SETTLEMENT RATE EXPERIENCE FOR THE USE OF SAND DRAINS IN A TIDAL MARSH DEPOSIT. ABRIDGMENT

Tidal marsh deposits are found over a wide range of coastal areas in the world. Technical publications have noted the results of the use of surcharge and sand drain treatment to stabilize tidal marsh deposits. This paper supplements existing information on settlement rates in tidal marsh deposits and compares it with previously published data. The use of surcharge treatment and conventional displacement sand drains was utilized to construct two approach roadway embankments over a tidal marsh deposit adjoining a bridge over the Maurice River at Mauricetown, New Jersey. The tidal marsh deposit generally ranges from 7.6 to 15.2 m (25 to 50 ft) in depth and consists of organic silty clay having a Unified Soil Classification System classification of OH. This soil exhibits a relatively wide variation in natural moisture content and compressibility. 1. A review of field settlement platform data showed that the range in the settlement rate was much narrower than that indicated by the laboratory test data. 2. The field settlement data corroborated that, for the design of displacement and sand drains in tidal marsh deposits, the average coefficient of consolidation from conventional laboratory consolidation samples should be used and that any increase in horizontal over vertical permeability should be neglected. 3. The plot of coefficient of consolidation versus sand drain spacing shows a significant trend for a large number of different tidal marsh deposits. For some of these data a closer spacing of conventional displacement sand drains showed a resulting reduction in the coefficient of consolidation as measured from field data and appears to be due to disturbance effects. These data also show that the total consolidation pressure has a marked effect on the field-measured coefficient of consolidation, as would be expected from the laboratory consolidation test data. /Author/

Media Info

  • Media Type: Print
  • Features: Figures;
  • Pagination: pp 41-42
  • Monograph Title: Tolerable Movement of Bridge Foundations, Sand Drains, K-test, Slopes and Culverts
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00196578
  • Record Type: Publication
  • ISBN: 030902823X
  • Files: TRIS, TRB
  • Created Date: Aug 28 1979 12:00AM