American Society of Civil Engineers


One-Dimensional Compression Behavior of a Soil with High Organic Matter Content


by Marika Santagata, (corresponding author), (Assoc. Prof., School of Civ. Engrg., Purdue Univ., 550 Stadium Mall, West Lafayette, IN 47907-2051 E-mail: mks@purdue.edu), Antonio Bobet, (Assoc. Prof., School of Civ. Engrg., Purdue Univ., 550 Stadium Mall, West Lafayette, IN 47907-2051. E-mail: bobet@purdue.edu), Cliff T. Johnston, (Prof., Dept. of Agronomy, Purdue Univ., 915 W. State St., West Lafayette, IN 47907. E-mail: cliffjohnston@purdue.edu), and Joonho Hwang, (Proj. Professional, Fugro Consultants Inc., 6100 Hillcroft, Houston, TX 77274. E-mail: jhwang@fugro.com)

Journal of Geotechnical and Geoenvironmental Engineering, Vol. 134, No. 1, January 2008, pp. 1-13, (doi:  http://dx.doi.org/10.1061/(ASCE)1090-0241(2008)134:1(1))

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Document type: Journal Paper
Abstract: This paper addresses the one-dimensional compression behavior of a highly organic sapric soil in both its natural intact and reconstituted states, based on the results of constant rate of strain and incremental loading oedometer tests. The soil investigated contains 40 — 60% organic matter, comprised mainly of highly processed humic substances, and represents a “transitional” material between inorganic clays and peats. The inorganic portion is entirely finer than 0.075 mm, with over 60% in the clay fraction (<2 μm), which XRD analyses indicate contains smectite and vermiculite. Testing of the soil in its intact state relies on high quality block samples and shows that the natural intact soil displays intermediate behavior between that typical of inorganic soft clays and that observed in peats, in terms of compressibility, hydraulic conductivity, and change in hydraulic conductivity with void ratio. As in the case of peats, the coefficient of consolidation is observed to decrease with increasing stress level and the soil shows a high tendency to creep, with Cα/Cc at the high end of values reported in the literature. Comparison of the compression results for the natural and the reconstituted soil serves to illustrate the degree of structuring of the natural soil, which is found to be consistent with that typical of natural sedimentary inorganic clays.


ASCE Subject Headings:
Compression
Creep
Microscopy
Minerals
Organic matter
Soil consolidation
Soil structures