Sedimentary Characterization Of Potential Quick Sand Layers Of Gudimao-Daxigou Cross Section In Jurassic Coalfield Of Western China

Currently, of the coal are being exploited in western China. Coalfields located inwestern are becoming new main base of energy,such as Ningdong and NorthernShannxi. In2010, the hazard of water inrush and sand inrush happened when thewells were exploited in Song Xinzhuang mine and Yingxing mine. In2012, Longdemine happened water inrush and sand inrush. Therefore, the research on relation ofthe Quaternary deposits and deposition environment on water inrush and sand inrushis particularly important and urgent.Under the "973" project (Geological Disaster Prevention and EnvironmentProtection Research under Western Coal Mining Intensively Exploited), weinvestigated the main coalfields in Xinjiang、Gansu、Ningxia、Shaanxi and InnerMongoli。At present, the disaster of water inrush and sand inrush happen focusing inErdos Jurassic coal basin.Selecting the section of Quaternary loose sand of Gudimao-Da xigou in Yulin, and sampling to research the section. Doing the laboratorysoil test and partial size analysis and X-Ray fluorescence test, analysing thecharacteristics of article size of loose sand group and the characteristics of thechemical components, recognizing the location where potentially occur the hazard ofwater inrush sand inrush, and analyzing the characteristics of sedimentary of the sand.(1) The trend of quaternary loose sand section of Gudimao-Daxigou is toapproximate NE-SW, and the length is about35km. This section consists of8layers,from bottom to top, which are the silt, fine sand, silt, fine sand, silt, fine sand, mediumsand and fine sand. Maximum thickness is located in Yulin Daxigou, to22.19m; thethinnest point is located in the Yulin Valley Mao, to18.60m.(2) The characteristics grain size of quaternary loose sand section ofGudimao-Daxigou:Grain size of sand sediment are mainly composed of fine sand, sand, silt, andfrequency distribution curve of sand sediment is peak. Average particle size isbetween2~3Φ, belongs sand group, and the standard deviation is between0.71~1.00Φ, and sorting moderate skewness is between-0.10~+0.10, wich is nearlysymmetrical, and kurtosis Kg value is0.90~1.11, which belongs to the medium type.(3) The chemical features of quaternary loose sand section of Gudimao-Daxigou:The constant composition are are mainly composed of SiO2and Al2O3, and theSiO2and Al2O3Group are with very high consistency. The distributions of K2O and Na2O are relatively balanced, and the distribution of CaO is the least balance. Andthe distribution of Fe2O3and MgO are not balanced. With trace elements, Ba, Sr andZr are enriched, and the others are less than100μ g/g.(4) The section is composed of8layers. The layers from the forth to the seventhmay occur the hazard of water inrush sand inrush, and the first to the third do notoccur the hazard of water inrush sand inrush. The eighth layer is not liquefied.(5) The sediment weathering degree is low, and the prediction of sedimentary forfreshwater environment, and hydrodynamic conditions are low.