不同粗糙度等级对冻土–混凝土界面剪切特性研究

Research on the Shear Characteristics of Different Roughness Grades at the Interface between Frozen Soil and Concrete

摘要: 冻土–混凝土界面的剪切力学特性是寒区基础工程抗冻胀设计的关键参数，其受界面粗糙度、法向应力与含水率的综合影响。本研究通过直剪试验，系统分析了不同界面粗糙度等级、法向应力及土样初始含水率条件下界面冻结强度的演化规律。试验结果表明：所有试样的剪切应力–剪切位移曲线均呈现应力软化特征。界面峰值剪切强度和冰胶结强度均随粗糙度等级提高而增大，但残余强度的增幅相对较小。伴随粗糙度等级提升，冰胶结强度对冻土–混凝土界面抗剪强度的贡献比例逐渐增加。峰值强度和残余强度均随法向压力增大而提高。峰值粘聚力随粗糙度等级提高而增大；残余粘聚力则随细粒含量增加而降低。峰值内摩擦角与残余内摩擦角均随粗糙度等级增大略有上升。

Abstract: The shear mechanical properties of the frozen soil-concrete interface are the key parameters of frost heave resistance design of foundation engineering in cold regions, which are affected by the combination of interface roughness, normal stress and moisture content. In this study, the evolution of interface freezing strength under different interfacial roughness grades, normal stress and initial moisture content of soil samples was systematically analyzed through direct shear tests. The test results show that the shear stress-shear displacement curves of all samples show stress softening characteristics. The peak shear strength of the interface and the ice cementation strength increased with the increase of roughness level, but the increase of residual strength was relatively small. With the increase of roughness level, the contribution of ice cement strength to the shear strength of the frozen soil-concrete interface gradually increased. The peak strength and residual strength increased with the increase of normal pressure. The peak cohesion increased with the increase of roughness level. The residual cohesion decreased with the increase of fine particle content. The peak internal friction angle and the residual internal friction angle increased slightly with the increase of roughness level.