Skip to Main Content
Skip Nav Destination
GEOREF RECORD

A comparison of small strain stiffness in till as measured by seismic refraction and barometric loading response

Ruth M. G. Kelly, P. Bergamo, D. A. B. Hughes, S. Donohue, S. L. Barbour and K. Lynch
A comparison of small strain stiffness in till as measured by seismic refraction and barometric loading response
Quarterly Journal of Engineering Geology and Hydrogeology (June 2018) 51 (4): 493-502

Abstract

Soil Stiffness can vary over several orders of magnitude depending on the actual range of strain imposed by testing, or as a result of operational strains in geotechnical structures. Soil stiffness changes rapidly with strain level at low strain levels (0.01-0.1%) and the variation with strain is not linear. Characterisation of the in situ small strain stiffness of stiff soils is important in geotechnical design; however, analyses of the mechanical behaviour of these soils is confounded by stiffness values that vary with strain level. Harley et al. (2016) demonstrate how stiff till cuttings are susceptible to progressive failure as a result of strain softening. As a consequence, the evolution of stiffness during progressive failure is both a key parameter in characterising pre-failure slope deformations and a key diagnostic of softening. Changes in strength (due to softening) should be reflected in commensurate temporal and spatial changes in stiffness; consequently, real-time, in situ measurements of stiffness would better define the progression of softening. Seismic surveys, which create small compression and shear strains, have been used to estimate in situ small strain elastic moduli. These spatially extensive measurements can be correlated to temporal variations in stiffness from the monitoring of barometric loading efficiency. In this latter method, the pore pressure response of a grouted (sealed) piezometer to barometric pressure fluctuations is used to measure the compressibility (stiffness) of the formation. This article summarises the results of field trials within a cutting in stiff till in Northern Ireland in which these two techniques were used to characterise small strain stiffness.


ISSN: 1470-9236
EISSN: 2041-4803
Coden: QJEGA7
Serial Title: Quarterly Journal of Engineering Geology and Hydrogeology
Serial Volume: 51
Serial Issue: 4
Title: A comparison of small strain stiffness in till as measured by seismic refraction and barometric loading response
Affiliation: Amey Consulting, Geotechnical Team, Belfast, United Kingdom
Pages: 493-502
Published: 20180612
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 52
Accession Number: 2018-057738
Categories: Engineering geologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
N54°00'00" - N55°30'00", W08°00'00" - W05°30'00"
Secondary Affiliation: Eidgenoessische Technische Hochschule Zuerich, GBR, United KingdomQueen's University Belfast, GBR, United KingdomUniversity College Dublin, IRL, IrelandUniversity of Saskatchewan, CAN, CanadaCentral Procurement Directorate, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201831
Close Modal

or Create an Account

Close Modal
Close Modal