Study On The Laboratory Test Of Rheological Characteristic Of Soft Clay And Long-term Strength

With the development of economy and social, the infrastructure projects must be done synchronization. During civil engineering constructing, it ofren happens that many projects build on the soft soil ground. The analysis of soft soil foundation deformation and stability play an important role in the designation and construction of geotechnical engineerings. Many buliding accidents are pay more attention resulted in non-uniform settlement or high settlement which caused by rheology characters of soft soil or slope disstability by long-term strength changed. Soft clay distributed in our country deposit in middle or late of the holocene epoch, which has the characteristic of higher water content, higher compressibility and lower permeability, higher sensitivity, bigger void ratio, lower shear strength, worst permeability and more obviously rheological characteristic, Some of which lies under compact hard soil horizons. The relation with stress and strain is not explained with very satisfaction by the methods of classical dynamics. So we must make a deeper research for rheology characters soft soil. At the same time, to study about soil engineering characters on the project, the rheology characters of soil is studied by triaxial shear-creep apparatus of stress-control under consolidation and drained.The main content in this paper are studied on the laboratory test of rheological characters of soft clay and long-term strength on the basis of papers abroad and in. The main work of the thesis is as follows:1 .In this paper study on soil rheology are simply narrated;The study of methods and achievements on rheological characters of soil and rheological models and its characters are summaried;the uses of rheological model are narrated.2. Consolidated-drained-shear-creep triaxial tests are made on soft soil which is from Shantou-Jieyang highway at the same temperature. Systematic test dates aboutε_a,ε_v,ε_sand time are achieved under different cell stress and stress level.Rheology characteristic of soft soil in Shantou-Jieyang highway are analysised according to test datum.3.A new 3D rheology model,which may influence on stress states is built on the basis of Mitchell's linear of strain-speed and time and according on test datum, and a new long term strength model is brought up on the basis of the equitime curves of stress-strain. It is concluded that long-term strength is bigger than standard strength on the condition of drainage by consolidation.4.Settlement deformation of soft soil foundation of Shantou-Jieyang highway is analysised by this new rheology model and rheology model of Plaxis FEM. Compared with the observational datum, the model is proved to be feasible and exactitude.