A Research Of Strength Characteristics And Damage Law Of Chromium Pollution In Guilin Red Clay

With the advancement of the western development strategy,the production of non-ferrous metal mines in Guangxi Province is increasing.However,a large amount of waste generated in the production process of Guangxi metal mine seriously pollutes the surrounding environment.The heavy metal chromium pollution of red clay around the lead-zinc mining area and industrial site in Guangxi is quite serious.chromium has a certain impact on red clay's engineering properties.Researching the impact of chromium pollution on the engineering properties of red clay is of great significance to the safety construction and disaster mitigation and prevention in Guangxi mining area.Through the indoor preparation of chromium-contaminated red clay and carried out the triaxial unconsolidated undrained test,direct shear test,mercury intrusion test and scanning electron microscopy to study the influence of chromium ion on the microstructure,mechanical properties and deamge of red clay under different conditions.The main contents of this paper include:(1)Electron microscopy and mercury intrusion tests show that as the chromium ions increase,the soil particles become larger and the arrangement of the surface structures becomes laminated,forming a flocculated structure that constitutes a vertical surface contact.The arrangement of the soil particles is changed from a lamellar arrangement to a scaly orientation,and the spacing between the colloids is also increased.The porosity of red clay also increases with increasing chromium ion concentration.The effect of chromium ions on the pore distribution of red clay is obvious.With the increase of chromium ion concentration,the small pores of 0.01um~0.1um decrease,and the large pores which larger than 0.1um increase.Chromium ions destroy the pore structure of red clay,dissolve the soluble salt cementing material,and make the pore volume of red clay larger.(2)Under the conditions of different initial dry density,different chromium ion concentration and different stress states,using triaxial unconsolidated undrained test and direct shear test to study the influence law of chromium-contaminated red clay's mechanical properties such as The shear strength,shear strength index and elastic modulus of chromium ion to red clay the relationship between quantity and stress-strain.The results show that chromium ions have obvious destructive effects on the mechanical properties of red clay.With the increase of chromium ion concentration,the deviatoric stress,shear strength and shear strength index of red clay decreased.When the chromium ion in the red clay exceeds a certain concentration,the cementation and adhesion between the red clay particles will be destroyed,and the cohesion of the red clay tends to zero.(3)As the chromium ion increases,the initial elastic modulus of the red clay shows a tendency to decrease.As the concentration increases,the secant modulus decreases.Using damage theory to analyze the damage law of chromium contaminated red clay,it is found that the damage variable decreases with the increase of chromium ion concentration,and increases with the increase of dry density and consolidation stress.