| With the rapid development of national economy, the demand for mineral resources increases sharply. Because of the lower grade ore, a lot of mine tailings generated during mineral processing. Used for tailings storage, the tailings reservoir is formed by building an artificial dam. There are three types in formulation, one through intersection the valley, one around the foot of the mountain slopes and the other enclose the flat terrain areas. While in recent years, the safety accidents of tailings storage happen frequently. Post tailings stacking dam which is built by using the tailings in the tailings reservoir is poor in stability especially in flooding season, due to the small size of tailing particles it used. Once the dam-burst occurs, tailings stockpiled in the tailings reservoir discharged together with floods, that may form artificial debris with a high velocity and a long impact extension, will bring disaster to the downstream region. Combined with toxic chemical composition and heavy metal ions in the flotation wastewater, directly discharge will pollute the farmland and villages and bring inestimable environmental damage. In view of its dangerous impact, tailings dam-break accident is ranking 18th in the world's most dangerous disasters.Through theoretical and numerical analysis of dam-break, the process of dam-break and debris mixed with flotation wastewater after the tailings-dam-break was simulated. The distribution hydrology on each time point of the regional area was obtained. These provide means and basis for the disaster early warning and control. The main research contents include:(1) Established a digital terrain model (DTM) of the study district. First the automatic vectorization tool of MapGIS was used to change the scanned-map into electronic contour lines. Then the break line and error were dealt with 3D-Mine. At last the fine contour lines were assigned elevation;(2) Calculated the rainfall of each whole time-point during 24 hours. According to "Differential Operators Manual of rainstorm and flood in Hunan Province" the design rainfall of the standard duration (1Omin, 60min,6h,24h) was found. The rainfall HD of any time-point D between the standard duration can be calculated by the index equation of design rainfall Hs and HL of the two adjacent standard durations (short as S, long as L).(3) The two-dimensional debris flow simulation software FLO-2D was introduced to simulate, the disaster development during 24 hours after the tailings dam collapse in the area in condition of correctly settling an amount of parameters such as regional rainfall, dam failure, inflow, outflow, infiltration, breach and others on the basis of survey and analysis. Simulation dynamically shows the process of depth and flow velocity change with time in the study region, which provides a ration method for safety estimation.(4) As there was a planned Xiamen Chengdu Expressway located at the foot of the tailings dam about 500 meters away, the depth change process of flooded embankment was simulated, providing a basis for the location of tailings storage, the plan of the highway route and the disaster warning of the downstream break-dam.(5) Disaster prevention and mitigation measures of tailings dam break accident were proposed. |
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