Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

The small strain shear modulus (G0) and the degradation of shear modulus (G/G0) with increasing magnitude of shear strain are important soil properties required for the evaluation of site response due to earthquake effects. While these properties are well established for geologically recent alluvial sand and clay materials, published data on the properties of materials derived from in-situ rock weathering and ancient alluvial deposits are limited. This paper presents the results of laboratory testing on completely decomposed granite and tuff in Hong Kong, and weathered Jurong Siltstone and Old Alluvium in Singapore. The small strain shear modulus (G0) of the materials was determined from bender element tests, while the shear modulus degradation (G/G0) was assessed from cyclic triaxial test with local strain measurement. The results are compared with the published data of similar materials. Apart from the laboratory bender element tests, G0 can also be determined by the in-situ shear wave velocity test. It has been found worldwide that there is generally a reasonable relationship between shear wave velocity and the SPT N value. In this paper, various in-situ shear wave velocity (Vs) testing results obtained from Singapore and Hong Kong have been reviewed and the observed correlations between VS and SPT N values for various soils are presented.

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

Determination of Small Strain Modulus and Degradation for in-Situ Weathered Rock and Old Alluvium Deposits

San Diego, California

The small strain shear modulus (G0) and the degradation of shear modulus (G/G0) with increasing magnitude of shear strain are important soil properties required for the evaluation of site response due to earthquake effects. While these properties are well established for geologically recent alluvial sand and clay materials, published data on the properties of materials derived from in-situ rock weathering and ancient alluvial deposits are limited. This paper presents the results of laboratory testing on completely decomposed granite and tuff in Hong Kong, and weathered Jurong Siltstone and Old Alluvium in Singapore. The small strain shear modulus (G0) of the materials was determined from bender element tests, while the shear modulus degradation (G/G0) was assessed from cyclic triaxial test with local strain measurement. The results are compared with the published data of similar materials. Apart from the laboratory bender element tests, G0 can also be determined by the in-situ shear wave velocity test. It has been found worldwide that there is generally a reasonable relationship between shear wave velocity and the SPT N value. In this paper, various in-situ shear wave velocity (Vs) testing results obtained from Singapore and Hong Kong have been reviewed and the observed correlations between VS and SPT N values for various soils are presented.