干湿循环条件下压实黄土变形特性试验研究

由于降雨及蒸发的周期性变化等原因，压实地基土经常处于干湿交替状态，这种干湿循环作用会影响路基及地基的长期稳定性。通过气压式固结仪测试压实黄土试样经过不同次数干湿循环作用后的侧限压缩应变与垂直压力( - )曲线，研究干湿循环作用对压实黄土变形特性的影响，同时利用已有模型对实测曲线进行拟合，并基于割线模量法分析了割线模量与初始压实度及干湿循环次数的关系。结果表明：初始压实度对黄土的压缩变形有显著影响，不同初始压实度的试样其各级压力下的侧限压缩应变均随着干湿循环次数的增大逐渐增加，之后趋于稳定；初始压实度越高，干湿循环作用影响效应越显著；干湿循环作用并不改变土体 - 曲线的形式；割线模量与干湿循环次数及初始压实度的关系均呈指数关系。

Experimental study of deformation characteristics of compacted loess subjected to drying-wetting cycle

Drying-wetting cycle usually occurs in compacted embankment fill due to periodic variation in precipitation and evaporation, which affects the long-term stability of embankment and subgrade. A series of compression tests are performed to measure the variation in vertical compression strain of compacted loess subjected to cyclic drying-wetting by using pneumatic oedometer apparatus so as to study the effect of drying-wetting cycle on deformation behaviors. The relationships between vertical compression strain and vertical pressure ( - ) at different initial compaction degrees are fitted with the existing models; and the relationships between secant modulus and as well as number of drying-wetting cycle are established. The results show that of compacted loess tend to increase with numbers of drying-wetting cycles and then keep fairly stable after 5-7 cycles; Moreover, the increment of remarkably affect by . The - curve of compacted loess can be depicted by the Gunary model exactly under uniaxial compression condition, and its behaviors are unchanged due to repeated drying-wetting cycle; The relationship between and as well as also can be formulated in exponential form without considering the effect of water content. It can be concluded that the change in deformation behaviors is irreversible after the compacted loess is subjected to drying-wetting cycle.