掺黏粒改良粉土的土水特征试验研究

Test Study on Soil-Water Characteristics of Clay Improved Silt

以河南开封金明大道北延道路路基工程低液限粉土为研究对象,通过滤纸法测定不同黏粒含量、压实度的粉土土水特征曲线,研究其基质吸力变化规律;采用扫描电镜试验从微观结构演化角度分析其影响机制。结果表明:加州承载比CBR值随黏粒含量与压实度的增加均单调增大;不同压实度下掺黏粒改良粉土的饱和含水率均随黏粒含量的增加呈先增大后减小趋势;任一黏粒含量下,土水特征曲线具有明显的阶段性特征,黏粒含量为15.5%、20.5%、26.5%的土水特征曲线存在基质吸力保持相对恒定的平台期;黏粒含量的增加使得重塑土样的微观结构逐渐紧密,粉黏粒间的接触方式由线或面的接触逐渐转变为胶结及包裹镶嵌作用。根据规范要求,掺黏粒改良粉土可应用于公路路基填筑。

Taking the low liquid limit silt of the subgrade engineering along the northern extension line of Jinming Ave.,Kaifeng,Henan as an example,its soil-water characteristic curve in different clay content and compaction degree were measured by means of filter paper so as to study the change law of the matric suction and,through scanning electron microscope test,the impact mechanism was analyzed from the point of microstructure evolution.The research shows that,California bearing ratio(CBR)increases monotonically with the increase of clay content or compaction degree;under different compaction degree,the saturated water content of clay improved silt increases first and then decreases with the increase of clay content;under any clay content,the soil-water characteristic curve is of obvious periodic feature and,when the clay content is 15.5%,20.5%and 26.5%,there exists on the curve a plateau phase where the matrix suction remains relatively constant;the increase of clay content allows the remolded soil sample to get gradually compact microstructure,and the contact mode between silty clay particles changes from line or surface contact to cementation,encapsulation and insertion gradually.According to the specification,clay improved silt can be applied to highway subgrade filling.