Marl, a transitional soft rock, exhibits complex geotechnical behavior due to its heterogeneous structure, parallel fissures, and variable cementation. The difficulty of obtaining undisturbed samples suitable for laboratory testing makes field-based calibration essential for realistic modeling of excavation performance. This paper presents field observations and numerical back-analysis of a strut-free excavation in marl rock supported by buttress pile walls. The study aims to calibrate the stiffness parameters of the Hardening Soil (HS) model to accurately reproduce the deformation behavior of the marl under actual excavation conditions. Field observations and a monitoring program, including systematic inclinometer measurements, were implemented to provide reliable reference data for model calibration and validation. The excavation was almost entirely in marl, ensuring consistent geotechnical conditions and eliminating the influence of other soil or rock layers that often complicate similar case studies. A three-dimensional finite-element back-analysis was conducted to evaluate the deformation behavior of the self-supporting buttress pile wall during staged excavation and to determine the stiffness parameters that best reproduce the observed field performance. Since both shear strength and stiffness govern wall displacements, shear strength values were fixed based on independent large-scale direct shear tests on intact marl and discontinuity samples from previous studies. Consequently, the analysis focused on identifying stiffness characteristics representative of marl rock under real excavation conditions. The calibrated parameters successfully captured the observed wall and ground deformations, providing a realistic representation of the excavation behavior. The findings offer valuable guidance for similar engineering problems, supporting more reliable prediction of system response in weak and transitional marl formations. Moreover, the results contribute to improved risk management and more informed geotechnical design decisions in future excavation projects under comparable geological and structural conditions.

Landmines and explosive remnants of war are still present in the Western Balkans and remain a deadly legacy of the hostilities at the end of the 20th century. Over the years, several incidents have occurred in Bosnia and Herzegovina, in Serbia, and in Croatia where intact ordnance has caused injuries and fatalities. Floods, torrential flows, and gravitational mass movements pose a particular threat. Landmines and explosive remnants of war are mobilized and displaced into previously uncontaminated areas. We first discuss the historical and technical background of this hazardous situation. We then show which hydro-morphological processes are responsible for the mobilization and displacement. We then illustrate how a prediction of the likely contaminated areas can be obtained. We show that the problem can only be tackled using a stochastic-deterministic model. However, for the eventual development of risk-hazard maps, preliminary work using laboratory experiments and field surveys is required. The article, therefore, proposes a novel approach to the problem in an international research project. The aim would be to produce risk-hazard maps that can be used by elected decision-makers, administrative authorities, and emergency personnel in affected municipalities.