基于冻融作用的固化硫酸盐渍土-混凝土界面力学行为

冻融作用下固化盐渍土强度发生劣化并影响土体与结构的相互作用。鉴于此，开展了不同固化剂对硫酸盐渍土力学特性的影响研究并得知石灰+硅灰双掺改良效果显著；在此基础上，探索了石灰-硅灰双掺固化剂、含盐量、冻融次数等因素对非饱和固化硫酸盐渍土-混凝土接触面力学性能的影响。结果表明， 石灰-硅灰固化硫酸盐渍土与混凝土界面内摩擦角随着冻融循环次数的增加先增大后减小再增大，黏聚力随着冻融次数的增加逐渐减小，接触面抗剪强度随着冻融次数的增加先增加后逐渐减小并趋于稳定；在相同的冻融次数下，接触面的内摩擦角及黏聚力均随着含盐量的增大先增大后减小，两者含盐量阈值分别为3%和2%。在本试验范围内，5%石灰+10%硅灰对含盐量为2%~3%的硫酸盐渍土改良效果较好；冻融前后，固化盐渍土-混凝土接触面剪应力-剪切位移曲线分为四个阶段：弹性变形阶段、强化阶段、软化阶段及流动阶段。

Study on mechanical behavior of solidified sulfuric acid saline soil concrete interface based on freeze-thaw

The strength of solidified saline soil deteriorates and affects the interaction between soil and structure. In view of this, the effects of different curing agents on the mechanical properties of sulfuric acid saline soil are studied, and it is found that the improvement effect of lime + silica fume is remarkable; On this basis, the effects of lime silica fume mixed with curing agent, salt content and freezing and thawing times on the mechanical properties of unsaturated solidified sulfuric acid saline soil concrete interface were explored. The results show that the internal friction angle between lime silica fume solidified sulfuric acid saline soil and concrete first increases, then decreases and then increases with the increase of freeze-thaw cycles, the cohesion gradually decreases with the increase of freeze-thaw cycles, and the shear strength of the contact surface increases with the number of freezing and thawing ,then gradually decreases and stabilizes; Under the same freeze-thaw times, the internal friction angle and cohesion of the contact surface first increase and then decrease with the increase of salt content. The salt content thresholds of the two are 3% and 2%, respectively. Within the scope of this experiment, 5% lime + 10% silica fume has a good effect on the improvement of sulfuric acid saline soil with salt content of 2% ~ 3%; Before and after freezing and thawing, the shear stress shear displacement curve of solidified saline soil concrete contact surface is divided into four stages: elastic deformation stage, strengthening stage, softening stage and flow stage.