Rate-dependent behaviour of a saturated clay under different stress histories and k 0 conditions
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RESEARCH PAPER
Rate-dependent behaviour of a saturated clay under different stress histories and K0 conditions Shengshen Wu1
•
Thomas Lok2 • Youwei Xu3 • Dong Wang4
Received: 17 February 2019 / Accepted: 21 June 2019 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract This paper investigates the results obtained from a series of K0-consolidated undrained triaxial tests, which were carried out on marine clay specimens under different stress histories and strain rates. All marine clay specimens were prepared from a slurry state and pre-consolidated in a consolidometer under a vertical pressure of 100 kPa. The specimens were then compressed to the same initial effective pressure of 400 kPa. Different over-consolidation ratios (= 1, 2 and 4) were achieved by unloading to 400, 200 and 100 kPa, respectively. After completing the K0-consolidation, specimens were sheared at three rates (= 0.1%/h, 1%/h and 10%/h). The responses of the marine clay under different strain rates and the influence of stress histories under K0 conditions are discussed. The results show that higher strain rates tend to result in higher undrained shear strengths and lower pore pressure for different over-consolidation ratios under K0 conditions. Conversely, higher over-consolidation ratios tend to result in lower shear strengths for all the strain rates. Further, two rate parameters used to study the strain rate effects are also discussed and interpreted, and the suitable rate parameters of the reconstituted clay are recommended in designs for the marine clay. Keywords K0-consolidated Over-consolidation ratios Shear strength Strain rate Triaxial Abbreviations qf Deviator stress at failure q Deviator stress Axial strain rate e_1 qfðrefÞ Reference deviator stress at failure Reference strain rate e_1ðref Þ
& Shengshen Wu [email protected] Thomas Lok [email protected] Youwei Xu [email protected] Dong Wang [email protected]
r0h r0v OCRMAX /0 e1 Duf Su p0 NC OC OCR K0-CU NC LL PI MMC
Effective horizontal stress Effective vertical stress The maximum over-consolidation ratio that the soil experienced The friction angle Axial strain Pore pressure at failure Shear strength Effective stress Normally consolidated Over-consolidated Over-consolidation ratio K0-consolidated undrained Normally consolidated Liquid limit Plastic index Macau marine clay
1
School of Engineering, Royal Melbourne Institute of Technology, Melbourne, Australia
2
Department of Civil and Environmental Engineering, University of Macau, Macau, China
1 Introduction
3
School of Civil Engineering, University of Queensland, Brisbane, Australia
4
School of Engineering, University of Wollongong, Wollongong, Australia
Undrained shear strength of cohesive soils is an important design parameter in geotechnical engineering. Both field and laboratory tests are used to obtain the shear strength of
123
Acta Geotechnica
soils. In particular, strain rate effects have been observed in tests performed under di
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