RESISTIVITY CHARACTERISTICS OF ACID-CONTAMINATED LOESS AND ITS RELATIONSHIP WITH TENSILE STRENGTH UNDER FREEZE-THAW CYCLES

With the acceleration of regional industrialization,loess-covered areas are increasingly exposed to seasonal freeze-thaw cycles and industrial acidification,resulting in significant alterations in soil structure and a continuous decline in mechanical performance. These processes threaten the stability of loess slopes and engineering sites,posing a critical risk to regional geological safety. In this study,intact loess specimens from the Tongchuan region were treated with distilled water and acidified solutions of HCl, HNO₃,and H₂SO₄ at four concentration levels. Under controlled laboratory conditions,the specimens underwent repeated freeze-thaw cycles,during which uniaxial tensile strength and electrical resistivity were measured synchronously. The test results indicate that the electrical resistivity of acidified loess increases progressively with the number of freeze-thaw cycles,stabilizing after approximately 10-15 cycles. Within each individual cycle,resistivity decreases with rising temperature until reaching a steady equilibrium. Under multiple freeze-thaw treatments,increasing the concentration of HCl or HNO₃ solutions leads to a noticeable decrease in soil resistivity,whereas H₂SO₄ exhibits the opposite effect,increasing resistivity with higher concentration. Furthermore,a positive correlation is observed between resistivity and tensile strength across all acid treatments. Based on the observed evolution of resistivity and its dependence on acid concentration and freeze-thaw history,we developed and validated a predictive model for electrical resistivity. This model incorporates acid concentration,number of freeze-thaw cycles,and measured resistivity parameters,providing a practical tool for assessing the stability of acid-polluted loess slopes and for quality evaluation in geotechnical engineering applications.