水泥改性黄土的抗液化特性与机制
Liquefaction behavior and mechanism of cement-stabilized loess
-
摘要: 以改性处理减轻饱和黄土的液化势为目标,通过对不同配比的水泥改性黄土进行SEM细观结构测试和动三轴液化试验,研究了水泥改性黄土的液化特征,得出了不同配比水泥改性黄土的动残余应变和动孔隙水压力发展趋势,分析了水泥固化饱和黄土的物化机制,并基于试验结果,提出了水泥改性黄土的最佳配比。结果表明:水泥改性处理在黄土中形成了凝块状胶接结构,优化了土中孔隙分布,增大了土体的结构强度;水泥对土体的密实效应、掺加水泥导致的细粒增加和离子交换对黄土结构的胶结效应和黏粒增加对土中游离水的吸附作用共同提高了水泥改性黄土地基的抗液化稳定性;水泥掺量大于3%后,水泥改性黄土的动残余应变和孔隙水压力随着振次的增加均增长缓慢,且在m=5%时峰值最小,表明5%是水泥改性黄土地基抗液化处理的最佳配比。Abstract: Using modification treatment to reduce the liquefaction potential of saturated loess, on the basis of SEM tests and dynamic triaxial tests on the cement-stabilized loess with different proportions, the evolution laws of its dynamic residual strain and pore water pressure are obtained, and its physical and chemical mechanism are analyzed. In addition, the optimum proportion of the cement-stabilized loess is suggested based on the test results. The results show that the cement modification treatment leads to clotted cementation structure in the soil, which optimizes the pore distribution in the soil and increases the structural strength of the loess. The anti-liquefaction stability of the cement-stabilized loess foundation is improved by the compact effect of the cement to the soil, the cementation effect of loess structures caused by adding cement to increase fine particles and ion exchange and the adsorption effect of free water caused by the increase of clay in the soil. The dynamic residual strain and pore water pressure of the cement-stabilized loess increase slowly with the increase of vibration times when the cement content is larger than 3%. Their peak values are the smallest when the cement content is 5%, which shows that 5% is the optimum proportion of anti-liquefaction treatment for the cement-stabilized loess foundation.