Hypergravity model tests of rainfall-groundwater coupling induced seepage failure of CDG filled subgrade slope
ZHAO Yu1, 2*, YAN Zhuang1, ZHAN Liangtong1, LIU Jingchun1, ZHANG Rui1, WU Yi1
(1. College of Civil Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China; 2. Institute of Supergravity
Science and Technology, Zhejiang University, Hangzhou, Zhejiang 310058, China)
Abstract：To elucidate the seepage-deformation failure mechanism of subgrade slopes filled with completely decomposed granite (CDG), hypergravity model tests and finite element analyses were conducted to examine the coupled effects of groundwater and rainfall. In both hypergravity tests, seepage failure occurred at the trailing edge due to a rapid rise in the water level. The critical water level at the trailing edge was approximately 12 m, and the critical hydraulic gradient within the slope model was around 0.47 for both tests. The finite element model, validated by the hypergravity tests, indicates that the onset of osmosis failure is primarily attributed to a surge in the local hydraulic gradient resulting from the swift increase in water level at the trailing edge; subsequently, seepage leads to backward piping failure within the slope. Furthermore, as fine particles accumulate and permeability decreases at the slope toe, the stability of the slope diminishes with the rise in groundwater level. Conversely, when fine particles at the slope toe are eroded and permeability increases, the groundwater level decreases, resulting in enhanced slope stability. The hydraulic gradient gradually diminishes from the slope surface to the trailing edge, aligning with the development process of backward piping failure, until the piping channel is fully formed and the hydraulic gradients on both the front and back of the slope become consistent. These findings provide valuable insights for mitigating water-induced failures in similar subgrade slopes.
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2026, Vol. 45 
