PRETREATMENT OF A SOFT SOIL BY SURCHARGING - A CASE HISTORY

A normally consolidated silty clay deposit, varying in depth from 0 to 15 m, was pretreated by surcharging combined with pvc vertical drains. Representative field values of the vertical coefficients of primary (0.0015 sq m/kn) and secondary consolidation (0.01) were calculated from the settlements caused by a preliminary fill placed some six years prior to the detailed geotechnical studies. A conservative representative field value of the horizontal coefficient of primary consolidation was established to be 8 sq m/year. Asaoka's method was used to predict future settlements due to both primary and secondary consolidation. The vertical drains were installed at a spacing of 1.8 M using a modified crawler crane. The average daily output was 158 drains over 128 working days with an average cycle time per pair of drains of eight minutes. The total cost was $0.40 (a) per cubic metre, or $3.23 (a) per square metre of the area treated. Surcharging decreased the settlements due to primary and secondary consolidation. Calculated values of settlement over a 10 year period were 80 mm for a 15 m deposit with 50 mm being contributed by secondary consolidation. (Author/TRRL)

  • Availability:
  • Corporate Authors:

    University of New South Wales

    Gate 9, High Street
    Kensington, New South Wales  Australia  2052
  • Authors:
    • Lakner, D
    • LEE, I K
    • Armstrong, E
    • Ingles, O G
  • Publication Date: 1983-11

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 21 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00392333
  • Record Type: Publication
  • Source Agency: ARRB
  • ISBN: 0-85841-184-9
  • Report/Paper Numbers: R-215 Monograph
  • Files: ITRD, TRIS, ATRI
  • Created Date: Mar 29 1985 12:00AM