Effects of Permafrost and Seasonally Frozen Ground on the Seismic Responses of Transportation Infrastructure Sites

Abstract and project information last updated: 16 March 2011. Project updates are dated below.

Three people watching one university student drive stakes into a frozen river beneath a bridge in Anchorage, Alaska

Credit: Joey Yang

Frozen soil depth survey by resistivity method at a bridge site in Anchorage, Alaska.

AUTC
Project
Number
107017
Principal
Investigator
Zhaohui Yang
afzy@uaa.alaska.edu
Funding
Agency

US Department of Transportation (RITA)

Alaska Department of Transportation & Public Facilities

Project
Budget
200000
Start
Date
3 August 2007
Estimated
End Date
28 February 2010

Abstract

This interdisciplinary project combined seismic data recorded at bridge sites with computer models to identify how highway bridges built on permanently and seasonally frozen ground behave during an earthquake. Two sites — one in Anchorage and one in Fairbanks — were selected for seismic site-response testing. In assessing seismic motion in frozen soil, the thickness of seasonally frozen soil, depth to permafrost and its thickness, and depth to bedrock were considered. Results show that the presence of frozen soil, particularly permafrost, significantly changes ground motion characteristics. The research team concluded that while it is generally safe to ignore the effects of seasonally frozen ground on site response, it is not always safe to classify permafrost soil sites using only the seismic motion of the upper 30 meters of frozen or unfrozen soil, or to use code-defined site coefficients for seismic design. Study results will contribute to new guidelines that help engineers design better highway bridges and embankments in Alaska, ideally identifying how to account for permafrost effects in a simpler manner.

Final Report

INE/AUTC 11.03
1 Feb 2011

Effects of Permafrost and Seasonally Frozen Ground on the Seismic Responses of Transportation Infrastructure Sites
Zhaohui Joey Yang, Utpal Dutta, Gang Xu, Kenan Hazirbaba
INE_AUTC_11_03.pdf