Geotechnical Characterization of Peats in Muthurajawela Region in the Western Coast of Sri Lanka

Abstract

Peatland covers a total area of 2500 hectares in Sri Lanka, and a more significant portion of it spreads in the western coast of the country through Muthurajawela wetland, which is the largest wetland in Sri Lanka extending from Colombo to Negombo. Colombo Katunayake Expressway (CKE) is a recently completed project in this region, and a lot of peatlands were encountered in the construction. To date, there are no studies focusing on characterization of peats in Muthurajawela region. Therefore, this study focused on investigating the geotechnical properties of peats in Muthurajawela region. Peat samples were obtained from six different locations in this area, and the samples were subjected to investigate the index properties including moisture content, density, specific gravity, fiber content, ash content, organic content and acidity, and consolidation characteristics. Further, Scanning Electron Microscopy (SEM) image analysis and Energy Dispersive X-ray (EDX) analysis were conducted to analyze the structure and to identify the elemental composition of peat samples. According to the basic investigations; Muthurajawela peats were classified as “Fibric and Hemic” peats with high acidity. The results further analysed to develop correlations for the easy prediction of some properties and, the developed correlations were compared with those reported in the literature. The obtained consolidation properties were indicated that the large portion of settlement occurs during the primary consolidation stage within a short time. On the whole, findings of this research will enable engineers to better understand Muthurajawela peat for the design and construction in this region.