| Mining industry is an important part of China's economic construction.During the exploitation of mineral resources,a large amount of solid and liquid waste will be produced.Tailings dam used to store tailings will suffer from dam instability and dam-break accidents caused by seepage control structure damage in acid environment for a long time.In order to avoid the long-term effects caused by acid conditions in the construction and use of tailings dam,the dam will be unstable and dam-break accidents will occur frequently.It is very important to adopt acid-resistant material as seepage-proof of tailings dam because of leakage pollution and dam-break risk.Asphalt mastic has been used in more and more anti-seepage projects because of its good anti-seepage performance,strong adaptability to deformation and strong crack self-healing ability.This paper studies the corrosion of asphalt film,asphalt-aggregate mixture and asphalt mastic under acidic conditions,and analyses the influence of acidic conditions on the basic performance of asphalt,the adhesion between asphalt and aggregate,and the quality loss of asphalt mastic,and the corresponding mechanism of acidic erosion.In addition,Geostudio finite element software was used to simulate the construction process of tailings dam using asphalt mastic to prevent seepage.Studied the stress and deformation law of the dam,especially for the stress distribution and displacement change of asphalt mastic with smaller modulus.Through the experimental study on the applicability of asphalt mastic in acid environment of the tailings dam and the calculation and analysis of the dam,it provides important technical support for the adoption of asphalt mastic in the tailings dam.The research contents and conclusions are as follows:(1)The asphalt film was immersed in acidic solution(PH=2,strong acidity)for one year and the three major indicators of asphalt were determined periodically.The results showed that penetration and ductility of asphalt slightly decreased,softening point remained basically unchanged,and the basic performance of asphalt did not change significantly after being eroded by acidic solution.(2)The aggregate coated with asphalt was immersed in different acidic solutions(PH=2,4,6,7)and then periodically adhered to the aggregate.The effect of acidic water environment erosion on the adhesion of asphalt to aggregate was studied.The test results show that acidic solution can weaken the cohesive force of asphalt-aggregate to a certain extent and make asphalt peel off from the aggregate surface locally.However,the solution erosion of strong acidic PH=2 only reduces the adhesiveness of asphalt-aggregate by one degree,and still meets the requirements of the specifications for the adhesiveness of asphalt-aggregate.(3)Bituminous mastic films with different mixtures(totally 10 types)were immersed in acidic solution(PH=2,strong acidity)and corroded for 1.5 years.Weight loss was observed and measured regularly to study the erosion of asphalt mastic in acidic water environment.Weight loss is related to asphalt properties and asphalt-aggregate mix ratio.The weight loss of CMO asphalt mastic is larger;the weight of pure asphalt film increases by about 1%,the weight of asphalt mastic added with mineral powder decreases to varying degrees,and the weight loss of sandy asphalt mastic is the largest by about 1.4%.(4)Based on Geostudio's SIGMA/W module,the finite element calculation of tailings dam and asphalt mastic impervious structure is carried out.The total deformation and stress-strain distribution of dam are within a reasonable range,and the displacement and stress-strain of asphalt mastic conform to the general situation in the process of static loading.The tensile strain 0.26%in the weak part of asphalt mastic impervious structure is much less than that of the specimen with two different mixtures in laboratory test,which is 23.3%and 52.2%.The asphalt mastic can adapt to the deformation of tailings dam body and can be used as impervious structure of tailings dam. |
PDF Full Text Request