Study On Stability And Environmental Protection Characteristics Of Saponified Slag Solidified Electrolytic Manganese Slag As Subgrade Fille

Electrolytic manganese slag is a solid waste generated in the process of industrial electrolytic manganese.Currently,it is mainly disposed of by building warehouses for stockpiling.This method not only wastes land resources,but also seriously harms the surrounding environment of the slag warehouse.Reasonable use of electrolytic manganese slag as road subgrade filler can achieve the purpose of utilizing its bulk resources and effectively alleviate its negative impact.Based on the science and technology project of the Department of Transportation of Guizhou Province,this thesis explores the physical and chemical properties and harmless treatment methods of electrolytic manganese slag,the geotechnical test characteristics of solidified manganese slag,the numerical analysis of slope stability and settlement deformation of manganese slag roadbed,the pollution leaching situation of manganese slag roadbed under acid rain and axle load,and the environmental protection scheme of manganese slag roadbed based on the scale model.The key technology of using electrolytic manganese slag as highway subgrade filler was studied,and the main research contents are as follows:（1）The internal crystallinity of electrolytic manganese slag is highest in quartz and hemihydrate gypsum,which contain not only a large amount of O and Si elements,but also various metal elements such as Mn,Ca,and Al;The concentration of Mn₂⁺and NH₄-N,the main pollutants leached from electrolytic manganese slag before treatment,far exceeds the upper limit of national emission standards.The use of 30%saponified slag combined with 3%quicklime can effectively solidify the electrolytic manganese slag,and the concentration of leached pollutants after solidification meets the national emission standards.（2）Through boundary moisture content test,compaction test,CBR test,modulus of resilience test,direct shear test and rapid consolidation test,it is found that the solidified electrolytic manganese slag has similar properties with low liquid limit clay.Under90%～96%compaction,its CBR value can reach 31.4%at the highest,modulus of resilience can reach 128.5MPa at the highest,immersion expansion rate is 0.67%～0.74%,the internal friction angle of solidified manganese slag is 27.13°,cohesion is 57.69k Pa,and compression coefficient is 0.28MPa^-1,the compression modulus is 6.04MPa,which belongs to medium compressibility soil,with excellent bearing capacity,and meets the index requirements of subgrade fillers of all grades of highways.（3）Slope stability analysis and settlement deformation calculation were conducted on 9 groups of manganese slag filled subgrade and manganese slag clay sub filled subgrade with different slope heights and gradients.It was found that the slope stability coefficients of each group of subgrade were high and the final settlement values met the specification requirements.Moreover,under the same conditions,the slope stability of manganese slag filled subgrade is higher and the settlement value is smaller than that of manganese slag clay filled subgrade.（4）Under the long-term effect of standard axle load,the maximum manganese leaching concentration inside the manganese slag roadbed appears in the lower roadbed structural layer.The manganese leaching concentration in each structural layer increases with time in the early stage and tends to stabilize in the later stage.The maximum ammonia nitrogen leaching concentration also appears in the lower roadbed structural layer,but decreases with time;Under mild acid rain conditions,the manganese leaching concentration gradually increases with time,and remains below the emission limit in the20th year.The ammonia nitrogen leaching concentration gradually decreases year by year.The leaching pollutant concentration of manganese slag roadbed meets the emission standards under traffic axle load and acid rain conditions.（5）Laying adsorptive materials such as activated carbon in the side ditch of manganese slag roadbed can effectively adsorb manganese and ammonia nitroge n in the roadbed leaching solution.Planting adsorptive plants such as grass on t he slope can adsorb a small amount of manganese leached from it.The concentr ation of manganese and ammonia nitrogen in the roadbed leaching solution after adsorption treatment is 46.7%and 28.0%lower than that before treatment,respec tively.Adsorption treatment can further improve the environmental safety of man ganese slag roadbed on the basis of material solidification,reduce the diffusion o f leaching pollutants generated by its use as roadbed filler to the surrounding en vironment,and achieve a dual path environmental protection goal from fixing ma nganese slag leaching pollutants with solidification agents to intercepting leachate s during the use of manganese slag roadbed.