be recognized as the superposition of pumping water with discharge Q and injecting water with discharge Q during the period from t_p to t. Based on the Theis's equation, the time needed for Luohe formation to drop to the lowest point is 7.9459 days. The consuming time of water recovery is 35.6090 days. The results are similar to the actual data. The water recovery of Luohe formation is faster in the initial period but slower in the later period.