Study of large-scale shaking table proportional model test of the dynamic property of foundation in unfreedom ground of liquefaction

On the basis of the large-scale shaking table 1:10 scale model test, the dynamic property of foundation in unfreedom ground of liquefaction is studied. In ground of liquefaction, compared to freedom foundation, the self-vibration frequency of unfreedom foundation obviously increases, yet its property of dynamic energy dissipation improves a little. Before liquefaction of soil and in input of a small shake, the dynamic deformation of foundation mainly appears linear characteristics, which primarily exhibits in the amplification effect to earthquake waves, the response of acceleration gradually strengthens from bottom to top. After soil liquefied entirely, the response of foundation acceleration also gradually strengthens from bottom to top, which is that the shear movement between layers of liquefied foundation is accelerated and the increased speed of the shear movement is gradually accelerated from bottom to top. The variation of pore pressure in foundation is primarily affected by following two factors: the first is that with depth decreasing, the pore pressure will decrease while the pore pressure ratio will increase; the second is that the smaller the distance to a pile, the bigger the pore pressure and pore pressure ratio. Before soil liquefied, and when the primary peak of inputted waves has gone, the dissipation of pore pressure becomes gradually slower from bottom to top. While inputting a bigger shake, the pore pressure is in the tendency of lowing from bottom to top, but the peak pore pressure ratio all arrives at the liquefaction pore pressure ratio, and when the primary peak of inputted waves has gone, the pore pressure dissipates very slowly, particularly the dissipation of pore pressure becomes slower and slower with the decrease of depth. In this test, it is occurred that an interesting phenomena of transient minus pore pressure is perhaps attributed to the transient shear swell effect of liquefaction soil.