School of Geometrics and Prospecting Engineering, Jilin Jianzhu University, Changchun, Jilin, P.R. China.
PLoS One. 2023 May 15;18(5):e0285484. doi: 10.1371/journal.pone.0285484. eCollection 2023.
To study the soil-water characteristics and shear strength of unsaturated complete-intense weathering mudstone, the soil-water characteristic curve of complete-intense weathering mudstone and the matric suction of mudstone samples under natural state were measured. This measurement was through a soil-water characteristic test using a pressure plate instrument. Based on the results of soil-water characteristic test, an unsaturated (saturated) triaxial shear test was carried out. Under different temperatures and confining pressure conditions, the shear strength and deformation characteristics of complete-intense weathering mudstone under natural water content and saturation conditions were investigated. The results show that the percentage of silt and clay in unsaturated complete-intense weathering mudstone in natural state is relatively high, with the mudstone having less sand, and a weak permeability and exhibiting a significant capillary phenomenon. The complete-intense weathering mudstone with a natural moisture content of 19.15% has a matric suction of 210 kPa. When the temperature is constant, the shear stress of the sample increases with the increase of confining pressure. When the temperature decreases from 0 to -20°C, the influence of confining pressure on the rock samples gradually decreases. The rock sample has the property of strain hardening during shearing. Under the same matric suction, the total cohesion increases with the decrease of temperature. At a positive temperature, the effective internal friction angle increases with the decrease of temperature. At a negative temperature, the lower the temperature, the smaller the effective internal friction angle. The test of shear strength parameters of saturated complete-intense weathering mudstone is simple and conservative. In practical engineering, the basic properties of unsaturated complete-intense weathering mudstone can be predicted by testing the shear strength parameters of saturated complete-intense weathering mudstone. The results of the study are important for better understanding the nature of unsaturated complete-intense weathering mudstone and improving the safety of engineering construction in complete-intense weathering mudstone areas.
为了研究非饱和完全风化泥岩的土水特征和抗剪强度，测量了完全风化泥岩的土水特征曲线和原状泥岩样的基质吸力。该测量是通过压力板仪进行的土水特征试验完成的。基于土水特征试验的结果，进行了非饱和（饱和）三轴剪切试验。在不同的温度和围压条件下，研究了原状含水量和饱和条件下完全风化泥岩的抗剪强度和变形特性。结果表明，原状非饱和完全风化泥岩中粉土和粘土的百分比相对较高，泥岩中砂的含量较少，渗透性较弱，表现出明显的毛细现象。天然含水量为 19.15%的完全风化泥岩的基质吸力为 210 kPa。当温度恒定时，试样的剪应力随围压的增加而增加。当温度从 0°C 降低到-20°C 时，围压对岩石试样的影响逐渐减小。岩石试样在剪切过程中具有应变硬化的性质。在相同的基质吸力下，总凝聚力随温度的降低而增加。在正温度下，有效内摩擦角随温度的降低而增加。在负温度下，温度越低，有效内摩擦角越小。饱和完全风化泥岩剪切强度参数的测试简单且保守。在实际工程中，可以通过测试饱和完全风化泥岩的剪切强度参数来预测非饱和完全风化泥岩的基本特性。研究结果对于更好地了解非饱和完全风化泥岩的性质和提高完全风化泥岩地区工程建设的安全性具有重要意义。
