In-situ shear modulus determination by pressuremeter tests in opalinus clay and reconciliation with laboratory tests

Liu, Lang; Giger, Silvio; Martin, Derek; Chalaturnyk, Rick; Schuster, Kristof; Deisman, Nathan; Keller, Lukas

doi:10.1007/s00603-022-02873-0

Publication type:	Article in scientific journal
Type of review:	Peer review (publication)
Title:	In-situ shear modulus determination by pressuremeter tests in opalinus clay and reconciliation with laboratory tests
Authors:	Liu, Lang Giger, Silvio Martin, Derek Chalaturnyk, Rick Schuster, Kristof Deisman, Nathan Keller, Lukas
et. al:	No
DOI:	10.1007/s00603-022-02873-0
Published in:	Rock Mechanics and Rock Engineering
Volume(Issue):	55
Issue:	8
Page(s):	4615
Pages to:	4635
Issue Date:	2022
Publisher / Ed. Institution:	Springer
ISSN:	0723-2632 1434-453X
Language:	English
Subjects:	Opalinus clay; Pressuremeter testing; Shear modulus; Nonlinear elasticity
Subject (DDC):	551: Geology and hydrology
Abstract:	Opalinus Clay is the designated host rock for a deep geological repository of radioactive waste in Switzerland. The determination of its geo-mechanical properties relies heavily on laboratory tests on small specimens. To assess the in-situ elastic stiffness at a larger scale, pressuremeter tests were performed in Opalinus Clay at the Mont Terri Rock Laboratory, with the testing probe oriented both perpendicular and parallel to the bedding planes. The shear modulus of the Opalinus Clay is determined using the unload data of the pressuremeter tests in different lithofacies and at multiple expansion pressure levels. The measured shear modulus is dependent on the expansion pressure at the initial stage of the test but approaches a relatively constant value when a pressure magnitude of about 5 MPa is reached. The stiffness anisotropy of the Opalinus Clay, the rock mass disturbance, and the local fractures at test intervals can affect the measured moduli. In this test program, the impact of lithofacies was not evident at low expansion pressures and could not be evaluated at a greater expansion pressure. The shear modulus of the Opalinus Clay exhibits a nonlinear dependence on strain increment, which can be interpreted using a power-law stress–strain relationship. The small-strain nonlinearity is also dependent on the expansion pressures for the Opalinus Clay. At expansion pressures greater than 5 MPa, the strain-dependent shear moduli obtained from pressuremeter tests are comparable with those determined by triaxial tests on intact core specimens. At the shear strain increment of 0.1%, a secant shear modulus (parallel to bedding) of approximately 3 GPa for the intact Opalinus Clay can be concluded from both the pressuremeter and triaxial tests.
URI:	https://digitalcollection.zhaw.ch/handle/11475/26170
Related research data:	https://doi.org/10.6084/m9.figshare.19607388.v1
Fulltext version:	Published version
License (according to publishing contract):	Licence according to publishing contract
Departement:	School of Engineering
Organisational Unit:	Institute of Computational Physics (ICP)
Appears in collections:	Publikationen School of Engineering

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Liu, L., Giger, S., Martin, D., Chalaturnyk, R., Schuster, K., Deisman, N., & Keller, L. (2022). In-situ shear modulus determination by pressuremeter tests in opalinus clay and reconciliation with laboratory tests. Rock Mechanics and Rock Engineering, 55(8), 4615–4635. https://doi.org/10.1007/s00603-022-02873-0

Liu, L. et al. (2022) ‘In-situ shear modulus determination by pressuremeter tests in opalinus clay and reconciliation with laboratory tests’, Rock Mechanics and Rock Engineering, 55(8), pp. 4615–4635. Available at: https://doi.org/10.1007/s00603-022-02873-0.

L. Liu et al., “In-situ shear modulus determination by pressuremeter tests in opalinus clay and reconciliation with laboratory tests,” Rock Mechanics and Rock Engineering, vol. 55, no. 8, pp. 4615–4635, 2022, doi: 10.1007/s00603-022-02873-0.

LIU, Lang, Silvio GIGER, Derek MARTIN, Rick CHALATURNYK, Kristof SCHUSTER, Nathan DEISMAN und Lukas KELLER, 2022. In-situ shear modulus determination by pressuremeter tests in opalinus clay and reconciliation with laboratory tests. Rock Mechanics and Rock Engineering. 2022. Bd. 55, Nr. 8, S. 4615–4635. DOI 10.1007/s00603-022-02873-0

Liu, Lang, Silvio Giger, Derek Martin, Rick Chalaturnyk, Kristof Schuster, Nathan Deisman, and Lukas Keller. 2022. “In-Situ Shear Modulus Determination by Pressuremeter Tests in Opalinus Clay and Reconciliation with Laboratory Tests.” Rock Mechanics and Rock Engineering 55 (8): 4615–35. https://doi.org/10.1007/s00603-022-02873-0.

Liu, Lang, et al. “In-Situ Shear Modulus Determination by Pressuremeter Tests in Opalinus Clay and Reconciliation with Laboratory Tests.” Rock Mechanics and Rock Engineering, vol. 55, no. 8, 2022, pp. 4615–35, https://doi.org/10.1007/s00603-022-02873-0.