Characteristics Of Rain Infiltration And Its Stability Research Of Coal Waste Dump In Mountainous Area

Coal mining waste is the wastes produced with the process of mining and laundering & picking in the coal industry. At present, some coal mining waste are filled in the mine, but mostly are discarded at valley and plain forming waste dump. The waste dump mostly are piled up for long, its using rate is very low. A great deal coal mining waste's piling not only take up a lot of infield, but also arose gravitation geological disaster for instance collapse,slide and debris flow etc if they are piled too high,their slope angle is too big or they are influenced by artificial digging and rainstorm eroding. Based on the results of exploration and in-site test of typical waste dump in southwest mountainous area,the analysis theory and method of waste dump rainfall infiltration are discussed beginning at analysing coal waste's mechanics characteristic and seepage theoty. Fllowed estimating method of waste dump stability is discussed influenced by rainfall. At last a typical engineering example of coal waste dump landslide influenced by rainfall is researched, acquiring research fruit hereinafter.①Particular exploration of typical waste dump in chongqing area and analysis estimate to its area engineering geology are done. Granule gradation,water content,nature density,dry densit etc parameter of waste granular media are tested. The mechanics characteristic of waste are researched by in-site shear experimentation,compressibility experimentation and infiltration experimentation.②The coal waste dumping is different from other consecutive solid material as incompact granule structure. Its shear strength and transforming characteristic also have itself characteristic. Based on analysing strength and deformation characteristic of waste granular media, the influence of water to these characteristic and phisical chemic action of water & coal waste is analysed. The infiltration characteristic of waste granular media and influence of its granule diameter,pore characteristic and discarding time to infiltration are discussed particularly. Besides, waste granular media seepage differential coefficient equation is educed based on porous media seepage theory and unsaturation seepage theory.③The rainfall infiltration theory of coal waste dump is analysed, the process of rainfall infiltration and its influence factor are introduced particularly at the same. The planar numerical simulation program of waste dump rainfall infiltration is developed by C language. By this program the motion rule of water in the waste granular media in the process of rainfall and the change of pore water pressure and suction of the waste granular media are calculated. Presently, for the calculation on the unsaturated seepage of slopes during the rainfall, that about gas-flow and simplified calculation of stress coupling is not considered. The paper also introduced the basic controlling equation, numerical computation formula and the stress-coupling formula of the Two-phase flow in FLAC2D . The software not only can obtain transitory seepage field by calculation considering gas-flow but also can realize the stess-coupling calculation expediently for using the obvious-formula equation.④The mechanism of rainfall infiltration influencing the stability of waste dump is analysed. The mechanism of waste granular media characteristic and rainfall influencing waste dump stability is researched by theory. Fllowed the estimation method of waste dump stability as rainfll factor is discussed. The stability safety storage of typical waste dump is analysed (using 3-D limit analysis theory) and desformation deformation stability is calculated (using FLAC analysis method). The relation of factor of safety and rainfall continuance time or rainfall intensity. Starting at confirm the effective rainfall, the randomicity of rainfall is considered into reliability calculation of waste dump slope. The influence of different return rainfall is calculated quantitatively and analysed qualitativly considering the randomicity of ranifall and waste granular media per se adequately.⑤A typical engineering example of coal waste dump landslide influenced by rainfall is researched. The slide plane simulated by dispersed element anastomose the actual plane. At last, the rational piling up measure and repairing measure of coal dump are bringed forward.