Experimental and numerical investigation on the effectiveness of plate piles in mitigating rainfall-induced slope failures in expansive soils.docx

Date

2025-9-01

Author

Aktaş Engin, Tuğçe

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Rainfall-induced landslides in expansive soils present a significant geotechnical challenge, particularly in regions with pronounced seasonal rainfall variation. Expansive soils, rich in montmorillonite, undergo substantial swelling upon wetting and shrinkage upon drying, leading to large volume changes and strength loss. Rainfall infiltration accelerates these effects by reducing matric suction and shear strength, frequently triggering shallow slope failures. Conventional stabilization measures, such as retaining walls or soil nails, are not always cost-effective or adaptable to the complex hydro-mechanical behavior of expansive soils. This study investigates the performance of plate pile systems—a novel reinforcement method comprising steel plates welded to pile shafts—in stabilizing rainfall-affected expansive soil slopes. A clay layer with a 2.0 m active zone depth was modeled at laboratory scale, focusing on the translational sliding behavior at the interface between the active zone and the underlying stiffer layer. Small and large direct shear devices were employed to assess interface shear strength mobilization under simulated rainfall infiltration, with different plate pile configurations tested to evaluate their influence on deformation control. The experimental program was complemented by advanced numerical modeling. Laboratory-scale behavior was simulated using PLAXIS 3D, and field-scale response was investigated through coupled hydro-mechanical analyses in GeoStudio, evaluating factor of safety reduction due to rainfall-induced suction loss and the improvement achieved with plate pile reinforcement. Results demonstrate that plate piles significantly enhance interface shear resistance, limit deformations, and improve slope stability. The combined findings confirm the potential of plate pile systems as a practical and adaptable solution for stabilizing expansive soil slopes subjected to rainfall infiltration.

Subject Keywords

Expansive soils, Slope stability, Plate pile, Coupled analysis

URI

https://hdl.handle.net/11511/116112

Collections

Graduate School of Natural and Applied Sciences, Thesis