Time-Dependent Dynamic Characteristics of Model Pile in Saturated Sloping Ground during Soil Liquefaction

Time-Dependent Dynamic Characteristics of Model Pile in Saturated Sloping Ground during Soil Liquefaction

In order to quantify the relation of reduction of soil stiffness and excess pore water pressure during liquefaction, the test data of a series of shaking table tests on model pile in saturated sand using a large biaxial laminar shear box conducted at the National Center for Research on Earthquake Engineering were analyzed. The test results showed that the frequency changes of model pile was dependent on the response of water pressure ratio. The pile top was mounted with 6 steel disks to simulate the superstructure. In addition, strain gauges and mini-accelerometers were placed on the pile surface to obtain the response of the pile under shaking. Therefore, the model pile can be considered as a sensor to evaluate the changes of dynamic characteristics of soil-pile system during the shaking by using the time-frequency analysis and system identification technique. The relation of stiffness of soil and pore water pressure ratio due to liquefaction during shakings were also studied.