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Geomechanics and Engineering
  Volume 5, Number 6, December 2013 , pages 575-594
DOI: https://doi.org/10.12989/gae.2013.5.6.575
 


Strength and compressibility characteristics of peat stabilized with sand columns
M. Ehsan Jorat, Stefan Kreiter, Tobias Mörz, Vicki Moon, and Willem de Lange

 
Abstract
    Organic soils exhibit problematic properties such as high compressibility and low shear strength; these properties may cause differential settlement or failure in structures built on such soils. Organic soil removal or stabilization are the most important methods to overcome geotechnical problems related to peat soils' engineering characteristics. This paper presents soil mechanical intervention for stabilization of peat with sand columns and focuses on a comparison between the mechanical characteristics of undisturbed peat and peat stabilized with 20%, 30% and 40% of sand on the laboratory scale. Cylindrical columns were extruded in different diameters through a nearly undisturbed peat sample in the laboratory and filled with sand. By adding sand columns to peat, higher permeability, higher shear strength and a faster consolidation was achieved. The sample with 70% peat and 30% sand displayed the most reliable compressibility properties. This can be attributed to proper drainage provided by sand columns for peat in this specific percentage. It was observed that the granular texture of sand also increased the friction angle of peat. The addition of 30% sand led to the highest shear strength among all mixtures considered. The peat samples with 40% sand were sampled with two and three sand columns and tested in direct shear and consolidation tests to evaluate the influence of the number and geometry of sand columns. Samples with three sand columns showed higher compressibility and shear strength. Following the results of this laboratory study it appears that the introduction of sand columns could be suitable for geotechnical peat stabilization in the field scale.
 
Key Words
    peat; sand; geotechnical stabilization; mechanical characteristics
 
Address
(1) M. Ehsan Jorat, Stefan Kreiter and Tobias Mörz: MARUM - Center for Marine and Environmental Sciences, University of Bremen, Klagenfurter Strasse, DE-28359 Bremen, Germany;
(2) Vicki Moon, and Willem de Lange: Department of Earth and Ocean Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand.
 

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