干湿循环下粉砂土改良膨胀土强度特性分析

干湿循环作用对膨胀土地基有较显著的影响，以黄泛区粉砂土改良膨胀土为研究对象，为研究改良膨胀土的强度受干湿循环作用的影响，设计并进行了不同含水率和干湿循环次数对改良膨胀土作用的直剪试验。试验发现：反复的干湿循环作用后，土体由于干缩产生裂隙，试件结构被破坏，整体稳定性下降，强度降低。改良膨胀土的抗剪强度和干湿循环次数呈负相关；前三次干湿循环作用时，土体粘聚力下降较迅速，随后几次干湿循环粘聚力下降幅度较小；随干湿循环次数的改变，内摩擦角基本没有较大幅度的变化。

Study on Dry-wet Cycle Strength Characteristics of Improved Expansive Soil of Silty Sand along the Yellow River

The dry-wet cycle has a significant influence on the foundation of expansive soil. To study the influence of dry-wet cycle on the strength of improved expansive soil. Direct shear tests of different moisture content and the number of dry-wet cycles on the improved expansive soil were designed and carried out. It is found that after repeated dry and wet cycling, the soil mass will crack due to dry shrinkage, and the specimen structure will be destroyed, the overall stability will decrease, and the strength will begin to decrease. The shear strength of modified expansive soil was negatively correlated with the number of dry and wet cycles. During the first three cycles of dry and wet cycling, the cohesiveness of soil decreased rapidly, and the subsequent cycles of dry and wet cycling decreased slightly. With the change of the number of wet and dry cycles, the internal friction Angle did not change significantly.