Analysis of the parallel seismic method for foundation reuse

Abstract

The focus of this thesis is the application of the Parallel Seismic method to determine the depths of unknown foundations. The method involves exciting stress waves in the pile foundations from impacts on the superstructure and recording waves radiating from the foundation in an adjacent borehole or seismic cone penetrometer (SCPT) sounding at different depths. The primary objective of this thesis is to determine the most effective procedures for collecting and analyzing Parallel Seismic data under real world conditions. The specific topics covered in this thesis include: (1) detectability of P-wave and S-wave arrivals under different field and measurement conditions, (2) comparisons of wave recordings using a 3-component borehole sensor with readings obtained using the Missouri Department of Transportation's (MoDOT's) SCPT sensor which lacks a vertical-oriented component, (3) comparing the accuracy of depth estimates using three data interpretation methods, and (4) using simulated wave arrival data to study the effects of battered piles and pile taper on the accuracy of Parallel Seismic measurements. Data were collected from two bridge sites in Southeast Missouri (Route WW and Route U) for four piles at each site using two boreholes and two SCPT soundings at each site. Unfortunately, the depth of penetration of the boreholes and SCPT was not sufficient at one of the sites (Route WW) so most of the observations are from data collected at the Route U site. The interpretation methods applied to the data were a simple intersection method performed by eye, the intersection method with a depth correction applied, and a curve fitting method using a model of wave arrivals.