Creep Behavior of Soft Argillaceous-Marly Rocks Interpreted Using the PIV Method: Case Study from Tabriz

Abstract

Particle Image Velocimetry (PIV) is a non-contact method for measuring particle velocity by tracking movements through sequential images. This study investigates the creep behavior of argillaceous-marly rock samples from Tabriz city using uniaxial compressive creep tests combined with the Geo-PIV technique. Understanding creep deformation in soft marly and argillaceous rocks is critical for the sustainable design and maintenance of underground structures, stratigraphic stability, and other geotechnical applications. Long-term creep tests were performed on five representative samples, and PIV analyses were used to capture displacement and velocity fields at the micro-scale. Results show that mineralogical composition, microstructure, and loading and environmental conditions strongly influence creep behavior. The samples exhibited creep failure within 3–12 days, progressing through all three creep stages. Gray marl samples displayed slower strain accumulation during the progressive stage compared to green and yellow samples, yet reached complete failure more rapidly. Observed differences in deformation modes, fracture patterns, and creep damage highlight the effects of anisotropy and internal structure. While macrocracks were visible in ruptured sections, PIV provided detailed insights into microstructural deformation, rupture mechanisms, and anisotropic behavior. These findings demonstrate the effectiveness of PIV for linking micro-scale processes with macroscopic failure, enabling more accurate predictions of time-dependent rock deformation and contributing to improved geotechnical design in argillaceous-marly formations. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.