Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

For moderately loaded structures founded on liquefiable soils, spread footings on improved ground can provide considerable cost savings over deep foundation options. Liquefaction mitigation by ground improvement must be properly designed and executed; and should include a field verification program. Although densification is the most effective method of achieving verifiable mitigation of liquefaction susceptible soils, vibro-densification methods are often disregarded for urban sites due to concern for adjacent structures and utilities. An alternative to vibratory methods is compaction grouting, which can achieve densification of cohesionless materials while avoiding excessive vibration of adjacent structures. Recently, compaction grouting was successfully applied to densify a thick loose sand layer (up to 40 feet) for a large development site in an urban environment. This densification significantly increased the factor of safety against liquefaction and reduced potential liquefaction-induced settlement to under 0.5 inch. The compaction grouting program included automated data acquisition and processing and three-dimensional visualization components to ensure quality control and assurance. In addition, the site improvement program was fully verifiable, as the ground improvement program included a comparison of cone penetrometer tests (CPT) conducted prior to and following treatment. Although compaction grouting has been well utilized for several years, the potential for liquefaction mitigation in urban environments is not well established. However, ground improvement through compaction grouting can be a cost-effective alternative to drilled shafts or driven piles on liquefiable sites. This paper includes a description of the site conditions, the compaction grouting program (including automated data acquisition instrumentation and visualization), site instrumentation, post-treatment evaluation of the mitigation procedures, and analysis of the response of adjacent structures.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

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

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Compaction Grouting for Seismic Mitigation of Sensitive Urban Sites

San Diego, California

For moderately loaded structures founded on liquefiable soils, spread footings on improved ground can provide considerable cost savings over deep foundation options. Liquefaction mitigation by ground improvement must be properly designed and executed; and should include a field verification program. Although densification is the most effective method of achieving verifiable mitigation of liquefaction susceptible soils, vibro-densification methods are often disregarded for urban sites due to concern for adjacent structures and utilities. An alternative to vibratory methods is compaction grouting, which can achieve densification of cohesionless materials while avoiding excessive vibration of adjacent structures. Recently, compaction grouting was successfully applied to densify a thick loose sand layer (up to 40 feet) for a large development site in an urban environment. This densification significantly increased the factor of safety against liquefaction and reduced potential liquefaction-induced settlement to under 0.5 inch. The compaction grouting program included automated data acquisition and processing and three-dimensional visualization components to ensure quality control and assurance. In addition, the site improvement program was fully verifiable, as the ground improvement program included a comparison of cone penetrometer tests (CPT) conducted prior to and following treatment. Although compaction grouting has been well utilized for several years, the potential for liquefaction mitigation in urban environments is not well established. However, ground improvement through compaction grouting can be a cost-effective alternative to drilled shafts or driven piles on liquefiable sites. This paper includes a description of the site conditions, the compaction grouting program (including automated data acquisition instrumentation and visualization), site instrumentation, post-treatment evaluation of the mitigation procedures, and analysis of the response of adjacent structures.