Location

St. Louis, Missouri

Session Start Date

4-2-1995

Session End Date

4-7-1995

Abstract

The stress dependence of the Young's modulus of two sands was studied with a computer controlled triaxial apparatus, capable of giving reliable measurements of the stiffness even at very small strains ≈ 0.001 %. It was therefore possible to determine the Young's modulus of the sands for a wide strain range, from very small to very large, up to 20 %. The tested sands were: a uniform fine quartz sand not containing fines (Toyoura sand- TOS), and a well graded coarse to medium carbonatic, crushable sand containing about 2% of fines (Quiou sand - QS). The specimens were reconstituted in the laboratory at a given density by pluvial deposition. Two test series were performed: 1) Compression loading triaxial tests, at a constant strain rate, on specimens consolidated at σ'vc = 100kPa and stress ratio K variable between Ko(NC) and 2.0 for TOS. For QS the consolidation stress ratio K ranged from Ko(NC) and 1.0. 2) Compression loading triaxial tests, at a constant strain rate, on specimens of TOS consolidated at σ'vc = 100kPa and K variable between Ko(NC) and 2.0. Specimens were prevalently normally - consolidated; however a few of them were subjected to mechanical over consolidation or prestressing at constant K. The main conclusions obtained from the above experiments are: - The small strain Young's modulus E0 depends on the vertical consolidation stress but is independent of the horizontal consolidation stress for both sands; - E0 of the quartz sand is independent of the loading history; this is not true for the carbonatic sand, where E0 increases with increasing of the over consolidation ratio (OCR) values, which is probably due to the sand crushability; -the secant Young's modulus E at larger strains is mainly controlled by the horizontal stress or by the mean stress.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

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

Meeting Name

Third Conference

Publisher

University of Missouri--Rolla

Publication Date

4-2-1995

Document Version

Final Version

Rights

© 1995 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 2nd, 12:00 AM Apr 7th, 12:00 AM

Stress Dependence of Sand Stiffness

St. Louis, Missouri

The stress dependence of the Young's modulus of two sands was studied with a computer controlled triaxial apparatus, capable of giving reliable measurements of the stiffness even at very small strains ≈ 0.001 %. It was therefore possible to determine the Young's modulus of the sands for a wide strain range, from very small to very large, up to 20 %. The tested sands were: a uniform fine quartz sand not containing fines (Toyoura sand- TOS), and a well graded coarse to medium carbonatic, crushable sand containing about 2% of fines (Quiou sand - QS). The specimens were reconstituted in the laboratory at a given density by pluvial deposition. Two test series were performed: 1) Compression loading triaxial tests, at a constant strain rate, on specimens consolidated at σ'vc = 100kPa and stress ratio K variable between Ko(NC) and 2.0 for TOS. For QS the consolidation stress ratio K ranged from Ko(NC) and 1.0. 2) Compression loading triaxial tests, at a constant strain rate, on specimens of TOS consolidated at σ'vc = 100kPa and K variable between Ko(NC) and 2.0. Specimens were prevalently normally - consolidated; however a few of them were subjected to mechanical over consolidation or prestressing at constant K. The main conclusions obtained from the above experiments are: - The small strain Young's modulus E0 depends on the vertical consolidation stress but is independent of the horizontal consolidation stress for both sands; - E0 of the quartz sand is independent of the loading history; this is not true for the carbonatic sand, where E0 increases with increasing of the over consolidation ratio (OCR) values, which is probably due to the sand crushability; -the secant Young's modulus E at larger strains is mainly controlled by the horizontal stress or by the mean stress.