Physical Model Test Of Tailings Dam Breach And Research On Dam Safety And Stabilit

Tailing pond is a place for storing waste residue after ore separation.As a permeable dam,the saturation line of tailings dam is also called "lifeline".In a large number of tailings dam stability analysis,it was found that the saturation line of tailings dam was inseparable from the stability.In order to explore the influence of reservoir water level fluctuation on the saturation line and the change of dam stability,taking the actual tailings dam project as the background,through the combination of physical model test and numerical simulation analysis,the variation law and instantaneous safety and stability of tailings dam saturation line were obtained.The main research results are as follows:(1)Tailings particle parameters were obtained by geotechnical test and particle image analyzer,and the deposition characteristics of tailings on dry beach surface were explored.The sampled tailings were coarse at the front and fine at the back.The poor grading of tailings near the ore drawing pipe is mainly affected by Cu,and the poor grading of tailings near the reservoir is mainly affected by Cc.The aspect ratio of tailings particles is mostly between 1 and 1.5,and the circularity is mostly between0.7 and 0.9.The fractal dimension decreases with the increase of the distance from the ore drawing pipe.The shape of tailings particles near the ore drawing nozzle is more complex,and the fractal characteristics of particles are more obvious.The particles washed away by water flow are more regular,the average particle shape is closer to circle,and the roughness was small.With the increase of Cu,the permeability coefficient of tailings suddenly drops and then slowly decreases,with the increase of Cc,it suddenly drops and then tends to be flat,and with the increase of d50,it tends to be stable,then slowly increases and finally suddenly increases.(2)Through physical model test,the dam-break process of tailings dam was analyzed,the saturation line data was measured.The saturation line rises with the increase of dam height,and the rising rate slows down with the increase of dam height.In the process of water level change of tailings pond,It is found that the saturation line changes instantaneously with time,and the lag phenomenon of the saturation line falling is slower than that of the water level rising.The development process of overtopping dam break is rapid.The process of overtopping water discharge is mainly downward scouring,lateral overtopping and cut-off deposition in time sequence.The occurrence and development of the breach are mainly the formation,cutting depth and widening of the breach.The final breach shape was deep breach at the top of the dam,widening breach in the middle of the dam,and the breach at the dam foot was filled with sedimentary tailings,forming a sedimentary beach surface.(3)FLAC3D software was used to simulate and analyze the instantaneous stability of the dam under normal working conditions,flood working conditions and the rising and falling process of water level at different times.The results show that the area with the largest displacement of tailings dam under normal and flood conditions was the top of the dam.Compared with normal conditions,the pore water pressure under flood conditions increases by 19.36%,the safety factor decreases by15%,the shear stress increases slightly,the shear arc is more obvious,and the range of shear failure increases.From the toe of the dam to the top of the dam,the displacement increment of seven displacement monitoring points(JC1-JC7)is getting bigger and bigger,and the stability were greatly reduced.In the process of the saturation surface rising gradually,the safety factor decreases,and the slip arc gradually becomes obvious,and finally runs through the whole dam,and the displacement of the dam gradually increases from the toe to the top of the dam.On the contrary,the safety factor increases,and the initial change is obvious,then it gradually slows down and tends to be flat.In this process,the dam displacement increases slightly,mainly in the middle of the dam body in the initial stage,and the dam body becomes more stable after the water level drops for a period of time.(4)Through Bow Tie model,the causes and consequences of groundwater disaster in tailings pond,the corresponding prevention and control measures were put forward.According to the Bow Tie model,the groundwater disaster in tailings pond can be systematically prevented,which has certain practical value in practical work.