The thermal conductivity of loess plays an important role in ecological restoration design and the calculation of roadbed and slope stability. This study uses 60 loess samples from Shaanxi Province of China as raw material. The loess samples were heated to high temperature in an unclosed muffle furnace and then cooled to room temperature. Subsequently, the heat conduction coefficient (λ), specific heat capacity (c) and thermal diffusion coefficient (α) of the sample were measured. Between 23–900 °C, with temperature increasing, λ decreased from 0.90 to 0.46 W/m·K, c decreased from 1.60 to 1.23 J/kg·K, α decreased from 0.59 to 0.38 m2/s. The test results show that, after being exposed to high temperature, the thermal conductivity of loess tends to weaken. This has a very important relationship with the pore characteristics of loess.

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In this paper, an experimental approach is employed to investigate the reinforcing impact of geogrids on the dry-shrinkage cracking of loess. At various evaporation temperatures and for varying specimen thicknesses, the evolution of the surface fissures induced in the loess samples with and without geogrids was monitored and analyzed. According to the findings, the evaporation rate of the samples increased when the evaporation temperature was increased, and the thickness of the samples was reduced under the same conditions. At higher temperatures, geogrids had a substantial impact on reducing the evaporation rate and suppressing the dry-shrinkage cracks. The occurrence and development of the dry-shrinkage cracks of loess are divided into three stages: the formation stage, the acceleration stage, and the stabilization stage. The maximum crack width was reduced by 20%–34% for different sample thicknesses. The ratio of the number of cracks to the number of fracture nodes in the reinforced soil was lower than that of the unreinforced soil. This reduction ratio changed further from 5.6% to 24.4% with the increased thickness. The geogrids can effectively reduce the evaporation rate of water and the development rate of the dry-shrinkage cracks in loess. Consequently, the crack distribution in the loess samples is uniform and prevents the formation of large and long cracks. Using a 3D discrete element model, it is feasible to simulate the loess before and after the geogrid reinforcement.

In this study, we investigated the effect of particle size distribution on the shear properties of sand. Direct shear tests were conducted using four types of sand samples with different particle size distributions obtained from standard sand produced by Xiamen ISO Co. Ltd. The results show that the influence of particle size distribution on the internal friction angle was significant. Typically, the internal friction angle increases with increasing the coefficient of non-uniformity (Cu) and decreasing the curvature coefficient (Cc). The discrete element results show that the initial particle size distribution significantly affects the porosity, coordination number, and particle slide fraction. In addition, the grey relation analysis revealed that the sliding fraction and coordination number have the greatest correlation with the internal friction angle. The research results of this study help to understand the changes in particle contact, internal stress, and particle sliding during the shear failure process of sand.