Fluid characteristics dependent on excess pore water pressure of saturated sand after growth of pore pressure

Shaking table model tests on free ground consisting of saturated liquefiable Nanjing fine sand are designed and accomplished. According to the acceleration response measured at different depths, the shear stress and strain of the model soils are obtained using the linear interpolation method conversion. Furthermore, based on the principles of fluid mechanics, the evolution characteristics of dynamic apparent viscosity of the saturated sand during the build-up of the pore water pressure are studied. The test results show that the dynamic apparent viscosity decreases with the growth of shear strain as well as the increase of shear strain rate during the sinusoidal wave excitations. In addition, a typical shear-thinning non-Newtonian fluid feature is discovered. Moreover, the excess pore pressure ratio plays a significant role in the development and change of apparent dynamic viscosity of saturated sand, and the apparent dynamic viscosity decreases as the excess pore pressure ratio increases; besides, the relationship curve of the apparent dynamic viscosity and pore pressure ratio can be well fitted using the power function. Additionally, the relationship curve of the apparent dynamic viscosity and pore pressure ratio might not be dependent on the effective overburden pressure. However, this conclusion needs further verification.