Experimental Research On Deformation Characteristics Of Unsaturated Loess

Loess is distributed widely in the arid and semiarid regions of China, Its special physical and mechanical properties, especially the special deformation character and its unique sensitivity to the water can affect the practical application in engineering. Soil deformation is closely related to the earth structure, the foundation seepage, the stability, and the settlement issues. Based on the unsaturated loess compression tests, rebound tests and re-compression tests, this paper is about the research on loess deformation through the whole stage of compression, rebound and recompression. The main work and achievements are as follows:(1) In this paper, a lot of reading and analysis on the basis of relevant literature have been done to summarize the main factors affect the deformation of loess. The main factors affected the unsaturated loess deformation such as the degrees of compaction; the water contents and axial compression have been analyzed through experiments.(2) After the analysis between the void ratio and the logarithm of compression, a formula has been set up to describe loess deformation. The loess deformation characters can be described through which coefficient dominant the deformation stage.(3) After giving the same pre-consolidation pressure, the final void ratio of loess samples which had a high initial degree of compaction is lower than the samples with a low initial degree of compaction in low water contents, but in the high water contents condition, the final void ratio of loess samples which had a high initial degree of compaction is little higher than the samples with a low initial degree of compaction.(4) After the time-history analysis of unsaturated loess, a fitting model of strain- time relation has been established based on Konder hyperbola relation, which can be used to forecast the whole stage of loess deformation, and the relation between the coefficients in this model and the factors such as axial stresses and water contents have been analyzed.(5) Some conclusions have been got through analysis of over consolidation ratio: with the increase of over consolidation ratio, the rebound quantity is increase and the increase ratio would be slow down while the over consolidation ratio is increase; there is a linear relationship between the logarithm of over consolidation ratio and the rebound quantity.(6) The different characters have been analyzed through the comparison of curve between the void ratio and the logarithm of compression between the rebound stage and the re-compression stage.