SYMPOSIA PAPER Published: 01 January 2000

Shear Strength and K of Peats and Organic Soils


Peats and organic soils are encountered in many geographical areas and because of their organic solids and high water content they exhibit mechanical properties somewhat different than the customary behavior of inorganic clays. Shear strength and coefficient of earth pressure at-rest are two mechanical properties that are commonly required in design of embankments and other structures over such soils. Various investigators have studied these properties of peats and organic soils and the reported results indicate important differences in behavior from inorganic soils both qualitatively and quantitatively. Because of the capacity of these materials to retain high water contents, they are generally weak in their natural states but significant strength gain is achievable with consolidation. The presence of fibers induces both some anisotropy and internal reinforcement. These effects are reflected in strength parameters and lateral earth pressure transfer. Using peat and organic soil samples from sites in Minnesota and Wisconsin, undrained strength, effective strength and coefficient of earth pressure at-rest behavior are investigated and comparisons are made with other reports of these properties to arrive at general behavioral trends.

Author Information

Edil, TB
Univ. of Wisconsin-Madison, Madison, WI
Wang, X
Assoc. Instr. Tech, Dept. of Civil & Environ Engr., Univ. of Wisconsin-Madison, Madison, WI
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Developed by Committee: D18
Pages: 209–225
DOI: 10.1520/STP14369S
ISBN-EB: 978-0-8031-5425-4
ISBN-13: 978-0-8031-2855-2