【摘要】 对不同掺入量粉土和石灰的改良膨胀土试样开展了物理力学特性及微观电镜扫描试验，分析其改良机理；在此基础上，采用GDS动三轴仪开展改良土动三轴试验，研究不同动应力幅值、含水率、循环湿化次数对改良膨胀土动力累积变形的影响规律，并构建了改良膨胀土累积变形预测模型。研究结果表明：掺入2.5%的低剂量石灰既可以通过“砂化”作用提高粉土和膨胀土的拌和性，又能提高单一粉土物理改良土的强度和水稳性；掺入粉土可改善膨胀土颗粒级配，增大土体孔隙率，抑制膨胀土的膨胀潜势，并提升改良土加州承载比(CBR)值；研究中采用40%粉土联合2.5%石灰改良膨胀土可满足公路路基填料各项指标要求；循环加载初期，改良土累积应变增长迅速，前2 000次循环加载后，改良膨胀土累积应变占79.3%,随后累积应变增长速率趋于稳定，呈塑性安定型；改良土最终累积应变与循环湿化次数成幂函数增长关系；最不利工况下最终累积应变小于1.0%,工后变形满足路基长期稳定性要求；构建的考虑动应力幅值、含水率及湿化次数影响的动力累积应变预测模型，可为粉土石灰改良膨胀土路基长期变形估算提供依据。更多还原

【Abstract】 The physical and mechanical property and microscopic electron microscope scanning tests were conducted on improved expansive soil samples with different silt and lime content. The improvement mechanism was analyzed. The dynamic triaxial test of the improved soil was carried out using the GDS dynamic triaxial apparatus. The influence rules of different dynamic stresses, water content, and cyclic wetting times on the cumulative deformation of the improved soil were studied. A cumulative deformation prediction model of improved soil was constructed. The results show that the addition of 2.5% low-amount lime can not only enhance the mixing property of silt and expansive soil through sanding, but also improve the strength and water stability of single silt physically improved soil. The addition of silt can optimize the particle gradation of expansive soil, increase the porosity of the soil, inhibit the expansion potential of expansive soil, and improve the California bearing ratio(CBR) value of improved soil. The requirements of various indexes of highway subgrade filling can be met by employing 40% silt combined with 2.5% lime to improve expansive soil. At the initial stage of cyclic loading, the cumulative strain of the improved soil increases rapidly. After 2 000 cycles of loading, the cumulative strain of the improved expansive soil accounts for 79.3%, and then the growth rate of the cumulative strain tends to be stable, showing plastic stability. The final cumulative strain of the improved soil has a power function growth relationship with cyclic wetting times. Under the most unfavorable conditions, the final cumulative strain is less than 1.0%. The post-construction deformation meets the long-term stability requirements of the subgrade. A dynamic cumulative strain prediction model is constructed considering the influence of dynamic stress amplitude, water content, and humidification times, providing a reference for the long-term deformation prediction of silt-lime improved expansive soil subgrade.更多还原