Shear Wave Velocity Measurements

The Missouri Department of Transportation (MoDOT) commissioned SCI Engineering, Inc. to investigate cost-effective, non-intrusive geophysical methods for determining time-averaged shear wave velocity (Vs) profiles to a depth of 100 feet, based on anticipated updates to AASHTO seismic site classification specifications. Following a comprehensive literature review, eight candidate methods were identified. Of these, four methods—Active Multichannel Analysis of Surface Waves (Active MASW), Passive Multichannel Analysis of Surface Waves (Passive MASW), Active Refraction Microtremor (Active ReMi), and Passive Refraction Microtremor (Passive ReMi)—were selected for field testing based on their practicality and effectiveness.

Field evaluations were conducted at three sites: the SCI Office in O’Fallon, Illinois; the I-270 Chain of Rocks Bridge; and the MLK Connector in Illinois. The sites were selected based on access, availability of existing groundtruth subsurface soil information, as well as representing a variety of subsurface profiles.  Various geophone spacings and array configurations were tested. Performance metrics included depth of investigation, ease of deployment, data quality, and interpretability. Results demonstrated that combining Active and Passive MASW methods offered the most reliable and practical solution, providing consistent results, minimal operational complexity, and shared equipment and software requirements.

SCI Engineering developed a comprehensive User Manual and conducted field demonstrations to train MoDOT personnel in the acquisition, processing, and interpretation of MASW data. Adoption of these methods will streamline MoDOT’s seismic site classification processes, align practices with forthcoming AASHTO requirements, and enhance MoDOT’s internal technical capacity.

VIEW FINAL REPORT

Report number: cmr 25-009
Published: June 2025

Project number: TR202403

Authors: Evgeniy "Eugene" Torgashov, Neil Anderson, and Thomas J. Casey

Performing organization: SCI Engineering, Inc.