A laboratory characterisation of the response of intact chalk to cyclic loading
Journal article, 2022

This paper reports the cyclic behaviour of chalk, which has yet to be studied comprehensively. Multiple undrained high-resolution cyclic triaxial experiments on low- to medium-density intact chalk, along with index and monotonic reference tests, define the conditions under which either thousands of cycles could be applied without any deleterious effect, or failure could be provoked under specified numbers of cycles. Intact chalk's response is shown to differ from that of most saturated soils tested under comparable conditions. While chalk can be reduced to putty by severe two-way displacement-controlled cycling, its behaviour proved stable and nearly linear visco-elastic over much of the one-way, stress-controlled loading space examined, with stiffness improving over thousands of cycles, without loss of undrained shear strength. However, in cases where cyclic failure occurred, the specimens showed little sign of cyclic damage before cracking and movements on discontinuities led to sharp pore pressure reductions, non-uniform displacements and the onset of brittle collapse. Chalk's behaviour resembles the fatigue response of metals, concretes and rocks, where micro-shearing or cracking initiates on imperfections that generate stress concentrations; the experiments identify the key features that must be captured in any representative cyclic loading model.

triaxial

fatigue

chalk

laboratory testing

cyclic loading

Author

Reza Ahmadi Naghadeh

Imperial College London

Tingfa Liu

Imperial College London

Ken Vinck

Imperial College London

Richard J. Jardine

Imperial College London

Stavroula Kontoe

Imperial College London

Byron W. Byrne

Imperial College London

Ross A. McAdam

University of Oxford

Geotechnique

0016-8505 (ISSN) 17517656 (eISSN)

Vol. In Press

Subject Categories

Geotechnical Engineering

Areas of Advance

Materials Science

DOI

10.1680/jgeot.21.00198

More information

Latest update

8/25/2022