The shear failures at Chingford and Muirhead Dams in 1937 and 1941 could be attributed to high pore pressures. Rates of construction had increased and there had been insufficient time for the dissipation of construction pore pressures. Measurements of pore pressures were made with standpipes at Knockendon: a dam similar to Muirhead being built at about the same time. During the designs of embankment dams on the rivers Usk and Daer consideration was given to pore pressures and twin tube hydraulic piezometers were installed during construction in 1951-3. The dams had similar sections and were both built from boulder clay, but while negligible pore pressures were measured at Daer, values greater than the overburden pressure were observed in the fill of the usk dam. Tests showed that there were marked differences in the values of coefficient of consolidation and water content of the two fills. The slip surface at Chingford passed through a layer of soft clay in the foundation. A layer of silt was found in the foundation at Usk and to ensure adequate dissipation of pore pressure from it to ensure stability when the dam was built, a simple system of sand drains was used. (TRRL)

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 16 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00311728
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0 7277 0069 3
  • Report/Paper Numbers: NCP82/78 Proceeding
  • Files: ITRD, TRIS
  • Created Date: Nov 19 1980 12:00AM