干湿循环下石灰改良膨胀土特性研究

为研究干湿循环下石灰改良膨胀土特性，进行了击实试验、自由膨胀率试验、裂隙发育试验及固结快剪试验。结果表明:随石灰含量增加改良膨胀土自由膨胀率显著降低，干湿循环条件下，石灰掺量为3 %时出现细微裂隙且表面脱落，5 %时未出现可见裂隙，表面局部脱落，7 %时未产生明显裂隙；内摩擦角和黏聚力随石灰含量增加而增大，干湿循环过程中内摩擦角基本保持不变，而黏聚力在第一次干湿循环后降低35 %，后续基本保持不变，根据现场施工和经济性，建议石灰掺量宜选5 %。

Study on Characteristics of Lime Improved Expansive Soil under Wetting-drying Cycles

In order to study the characteristics of lime improved expansive soil under wetting-drying cycles, compaction test, free swelling ratio test, fissure development test and consolidated quick direct shear test were carried out. The results show that, as the lime content increases, the free swelling ratio is significantly reduced; under wetting-drying cycles condition, there appear micro fissures and surface peeling when the content of lime is 3 %, when 5%, there are no visible fissures and has partial surface peeling, and when 7 %, there are no obvious fissures; the internal friction angle and cohesion increase with the lime content and, under wetting-drying cycles, the internal friction angle remains unchanged basically, while the cohesion decreases by 35 % after the first dry-wet cycle and then keep the same subsequently. According to the site operation and economical efficiency, it is suggested that the content of lime should be 5 %.