Research on the damaging mechanisms of expansive soil in subgrade

Fractures are considered the most characteristic property of expansive soils distinguishing it from other soils. The cause of many problems in engineering geology is directly or indirectly attributed to the existence of fractures, which makes the soil poor in mechanical properties and damages the overall structure. To this end, based on the detailed information obtained from on-site geological and engineering investigations, we studied the formation mechanisms of an expansive soil trench landslide under a roadbed and the resulting damages in the Ningming area of Guangxi, China. The landslide inversion was carried out with discrete element numerical simulation, and the relationship between fracture development and expansive soil slope instability was explored. The consistent results of field investigation and discrete element numerical simulation show that under alternating seasonal dry-wet stimulation, fractures appear at the surface of the expansive soil slope, which is then more conducive to rainwater infiltration. Under this cycle, the soil gradually softens, and its stability reduces. Additionally, the influence of human activities, such as traffic loading at the trailing edge, assisted in the formation of the landslide. The results of this study provide valuable references for the prevention of subgrade landslide and expansive soil-related damages in other expansive soil areas.