Research on the damaging mechanisms of expansive soil in subgrade

Abstract

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.

Keywords:

• Damage of expansive soil
• fracture
• cause mechanism
• discrete element method
• slope stability

Authors’ contributions

Conceptualization, Xudong Zha and Jian Xiao; methodology, Jian Xiao and Hongri Zhang; software, Jiming Yang; validation, Jian Xiao, Hongri Zhang and Jiming Yang; formal analysis, Jian Xiao and Hongri Zhang; investigation, Jian Xiao and Hongri Zhang; resources, Hongri Zhang; data curation, Jian Xiao and Hongri Zhang; writing—original draft preparation, Jian Xiao and Hongri Zhang; writing—review and editing, Xudong Zha; visualization, Jian Xiao; supervision, Hongri Zhang; project administration, Jian Xiao; funding acquisition, Xudong Zha. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This work is supported financially by The National Key Research and Development Program of China（2019YFC1509800）：Standardization of prevention and control technology of expansive soil landslide and engineering slope and comprehensive ecological protection technology and The project of improving the basic scientific research ability of young and middle-aged teachers in Guangxi Universities in 2019（2019KY1338）：Study on interaction mechanism of rice straw and soil crust structure and slope protection technology.