THE PROBLEMS OF TUNNEL EXPLORATION

THE OPTIMUM APPROACH FOR A TUNNEL INVESTIGATION IS DISCUSSED FROM THE STANDPOINT THAT THE DESIGNING ENGINEER NEEDS DETAILED GEOLOGICAL INFORMATION, PROJECTION OF SURFACE GEOLOGICAL DATA TO TUNNEL GRADE, AND INTERPRETATION OF THE EFFECTS OF THE GEOLOGIC STRUCTURES ON CONSTRUCTION. THE BUREAU OF RECLAMATION PROGRAMS NOW REQUIRE SURFACE GEOLOGIC MAPPING IN RECONNAISSANCE FASHION ON A SCALE OF 2,000-FT. TO THE INCH FOUR OR FIVE MILES EITHER SIDE OF THE ALIGNMENT CORE HOLES ARE DRILLED WHERE POSSIBLE FOR THE PURPOSE OF DETERMINING ROCK CONDITIONS AND TYPE AT GRADE AND FOR GEOLOGIC REASONS TO CONFIRM THE PROJECTION OF SURFACE GEOLOGIC STRUCTURES TO GRADE. THE SEQUENCE OF REGIONAL RECONNAISSANCE MAPPING FOLLOWED BY DETAILED ALIGNMENT MAPPING, FOLLOWED BY SEISMIC AND/OR RESISTIVITY INVESTIGATIONS CONFIRMED BY DRILLING ARE FOLLOWED WHEREVER POSSIBLE. ENGINEERING GEOLOGIC MAPS ARE RECOMMENDED TO PLACE THE ENGINEERING CHARACTERISTICS OF A PARTICULAR ROCK OR FORMATION DIRECTLY ON THE GEOLOGIC MAP. REFRACTION SEISMIC OR RESISTIVITY STUDIES ARE NEEDED. THESE GEOLOGIC TECHNIQUES FOR VARIOUS AREAS ARE DISCUSSED. GEOLOGICAL WORK IS NOT COMPLETED WHEN THE EXCAVATED TUNNEL HAS BEEN MAPPED BECAUSE CLAIMS OF CHANGED CONDITIONS ARE CONTINUALLY A PROBLEM. THE USE OF A HELICOPTER MAY BE NECESSARY IN INACCESIBLE AREAS, EVEN THOUGH IT IS HAZARDOUS AND SOMETIMES UNDEPENDABLE.

• Authors:
  • Hall, C E
• Conference:
  • Engineering Geology and Soils Engineering Symposium, Proceedings of the 6th Annual
  • Location: Boise ID, United States
  • Date: 1968-4-17 to 1968-4-19
• Publication Date: 1969-4

Subject/Index Terms

• TRT Terms: Core samples; Drilling; Excavation and tunneling; Geological surveying; Mapping; Refraction; Resistivity method; Rocks; Seismicity; Tunneling; Tunnels
• Uncontrolled Terms: Seismic investigations; Seismic refraction
• Old TRIS Terms: Core drilling; Geologic investigations; Geologic mapping
• Subject Areas: Bridges and other structures; Geotechnology; Highways;

Filing Info

• Accession Number: 00229734
• Record Type: Publication
• Report/Paper Numbers: pp 3-8
• Files: TRIS
• Created Date: Mar 9 1970 12:00AM