降雨作用下土工袋加固膨胀土边坡的稳定性：离散元探究与简化稳定性分析

Rainfall-induced stability of geobag reinforced expansive soil slopes: DEM investigation and simplified stability a nalysis

Abstract: Expansive soil slopes widely encountered in transportation infrastructure are highly susceptible to rainfall- induced instability, and geobag reinforcement has recently been applied as a flexible technique for slope sta bilization. Existing studies on geobag-reinforced slopes mainly focus on macroscopic stability, while particle- scale a nalyses considering moisture-induced swelling and strength degradation remain limited. In this study, a discrete element model of expansive soil slopes was developed using the MatDEM framework to investigate the behavior of geobag-reinforced slopes under rainfall infiltration and surcharge loading. Microscopic soil param eters were calibrated using laboratory test data, and rainfall infiltration, particle swelling, and moisture- dependent strength reduction were incorporated into the model. The results show that rainfall infiltration forms saturated, wetted, and unsaturated zones and induces progressive shallow sliding in untreated slopes. Geobag reinforcement reduces rainwater penetration and restricts soil particle movement, thereby improving slope stability. Increasing geobag width and slope ratio enhances the reinforcement effect, whereas increasing the expansive soil cover thickness leads to larger slope deformation. In addition, a simplified stability ana lysis model combining infinite slope theory with the mechanical behavior of geobag retaining structures was devel oped to evaluate the stability of reinforced slopes. The findings provide insight into the reinforcement mecha nism and stability behavior of geobag-reinforced expansive soil slopes under rainfall conditions.

Keywords: Geobag reinforcement；Expansive soil slope；MatDEM；Rainfall infiltration；Stability an alysis

Fig.1 Soil laboratory tests: (a) uniaxial compression test; (b) direct shear test; (c) ring knife density test.

Fig.2 DEM direct shear calibration: (a) shear model; (b) contact force distribution; (c) strength calibration.

Fig.4 Clump cluster interaction states: (a) equilibrium; (b) tension; (c) bond breakage; (d) compression; (e) clump cluster.

Fig.6  Rainfall infiltration mechanism.

Fig.13 Combined evolution of coordination number and force chains in case 1: (a) 0.2T; (b) 0.5T; (c) 0.8T; (d) 1.0T.

Fig.17 Horizontal displacement in case 2: (a) q = 1 MPa; (b) q = 2 MPa; (c) q = 3 MPa; (d) q = 4 MPa.

Wu J, Zhang M, Yin J, et al. Rainfall-induced stability of geobag reinforced expansive soil slopes: DEM investigation and simplified stability an alysis[J]. Transportation Geotechnics, 2026: 102113.