Experimental Study on Shear Strength Parameters of Natural Sulfate Saline Soil
The factors affecting the shear strength of sulfated saline soil are complex, and the variation law is difficult to explore. In order to determine the variation of shear strength of sulfate-based roadbed saline soil under different water content, compaction and confining pressure, the internal friction angle and cohesion, which are two important parameters of shear strength, were analyzed. The test results show that the stress-strain curve of sulfate-based saline soil is strain-softening type distribution, and the smaller the confining pressure, the more obvious the softening type; the shear strength increases with the increase in confining pressure and compaction. The cohesive force first increases and then decreases with the increase in water content, and the maximum cohesive force occurs near the optimal water content; the cohesive force increases slowly with the increase in compaction degree; the cohesive force increases most obviously when the water content is 10.8%. The internal friction angle decreases with the increase in water content, and the peak area is not obvious; the internal friction angle increases as the degree of compaction increases. Introduction Saline soil is widely distributed in China, especially in the northwest inland basins and desertification areas. Saline soil is mainly composed of chloride salt and sulfate in the northwest. Compared with non-saline soil, saline soil is a kind of special soil which is more sensitive to the environment. The amount of soluble salt existing in the soil will change in quantity and phase under certain environmental conditions. Therefore, it affects the connection mode between the soil particles, and further changes the density, pore ratio, shape composition and structure arrangement of the soil. Because saline soil has strong regional characteristics, the physicochemical properties of saline soil vary greatly in different regions. Therefore, the existing research results cannot be effectively used for reference and application. The environmental conditions in the northwestern regions are complex, such as the Qinghai area in the eastern Qinghai-Tibet Plateau [1]. It is located in the high-altitude and cold region of the world, and its geographical location, topography, climate change and engineering geological structure are unique. If the ambient temperature changes, the construction of the saline soil area will cause salt swelling, tumbling, disintegration and corrosion [7]. At the same time, salt can reduce the strength of the structure, causing it to break earlier in the design life and lose its function. In this paper, based on the conventional indoor triaxial test, the in-depth analysis of the shear strength of natural subgrade saline soil in eastern Qinghai is carried out [4]. Further change the stress-strain curve, internal friction angle and cohesive force under different confining pressure, water content and compaction degree. This provides a strong data support and technical reference for the construction of cold and high-altitude saline soil areas, and it ensures the quality of engineering construction and design. Experiments Basic Test The representative saline soil sample collected was subjected to basic physical and chemical tests,