Study On The Strength Degradation Of Tailings Material And The Stability Of The Dam Under The Action Of Reservoir Water

A tailings pond refers to a place constructed by damming intercepting valley mouths or enclosures for storing metal and nonmetallic mine tailings,and is a necessary facility to maintain the normal production of the mine.As a man-made danger source with high potential energy and high destructive power,once the tailings dam is destabilized and destroyed,it will bring great harm to people's lives and property safety,and it will also cause irreversible damage to the surrounding environment.The tailings discharge is usually accompanied by a large amount of beneficiation water,which makes the tailings reservoir water show different acidity and alkalinity,and the tailings under long-term immersion will have ignorable physical and chemical characteristics that will affect the stability of the dam.Therefore,in this paper,combined with actual engineering projects,through laboratory tests and numerical simulations,we carried out a study on the influence of acid and alkaline solutions on the physicochemical properties of tailings materials and the long-term stability of the dam body.The following main results have been achieved:(1)Explore the influence of acid and alkaline solutions on the macro-physical and mechanical properties of tailings.The results show that under the action of acid and alkaline solutions,the tailings particles are refined,and the content of powders and clays increases,which is mainly manifested by the increase in the intermediate particle size content;the pore ratio of the tailings material under different consolidation pressures the increase of the solution PH value shows a trend of increasing first and then decreasing,and overall it decreases;the permeability coefficient gradually decreases with the increase of the acidity and alkalinity of the solution;the cohesion of the tailings under the action of the chemical solution Gradually increasing,the internal friction angle gradually decreases,and the shear strength decreases.(2)A mesoscopic study on the morphological changes of tailings particles under the action of acid and alkaline solutions was carried out.Scanning electron microscopy images showed that both acidic and alkaline solutions weakened the tailings' graininess and reduced their integrity.Specifically,the tailings particles were finely crushed after acid leaching,and the angularity was weakened.After alkali leaching,the tailings were clustered and flocculent.;The tailings pore area after soaking in acid and alkaline solutions is reduced,and the proportion of medium and large pores is high.It can be used to express the arrangement entropy of tailings,that is,the arrangement of framework particles in the tailings;the particle surface fractal dimension As the particle size increases,the roundness decreases with the increase in particle size,the roundness does not change significantly with the particle size,and the correlation between fractal dimension and shear strength is the highest.(3)Through COMSOL and Geo-studio software simulation,the change law of the seepage field of the tailings dam under chemical action is revealed.Under the action of acid and alkaline reservoir water,the dam body has poor drainage capacity,the flow velocity in the seepage field of the dam is low,and the dry shoal surface of the tailings dam is shortened.The ratio of the permeability coefficients of the materials of each layer of the tailings dam has a great influence on the depth of the infiltration line.When the permeability coefficient of the upper layer of the dam is lower than the permeability coefficient of the lower layer,the depth of the infiltration line is shallow,and the location of the outflow point may be on the slope of the accumulation dam,which is not conducive to the stability of the dam body,and the greater the difference between the permeability coefficients of the upper and lower layers,the greater the depth of the infiltration line shallow.(4)Through the COMSOL software simulation,the safety and stability of the tailings pond under multi-field coupling are analyzed.The results show that the deformation deformation of the dam body increases under the multi-field coupling action,and the displacement component in the z direction changes most obviously,indicating that settlement is the main way of dam body deformation;the calculation result of the safety factor of the tailings pond shows that the water of different pH values acts The current structure of the lower dam body is stable,but compared with the original working conditions,the role of acid and alkaline reservoir water makes the safety factor of the dam continue to decrease,and the bearing capacity for special working conditions also gradually weakens.