The interface between geotextile and geomaterials plays a crucial role in the performance of various geotechnical structures. Soil-geotextile interfaces often suffer reduced performance under environmental stressors such as rainfall and cyclic loading, limiting the reliability of geotechnical structures. This study examines the influence of gravel content (Gc), compaction degree (Cd), and rainfall duration (Rd) on the mobilized shear strength at the silty clay-gravel mixture (SCGM)- geotextile interface through a comprehensive series of direct shear tests under both static and cyclic loadings. A novel approach using Polyurethane Foam Adhesive (PFA) injection is introduced to enhance the interface behavior. The results reveal that increasing Gc from 0 % to 70 % leads to a 35-70 % improvement in mobilized shear strength and friction angle, while cohesion decreases by 15 %-60 %, depending on Cd. A higher Cd further boosts shear strength by 6 %- 70 %, influenced by Gc and normal stress levels. Under cyclic loading, increasing displacement amplitude reduces shear stiffness (K), while having minimal impact on the damping ratio (D); K and D appear unaffected by the number of cycles in non-injected samples. Rainfall reduces mobilized shear strength by 8 %-25 %, depending on the normal stress, with a 47 % drop in friction angle and a 24 % increase in cohesion after 120 minutes of rainfall exposure. In contrast, PFA-injected samples exhibit a marked increase in mobilized shear strength under both dry and wet conditions, primarily attributed to enhanced cohesion. Notably, PFA treatment proves particularly effective in maintaining higher shear strength and stiffness in rainfall-affected interfaces, demonstrating its potential in improving geotextile-soil interaction under challenging environmental conditions.

In this paper, the resonant column tests were utilized to examine the small-strain stiffness and attenuation of clay-gravel mixture (CGM) under various effective consolidation pressures and freeze-thaw cycles, on the basis of investigating the electrical resistivity variation trend of CGM samples undergoing various freeze-thaw cycles. It is shown that the resistivity of CGM tends to stabilize when the freeze-thaw cycles (N) reach 9, and, thus, the samples after 0, 3, 6, 9, and 12 cycles were selected for resonance column testing. The results show that, once N > 9, the decay in dynamic shear modulus demonstrates a weakened association with Nand the stiffness degradation effect of freezing-thawing would be weakened and inhibited by high effective consolidation stress. Additionally, a mathematical model was constructed to predict the maximum dynamic shear modulus (Gmax) in the basis of freeze-thaw cycles and effective consolidation stress. Microscopic analysis results suggest that the freeze-thaw effect on CGM lies in the development of soil aggregates and porosity variation within the fine-grained soil. Compared to gravel soils and frozen soil, the cementation of matrix soil and the effect of blocky structure are considered as fundamental reasons for the improved small-strain stiffness and reduced vulnerability to freeze-thaw cycles of CGM.