Liquefaction and Lateral Spread Evaluation and Mitigation for Highway Overpass Structure: Cherry Hill Interchange, Davis County, Utah

Abstract

Transportation structures constructed in areas of significant seismic hazards are subject to lateral and vertical movements that can threaten the integrity of structures built on liquefiable subsoils. This case history summarizes the geology, analysis methods, mitigation requirements, and proposed quality control for the Cherry Hill Interchange project in Davis County, Utah. A liquefaction and lateral spread liquefaction hazard during the design earthquake has been identified that threatens failure of the proposed bridge. Cone penetration tests were determined to be a cost-effective method for supplementing standard penetration test borings to gain sufficient subsurface information for the liquefaction and lateral spread analysis. A cost-effective solution for protecting the bridge from the hazard has been developed using geotechnical principles combined with recent developments in liquefaction mitigation. The cost of the mitigation is a minor percentage of the overall project cost but is anticipated to protect the bridge from collapse and save lives.