The Research On Sandy Soil Subgrade's Wetting Deformation

It is one of the long-term concerning probleme of wetting deformation in the field of Geotechnical engineering. By reviewing the available literature of our country and abroad ,and join together with the fact of K91 ?K94 segment of shen-shan superhighway, thorough research has been done on the wetting deformation of sandy soil in this paper. As a result,the characteristic of sandy soil's wetting deformation has been drawn. All of these , conclusions are valuable and will practice to the Geotechnical engineering.Making use of the three axis shear instrument and matching to the actual circumstance in engineering , the soil sample wet and turn to saturation gradually in the experiment. Under the control of stress condition, many wetting experiment have been done about different stress condition and different density of sandy soil. The result of wetting experiment expresses that wetting of sandy soil can not only cause considerable change of additional axial strains but also can cause very bigly additional volume changes. Based on the results of the wetting experiment, the Duncan- Chang's non-linear model of sandy soil is established before and after wetting, as a result ,the mold of deformation and parameter of Duncan- Chang's non-linear model decreased after wetting. At the same time ,it can be concluded that the relativity density of sandy soil is an key factor of the wetting deformation. The amount of wetting deformation decreased quickly with the increase of relativity density of sandy soil.According to the Duncan- Chang's non-line model of soil and based on the theory of wetting deformation , the finite element method (FEM) calculation model of sandy soil subgrade is established. The displacement and stress of sandy soil subgrade are calculated before and after wetting. Based on these conclusions, the stability of the sandy soil subgrade is evaluated.Based on the stochastic finite element method(SFEM) and Duncan- Chang's non-linear model, the stability of sandy soil subgrade and its slope after wetting are researched. The reliability index of slope stability is calculated by non-linear SFEM. Theresults obtained by the non-linear SFEM sufficiently agree with the results of deterministic non-linear FEM. All of these conclusions suggested that the sandy soil subgrade and its slope have sufficiently reliability index and will not lose steady after absorbing water.