Vertical sand or cardboard drains used in the construction of roads on saturated soil, facilitate the evacuation of pore water and accelerate consolidation. This increases the shear strength of soil, reduces later settlement or fulfils both at the same time. The theories on consolidation demonstrate that the latter occurs after radial flow in the layer to be consolidated and then after vertical drainage. Taking into account the aptitude of soil to be stabilized with vertical drains, its shear strength and strength variations, and coefficient of consolidation, it is possible to determine the spacing diameter of the drains with a view to obtaining an adequate degree of consolidation. Calculations have shown that the spacing of drains has a greater influence than their diameter. The sands to be used should have a specific permeability for their respective use. If temporary surcharges are applied, secondary compression, which can be harmful, can be neutralized. Piezometers, settlement meters and alignment bench marks enable soil behaviour to be observed during consolidation. Numerous techniques can be used to install drains. A statistical study of sand drains shows some defects: sliding during construction, disturbance of the soil during the driving of drains, too slow primary consolidation, important secondary consolidation. These deficiences could be remedied if the number of measurements was increased. /TRRL/

  • Corporate Authors:

    Road Research Centre, Belgium

    Boulevard de la Woluwe 42
    B-1200 Brussels,   Belgium 
  • Authors:
    • Thienpont, P
  • Publication Date: 1977


  • Undetermined

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 66 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00188400
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Research Rpt CR 4/76Monograph
  • Files: ITRD, TRIS
  • Created Date: Apr 12 1979 12:00AM