The adhesion property of soil on the metal surface was tested by the orthogonal experiment with 4 factors and 3 levels based on piston pull out method. A regression model of adhesion stress and the factors including moisture content(X-1), pressing time(X-2), settling time(X-3) and separation velocity (X-4) was established. The experiment results show that the influence of each factor on adhesion stress is ranked as X- 1 approximate to X (2) approximate to X (3) > X (4) > X- 3 X- 4 , and the adhesion stress shows an 'S' curve with the increase of separation velocity. The DEM parameters of the soil were calibrated based on the test results, and the contact and disturbance state of soil particles during the test were studied by discrete element method (DEM) using JKR model. The simulation tests show that the maximum adhesion stress occurs when the particles are about to separate from the probe surface, and the soil disturbance state is hierarchical.

The deformation characteristics of soil after thermal desorption are crucial for the evaluation of engineering properties, but the evolution mechanism is currently unclear. This study focuses on the thermal desorption of contaminated soil, conducting Geo-dynamic Systems consolidation-rebound tests to reveal the evolution mechanism of consolidation-rebound deformation and pore pressure characteristics, and exploring the evolution mechanism through pore structure, particle size distribution, and Cation Exchange Capacity tests. Results show that the consolidation characteristics of uncontaminated soil increase and then decrease with heating temperature, with 400 degrees C as a turning point. In contrast, the consolidation deformation of contaminated soil continues to decrease. The vertical deformation of the soil in the pre/early consolidation stage is greater before 400 degrees C, while after 400 degrees C, the deformation continues to increase with consolidation pressure, and higher heating temperatures enhance the soil's rebound deformation ability. Pore water pressure changes in two stages, with temperature ranges of 100-300 degrees C and 300-600 degrees C, and with increasing heating temperature, the characteristics of pore pressure change from clay to sand. Mechanism tests reveal that inter-aggregate pores affect initial deformation, while intra-aggregate pores affect later deformation, both showing a positive correlation. Aggregate decomposition increases initial deformation capacity at 100-400 degrees C while melting body fragmentation increases later deformation capacity at 500-600 degrees C. CEC decreases with increasing heating temperature, reducing inter-particle resistance and increasing soil deformation capacity. Particle size distribution and Cation Exchange Capacity impact consolidation-rebound pore pressure.

In this study, a series of dynamic triaxial tests and corresponding simulations using discrete element method (DEM) were conducted on sand with different clay particle contents. The development of pore pressure, axial strain, stress path, and stress-strain curve were analyzed. The contact and pore structure characteristics were further examined through electron microscopy. Subsequently, the concept of a contact-to-particle ratio is proposed to describe the connection behavior. The results show that the influence of the clay particle content on the liquefaction resistance is not monotonous. With an increase in clay particle content, the effective stress of sand cannot reach zero. However, the increase in clay particles reduced the permeability coefficient of the sand, which resulted in weak liquefaction resistance of sand. When clay particle content reached 30-35%, the stress-strain curve failed at an early stage. The contact-to-particle ratio was the smallest when the clay particle content was 35%, that effective contact of the particles is only 15% of that in the pure sand sample. When clay content reached 40-50%, the sand sample gradually exhibited the characteristics of clay.

Soil texture data are the basic input parameters for many Earth System Models. As the largest middle-low altitude permafrost regions on the planet, the land surface processes on the Qinghai-Tibet Plateau can affect regional and even global water and energy cycles. However, the spatial distribution of soil texture data on the plateau is largely unavailable due to the difficulty of obtaining field data. Based on collection data from field surveys and environmental factors, we predicted the spatial distribution of clay, silt, and sand contents at a 1 km resolution, from 0-5, 5-15, 15-30, 30-60, 60-100, and 100-200 cm soil depth layers. The random forest models were constructed to predict the soil texture according to the relationships between environmental factors and soil texture data. The results showed that the soil particles of the QTP are dominated by sand, which accounts for more than 70% of the total particles. As for the spatial distribution, silt and clay contents are high in the southeast plateau, and low values of silt and clay mainly appeared in the northwest plateau. Climate and NDVI values are the most important factors that affect the spatial distribution of soil texture on the QTP. The results of this study provide the soil texture data at different depths for the whole plateau at a spatial resolution of 1 km, and the dataset can be used as an input parameter for many Earth System Models.