|
Section 3: Highway construction |
Acer Wallace Evans, 18/F, Harbour Centre, 25 Harbour Road, Hong Kong
Delays to earthworks construction and difficulties in winning material potentially suitable for fill commonly occur in the UK due to adverse climatic conditions, especially where wet fills comprise a major proportion of the earthworks. The moisture content of wet fills is such that the materials cannot be compacted to the required dry density or maximum voids content. If the moisture content could be reduced, then the materials may become acceptable and be incorporated into current earthworks specifications.
Depending on the soil type, wet fills may variously be treated by consolidation with or without drainage, by mixing with lime addition, or by evaporative drying. Research was undertaken in developing methods to accelerate the evaporative dewatering of fine-grained soils. Dewatering was examined using appropriately scaled test plots and full-scale trials. This led to the development of a mathematical model of the evaporative dewatering process which uses readily determined soil dewatering parameters. The model was validated against the test data and used to describe the dewatering process under laboratory and field conditions. The application of the dewatering model for estimating the optimum dewatering conditions for earthworks fill is described. The method may reduce the amount of ‘unsuitable’ soil sent to a tip, with the potential for substantial cost savings on large earthworks contracts.
