Dynamic elasticity modulus of weathered red sandstone soil subject to drying-wetting cycles

Abstract

The drying-wetting cycles has a significant effect on the dynamic behavior of the weathered red sandstone soil. A series of the unconsolidated undrained dynamic triaxial tests were conducted on the weathered red sandstone soil samples under different numbers of drying-wetting cycles N, and the hysteresis curves and dynamic backbone curves were obtained under different confining pressures σ3. A hyperbolic model of dynamic backbone curve based on Hardin-Drnevich model was proposed, and the regression expressions between the parameters of the proposed model and N were presented. The relation between the maximum dynamic elasticity modulus Edmax and N, σ3 was analyzed based on the proposed hyperbolic model. The fitting equation of dynamic elasticity modulus Ed and dynamic stress σd was put forward, and the relation between dynamic elasticity modulus Ed and N was studied. The main conclusions from this work as follows: (1) Hardin-Drnevich model can well express the hyperbolic behaviors of dynamic backbone curves of the weathered red sandstone soil. The proposed hyperbolic model and the expressions of Edmax and Ed can well reflect the influences of the numbers of drying-wetting cycles and σ3 on Edmax and Ed respectively. (2) Edmax and Ed increase with the increase of σ3 under certain N; and decrease with N under a certain σ3. (3) Ed of the weathered red sandstone soil increases non-linearly with the increase of dynamic strain εd. The introduced factor β can quantitatively reflects the influences of N on Edmax .