Study On Deformation And Strength Characteristics Of Unsaturated Soils In Three Gorges Reservoir Area

The researches about the fundamental properties of unsaturated soils such as the permeability, shear strength and constitutive model are the basis and starting points of analyzing unsaturated soils mechanical characters as well as developing numerical simulations, and they are also the key to study the landslides with unsaturated soils. As far as unsaturated soils are concerned, there are very important realistic senses to gain abundant experimental data for the foundation and development of theory frame, however, the experimental data are very scarce due to the complexities of the testing instrument and experimental method.With the conjunction of the project of Three Gorges Reservoir area geologic disaster prevention and research of National Land and Natural Resource, the unsaturated soil of Three Gorges Reservoir is the key point. Firstly, this paper summarizes the main background of experimental researches, and then the research history and current status of unsaturated soil strength and deformation, then narrates the essential theory and methods about every experimental research. Experiments were commenced from four aspects, with the experimental principles recounting and testing instrument introducing, then the experimental data were listed and analyzed to draw the conclusion.1) measured the basic physical parameters of unsaturated soils in Three Gorges Reservoir area;2) measured the initial sample matric suction using the unsaturated triaxial testing system, which can be used to evaluate the unsaturated soil strength and stress;3) the drying and moisture absorption experiments were executed using the Tempe apparatus, and got the Soil-Water Characteristic Curve (SWCC), permeability coefficients of every stress level were simulated according to the parameters from the SWCC;4) the unsaturated soil strength tests were carried out using the GDS triaxial testing system, then got the Mohr circle and shear strength parameters; the results from different stress paths were compared; meanwhile, the axial strain-stress ratio-volume strain curve of different matric suction and different radial pressure was got, as well as their relationship;The research, which provided the necessary data and reference for Three Gorges Reservoir area geologic disaster, is the basic component of Three Gorges Reservoir geologic disaster prevention and research, and experimental results will be used directly in the project.