The influence of Anisotropic Stiffness on the Consolidation of Peat

Zwanenburg, C.; Barends, Frans B. J.

doi:10.3208/sandf.47.507

Cited by 7 publications

(9 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the significantly higher   range of 0.13-0.16 deduced for drained blended peat presumably arises from its general isotropic structure and considerably lower fiber content. The experimental   ranges determined for undisturbed and reconstituted pseudo-fibrous peat in the present study are considerably lower than reported   values for fibrous peat of 0.10 (Zwanenberg, 2005), 0.11 (Rowe et al, 1984) and 0.15 Mylleville, 1996, Tan, 2008), although these values were determined from undrained triaxial compression tests. This can be explained by considering the lateral resistance (internal tensile force) induced by the fibers, which is a function of the friction developed between the fibers (or between fibers and the cellular-spongy matrix) and also of the tensile strength of the fibers themselves (Landva and La Rochelle, 1983).…”

Section: Drained Poisson's Ratio and Fiber Effectscontrasting

confidence: 82%

“…However peat soils have significant micro-structural and fabric differences compared with most inorganic soils (Zwanenberg, 2005, O'Kelly, 2005b, 2006, Hendry et al, 2012. Laboratory testing methods used to determine the strength properties of peats are generally the same as used for mineral soils, without special consideration being given to the fiber content, high compressibility or relatively high permeability and gas content of some fibrous peats (Farrell, 2012).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Consolidated-Drained Triaxial Compression Testing of Peat

O’Kelly

Zhang

2013

Geotechnical Testing Journal

View full text Add to dashboard Cite

Abstract:Recent peat soil problems, including failures of dykes, foundations and slopes in peat deposits, have focused greater attention on understanding the mechanical behavior of peat. Stability calculations routinely involve effective stress analysis, with pertinent strength and stiffness parameters often determined from standard triaxial testing, without special consideration given to internal tensile reinforcement provided by the fiber content and also the high compressibility of the peat material. This paper investigates consolidated-drained triaxial compression testing applied to peat soils. Significant differences in mini-structure and fiber content between test-specimens of undisturbed, reconstituted and blended peat materials were found not to cause significant differences in shear resistance under drained triaxial compression, with mobilized shear resistance increasing approximately linearly with increasing axial strain. Hence it was concluded that c and  deduced from drained triaxial -2-compression testing of peat are unlikely to be intrinsic material properties, and rather are largely a function of strain level, with higher values of  deduced for higher strain levels.End of primary consolidation should be deduced from pore-water pressure measurements rather than volume change response; although the repeatability of the triaxial consolidation tests was generally found to be poor on account of the natural variability of peat and small size of the test specimens.

show abstract

Section: Drained Poisson's Ratio and Fiber Effectscontrasting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Consolidated-Drained Triaxial Compression Testing of Peat

O’Kelly

Zhang

2013

Geotechnical Testing Journal

View full text Add to dashboard Cite

show abstract

“…Peat generally has high values of primary compression index (C c ), secondary compression index (C α ) and of the C α /C c ratio (Mesri and Ajlouni, 1997;Colleselli et al, 2000). The compressibility of fibrous peat is also strongly cross-anisotropic (Zwanenburg, 2005;Wong et al, 2009), arising from the general horizontal alignment of the constituent fibres in-situ (Yamaguchi et al, 1985;Zhang and O'Kelly, 2013). For example, O'Kelly (2006) reported one-dimensional compression data for sets of undisturbed specimens prepared in the vertical and horizontal directions from adjacent sections of carefully sampled borehole cores.…”

Section: Compressibility Characteristicsmentioning

confidence: 99%

Effects of decomposition on the compressibility of fibrous peat — A review

O’Kelly¹,

Pichan²

2013

Geomechanics and Geoengineering

View full text Add to dashboard Cite

Peat deposits are comprised of high organic content substances primarily derived from dead plant vegetation. Peat itself is not inert but undergoes continuous biological decomposition that causes progressive destruction of the peat fabric, reductions in fibre and organic contents and biogas generation. Depending on the degree of decomposition, the organic solids can exist as fresh (intact) fibres, slightly decomposed or ultimately completely decomposed (amorphous) material. From a geotechnical perspective, an understanding of the relationship between degree of decomposition and engineering properties, including the level of compressibility, is important in dealing with such problematic deposits. However a review of the literature indicates that such relationships have not been sufficiently investigated. Moreover, potential impacts of uncontrolled or unexpected decomposition in-situ are regularly discounted in geotechnical practice. This paper reviews decomposition effects in peat and potentially significant knock-on effects in terms of the material's physical properties and compressibility. Progressive reduction in solids volume and deterioration in the integrity of the organic structure due to on-going decomposition may cause significant additional settlement to occur over time. More decomposed peat generally undergoes lower primary consolidation and creep strains and is also less prone to future decomposition, compared with lesser decomposed peat.

show abstract

“…This so-called fibre tensioning occurs during expansive (tensile) strain on the horizontal plane, giving the material its low drained Poisson's ratio, n 0 , and strong anisotropy in strength (see Den Haan and Kruse (2007)). For instance, n 0 values of 0·10 (Zwanenburg, 2005), 0·11, 0·14 (Rowe et al, 1984) and 0·15 (Rowe and Mylleville, 1996;Tan, 2008) have been reported from CU TC testing of fibrous peats.…”

Section: Cu Tc Testingmentioning

confidence: 99%

“…CU triaxial testing of large-diameter specimens creates its own challenges -for example, inhomogeneous consolidation behaviour, with a clear Mandel-Cryer peak occurring for the triaxial consolidation stage (see Zwanenburg (2005)). In this experimental programme, the CU TC tests performed on 400 mm dia.…”

Section: Geotechnical Research Volume 4 Issue Gr3mentioning

confidence: 99%

Measurement, interpretation and recommended use of laboratory strength properties of fibrous peat

O’Kelly

2017

Geotechnical Research

View full text Add to dashboard Cite

Peat deposits are complex natural formations encountered in many geographical areas. Peat itself is considered as a challenging geomaterial, with many aspects of its behaviour seemingly remaining enigmas. This state-of-the-art review paper provides an extensive summary of current knowledge on the strength and shear behaviour of fibrous peats. Critical assessments and interpretations of the undrained strength, effective-stress strength and at-rest earth pressure coefficient parameter values determined for fibrous peat materials using standard and advanced laboratory apparatus are presented, focusing particularly on the consolidated undrained triaxial compression and direct simple shear approaches. Based on documented case histories of embankments, dikes and natural peat slopes, guidance is given for operational shear strength assessments in peat, aimed at bearing capacity and slope stability calculations, considering both the normalised undrained strength ratio and limit equilibrium effective-stress strength approaches. In particular, the botanical origin, structural anisotropy, humification level, likely initial overconsolidated state, tensile resistance associated with the peat fibres and possible scale effect related to the test-specimen size are discussed in the context of the strength mobilised for different testing apparatus. The test methodologies and interpretations of experimental results presented for fibrous peat in this paper should be transferable to other fibrous soil and soil-like materials. Notation

show abstract

The influence of Anisotropic Stiffness on the Consolidation of Peat

Cited by 7 publications

References 12 publications

Consolidated-Drained Triaxial Compression Testing of Peat

Consolidated-Drained Triaxial Compression Testing of Peat

Effects of decomposition on the compressibility of fibrous peat — A review

Measurement, interpretation and recommended use of laboratory strength properties of fibrous peat

Contact Info

Product

Resources

About