ERI: Reducing Risk of Liquefaction-Induced Ground Failure by Deciphering Seismic Soil-System Response Through Field Forensics and Advanced Laboratory Testing

This Engineering Research Initiation (ERI) award supports the evaluation of liquefaction effects within the context of seismic soil-system response through advanced field investigation and laboratory testing. Conventional liquefaction evaluation procedures overestimate the severity of ejecta at sites with stratified silty soil deposits and underestimate it at sites with thick, clean sand deposits, leading to overspending and economic losses, respectively. Nonlinear dynamic analyses suggest the in-situ soil-system response effects associated with pore water pressure redistribution and flow of water govern the formation of ejecta. However, those effects are not incorporated into conventional procedures. In addition, defects, such as voids and fissures, enhance the formation of ejecta yet are not captured by conventional procedures and numerical models. This research will generate new knowledge regarding liquefaction and its consequences and will significantly advance resilient engineering design and practice. It will deliver high-quality laboratory and field data to the worldwide research community to develop and improve empirical correlations regarding soil parameters, liquefaction triggering, and consequential effects. It will also improve the assessment and mapping of liquefaction effects by non-invasive cost-effective methodologies. Collaborations with US and New Zealand geotechnical engineers will result in the implementation of research findings in practice. The project will be complemented with educational materials that will expose students from diverse backgrounds to cutting-edge research in earthquake engineering.This research seeks to advance the state of knowledge and practice regarding the evaluation of liquefaction ejecta and its effects on structures at both stratified silty and thick, clean sand sites. The primary research objectives are: 1) document and characterize subsurface features (dikes, crust, liquefaction source layer, etc.) through ground penetrating radar and electrical resistivity imaging, unconventional trenching explorations using light detection and ranging and multispectral imaging techniques, detailed logging, and triaxial testing of “undisturbed” samples from a liquefaction source layer to identify mechanisms responsible for the formation or abatement of ejecta at sites where conventional procedures misestimated its severity; 2) use the subsurface data to validate the dynamic nonlinear effective-stress models for stratified silty deposits; 3) develop fundamental insights into the cyclic response of stratified silty deposits through advanced triaxial testing of reconstituted stratified silt-sand specimens; 4) develop recommendations for assessing the vulnerability of soil deposits to the formation of ejecta. This award will allow the PI to form the sound basis for the development of robust methods for evaluating ejecta and its effects on infrastructure and to establish an impactful research program and advance as a researcher and innovator in earthquake engineering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.