DEWATERING OF AN EXCAVATION PIT OF 57000 SQ M IN VERY PERMEABLE ALLUVIUM BY PUMPING

MISE HORS D'EAU D'UNE FOUILLE DE 57000 M2 DANS DES ALLUVIONS TRES PERMEABLES

IN THE COURSE OF RECONSTRUCTION WORK IN A SECTION OF THE CITY OF LYON, SEVERAL OPEN EXCAVATIONS WERE MAINTAINED DRY BY MEANS OF A SIMPLE, 1000 M LONG, WATERTIGHT SHEET PILE WALL, WHICH WAS ANCHORED FIRMLY IN THE SLIGHTLY PERMEABLE (10 - 5 M/S) MOLASSE SUB-STRATA. THE GROUNDWATER LAY IN VERY PERMEABLE ALLUVIUM (10 - 2 M/S). THE REQUIRED DROP IN THE GROUNDWATER LEVEL WAS 8.5 M. FIELD TESTS CONSISTED OF THE MEASUREMENT OF THE OUTFLOW FROM SEVEN PUMPS AND THE DATA OBTAINED FROM SIX PIEZOMETERS WITHIN THE EXCAVATED AREA AND FROM THREE OUTSIDE THE AREA. THE OUTFLOW AMOUNTS TO APPROXIMATELY 1000 CU M PER HOUR AT 7.5 M DROP. IT IS SHOWN THAT THE ACTUAL POROSITY AS CALCULATED FROM THESE MEASUREMENTS, IS TEN TIMES AS HIGH AS THAT OBTAINED FROM CLASSICAL PUMP TESTS. THE RESULTS ARE COMPARED WITH THOSE OBTAINED FROM ANALOG SIMULATION WITH A RESISTANCE NETWORK. THE SATISFACTORY CORRELATION MADE IT POSSIBLE TO LOCATE AND TO MONITOR A LEAK IN THE PROTECTIVE WALL AND TO ESTIMATE THE EFFECT OF RE-ARRANGING THE PUMP SHAFTS AND THEIR EFFECTIVENESS. THE COVERING ABSTRACT FOR THE CONFERENCE IS IRRD NO 306088.

  • Authors:
    • KASTNER, R
    • LAREAL, P
  • Publication Date: 1976-3

Language

  • French

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01301862
  • Record Type: Publication
  • Source Agency: Bundesanstalt für Straßenwesen (BASt)
  • Files: ITRD
  • Created Date: Nov 21 2010 8:25AM