Hydrogeologic And Engineering Geologic Characteristics Overlying Thin Bedrock During Mining

Panxie mining area is the main part of the Huainan coal field in Anhui province and its coal-bearing strata were covered with Cenozoic loose deposits. Shallow coal resources mining is affected by both the aquifers at the bottom of Cenozoic and other factors such as the rugged topography of bedrock, properties of weathered zone, lithology structure of coal seam roof, water-bearing abundance of thin bedrock and so on. In the process of,mining, some serious accidents occur in some working faces with collapse of coal seam roof, which causes threat on mining safelyTherefore, based on consulting domestic and foreign literatures,thin bedrock of coal-bearing start in Panxie mines has been chosen as the research objects,and some regularity and conclusions are obtained as follows:(1)Through analysis of basic data, some features of bedrock geo-topography and sediments at the bottom of the Cenozoic are recognised, and model of sediments at the bottom of the Cenozoic is established,which indicates sediment environments include diluvium, residual deposit and river deposit,and all results show the rank of water-bearing strata is middle and more abundant,which is one of source of water rush in Panji mines; whereas the aquitard named "red stratum", which rank of water-bearing strata is very lower in Zhangxie mines.(2) Through the analysis about weathering zone thickness, lithologic components and hydrogeological parameters and engineering mechanics parameters of overlying strata, paper received that coal seam roof lithologic and structural combination, Structure and the degree of fracture and the weathering degree of the rock are the key factors that impact the thin bedrock mining.(3) Fissure water in roof sandstone exist in the form of static reserves, which has the characteristics of the attenuation change and heterogeneity of the space.(4) Under the analysis of hydrological, geological and mining conditions from the "supports collapse", two modes have been established, which provide reference for safety mining in coal seam of thin bedrock.