Liquefaction Triggering of Gravelly Soils

Project ID: 712
Principal Investigator: Robert Rinehart
Research Topic: Improving Geotechnical Infrastructure Reliability
Funded Fiscal Years: 2016
Keywords: None

Research Question

While there has been extensive work performed to understand and predict liquefaction of sandy soils, liquefaction
of gravel-dominated soils is poorly understood and poses a risk to any Reclamation infrastructure founded on
such soils (e.g, canals, levees, dams, power plants and appurtenant structures, etc). Liquefaction refers to the
complete or near complete loss of soil shear strength due to the buildup of excess pore water pressures. With
respect to gravelly soils, there are a limited number of articles published on the topic and only a few case
histories have been studied and documented.
Basic research questions related to liquefaction of gravelly soils include:
1. What is the pore pressure response of gravelly soils to seismic shaking?
2. What intensity and duration of shaking leads to liquefaction?
3. What are the effects of gradation and in-place moisture and density?
Applied research questions include:
1. Can existing site investigation tools be used to determine liquefaction susceptibility of gravelly soils?
2. What new and emerging technologies could be employed to determine susceptibility?
The scoping study described here proposes to perform a comprehensive literature review, along with interviews of
industry and academia experts to gain a thorough understanding of the current state-of-the-art and studies
performed in the past or currently underway. In addition, based on the results of the literature review, a research
study aimed at addressing both the basic and applied research questions posed above will be developed. Input
will be sought and considered from various Reclamation experts with respect to key Reclamation needs in the
area, possible inclusion of research findings with field investigation practices, and with respect to existing
Reclamation physical modeling capabilities.

Need and Benefit

In order to perform more cost effective (i.e., not necessarily overly conservative) designs and perform more
accurate site evaluations for new infrastructure as well as risk assessments of existing infrastructure, Reclamation
needs to gain a deeper understanding of liquefaction of gravel soils. The specific infrastructure at risk includes
canals, levees, dams, power plants, and appurtenant structures, and with the constant (seemingly upward) revision
of potential earthquake magnitudes, and the increase in human-induced seismicity (i.e., potentially due to
hydraulic fracturing), Reclamation is poised to increasingly need and greatly benefit from this research.
Liquefaction is recognized as a threat to essentially the entirety of Reclamations infrastructure, and while
liquefaction in sandy soils is relatively well understood, there is a gap in the geotechnical engineering professions
knowledge base with regard to liquefaction of gravelly soils. When tasked with assessing the hazards and risks
related to liquefaction of gravelly soils the best engineers can do is attempt to apply their knowledge of sand
liquefaction or perform correlations of field tests appropriate for gravels (e.g., Becker penetration test) to tests
commonly used to investigate sands (e.g., standard penetration tests, cone penetration tests). These
extrapolations and correlations are not precise, are not well developed, and result is a high degree of uncertainty
with respect to the actual level of risk due to gravel liquefaction.
The scoping study proposed here along with the potential for a larger-scale conducting study, hold the potential
to advance the state-of-the-art of assessment and treatment of liquefaction of gravel soils and to develop and
promote new and emerging field investigation technologies. In addition, the research has the potential to aid in
the evaluation of the range of remediation strategies available for use for example, the question of what if the
stone columns often used to remediate sand liquefaction hazards are in fact susceptible to liquefaction
themselves, cannot currently be answered, but is often asked.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Liquefaction Triggering of Gravelly Soils (final, PDF, 523KB)
By Robert Rinehart
Publication completed on September 30, 2016

Liquefaction is recognized as a threat to much of Reclamation's infrastructure, and while liquefaction in sandy soils is relatively well understood there is a gap in the geotechnical engineering profession's knowledge base with regard to liquefaction of gravelly soils. A literature review was conducted to better understand the state-of-the-art of liquefaction triggering assessment of gravelly soils. Several tools are available to aid in the assessment of gravel liquefaction potential, but considerable uncertainty still exists. This report presents the finding of the literature review and makes recommendations for future research to advance the state-of-the-art.

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Last Updated: 4/4/17