It is noted that the interest of water pressures lower in the foundation than in the core (although they are likely to accelerate the consolidation of the core) is rather limited because of the lateral filters along the core. In fact, preferential seepage is inhibited from jumping over the crest of the curtain through the bottom part of the core. However this is only an additional safety if surface cracks of the foundation rock are to be sealed with e.g., guniting. The Lugeon values given in the paper seem rather theoretical, it being almost impossible to measure the same Lugeon value in repeated tests on the same section of core hold, and should only be regarded as representing an order of magnitude. However, while there is no general rule about the correlation between Lugeon values and cement take, a correlation can be found at a particular site. The crack pressure of the foundation seepage mentioned in the paper may apply to masonry gravity dams but not to concrete dams where as a result of the permeability of the material, the hydrostatic pressure is the same in the joint and in the pores and, therefore, no opening is possible. In the case of water injection that induces a radial flow net from the bore hole, the seepage pressure enlarges the bore-hole diameter; and, if shear stresses along the walls of the hole are high enough, a crack strats to develop. As regards the grouting technology, increasing grouting pressures, as opposed to decreasing closures between holes, is recommended as this allows the grout to migrate farther. Grouts with water-cement ratio of 3:1 (the ratio recommended in the paper) are felt to have too low a penetrability, and it is suggested that grouting should begin with a high water-cement ratio (4:1 to 8:1) which can be reduced as work proceeds.

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  • Supplemental Notes:
    • This paper is a discussion of ASCE Proceeding Paper 13214 by Adam Clive Houlsby.
  • Corporate Authors:

    American Society of Civil Engineers

    345 East 47th Street
    New York, NY  United States  10017-2398
  • Discussers:
    • Cambefort, H
  • Publication Date: 1978-7

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Filing Info

  • Accession Number: 00179324
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 13902 Proceeding
  • Files: TRIS
  • Created Date: Sep 14 1978 12:00AM