Experimental study on moistening deformation characteristics of compacted loess and their influencing factors

As a building material, the loess is usually required to be compacted in engineering construction, thus the deformation characteristics of compacted loess with the increase of water content are closely related to the safety of the project. The compressible and collapsible deformations of the compacted loess with the increase of water content are studied using collapse tests carried out with the double line method, and their influencing factors are investigated by both single and multivariate analyses of variance. The research results indicate that: (1) With the increase of moistening water content, the compressibility of compacted loess increases, and the collapse property decreases; the smaller the degree of compaction, the more obvious the effect; the sensitivity of collapsible deformation to moistening water content is different under different pressures; (2) With the increase of moistening water content, the initial pressure of moistening collapse decreases, the termination pressure of moistening collapse increases, and the collapsible pressure range increases. The moistening collapsibility coefficient can be used to reflect the collapsibility degradation degree under the existing moistening water content; (3) The single and multivariate analyses of variance indicate that the final amount of deformation is affected mainly by the ultimate pressure, and the influences of loading path, immersion path and their coupling path are very small; (4) Three influencing factors of compaction degree, initial water content and pressure, and their interaction have significant influences on the compressible deformation; (5) Three influencing factors of compaction degree, initial water content and pressure, and their interaction have significant influences on the compressible deformation under unsaturated compression, and the influences of pressure are the largest, followed by the density and initial moistening water content; compared with those of the unsaturated compression, the influences of the initial moistening water content on compressible deformation are very small; (6) Three influencing factors of water content, compaction degree and pressure, and their interaction have significant influences on the collapsible deformation, and the influences of the initial water content are the largest, followed by the compaction degree, and the influences of pressure are the least.