干湿循环下纤维改良膨胀土强度与微观结构特征研究

Research on Strength and Microstructure Characteristics of Expansive Soil Modified with Fiber under Dry-wet Cycle

为了改善膨胀土的胀缩特性,提高膨胀土抵抗干湿循环的能力,本文以江苏南京原始膨胀土为研究对象,研究了在水泥单独作用和玻璃纤维与水泥联合作用两种改良方式下膨胀土的胀缩特性和抵抗干湿循环作用的能力,并结合微观结构分析探索其改良机理。研究发现:两种改良方式均能降低膨胀土的自由膨胀率和收缩率,提高膨胀土的抗压强度、黏聚力和内摩擦角等参数,并显著提高膨胀土抵抗干湿循环作用的能力;玻璃纤维与水泥联合改良比水泥单独改良效果更好,综合实验结果得出玻璃纤维的最佳掺量为0.6%;微观结构表明水泥和纤维能分别以化学作用和物理作用的方式增强土颗粒之间的黏结性能。上述研究成果能为膨胀土的有效治理提供理论依据。

In order to improve the shrinkage characteristics and the resistance to dry-wet cycle of expansive soil,the original expansive soil in Nanjing was taken as the research object to study the shrinkage characteristics and the resistance to dry-wet cycle of expansive soil modified with cement alone and glass fiber-cement together.The improvement mechanism was explored by microstructure analysis.The results show that both of the two improved ways can reduce the free expansion rate and shrinkage rate of expansive soil.The compressive strength,cohesion and intemal friction angle of improved expansive soil and its resistance to dry-wet cycle are all improved.The improvement effect of glass fiber and cement together is better than that of cement alone and the optimal dosage of glass fiber is 0.6%.The microstructure shows that cement and fiber can enhance the bond of soil particles by chemical and physical interaction,respectively.The above research results can provide theoretical basis for the efective management of expansive soil.