Experimental Study on Structural Stability of Expansive Soil-Anchor Cable System under Dry–Wet Cycle Effect

The dry–wet cycle greatly impacts the anchoring effect of prestressed anchor cables in expansive soil. Moreover, the stress relaxation of the soil and prestress loss of anchor cables are correlated. This is due to the special expansion and contraction characteristics of this soil. To explore the influence of the dry–wet cycle, this study experimentally analyses the stress change mechanism of the anchor supporting structure in expansive soil; meanwhile, the coupled expansive soil-anchor stress model for the dry–wet cycle case is derived. Expansive soil possesses unique viscoelastic-plastic mechanical characteristics. These were simulated using a calculation framework based on the Bingham model. This was used to describe the coupling effect between expansive soil and anchor cable with equal strain. Dry–wet cycle tests were set up under three different conditions: moisture contents, the amplitude, and number of the wet–dry cycles, which verified the accuracy of the model. The experimental results show that the number and amplitude of dry–wet cycles determine the number and amplitude of cycles of anchor stress change, respectively, and the initial water content determines the reference value of stress change. The primary inference is that the number of dry–wet cycles has the greatest influence on stress attenuation of anchor, as shown in the experiment, where the stress attenuation of stress anchor was 88.12% of initial stress after three dry–wet cycles.