| For a long time in engineering design,soil mechanics parameters is mostly according to the reduction results of load test which is used by the deformation calculation and stability analysis of unloading engineering.But the stress condition and stress path of soil under unloading is different from it under loading.So the research of unloading characteristics and parameters have important theoretical and practical value.In this paper,unloading mechanical properties of remodeled loess would be researched according to the unloading test of one and three dimensional and the one-dimensional unsaturated soil unloading test.The conclusion is as follows:Firstly,a one-dimensional unloading features in different preloading load,initial dry density and moisture content conditions and the initial dry density and water content on the influence degree of the springback amount were obtained according to one-dimensional unloading test.The loess critical unloading ratio range was also be obtained.The relationship between unloading modulus Er and unloading ratio R was obtained according to the comparison of compression modulus Es and unloading modulus Er.The changing rule of unloading modulus with the initial dry density and moisture content was researched when unloading ratio R=1 and the function formula and a new calculation method for unloading the springback amount of loess were obtained.Secondly,one-dimensional unloading experiment of unsaturated loess was carried out by using the unsaturated consolidation apparatus.The deformation characteristics between compression and unloading was compared in the test.The change rule of one dimensional unloading deformation characteristics and the unloading parameters was obtained.The matrix suction’s influence range of unloading deformation characteristics and unloading parameter was obtained according to researching the relationship between void ratio and the vertical pressure.Thirdly,the self-made simple loading and unloading device of three dimensional was designed and debugged.Test process,the sample’s standard,the steps and the matters needing attention were formulated for this instrument.Three-dimensional unloading test of loess was completed by using this instrument.With the initial dry density and consolidation confining pressure as variables,deformation and strength properties of remodeled loess was obtained under the condition of three dimensional unloading. |
