风化砂改良膨胀土机理及边坡稳定性分析

Improving mechanism of expansive soil by weathered sand and slope stability analysis

研究了风化砂改良膨胀土的作用机理,揭示了风化砂与膨胀土发生的物理化学反应,得到了风化砂掺量与膨胀土的胀缩特性及强度特性之间存在的关系.结合宜昌市小溪塔至鸦鹊岭一级公路施工项目,采用条分法对填土高度为10 m路堤的整体稳定性进行了分析.结果表明:现采用原状膨胀土填筑路堤安全系数较小,不能满足规范要求;而采用风化砂改良之后的膨胀土填筑的路堤边坡稳定系数比原状膨胀土均有显著提高,能够满足规范要求;路基的安全系数随着掺砂比例的增加先增大后减小,当掺砂比例达到20%,改良膨胀土填筑的路基安全系数达到最大值.

The improving mechanism of expansive soil by weathered sand was investigated through the indoor experiment.The physical and chemical reactions between weathered sand and expansive soil were revealed to discuss the relationship between weathered sand content and swelling shrinkage characteristics of expansive soil.Based on laboratory experiments,for the first-class highway rebuilding engineering construction project from Yichang Xiaoxita to Yaqueling,the overall stability analysis of embankment with 10 m height was conducted by strip method.The results show that the safety coefficient of embankment with natural expansive soil is small,which can not meet the specification requirements.Compared with the embankment with undisturbed expansive soil,the slope stability coefficient of embankment with weathered sand improving expansive soil was significantly improved,which can meet the code requirements.With the increasing of sand mixing ratio,the safety coefficient of subgrade is increased first with later decrease.When the sand ratio reaches 20%,the maximum safety coefficient of improved expansive soil filling roadbed is achieved.