Study On Overburden Failure Regularity Of Fully Mechanized Caving Face With Q_2l Loess Covered And Water Disaster Partition

The characteristics of the Jurassic coalfield in northern Shaanxi with large coal reserves,excellent coal quality,simple geological conditions,shallow depth of coal seams,and large thickness of coal seams have become one of the important energy continuations in China's modernization construction.The loess aquifuge generally covers the top of the bedrock in this area.It is necessary to study the development of the water flowing fractured zone in the loess layer.At present,there are deficiencies in the prediction of the water abundance of the roof and the prediction of the degree of water damage in the coal mining,leading to frequent occurrence of mine water disaster.Combined the engineering geological conditions and the mining technology conditions of mine field to analysis the water abundance of the roof and the water disaster will be of great value to ensure the safe production of the mine.This paper takes the first mining area of the Jinjitan Coal Mine in the southern margin of the Maowusu Desert as the research object,summarizing the engineering geological conditions and hydrogeological conditions in the study area.The water-filling of the coal seam roof is mainly affected by the phreatic water,bedrock weathering zone and bedrock water.There is a hydraulic connection between the aquifers.The paper has collected 37 water flowing fractured zone cases of Jurassic coal mining and analysis relationship between the development of water flowing fractured zone and its influencing factors through single-factor and multi-factor non-linear analysis methods,and the guidance height was fitted.It was found that the loess obviously inhibited the development of water flowing fractured zone by using the 3DEC simulation software to study the failure process of the coal seam mining roof,and the fitting formula which was applied to predict the height of water flowing fractured zone was corrected.In this paper,aquifer thickness,lithology coefficient,core rate,permeability coefficient and unit inflow are selected as the main controlling factors for evaluating the water abundance of phreatic water aquifers,weathered zone aquifers and bedrock aquifers.The 117 fully mechanized caving face had been divided into different zone according to water abundance and water hazard combined with the previous study of the development of water flowing fractured zone in study area.The water inflow of the bedrock aquifer,weathering zone aquifer and phreatic aquifer of the 117 fully mechanized caving face was predicted by analytical method,and the preliminary design of water control measures was carried out in combination with the actual project.