Effects of stress and temperature on secondary compression of peat

Patrick Joseph Fox, Tuncer B. Edil

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Results from field and laboratory tests illustrate the influence of vertical effective stress and temperature on the secondary compression of peat from Middleton, Wisconsin, U.S.A. A large fraction of the total settlement of the peat is due to secondary compression. The coefficient of secondary compression, Cα, generally increases with time, and settlement predictions using a constant Cα may underestimate field settlement. Laboratory step-stress and step-temperature tests indicate that the rate of void ratio change during secondary compression varies exponentially with both temperature and vertical effective stress. A stress coefficient of creep, Cσ, and a temperature coefficient of creep, CT, are defined to characterize these relationships. For Middleton peat, the logarithm of Cσ decreases linearly with void ratio and Ct is constant. The results suggest that laboratory stress and temperature conditions should match those in situ for accurate determination of secondary compression parameters. Cooling also has an important effect on the secondary compression of peat. For large decreases in temperature, an overconsolidated condition is created for which additional secondary compression is greatly reduced. Settlement data from two test embankments on peat illustrate the effect of staged construction and subsurface heating on secondary compression in the field. The temperature changes achieved in situ were not large enough to cause a strong thermal precompression effect.

Original languageEnglish (US)
Pages (from-to)405-415
Number of pages11
JournalCanadian Geotechnical Journal
Volume33
Issue number3
DOIs
StatePublished - Jan 1 1996

Fingerprint

Peat
peat
compression
temperature
Temperature
void ratio
effective stress
Creep
creep
Embankments
effect
Thermal effects
temperature effect
embankment
Cooling
Heating
heating
cooling
prediction

All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology

Cite this

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abstract = "Results from field and laboratory tests illustrate the influence of vertical effective stress and temperature on the secondary compression of peat from Middleton, Wisconsin, U.S.A. A large fraction of the total settlement of the peat is due to secondary compression. The coefficient of secondary compression, Cα, generally increases with time, and settlement predictions using a constant Cα may underestimate field settlement. Laboratory step-stress and step-temperature tests indicate that the rate of void ratio change during secondary compression varies exponentially with both temperature and vertical effective stress. A stress coefficient of creep, Cσ, and a temperature coefficient of creep, CT, are defined to characterize these relationships. For Middleton peat, the logarithm of Cσ decreases linearly with void ratio and Ct is constant. The results suggest that laboratory stress and temperature conditions should match those in situ for accurate determination of secondary compression parameters. Cooling also has an important effect on the secondary compression of peat. For large decreases in temperature, an overconsolidated condition is created for which additional secondary compression is greatly reduced. Settlement data from two test embankments on peat illustrate the effect of staged construction and subsurface heating on secondary compression in the field. The temperature changes achieved in situ were not large enough to cause a strong thermal precompression effect.",
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Effects of stress and temperature on secondary compression of peat. / Fox, Patrick Joseph; Edil, Tuncer B.

In: Canadian Geotechnical Journal, Vol. 33, No. 3, 01.01.1996, p. 405-415.

Research output: Contribution to journalArticle

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