PLASTIC CONCRETE CUTOFF WALLS FOR EARTH DAMS. TECHNICAL REPORT

Remedial seepage control of earth dams is a critical problem. A concrete cutoff wall may be used as a remedial measure in some situations. Since the wall in its simplest stuctural form is a rigid diaphragm, deformations of earth embankment due to increase in reservoir level or seismic activity could cause its rupture which would greatly decrease the flow efficiency of the cutoff wall and jeopardize the safety of the dam. In response to this dilemma, engineers in Europe, Asia, and South America have used plastic concrete, which has deformation characteristics similar to the earth dam, to construct cutoff walls. Plastic concrete consists of aggregate, cement, water, and bentonite clay mixed at a high water-cement ratio to produce a ductile material. Geotechnical engineers in the United States have been reluctant to specify the use of plastic concrete for cutoff walls due to limited documentation of field performance of existing cutoff walls and lack of laboratory test data on plastic concrete under test conditions which approximate field behavior. This research was conducted to quantify the stress-strain-strength behavior and permeability of plastic concrete, and to develop design data for specifying plastic concrete for use in a diaphragm cutoff wall for an earth dam. The results of this research indicate that the addition of bentonite clay to conventional concrete significantly increases the ductility and plastic deformation of the concrete while simultaneously reducing its shear strength. The permeability of plastic concrete was found to be the same or less than conventional concrete, and it decreased significantly with consolidation. A design method is given for determining the mix design of a plastic concrete cutoff wall based upon the unconfined compressive strength and/or modulus of the embankment soil.

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 186 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00607583
  • Record Type: Publication
  • Report/Paper Numbers: Tech Rept REMR-GT-15
  • Files: TRIS
  • Created Date: Apr 30 1991 12:00AM