Study On Deformation Of Normal Consolidated Sand Under Cyclic Loading By Particle Flow Code

Sand is a common kind of ground soil in civil engineering. When it meets cyclic loadings, the deformation may develop with cycles, which may have a bad effect on the safety, stability and utility of the project. Essentially, the mechanics of sand is determined by its microstructure changed. So it is necessary to study sand behavior and its response to cyclic loadings both in macro and micro respects. The PFC2D (2 dimensional particle flow code) is applied to research on this problem. The research works are as below:1. Firstly, the K₀-consolidation was simulated. The velocity of loading, the way of loading, the friction property of particles and the horizontal stiffness of side confinement were considered in simulation. Besides, the utility of the Jaky's formula into PFC2D modeling were also discussed. The results showed that the magnitude of K₀ is irrelevant to velocity of loading or to the way of loading. However, K0 will reduce as the friction of particles increase; The horizontal stiffness has effect on K0 as well. A modification coefficient of 0.72 was suggested when the Jaky formula is used into PFC2D modeling.2. Secondly, the cyclic loading process was simulated while the rate of cyclic shear stress, the way of consolidation and the level of stress state were considered, The results are as below: (a)The residual shear strain and the dilatancy of the sample were appeared more easily as the increment of cyclic shear stress.(b)The shear strain would be large in the first cycle and accumulated in one direction because of the previous shear stress under K₀-consolidation.(c)The volumetric strain would have catastrophic property as the stress level increased.