PROPOSAL OF A NEW CONCEPT FOR THE VERTICAL DRAIN DESIGN CONSIDERING THE EFFECTS OF INTERMEDIATE PERMEABLE LAYERS AND SMEAR

SOILS AND FOUNDATIONS

UDENI P. NAWAGAMUWA¹  GORO IMAI² 

[1] Department of Civil and Environmental Engineering, University of Ruhuna;Department of Civil Engineering, Yokohama National University

关键词: design methodology;    intermediate permeable layers;    sediment classification;    smear;    vertical drains;    (IGC: E13);   

DOI  :  10.3208/sandf.47.533

学科分类：建筑学

来源: Japanese Geotechnical Society / Jiban Kogakkai

【 摘 要 】

References(29)For more than 60 years, vertical drains have been employed to promote more rapid consolidation of relatively thick deposits of fine-grained soils. Although the design of vertical drains is based on Barron's or Hansbo's theory considering the clay layer to be homogeneous, some field data from the improved grounds using the vertical drains have sometimes shown that the advantage of modifying the commonly used equations due to the presence of permeable laminations in the clay. So there is a necessity of thorough study in the effects of intermediate permeable layers to have an optimum design, which will save time and money. This paper discusses the effects of the presence of intermediate permeable layers and smear using the consolidation equations developed by considering the balance equations regarding the movement of water in a small element and non-linear relationships in order to take the change of permeability and effective stress due to the change in void ratio into account. Finite difference analysis has been done for the combined effect of vertical and radial consolidation and the results are given with two defined parameters, such as; K=[ks/kc]•[Hs/Hc] and α98=t98(2D)/t98(radial). A new design methodology and a sediment classification considering both permeability and thickness of different layers are proposed here with a set of graphs and a design example.

【 授权许可】

Unknown