Laboratory tests on flow characteristics of liquefied and post-liquefied sand

According to the theory of dropping ball viscosimeter,the test apparatus of flow characteristics of liquefied and post-liquefied sand is developed based on the shaking table tests.A steel sphere,embedded in the sand box,can be moved in the horizontal direction when the soil liquefaction occurs.Resistance force and velocity are measured during sphere dragging and apparent viscosity is evaluated.The initial relative density of the deposited sand,the velocity of the sphere and excess pore pressure ratio are the main factors in the tests.The results show that the apparent viscosity of the liquefied and post-liquefied sand decreases with the increase of the strain rate.The liquefied and post-liquefied sand is shear thinning non-Newtonian fluid.The apparent viscosity of the post-liquefied sand increases with the decrease of the excess pore pressure ratio,and the curve slope of the apparent viscosity vs.the excess pore pressure ratio decreases with the increase of the strain rate.