干湿循环下石灰改良膨胀土特性研究

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

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%。

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 drywet 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%.