基于大三轴试验的丘陵山区填方路基填料剪切特性研究

Study on the Shear Characteristics of Fill Materials in Hilly and Mountainous Areas Based on Large Triaxial Test

摘要: 我国丘陵山区公路路基因地形复杂，路基滑坡、沉降变形等灾害频发，严重威胁公路安全运营。但进行边坡稳定性分析时，经常由于填料粒径大、力学性质不易获取而影响计算结果。因此，为了解决该问题，针对丘陵山区常见的风化砂、含砾黏土以及角砾三类填料，考虑围压与含水率的影响，通过粗粒土大三轴剪切试验，揭示了各自的剪切力学特性。结果表明：承受加载时含砾黏土三轴试样产生明显的塑性破坏特征；相同含水率条件下，风化砂的黏聚力随含水率先增后减、内摩擦角单调递减，存在最优含水率区间；含砾黏土的黏聚力单调递减、内摩擦角先增后减，试样峰值强度随围压升高呈线性递增。并由此给出了不同填料抗剪强度与含水率的相关关系。研究成果为丘陵山区公路路基稳定性分析及灾害防控提供试验支撑。

Abstract: The genetic terrain of highways in hilly and mountainous areas of China is complex, and disasters such as roadbed landslides and settlement deformations occur frequently, seriously threatening the safe operation of highways. However, when conducting slope stability analysis, the calculation results are often affected due to the large particle size of the filling material and the difficulty in obtaining its mechanical properties. Therefore, in order to solve this problem, considering the influence of confining pressure and moisture content, the shear mechanical properties of weathered sand, gravel clay, and angular gravel commonly used in hilly and mountainous areas were revealed through large triaxial shear tests on coarse-grained soil. The results indicate that triaxial specimens of gravel clay exhibit significant plastic failure characteristics under loading; Under the same moisture content conditions, the cohesion of weathered sand increases first and then decreases with moisture content, and the internal friction angle decreases monotonically, indicating the existence of an optimal moisture content range; The cohesion of gravelly clay decreases monotonically, and the internal friction angle first increases and then decreases. The peak strength of the sample increases linearly with the increase in confining pressure. Thus, the correlation between the shear strength and the moisture content of different fillers was given. The research results provide experimental support for the stability analysis and disaster prevention of highway subgrades in hilly and mountainous areas.