Abstract:To study the change law of hysteresis curve of expansive soil improved by Sodium Chloride Solution, based on GDS dynamic triaxial tests, the dynamic triaxial test of expansive soil under different concentrations of sodium chloride solution and different consolidation confining pressures was carried out. By four characteristic parameters: long axis slope (k), internal area (S), non-closure (εp) and fullness (α) were used to quantitatively describe the degree of strain axis tilt, area size, non-closure degree and width of hysteresis curve. The results showed that: The hysteresis curve of expansive soil is oblique ellipse; under the same sodium chloride solution concentration, as the loading confining pressure increases, k increases, and S, εp and α all decrease non-linearly; under the same loading confining pressure, as the concentration of sodium chloride solution increases, εp decreases, and S, k, and α all increase non-linearly; under different loading conditions, S and α have a similar change relationship, when the dynamic strain is less than 0.1%, there is no change in S and α, as the dynamic strain gradually increases, S and α increase exponentially; compared with unimproved expansive soil, the hysteresis curve k, S and α of expansive soil improved by Sodium chloride solution increase, and the value of εp decreases. Comprehensive analysis shows that the dynamic characteristics of the expansive soil modified with sodium chloride solution are significantly improved compared with that of the unmodified soil.