G. Mesri et al., SECONDARY COMPRESSION OF PEAT WITH OR WITHOUT SURCHARGING, Journal geotechnical and geoenvironmental engineering, 123(5), 1997, pp. 411-421
Secondary compression is important in pl:at deposits because they exis
t at high void ratios and exhibit high values of compression index C-c
, display the: highest values of C-a/C-c among geotechnical materials,
and primary consolidation is completed in weeks or months in typical
field situations. Secondary compression of Middleton peat was investig
ated by oedometer tests on undisturbed specimens. The observed seconda
ry compression behavior of this fibrous peat, with or without surcharg
ing, is in accordance with the C-a/C-c concept of compressibility. Nea
r the preconsolidation pressure, the secondary compression index, C-a,
increases significantly with time. In the compression range C-a decre
ases only slightly with time, and for most practical purposes a consta
nt C-a with time can be used to compute secondary settlement. Postsurc
harge secondary compression index, C-a', always increases with time. T
his is predicted by the C-a/C-c concept of compressibility. A secant p
ostsurcharge secondary compression index, C-a'', is therefore introduc
ed for a simple computation of secondary settlement.