Travel-time Inversion of Parallel-seismic Data for Foundation Length Estimation

The parallel-seismic method for foundation length estimation has proven to be one of the most reliable and versatile methods for foundation (mostly piles) length estimation. The interpretation is mainly based on simple graphical interpretation of the seismograms or first arrival travel-time curves. Recently introduced methods lead to better estimation but still contain several approximations. Intensive paramter studies have been carried out using the CEFIT simulation technique. The influence of certain geometry parameters as well as material changes in pile and soil have been studied. Based on theses studies improved algorithms have been developed to predict first arrival times. They are used as forward operator in inversion schemes based on the Levenberg-Marquardt method and Simulated Annealing. The advantages and limitations of both methods have been tested by simulated and field data. The developed methodology and software programs are currently used in field studies leading to improved foundation length estimations.