Experimental Studies And Analysis Of Solute Transport Law Of Acid-corroded Sandstone

With the rapid development of modern industry,the degree of acidic environment in the atmosphere are constantly increasing.The rock and concrete materials have suffered different degrees of corrosion and destruction during their service,which leads to adverse engineering effects.Solute transport for rock corrosion and its adverse engineering effects have become one of the emerging research directions in rock field.In this paper,physical,chemical and mechanical properties of sandstone corroded by two different acidic solutions(HCl?H₂SO₄)with p H=1 and p H=3 were compared and analyzed by long-term accelerated corrosion test in the laboratory.Based on uniaxial compression test,a damage constitutive model of acid-corroded sandstone was established by introducing chemical damage variables,and a strength damage model based on solute migration law was proposed,which was applied to practical engineering.The main research results are as follows:(1)The physical and chemical properties of sandstones under different p H values of acidic solution(HCl?H₂SO₄)were compared.The corrosion law of sandstone under different acidic solutions was reflected by the mass change of sandstone rock samples before and after corrosion,the change of hydrogen ion concentration in solution and the rate of cation dissolution.At the same time,SEM and CT nondestructive testing techniques were used to compare and analyze the microstructure of sandstone before and after acid corrosion.(2)The uniaxial compression tests were carried out on sandstone samples immersed in two different acid solutions with different concentrations and properties.The failure modes and stress-strain law of sandstones in different acidic solutions were compared and analyzed.Through the study of the mechanical properties of sandstone,the Weibull function was used to analyze the strength characteristics of sandstone micro-element.Finally,the damage constitutive model of acid-corroded sandstone was established by introducing the damage variable based on CT number.(3)According to Fick's second law,the diffusion control equation of solute considering the influence of chemical reaction was established,and the analytic solutions was obtained.According to the acid corrosion test of sandstone in laboratory and the corresponding MATALB calculation program obtained the numerical solution of the acid corrosion solute transport problem.The uniaxial compressive strength degradation rule of sandstone based on solute transport model was established,and the influence of transport and corrosion of acidic chemical pollutants on the strength of bulk geotechnical materials was analyzed and their service life was predicted.