Master of Engineering in Geotechnical Engineering

Permanent URI for this collectionhttp://192.248.9.226/handle/123/16121

Browse

Browsing Master of Engineering in Geotechnical Engineering by Author "Kulathilake, SAS"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    item: Thesis-Abstract
    Improvement of engineering properties of peat by preconsolidation : a comparison of field and laboratory test results
    Karunawardena, WA; Kulathilake, SAS
    Sri Lanka lies in the monsoon region of South- East Asia. Colombo, the Capital city situated on the Western cost of the island experiences a humid tropical climate with an annual rainfall of 2500 mm. In the Colombo region there exists flood plains of Kelani Gaga to the North and in the in the coastal belt there are some water bodies such as the Kotte Lake, Bolgoda Lake etc. The fluctuation of water table due to excessive rainfall provides suitable condition to accumilate peat deposits in the above areas, as these are poorly drained grounds. The above process has been occuring for a long time and as a result of that now there exists around 2500 acres of marshy land underlain with peat in and around Colombo city. These marshy lands consist of peat layers having thickness around 5m-10m. As most of the lands with good subsoil condition around Colombo are already used up with the development of the country, it is now necessary to use these unused marshy lands for housing and infrastructure development.
  • Thumbnail Image
    item: Thesis-Full-text
    Methods for improvement of engineering properties of peat - a comparative study
    Munasinghe, WGS; Kulathilake, SAS
    Development of cost effective methods for improvement of engineering properties of peat is a need of the hour in Sri Lanka in view of the number of major infrastructure development projects that are proposed over the lands underlain by peat. In this research several different methods of improvements were tried out in Sri Lankan peat, which have a rather low organic content around 20%-40%. The improvement methods tried out were namely; pre-consolidation through preloading, mixing with cement at percentages of 5%, 10% and 15% and mixing 15% of lime. Peats at different levels of humification were used in the study. It was shown that the preconsolidation causes a significant improvement in both the primary and secondary consolidation characteristics irrespective of the degree of humification. Improvements were achieved in both the fibrous and amorphous peat. Even after the mixing of 15% of cement or 15% of lime significant improvements of consolidation characteristics could not be achieved in fibrous peat. But, even the mixing of 5% cement caused significant improvements in both the primary and secondary consolidation characteristics in amorphous peats. The organic contents of the two types of peat considered were similar. Improvements of shear strength were achieved in all types of peat due to preconsolidation. Mixing with cement also caused some improvements in undrained shear strength of Peat. However, these improvements were not as high as those reported for inorganic soils. Consolidation tests were conducted with simultaneous measurement of settlement and pore water pressure, in a new experimental setup developed. The data obtained were used to check the validity of the Terzaghi theory to model the consolidation behaviour of peat. Some experiments were conducted to derive Bjerrum curves for Peat.