Graphene is regarded as a promising additive to enhance the thermal conductivity of bentonite in the geological repository, yet the hydro-mechanical properties of its mixture with bentonite under chemical conditions remain unclear. This work examined the one-dimensional swelling deformation of high-density graphene-modified bentonite (GMB) in NaCl solutions, considering the influences of graphene content and NaCl concentration. Results indicate that both graphene and NaCl reduced the maximum swelling strain and the primary and secondary swelling coefficients of GMB. Additionally, graphene enhanced the stability of swelling deformation in bentonite across various NaCl concentrations and decreased the GMB's test duration. The relationship between test duration and NaCl concentration was nonmonotonic. The ratio of swelling strain at each stage to total swelling strain was rarely affected by graphene content or NaCl solution. Scanning electron microscope examinations on selected samples post-swelling tests unveiled a unique soil structure in GMB. Furthermore, a model was put forward to predict the maximum swelling strain of GMB inundated in NaCl solutions, and its feasibility was verified.

Understanding the thermo-mechanical behavior of deep-water sediments is essential for the safe design of hightemperature oil/gas pipelines. In this study, a series of temperature-controlled triaxial tests was conducted to investigate the thermo-mechanical behavior of reconstituted deep-water sediments sampled from the South China Sea. The experimental results revealed the thermo-mechanical behavior of sediments was closely related to their thermo-mechanical loading paths and sodium chloride (NaCl) concentrations. The increasing rate of excess pore water pressure decreases with an increase in temperature increment, effective confining pressure, and overconsolidation ratio, regardless of NaCl concentration. For normally consolidated specimens, the undrained shear strength generally decreases as temperature increases. The undrained shear strength of specimens was lower under undrained heating and higher under drained heating than that at 5 degrees C, respectively. Factors such as thermal softening, thermal consolidation, and thermal-induced excess pore water pressure significantly impacted the undrained shear strength of sediments under isothermal, drained, and undrained heating conditions. Additionally, the undrained shear strength decreases with increasing NaCl concentration. The results highlighted that the critical state line is unique under varying loading paths and NaCl concentrations. Furthermore, the effect of changes in void ratio induced by NaCl solution on the shear strength of sediments was more pronounced than that of the intergranular stress.