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Saturation and its effect on the resilient modulus of a pavement formation material

Saturation and its effect on the resilient modulus of a pavement formation material
Saturation and its effect on the resilient modulus of a pavement formation material
This paper reports the effects of changing degree of saturation on the stiffness of a typical railway formation material. Material dynamically compacted to a target dry density over a range of water contents was cyclically loaded in triaxial and hollow cylinder apparatus. The results of both test types show the large effect of the degree of saturation on stiffness. In both the cyclic triaxial apparatus and the equivalent stress path in the cyclic hollow cylinder apparatus, the resilient modulus (MR) increased considerably (from ∼36 MPa to ∼467 MPa) as the degree of saturation fell. MR at a water content of 7% (optimum under the 2·5 kg rammer) was approximately 1·5 times the near-saturated value (at w = 8%). MR at the driest state tested (w = 4%) was approximately 6 times that measured for the near-saturated specimen. In the hollow cylinder apparatus, these trends were seen regardless of whether principal stress rotation was applied. The increase in MR associated with decreasing water content is thought to result from an increase in matric suction. Increased scatter in MR at higher suction may be the result of a more variable distribution of water within drier specimens. Comparison of suction stresses derived from the soil water retention curve with values back-calculated from cyclic triaxial testing suggests that useful estimates of railway formation resilient modulus, MR, may be made on the basis of measurements of matric suction.
0016-8505
292-302
Blackmore, Letisha
fe6fec65-47d0-4554-b3cb-6f2b746a8306
Clayton, Christopher R.I.
8397d691-b35b-4d3f-a6d8-40678f233869
Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Priest, Jeffrey A.
351c5a60-8c47-4050-904b-5a920d376e45
Otter, Louise
4bae3c05-20e8-47dd-bd9d-eb930e54b8d1
Blackmore, Letisha
fe6fec65-47d0-4554-b3cb-6f2b746a8306
Clayton, Christopher R.I.
8397d691-b35b-4d3f-a6d8-40678f233869
Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Priest, Jeffrey A.
351c5a60-8c47-4050-904b-5a920d376e45
Otter, Louise
4bae3c05-20e8-47dd-bd9d-eb930e54b8d1

Blackmore, Letisha, Clayton, Christopher R.I., Powrie, William, Priest, Jeffrey A. and Otter, Louise (2020) Saturation and its effect on the resilient modulus of a pavement formation material. Géotechnique, 70 (4), 292-302. (doi:10.1680/jgeot.18.P.053).

Record type: Article

Abstract

This paper reports the effects of changing degree of saturation on the stiffness of a typical railway formation material. Material dynamically compacted to a target dry density over a range of water contents was cyclically loaded in triaxial and hollow cylinder apparatus. The results of both test types show the large effect of the degree of saturation on stiffness. In both the cyclic triaxial apparatus and the equivalent stress path in the cyclic hollow cylinder apparatus, the resilient modulus (MR) increased considerably (from ∼36 MPa to ∼467 MPa) as the degree of saturation fell. MR at a water content of 7% (optimum under the 2·5 kg rammer) was approximately 1·5 times the near-saturated value (at w = 8%). MR at the driest state tested (w = 4%) was approximately 6 times that measured for the near-saturated specimen. In the hollow cylinder apparatus, these trends were seen regardless of whether principal stress rotation was applied. The increase in MR associated with decreasing water content is thought to result from an increase in matric suction. Increased scatter in MR at higher suction may be the result of a more variable distribution of water within drier specimens. Comparison of suction stresses derived from the soil water retention curve with values back-calculated from cyclic triaxial testing suggests that useful estimates of railway formation resilient modulus, MR, may be made on the basis of measurements of matric suction.

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Accepted/In Press date: 5 March 2019
e-pub ahead of print date: 11 March 2019
Published date: April 2020

Identifiers

Local EPrints ID: 431629
URI: http://eprints.soton.ac.uk/id/eprint/431629
ISSN: 0016-8505
PURE UUID: 69a04424-be8f-48c9-ac87-7578fd271792
ORCID for Christopher R.I. Clayton: ORCID iD orcid.org/0000-0003-0071-8437
ORCID for William Powrie: ORCID iD orcid.org/0000-0002-2271-0826

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Date deposited: 11 Jun 2019 16:30
Last modified: 07 Oct 2020 01:44

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Contributors

Author: Letisha Blackmore
Author: William Powrie ORCID iD
Author: Jeffrey A. Priest
Author: Louise Otter

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