Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

The effects of liquefaction on deep foundations are very damaging and costly, and they keep recurring in many earthquakes. The first part of the paper reviews the field experience of deep foundations affected by liquefaction during earthquakes in the last few decades, as well as the main lessons learned. The second part of the paper presents results of physical modeling of deep foundations in the presence of liquefaction conducted mostly in the U.S. and Japan in the 1990’s, with emphasis on the work done by the authors and others at the 100 g-ton RPI centrifuge. Centrifuge models of instrumented single piles and pile groups embedded in both level and sloping liquefiable soil deposits have been excited in-flight by a suitable base acceleration. End-bearing and floating piles with and without a pile cap, with or without a mass above ground, free at the top or connected to a lateral or rotational spring to simulate the superstructure's stiffness, with the foundation embedded in two- or three-layer soil profiles, have been tested. Tests with a mass above ground have allowed backfiguring the degradation of the lateral resistance of the loose saturated sand against the pile as the soil liquefies, while tests in sloping ground without a mass have allowed studying the effect of lateral spreading. Interpretations of these centrifuge experiments and their relation to field observations, soil properties, theory and analytical procedures are also discussed.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fourth Conference

Publisher

University of Missouri--Rolla

Publication Date

3-26-2001

Document Version

Final Version

Rights

© 2001 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 26th, 12:00 AM Mar 31st, 12:00 AM

Recent Studies on Seismic Centrifuge Modeling of Liquefaction and Its Effects on Deep Foundations

San Diego, California

The effects of liquefaction on deep foundations are very damaging and costly, and they keep recurring in many earthquakes. The first part of the paper reviews the field experience of deep foundations affected by liquefaction during earthquakes in the last few decades, as well as the main lessons learned. The second part of the paper presents results of physical modeling of deep foundations in the presence of liquefaction conducted mostly in the U.S. and Japan in the 1990’s, with emphasis on the work done by the authors and others at the 100 g-ton RPI centrifuge. Centrifuge models of instrumented single piles and pile groups embedded in both level and sloping liquefiable soil deposits have been excited in-flight by a suitable base acceleration. End-bearing and floating piles with and without a pile cap, with or without a mass above ground, free at the top or connected to a lateral or rotational spring to simulate the superstructure's stiffness, with the foundation embedded in two- or three-layer soil profiles, have been tested. Tests with a mass above ground have allowed backfiguring the degradation of the lateral resistance of the loose saturated sand against the pile as the soil liquefies, while tests in sloping ground without a mass have allowed studying the effect of lateral spreading. Interpretations of these centrifuge experiments and their relation to field observations, soil properties, theory and analytical procedures are also discussed.