The rheometry approach in modern soil studies: a review

Digital soil rheometry is a relatively new and rapidly developing research direction that currently occupies a small niche in soil and agrophysics studies. This paper presents a review of studies based on the rheometry approach as part of soil mechanics research in different countries. The fundamental principles and equations of oscillatory amplitude sweep tests and oscillatory tests with controlled strain (resilience test) are described, with a focus on soil structure as the main object of the study. Key deformation and strength parameters (storage and loss moduli (G' and G``), the linear viscoelasticity range (LVE-range), shear stress (t), structural recovery index (R), etc.) describing the mechanical behavior of the soil at the microstructural level are discussed. This paper also highlights the influence of soil preparation: soil structure, water content, temperature, and the normal force applied during tests as parts of the research protocol – on the obtained results. Furthermore, this review examines research trends within the rheometry approach that have emerged over the past two decades of its application to soil studies. Based on the analysis of existing studies, potential directions for the further development of rheometry in soil research are proposed.