| Huiling tailings pond is located under Huiling Village,Chehe Town,Nandan County,Hechi City.It was completed and put into operation in December 1979.It is the tailings storage facility of Chehe Concentrator.With the use of upstream dam construction,the elevation of the accumulated dam crest is 486m,the dam height is 99m,the total designed dam height is 103m,and the designed total storage capacity is 38.8675 million m3 at present.There are important production facilities and residential areas within 1 km downstream of the tailings pond,so it is essential to ensure the safe operation of the main dam in operation.Taking Huiling tailings pond as an example,this dissertation combined with laboratory test and numerical simulation ways,carried out the seepage characteristics analysis and static and dynamic stability evaluation of the dam body.The main research contents and results are as follows:(1)The analysis of Three-dimensional finite element seepage characteristics of tailings dam.A three-dimensional model of the reservoir area was established to explore the buried depth of the infiltration line in the main dam area and its variation law,and to analyze the overall three-dimensional seepage field and partial profile of the dam area and the distribution of water head lines and seepage gradient vectors.The results showed that the distribution of the calculated infiltration line was consistent with the measured infiltration line,the characteristics of the free surface were basically in line with the trend of the observed water level,and the seepage gradient of the dam body under different water level changes was small.(2)Two-dimensional profile static analysis was carried out t to evaluate the static stability of tailings dams.The finite element stress analysis method was used to analyze the internal stress distribution of three geological sections under different dam height conditions,and calculate the minimum safety factor of the dam slope before and after the heightening.The results showed that the stress on the dam was equally distributed,and there was no obvious stress concentration phenomenon.The calculated safety factor met the requirements of the specification.In the final design stage,the static stability of the tailings dam was good.(3)Based on the results of static analysis,two-dimensional dynamic response analysis was carried out.Seismic waves with different amplitudes were selected to calculate the peak acceleration and horizontal dynamic displacement of the dam body under different accumulation heights,so as to determine the liquefaction situation of local units.The results showed that the acceleration response in the dam indicated a fluctuating trend after the heightening and capacity expansion;the maximum displacement deformation were 9.3cm and-15cm at different stacking heights.The dynamic response of the lower part of the accumulation dam near the initial dam was strong,but the soil unit in this area did not vibrate and liquefy during the earthquake.(4)Based on the dynamic response results,the dynamic stability of the tailings dam was evaluated.The finite element method and the minimum average safety factor method are used to calculate the safety factor of the dam slope under earthquake action.When the dam height is 99m,the minimum safety factor is 1.39,and the minimum average safety factor is 1.45;when the dam height is 103m,the minimum safety factor is 1.15,and the minimum average safety factor is 1.22.There was a certain safety margin in the tailings dam,and the overall anti-skid stability was good in operation.The research results above provided design reference and scientific basis for the subsequent expansion design and closed warehouse safety management of the project,which can be used as reference for other projects. |
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