Loess landslides represent significant geohazards occurring on the Loess Plateau, China, yet their failure mechanisms remain poorly understood due to complex hydro-mechanical interactions at soil-rock interfaces. This study investigates the Zhangjiawan ancient landslides (ZJWALs) with a loess-mudstone sequence. The multidisciplinary approaches integrating field surveys, Interferometric Synthetic Aperture Radar (InSAR) deformation monitoring, and numerical simulation were employed to unravel their basic characteristics, deformation process, and failure mechanisms. Key findings reveal that loess-mudstone slope structures exert fundamental control on landslide initiation, with frontal anthropogenic activities and rainfall identified as primary triggers for current erosion and reactivation. The ZJWALs are classified as a thrust-type landslide with a total area of 2.85 × 105 m2 and a reactivated volume of 3.33 × 106 m3, accounting for 38.9% of the original landslide mass. Kinematic analysis identifies four deformation zones that are spatially correlated with existing geological structures, and field evidence confirms pervasive creep deformation across the landslides. Further simulations using a depth-averaged model indicate that the landslide would compromise roughly 55% of the cement plant's footprint and its associated infrastructure through extensive burial. These insights advance our understanding of ancient landslide reactivation mechanisms in loess-mudstone terrains and inform disaster mitigation strategies.
Distinguishing between chalk and shale remains a fundamental challenge in engineering geology. Traditional sedimentological classifications rely on visual or genetic criteria that fail to predict mechanical behavior, creating ambiguity across transitional lithologies such as "marly chalks" and "chalky marls." To bridge descriptive geology and functional rock mechanics, this study introduces a novel, quantitative framework that redefines the chalk–shale transition based on geomechanical performance rather than arbitrary mineralogical limits. Integrating mineralogical, petrophysical, and mechanical data from the Ghareb Formation (Israel), we identify the clay/carbonate ratio (R=0.2−0.5) as a critical geomechanical boundary. Across this zone, material behavior shifts from a stiff, carbonate-bound matrix to a moisture-sensitive, clay-dominated domain characterized by distinct strength (UCS) degradation, permeability variations, and laboratory testing and preparation challenges.By grounding classification in objective mechanical behavior, this framework unifies the language and nomenclature for formation evaluation across disparate investigation scopes from energy exploration to civil infrastructure. This eliminates scope-dependent mischaracterizations, enhances geotechnical design assumptions, improves laboratory testing protocols, and standardizes site characterization globally.
