GROUTED CUTOFF CURTAINS IN FISSURED ROCK

THE EFFECT OF GROUT CURTAINS ON SEEPAGE IS VERY OFTEN OVERESTIMATED AND IN MOST CASES LITTLE IS KNOWN ABOUT THE FLOW NETS BELOW DAMS. THE AUTHOR STATES THAT THE STATISTICAL DISTRIBUTION OF JOINTS AND FISSURES PERMITS THE SEEPAGE PROBLEM TO BE CONSIDERED AS A GRAVITATIONAL POTENTIAL FLOW THROUGH A HOMOGENEOUS POROUS MEDIUM (DARCY'S LAW). NEVERTHELESS THE DETERMINATION OF K (FOR INSTANCE BY MEANS OF THE LUGEON TEST) IS QUITE DIFFICULT, MAINLY DUE TO THE OPENING OF THE FISSURES WITH THE IMPOSED PRESSURES AND BECAUSE THE WEIGHT OF THE DAM TENDING TO CLOSE THE JOINTS IS ABSENT IN THE TEST. GROUTING TESTS AND THE METHOD KNOWN AS "SPLIT SPACING" ARE ALSO RECOMMENDED. WITH REFERENCE TO GROUTING PRESSURES, THE DATA GATHERED FROM SOME PROJECTS SHOW THAT THE SAFE PRESSURE RANGES FROM 2 TO 4 TIMES THAT OF THE OVERLOAD, DOWN TO 50 M DEPTH - WITHOUT EXCEEDING 60 TO 70 ATM FOR DEPTHS BETWEEN 100 AND 200 M. THE AUTHOR CONCLUDES THAT AN AVERAGE PERMEABILITY OF K X 10 TO THE 6TH CM/S IS SELDOM ATTAINED WITH GROUT CURTAINS. THE USE OF MODELS OR COMPUTERS PERMITS THE STUDY OF THE EFFECT OF DEPTH AND THICKNESS OF THE GROUTED ZONE ON THE SEEPAGE PATTERN. /RRL/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 389-400

Subject/Index Terms

Filing Info

  • Accession Number: 00235257
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: TRIS
  • Created Date: Apr 23 1972 12:00AM