Study on the Deformation and Damage Patterns of Rock–Soil Bodies with Flat-Cave-Containing Slopes Under Wet–Dry Cycling

The stability of slopes containing flat caves, frequently employed in mining for transportation and drainage, is critically compromised by alternating dry and wet cycles, posing significant geohazard risks. This study investigates the deformation and damage mechanisms of such a slope at a fluorspar mine in Hunan Province, China. An integrated methodology combining indoor physical similarity simulation and Abaqus CAE finite element numerical simulation was employed. The experimental and numerical results demonstrate that: (1) slope stability deteriorates through three stages: latent, developmental, and eruptive. The highest localized strain reached 0.253% in the mid-to-lower slope area, with a maximum overall deformation of 0.838%. (2) Crack formation was most pronounced during the first two cycles, with a rapid increase in total crack length and area, after which the crack network stabilized. (3) Saturation levels gradually rose from the slope base to the middle section, reaching nearly full saturation at the base after the fourth cycle, which corresponded with concentrated displacement in the mid-lower slope. This research clarifies the phased failure mechanisms of flat-cave slopes under hydrological cycling and offers practical technical guidance for safety monitoring, early warning system development, and protective engineering design for mine slopes with similar geological settings.