Study On Wetting Deformation Characteristic Of High Liquid Limit Red Clay In Southern Hunan

High liquid limit red clay caused wetting deformation under the influence of water andother natural factors, which will cause engineering diseases such as instability of side slop,highway frost boiling, etc, and bring serious hidden dangers to the engineering. Thisdissertation chooses high liquid limit red clay in Southern Hunan as the research object andreveals the wetting deformation behavior of high liquid limit red clay through the triaxialapparatus of wetting tests. This report comprises to be analysed:(1) Based on the principle of filter paper method of unsaturated soil,a new matric suctionmeasurement device was made,and it was used to study the influence of dry density andtemperature on SWCC of high liquid limit red clay. The results indicate that dry density andtemperature have great effect on SWCC of high liquid limit red clay. Under the samesaturation,the matric suction decrease with the increase of dry density and temperature.Thesaturation is linear with the logarithm values of matric suction.(2) Starting from the idea of double-line method in this article, the subject test is dividedinto two parts: tests of dry soil samples and wetting soil samples. In order to analyze thecharacteristics of wetting deformation of high liquid limit red clay from different perspectives,the experiment is designed on the ground of different confining pressures and differentdegrees of compaction. Desiccation crack and wetting test is also carried out on the soilsamples with0.9degree of compaction to simulate the phenomena that high liquid limit redclay caused wetting deformation after embankment desiccation cracks tends to occur whileexposed to the high temperature of scorching sun in actual practice of engineering. Tests showthat the shear strength of high liquid limit red clay would be reduced after wetting ordesiccation crack and wetting, and desiccation and wetting crack and wetting decreases hard.(3) Through the collection and analysis of test data, Duncan-Chang model parameters ofdry samples and wetting samples under different degrees of compaction were calculated. Asthe result shows, high liquid limit red clay’s Duncan-Chang model parameters changed afterwetting. At the same time, it can be concluded that the degree of compaction and confiningpressure of high liquid limit red clay are major factors of the wetting deformation, and theamount of wetting deformation decreased quickly with the increase of the degree ofcompaction and confining pressure of high liquid limit red clay. (4) Because the initial state of compaction of high liquid limit red clay has effects on therules of deformation, several simple models that adapt to different initial compaction areproposed to calculate their wetting deformation in this article. At the same time, formula forcalculating the wetting deformation which is applicable to three kinds of initial compaction islaunched based on the idea of double-line method combining hyperbolic model of soil, andvalues of relevant parameters are proposed, which can be applied in analyzing the rules ofembankment wetting deformation.