Project Title/ID Number Improved Assessment of Liquefaction-Induced Lateral Spreading Hazard—3G02
Start/End Dates 6/1/03 – 5/31/04
Project Leader Raymond Seed (UCB/F)
Team Members Allison Faris (UCB/GS)

F=faculty; GS=graduate student; US=undergraduate student; PD=post-doc; I=industrial collaborator; O=other

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1. Project Goals/Objectives:

The goal of this research effort is to use the field case history database developed in previous year’s efforts regarding liquefaction-induced lateral spreading, as well as new relationships developed by PEER-supported laboratory testing programs to better define post-liquefaction strain and displacement behaviors, to develop improved engineering methods for estimation/prediction of lateral spreading deformations. This work has previously been funded for 2 years by the USGS, and the current PEER Lifelines Program support covers the third year of what is currently envisioned as a three and a half year overall effort.

2. Role of this project in supporting PEER’s mission (vision):

Development of improved, and formally probabilistically based, methods for prediction of liquefaction-induced ground deformations and displacements is a high priority within the Lifelines Program, as it affects all types of structures and distributed systems. We are currently generally well able to accurately predict the likelihood of “triggering” or initiation of liquefaction, but are generally lacking with regard to analytical tools for prediction of the ensuing consequences in terms of post-liquefaction stability and liquefaction-induced deformations. This project addresses one of the most dramatic types of liquefaction-induced deformation modes: lateral ground spreading.

3. Methodology Employed:

The approach is to back-analyze the world’s accumulated database of field case histories of liquefaction-induced lateral spreading, and then to use Bayesian Updating (regression) methods to develop empirical predictive tools for prediction of future lateral spreads. What makes this project different from previous efforts are:

  1. The use of post-liquefaction strain potential (a new concept) as the principal index of soil resistance to deformations,
  2. The use of significantly improved characterization of both seismic loading and gravitational driving forces, and
  3. The use of higher-order probabilistic regression methods able to accurately track and deal with covariance’s between variables as well as with the multiple sources of uncertainty inherent in these field case studies.

4. Brief Description of past year’s accomplishments (Year 6) & more detail on expected Year 7 accomplishments:

The bulk of the past year has been spent processing and analyzing field performance case histories, and in reviewing the interpretations of these with various experts. An initial framework and mathematical model for the proposed Bayesian regression has also been established, but numerous potential options continue to persist here, and the final form of the regressions are not yet clear.

figure 1
Figure 1: Ground Deformation Measurements and Locations of Borings and CPT
Probes at the Hotel Sapanca Site, Turkey

5. Other Similar Work Being Conducted Within and Outside PEER and How This Project Differs:

There is no similar work currently in progress.

6. Plans for Year 8 if project is expected to be continued:

Year funds have been banked from USGS sources, and the bulk of the probabilistic regression analyses will be performed over the next roughly six months.

7. Describe any actual instances where you are aware your results have been used in industry:

None as yet.

8. Expected Milestones & Deliverables:

Target for December 2004:

  1. Formally probabilistically based empirical/analytical methods for prediction of liquefaction-induced lateral spreading displacements and deformations.
  2. Edited, vetted and interpreted/analyzed suite of field performance case histories, documenting all key data and associated sources.
  3. A new “strain potential” basis for estimation of deviatoric liquefaction-induced ground deformations, to complement a similar (recent) volumetric strain potential approach for assessment of post-liquefaction volumetric ground settlements.
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