Study On Different Consolidation Stratification Characteristics Of Tailings Dam And Its Influence On Stability

The consolidation process of tailings dam is affected by many factors,and the degree of consolidation in different sections above and below the dam body is completely different,which will affect the seepage distribution and strength of the dam body,and thus affect its safety.Therefore,with a tailing reservoir in Miyun District of Beijing as the research background,this paper established a three-dimensional visualization model of tailings dam based on actual survey data and Arc GIS software.Theoretical research,numerical simulation analysis and similar model test were adopted to study the distribution law of pore water pressure and consolidation degree of the dam body in the process of tailings reservoir drawing under spatiotemporal coupling.The characteristics of its layered structure are determined,and the stability of tailings DAMS under different working conditions is evaluated.The main research results are as follows:(1)According to the test results of particle size,plastic index and compactness in the survey data,the structure stratification method of tailings dam is established;Based on Arc GIS and other technologies,a 3D hierarchical visualization model of tailings dam is established.Three different research schemes are designed in combination with the actual project.Scheme one is to establish the dam body model with a single homogeneous density tailing;scheme two is to establish the dam body model with the tailing classification standard stipulated in the specification;scheme three is to establish the dam body model with the stratification method proposed in this paper.The variation law of the dam body infiltration line in the three schemes is systematically simulated and analyzed.The results show that under the rainfall condition,the average point position of scheme 3 increases by 37.32% compared with scheme 1,and the average point position of scheme 2 increases by 17.64%.In addition,the coincidence rate between the wetting line position and the initial wetting line position after drainage consolidation in Scheme 3 is 99.08%,while the coincidence rate of Scheme 1 is 73.19%and that of scheme 2 is 97.42%.Therefore,the three-dimensional modeling method proposed in this paper can better reflect the actual working conditions and is more safe and reliable.(2)The stratified model is divided into five sub-regions according to the time sequence of dam stacking and the number of tailings DAMS.Through numerical simulation and similar model tests,the distribution law of pore water pressure and consolidation degree of the dam body is studied during the operation of the tailings reservoir.It is concluded that the pore water pressure increases successively from the dam body to the reservoir area and from the top to the bottom of the dam during the operation of the tailings reservoir.The degree of consolidation increases gradually from the top to the bottom of the dam,which reveals the mechanism of the effect of the height of the load on the degree of consolidation.The pore-water pressure and consolidation degree of early subdams are affected in the later subdam stacking process,which increases with the increase of the stacking depth and decreases with the increase of the distance between the subdams.The mechanism of the influence on the distribution of pore-water pressure and consolidation degree of early subdams in the later subdam stacking process is illustrated.(3)The limit equilibrium method is used to analyze the static stability of the stratified section of tailings dam.The results show that the minimum safety factor of the stratified tailings dam under normal operation,flood operation and special operation conditions meets the specification requirements.However,the stability results obtained from the dam model based on single homogeneous compactness tailing sand and the dam model based on the classification standard of tailing sand stipulated by the code are both larger.