强降雨作用下岩土界面含粗粒富集区边坡的破坏机理

Yixiang Song¹, Tengyu Lv¹, Hong Liu², Da Huang³, Dongming Gu⁴

¹School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin 300401, China

²Offshore Oil Engineering Co. Ltd., Tianjin 300456, China

³School of Geological Engineering and Geomatics, Chang’an University, Xi’an 710064, China

⁴Engineering Faculty, China University of Geosciences(Wuhan), Wuhan 430074, China

Abstract: Internal erosion caused by seepage at the soil–rock interface with local coarse particle enrichment zones (CPEZ) is a significant factor contributing to geological disasters during rainfall events. The mechanism of landslides induced by internal erosion at the soil–rock interface within CPEZ with high permeability remains unclear. This study incorporated a degradation model of bonding strength and a viscous force model into the discrete-element software MatDEM to analyze the evolution of seepage erosion at the soil–rock interface. The numerical simulations investigated the impact of the number and spacing distance of CPEZ on erosion characteristics within the interface seepage. Subsequently, the study analyzed the infiltration process and stability of the Gendakan slope during heavy rainfall to understand the failure mechanism of rainfall-induced landslides with local CPEZ at the soil–rock interface. The findings suggest that the seepage erosion process can be divided into three stages: initial, development transition, and destruction stages. Moreover, the overall permeability of the numerical model strengthens with the increase in CPEZ scale and permeability difference. A higher number of CPEZ distributed throughout the sample increases susceptibility to seepage erosion, while wider spacing between CPEZ reduces their impact on overall permeability. The numerical analysis of the Gendakan landslide highlights the importance of instability at the foot of the slope due to internal erosion of CPEZ in triggering traction landslides across the accumulation mass. This paper delves into the failure mechanism of seepage erosion at the soil–rock interface, offering theoretical support for the prevention and control of landslide geological disasters.

Keywords: Soil–rock interface, Internal erosion, Coarse particle enrichment zones,  Failure mechanism, Gendakan landslide

Fig. 1 Schematic diagram of permeation test apparatus (Huang et al. 2021)

Fig. 3 Numerical model used in the seepage erosion test (model A-20)

Fig. 6 Engineering geological section of the landslide

Fig. 7 Numerical model for simulation of the landslide deposit

Fig. 9 Migration of particles under different hydraulic gradients: a i = 10, b i = 30, c i = 50, d i = 70, e i = 80 and f i = 90 (model A20-100)

Fig. 10 Evolution of pore water pressure within the landslide during the rainfall

Fig. 13 The displacement field diagram of the landslide deposit (5.5 h and 6 h)

SONG Y et al., Failure mechanism of the slope containingcoarse particle enrichment zones located at the soil–rock interface under the heavy rainfall[J/OL].Environmental Earth Sciences, 2024, 83(10): 302.DOI:10.1007/s12665-024-11590-6.