Geotechnical Investigation of a Construction-Site Failure: Insights from Field and Numerical Analyses

This study provides a comprehensive evaluation of the causes of slope instability occurring at a construction site characterized by complex geotechnical conditions. It is well established that slope stability problems rarely arise from a single factor; rather, they are the result of interactions among multiple parameters such as soil lithology, plasticity characteristics, discontinuities, groundwater level, rainfall–infiltration processes, dynamic loading conditions, and excavation geometry. In this context, the subsurface profile of the study area was thoroughly characterized through field borehole investigations, laboratory tests, and groundwater observations. The slope behavior was subsequently analyzed under static, pseudo-static, and seepage-induced conditions using the finite element method. The analysis results indicate that groundwater level and drainage conditions substantially increase pore-water pressures along critical slip surfaces, thereby triggering instability. Consistent with existing literature, even minor variations in soil engineering parameters were observed to produce significant changes in the factor of safety, while inadequate drainage conditions accelerated the loss of stability. Overall, the study systematically addresses the multifactorial nature of slope instability from an engineering perspective and presents a comprehensive assessment that integrates field data with advanced numerical modeling. The findings contribute to the development of safe, optimized, and technically robust slope design solutions under complex geotechnical conditions.