Evaluation of Strength Index and Resistivity of Acid-contaminated Loess

In order to verify the evolution law of the strength characteristics of acid-contaminated loess by resistivity method, the engineering performance of contaminated loess sites in different degrees was retrieved. Distilled water was used as the base liquid to prepare loess samples with different pollution states. The resistivity characteristics of the loess contaminated with hydrochloric acid, nitric acid, and sulfuric acid were studied by the two-phase resistivity test method, and the pollution was tested by the indoor tests using a quadruple direct shear tester. The change law of the shear strength of loess has been obtained. And the quantitative relationship between resistivity and shear strength index has been further discussed. The test results show that the shear stress-shear strain curve of acid-contaminated loess generally shows a hardening type; as the concentration of hydrochloric acid and nitric acid increases, the shear strength of the contaminated soil weakens and the resistivity decreases; as the concentration of sulfuric acid increases, the shear strength of the soil increases, and the resistivity increases. Taking the pollution concentration as the intermediate variable, the shear strength and resistivity are positively correlated. The model relationship between the resistivity and cohesiveness parameters of the acid-contaminated soil and the pollution concentration is established. The results can better characterize the correlation of the three parameters. Based on the discussion of the hardening curve, a prediction model for the shear stress-shear strain curve considering the influence of the concentration of acid pollution is proposed, and through the anti-shear strength cohesion index and resistance. Based on the analysis of the parameters, combined with the change rules of shear strength and resistivity, a grade standard for evaluating the degree of acid contamination of the undisturbed loess by the resistivity method is initially proposed.