Journal of Engineering Geology

The urban development of Tabriz faces numerous geological and engineering challenges due to the presence of Neogene argillaceous-marly-marly rocks, which exhibit low mechanical strength and bearing capacity, along with high deformability. This study aims to analyze these rocks to establish practical correlations among petrographic, physical, and mechanical properties, alongside ultrasonic test results, which can help estimate uniaxial compressive strength (UCS), compression wave velocity (Vp), and elastic modulus (E).The findings indicate that argillaceous-marly-marly samples, classified as very weak to weak rocks or hard soils with significant deformability, exhibit low compression and shear wave velocities. These samples are predominantly found in yellow, olive green, gray to dark gray, and brown colors throughout the city. The study reveals significant linear relationships between physical properties, mineralogical composition, UCS, and E with seismic wave velocity. Notably, a strong correlation exists between compression wave velocity and uniaxial compressive strength, shear strength parameters, cement content, and mineralogical composition in these rocks. These relationships suggest that mineralogy, porosity, density, and slake durability index are key factors influencing seismic wave velocity. Additionally, the variations in textural and microstructural diversity of argillaceous-marly-marly samples contribute to unpredictable mechanical behavior, which can pose potential hazards. Furthermore, a qualitative fissure index (I_f) was established based on the P-wave velocity of the samples, leading to the classification of samples into highly fissure categories.