The Stability Analysis Of High Tailings Dam And The Research On Key Consolidation Technique Thereof

Tailings dam is a kind of depository structure where mineral wastes from metallic and nonmetallic mines are piled. With'the great demand of our country for mineral resources, its number and height increased rapidly. However, tailings dam failures which frequently caused incidents including the death of the people and containment of the environment brought about huge loss to people's life and property, as well as serious threat to environment safety. The stability and consolidation of tailings dam has become an important subject that attracts attentions of the governments, mining enterprises and academic world. Here, in combination with the eningeering practice, the variation law of physical index, the three-dimensional seepage control and optimization, the three-dimensional static and dynamic stability, the effect of drainage body clogging on seepage stability as well as the key techniques of heightening and storage increase of high tailings dam were explored and studied. The results have been applied to practice of the heightening and consolidation thereof. The main conclusions are as following:(1)The indexes statistics of deep borehole prospecting and the various in-situ tests results showed:The dry bulk density of deep part significantly was significantly higher than that of shallow part of high tailings part. At the same spatial depth, the dry bulk density index increased significantly with time (theγd increase was about 10%). Therefor, the theory that the mechanic index can be selected statistically according to time zone (early-middle-later) during the stability analysis of tailings dam was proposed and was put into practice.(2)The mathematical models were obtained by actual measuremeng of the dam exploration profile, zoning by permeability coefficient at the first time and inverse analysis through fitting the real drainage and seepage facilities. The drainage system complied with the safety demand of heightened dam was predicted including the forms and quantity. According to the seepage control results of the established drainage system at the present and planning height of the dam, the various seepage control facilities were added and the optimized seepage control layout of planning height was put forward through the calculation and analysis. (3)The three-dimension static and dynamic stability analysis was carried out, and the time-history curve of the dynamic seismic acceleration of the dam site was composed with the inspection of seismic parameters based on the three-dimension seepage control study, therefore the seismic parameters reflected the onsite situation was provided for the dynamic analysis. EFES-3D calculation program based on the effective stress method was applied to the numerical simulation of the stress-strain field and stability analysis of dam slope after the dam height was increased. Then, the stress and strain field distribution diagram and liquification evaluation were obtained and the calculation method of three-dimension static and dynamic stability safety coefficient was presented.(4)The laboratory as well as onsite tests were carried out on the mechanism of clogging during drainage and the effects of the clogging degree on the seepage stability was studied. The results showed the efficiency was more than 70% and the saturation line met the safety requirements. Further more, the technical and engineering measures on reducing and preventing clogging were proposed.(5)The stereo drainage system which including wide diameter radiation well, horizontal holes and flashboard was used to lower soakage lines with the comprehensive technology which was used to raise the dam were developed and applied in practice. It was turned out by the engineering verification that these key technologies were practical.This dissertation is supported by National Natural Science Foundation(10572090)-The coupling model research on the deformation-seepage-chemical process of variable saturated medium and Jinduicheng Molybdenum Group-scientific research project "Research on the Lixi tailings dam serve period prolonging and the environment protection in Jinduicheng".