This report presents a summary of the outcomes from a research project commissioned by the NZ Transport Agency to develop design guidance for bridges in New Zealand for liquefaction and lateral spreading effects. The study involved review of relevant case studies and available design methods. The report summarises available design procedures that are based on observed seismic behaviour of bridges and on the most recent research findings, and identifies design methods appropriate for New Zealand conditions. The report also considers issues associated with liquefaction and lateral spreading and their effect on bridge structures and summarises requirements for geotechnical investigations, evaluation techniques for liquefaction and lateral spreading, methods of ground improvements, methods of liquefaction analysis, structural mitigation solutions, construction and monitoring issues.
The report also identifies areas where supporting information is not available and further research work is required. Additional work is recommended to summarise the findings in a form of a technical memorandum which can be later incorporated into the NZ Transport Agency’s Bridge manual and disseminated to the wider New Zealand engineering community. This report is intended for engineers who are familiar with geotechnical and structural design practice for static and seismic loading of bridges.
Subsequent to the publication of this research report, further research was undertaken. See the stage 2 report Analysis of piled bridges at sites prone to liquefaction and lateral spreading in New Zealand.