DOI: 10.17603/ds2-g348-kk89
title: 3D Full Waveform Inversion Test Conducted at the Construction Site of the New Washington State Convention Center Building Located in Downtown Seattle, WA
title: in RAPID Collaborative Research: Spatial variability of small-strain stiffness, Go, and the effect on ground movements related to geotechnical construction in urban areas (field and laboratory seismic studies)

description: Results of 3-D full waveform tomography to develop a 3-D map of Go is shown in this experiment. This 3D Full Waveform Inversion study utilized 48 4.5 Hz geophones. The sensors were laid out in a 4-by-12 10-ft spacing grid.  Thumper was used as a vibrational source at a total of 65 shaker points in a 5-by-13 grid.  An 8 to 80 Hz 12 seconds chirp forcing function was applied at each shaker location. The time-domain 3D Gauss-Newton FWI method developed by Co-PI Tran and his research group was used to determine the 3D velocity model of the test region. Results from this experiment can be used as design reference of nearby structures and for future studies on ground deformations due to excavations.
description: Spectral-Analysis-of-Surface-Waves (SASW) tests and 3-D Full Waveform Inverstion (FWI) tests conducted at the construction site of the new Washington State Convention Center (WSCC) Building are presented in this project.  The WSCC Building is located in downtown Seattle, WA. This study is part of a Rapid Response Research (RAPID) project funded by the National Science Foundation (Project Title: “RAPID Collaborative Research: Spatial variability of small-strain stiffness and the effect on ground movements related to geotechnical construction in urban areas”; project PI: Richard Finno).  It is a collaboration research project among Northwestern University, the University of Texas at Austin, the University of Florida and GeoEngineers, Inc.  This goal of the RAPID project was to determine the spatial variations of small-strain shear modulus, Go, and quantify the effects of the variations on measured and predicted ground movements that arise during excavation. 
Natural soils are heterogeneous and Go values vary laterally and with depth around the plan area of typical urban excavations. The research effort of this RAPID project includes: (1) obtaining spatially dependent Go values prior to start of construction using NHERI@UTexas field equipment, (2) analyzing the seismic data gathered via the SASW method and the method of 3-D full waveform tomography to develop a 3-D map of Go, (3) conducting detailed experimental programs using both advanced triaxial testing and combined dynamic torsional resonant column and cyclic torsional shear testing on thin-walled tube and block samples, (4) developing soil parameters for an advanced constitutive model that includes small-strain stiffness using optimization techniques based on the laboratory data and the field measurements collected during the excavation process, (5) collecting and recording field performance and relating it to construction activities during construction, and (6) simulating the excavation process using the finite element method.  The majority of these analyses (items 4, 5, and 6) were conducted at Northwestern University under the guidance of Prof. Richard Finno, and data from these analyses are presented in another project (DOI 10.17603/ds2-pm8d-ps83).  This project contains two experiments. These two experiments are: (1) seismic data gathered via the SASW method, and (2) seismic data gathered for the method of 3-D full waveform tomography to develop a 3-D map of Go.  Results from dynamic torsional resonant column and cyclic torsional shear testing on thin-walled tube and block samples are added in the report of the SASW experiment.  
The objective of this project to determine the spatial variations of Go around a large excavation in Seattle, WA, specifically the Washington State Convention Center Addition (WSCC), and quantify the effects of the variations of Go on measured and predicted ground movements that arise during excavation.  Results from this study can be used as design reference of nearby structures and for future studies on ground deformations due to excavations.