Guide to Remedial Measures for Liqufaction Mitigation at Existing Highway Bridge Sites

Keywords: Highway bridges. Liquefaction risk. Excessive deformations. Liquefaction induced damage. Remediation methods. Performance evaluation. Liquefaction induced failure mechanisms. Improvement methods. Grouting. Compaction grouting. Particulate permeation grouting. Chemical permeation. Grouting. Jet grouting. Vibro systems. Vibratory probes. Vibro compaction. Stone column vibro replacement. Surcharge fills. Buttress fills. Mixed in place walls. Mixed in place columns. Root piles. Drains. Gravel drains. Sand drains. Pre fabricated wick drains. Underpinning mini piles.

Abstract: The overall objective of the task reported was to develop methodologies to assess liquefaction risk at existing highway bridges, select appropriate ground and/or foundation improvements methods to reduce the risk of damage, design the improvements, and verify that these improvements had been achieved in the field. The report describes the methodologies developed, which focus on assessing liquefaction risk at existing bridges. Procedures to assess liquefaction are present in flowchart form, progressing from simple to more complex methods. A number of remediation methods are considered, including grouting compaction, vibro systems, surcharge and buttress fills, reinforcement and containment, vertical drains and underpinning. Field testing of these mitigation measures was performed and the results are presented.