Pile-Soil Interaction of Scaled Model Piles Subjected to Seismic Loading

Abstract

Taiwan is located in Circum-Pacific Seismic Belt and the seabed where offshore wind turbines are installed is mostly composed of saturated sandy soil which is liquefiable during earthquakes To investigate the pile-soil interaction of offshore wind turbines at different levels of liquefaction results of shaking table tests of a scale-model offshore wind turbine with jacket foundation were utilized which were performed using the large shaking table and large bi-axial laminar shear box of National Center for Earthquake Engineering In order to exhibit the variation of dynamic behavior of pile and soil during excitation the data of mini-accelerometers and strain gauges placed on the pile surface and the piezometers in the soil which can be used to monitor pore water pressure were analyzed Three of the seismic loading tests were examined On the basis of Winkler beam theory the bending moment can be obtained through the strain gauges on the pile The distribution function of the bending moment curve of the pile body in the form of 4th order polynomials was obtained by the least square method and by setting proper boundary conditions During the analysis soil resistance(p) can be obtained by twice differentiating the bending moment curve whereas the pile deflection(yp) involves twice integrating the moment curves In addition the measurement of the displacement transducers on the movable frames of the laminar shear box can be treated as the soil displacement(ys) The difference between yp and ys is the relative displacement of pile and soil(y) Thus the p-y curve of the soil before and after liquefaction can be obtained and the coefficients of subgrade reaction can be calculated at different excess pore water pressure ratios

Date of Award	2020
Original language	English
Supervisor	Sheng-Huoo Ni (Supervisor)