Coal Gangue Weathering Strength Characteristics And Stability Study

Coal gangue is one of solid waste produced in the process of coal mining and washing which is the largest annual emissions and accumulated stock of industrial waste residues in the present china. The composition of coal gangue is mixture of soft or hard rock and a certain amount of residual coal which is rich in organic components and volatile combustible sulfur content. The particles from tens of centimeters stone to the tiny particles under 0.1 mm, particle size distribution, physical and chemical properties and mechanical characteristics significantly different from that of general clay, gravel soil, and other medium materials.If coal gangue piled up in an open-air way, it could occupy farmland, produce environmental geotechnical effect such as pollution(water, soil and atmosphere) and structure erosion, spontaneous combustion, explosion. After it's weathering, coal gangue's mechanical properties can be changed, it could produce environmental geotechnical effect such as structural damage, the slope stability. All these effects constitute a threaten for wellbore safety operation, the mining area of people's life, and property safety. Therefore, the environmental and geotechnical problems caused by coal gangue are urgently needed to solve in our country.This paper, aim at typical coal gangue mountain in chongqing area, and one of the coal gangue piles in Chongqing as the research background, combining with the reconnaissance, field test and indoor large-scale triaxle test, coarse grained soil from the weathering of coal gangue, the analysis of the mechanism of the weathering coal gangue piles and build the maximum limit analysis method and imbalance thrust method for analyzing the stability of coal gangue. Moreover, the internal failure mechanism of coal gangue piles are numerical simulation analysis, obtained the following results:(1)Through screening, gradation of coal seams of the new south ore old waste rock and coal gangue waste rock will be determined, then, grading the new after screening waste rock as the same as the weathering coal gangue. Taking natural moisture content and saturation moisture content as the control conditions, through the indoor large-scale triaxle test, compared two kinds of mechanical properties of coal gangue getting studied, contrast analyze the diffenrence of new coal gangue and weathering coal gangue in triaxial strength and mechanical properties.(2)The imbalance thrust method is used in this paper to calculate the slope stability of the coal gangue in Chongqinag. At the same time, according to the internal sliding instability mode of coal gangue piles, analysis of the limit analysis upper bound method is established and applied to make sure the stability of coal gangue.(3) Based on the analysis of mechanical properties of coal gangue, the corresponding Mohr-coulomb constitutive relation can be adopted. Aiming at coal seams in chongqing coal mine gangue mountain, the stability of FLAC numerical simulation have being conduct, in order to master the stability of and influence factors of coal gangue piles in Chongqing.