Experimental investigation and parametric analysis for shear behavior of frozen clayed soil containing lens ice

As a composite geomaterial characterized by heterogeneity and anisotropy, the mechanical properties of frozen soil are strongly governed by its internal cryostructure. However, existing research predominantly relies on models of homogeneous frozen soil or those containing a single ice lens, leading to an insufficient understanding of the mechanical behavior of frozen soil with more representative reticulated cryostructures and its coupling mechanisms with temperature and stress. This study systematically prepared five types of frozen soil specimens with varying spatial configurations of ice structures (ranging from homogeneous to those containing lens ice with different quantities, dip angles, and combinations) using a controlled remolded sample preparation method. Direct shear tests were conducted under different temperatures (-5°C to −1°C) and normal stresses (100–500 kPa) to investigate the effects of frozen soil structure type, temperature, and stress on its shear mechanical properties and deformation mechanisms. Based on the experimental results, prediction models for the shear strength and shear modulus of frozen soil were established, which considered structure type, temperature, and normal stress. This research reveals the intrinsic control mechanism of cryostructure on the mechanical behavior of frozen soil, providing an important theoretical basis and parameter determination method for the stability assessment, and design of heterogeneous frozen soil foundations and slopes in cold regions engineering.