SOFT-GROUND TUNNELS FOR BART

SEVERAL SOIL TYPES UNDERLIE THE BARY AREA RAPID TRANSIT (BART) PROJECT SITES, AMONG THEM WEATHERED ROCK, STIFF CLAY, SOFT CLAY AND PEAT, AND COARSE AND FINE-GRAINED SANDS. MANY OF THE STRATA ARE WATER BEARING, AND IN SOME CASES COMPRESSED AIR MUST BE USED TO CONTROL THE GROUND WATER DURING TUNNEL DRIVING. IN DESIGNING THE TUNNELS, THE FIRST TASK WAS THE DETERMINATION OF ALIGNMENT. HORIZONTAL ALIGNMENT WAS SUBJECT OF TWO CONTROLLING OBJECTIVES: THE DESIRE TO MINIMIZE COST OF SUBSURFACE EASEMENTS BY PLACING TUNNELS UNDER EXISTING ROAD RIGHTS-OF-WAY WHEREVER POSSIBLE AND THE OPTIMUM GOAL OF ACCOMMODATING TRAINS MOVING AT SPEEDS OF 70 MPH. AN EXTENSIVE STUDY WAS CONDUCTED OF TUNNEL LININGS AND TUNNEL VENTILATION METHODS. IN TUNNELING UNDER HIGHLY URBANIZED AREAS, A MAJOR PROBLEM IS PROVIDING FOR DAMAGE TO ADJACENT PROPERTY. SOME OF THESE REQUIREMENTS ARE MENTIONED. A MECHANICAL MOLE IS BEING EMPLOYED FOR TUNNELING. GROUND SETTLEMENT ABOVE THE TWIN 5,000-FT TUNNELS HAS PRESENTED NO SERIOUS PROBLEMS. A SLURRY WALL SHAFT IS DESCRIBED.

  • Availability:
  • Supplemental Notes:
    • Vol 38, No 6, PP 52-55, 2 FIG, 3 PHOT
  • Authors:
    • Thon, J G
    • Amos, M J
  • Publication Date: 1968-6

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  • Accession Number: 00215127
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 24 1994 12:00AM