PROBE DRILLING FOR RAPID TUNNELING

ALTERNATIVE MEANS FOR DETERMINING ROCK AND GEOLOGICAL CONDITIONS IN ADVANCE OF A TUNNEL BORING MACHING (TBM) ARE EXPLORED. ONE POSSIBILITY INVOLVES USING A LONG HORIZONTAL DRILL HOLE THAT PRECEDES THE TBM BY SEVERAL DAYS IN ORDER TO FORECAST RUSHING WATER, BAD ROOF CONDITIONS, EXPLOSIVE GAS, CHANGING GROUND CONDITIONS, OR A CHANGE IN ROCK STRENGTH. AN ANALYSIS OF THE STATE-OF-THE-ART REVEALED THAT IN ORDER TO FULFILL THE OBJECTIVE OF DRILLING A 1,000 FT. HOLE, ONLY ONE DRILLING METHOD - ROTARY DRILLING WITH DIAMONDS - WAS SERIOUSLY CONSIDERED ALTHOUGH OTHER METHODS - ROTARY DRILLING WITH ROLLING CUTTER BITS, PERCUSSION DRILLS, ETC, - HAD BEEN SUGGESTED. SINCE DRILL ROD HANDLING CONSTITUTES A DIFFICULT PROBLEM IN UNDERGROUND HORIZONTAL DRILLING, THE 1,000 FT. OF DRILL ROD WAS PUT TOGETHER, AND NEVER TAKEN APART UNTIL THE DRILLING HAD BEEN COMPLETED. AS FOR FLUID CIRCULATION, THIS MEANS THAT THE DRILL'S FLUID IS PUMPED INTO THE STORAGE PIPE, THEN THE FLUID, HAVING BEEN BLOCKED FROM FLOWING OUT BY PLUGGING THE REAR END OF THE STORAGE PIPE, CAN MOVE OUT THE REAR END OF THE DRILL ROD. IT THEN MOVES FORWARD THROUGH THE DRILL ROD AND DRILLING TOOLS INTO THE DRILL HOLE, THUS COOLING THE BIT AND REMOVING THE CUTTINGS. A STUFFING BOX TO SEAL THE DRILL ROD, FOR BOTH WATER AND AIR FLUSHING, IS LOCATED ON THE CASING SET INTO THE COLLAR OF THE HOLE BEING DRILLED.

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 65-87
  • Serial:
    • Volume: 1

Subject/Index Terms

Filing Info

  • Accession Number: 00236527
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 11 1974 12:00AM