چكيده لاتين
Abstract
The Dorud–Khorramabad railway line, with an approximate length of 114 km, was designed to connect the center of Lorestan Province to the national railway network and to replace the deteriorated Dorud–andimeshk route. One of the major challenges of this project was the occurrence oLf multiple landslides within the cut slope at kilometer 86, which posed serious threats to slope stability and the safety of adjacent structures. Geological, geotechnical, and hydrogeological investigations revealed that the type of materials (marly clay with embedded limestone boulders) and stratification of the cut, in combination with triggering factors such as intense precipitation and fluctuations in the groundwater table, played a decisive role in landslide initiation.
Seasonal precipitation within the upstream catchment (approximately 0.6 km²) increased both surface runoff and subsurface interflow, which in turn elevated pore water pressure along low-permeability horizons. This condition reduced soil shear strength and activated both planar and rotational failures. Field observations confirmed the presence of localized seepages, low-discharge springs located 60 to 360 m upstream of the failure zone, and groundwater table variations ranging from 25 m in the north to less than 10 m in the south. The regional hydraulic gradient, directed from the northeast to the southwest, coincides with the landslide zone, highlighting the direct role of subsurface hydrodynamics in slope instability.
The study results indicate that simultaneous management of surface and subsurface water (including horizontal and deep drains, relief wells, and rehabilitation of surface drainage networks), together with geometric modification of slopes, represents the most effective stabilization strategy. Overall, the findings demonstrate that precipitation and groundwater fluctuations are the dominant triggering factors of slope failures in this area, and their control can serve as a practical model for similar railway and infrastructure projects in regions with comparable geological and climatic conditions.
