Research On Characteristics Of Deformation And Strength As Well As Moisture Retention Of Loess In Yan’an New Area

Taking the first phase of turning the mountain into plat ground project of yan’an new district as background, the research is based on the unsaturated soil mechanics and the characteristics of deformation and strength and moisture holding capacity of the undisturbed Q3 loess and remolded loess with three dry densities are studied by unsaturated triaxial tests.To study the deformation and strength of loess, do four groups, a total of 36 triaxial consolidation draining shear tests with control matrix suction and net confining pressure. Including the undisturbed Q3 loess and remolded loess with three dry densities. The test results show that the damage form and characteristics of the deformation and the strength have an remarkable influences with dry density and matric suction; The relation curves of stress and strain from the strain hardening model transform to the ideal elastic-plastic model then to the strain softening model gradually with the increasing of dry density; The greater dry density and suction have the more obvious dilatancy and have the higher the strength; the cohesion and the friction Angle of the suction and the internal friction angle increased with the increasing of the dry density; The friction angle of unsaturated loess soil has little change with the change of matric suction, but the cohesion has a linear increase with the increasing of matric suction; The initial tangential modulus and the volumetric deformation modulus improved with the increasing of the dry density and the suction. The strength expression and the nonlinear model parameters including impact of dry density and suction and values of relevant parameters of the soil are proposed according to the test disciplinarian, which could be forecast the parameters of the strength and deformation of remolded loess soils under different densities and different matric suction, can be used as a reference in numerical simulation and field applications.To study the moisture holding capacity of loess, using four triaxial shrinkage tests to study the general soil-water characteristic curve with net confining pressure take into consideration. The test results show that the higher net confining pressure, the lower moisture content; fitting the soil-water characteristic curve with VG model, to study the change rule of model parameter by the influence of net confining pressure; forecasting hydraulic conductivity of the unsaturated loess based on the fitting model.In this paper, the research achievements that deepen the understanding of unsaturated loess mechanics characteristics and enrich the theory of strength and deformation of unsaturated loess, can offer helpful data and scientific basis in the loess area for the design and construction.