GEOPHYSICAL PROBING AHEAD FOR TUNNELLING

The report describes the results of research to determine if machine noise could be accepted as a suitable seismic source, and if so to see if it could be used to predict ground condition ahead of tunnelling by spectral analysis and other processing techniques, with particular reference to attenuation. Various geophone configurations were used to record signals on a FM tape recorder for further analysis. Analogue signals were then digitised and autocorrelation and power spectral density functions were computed for each configuration. Background noise was, as far as possible, eliminated from the analysis. The analysis showed that the attenuation vs frequency curve can be used to identify at least one geological environment. The loss of power with distance produced curves which were more or less similar; the form of the attenuation curves was of importance at present, rather than the actual amplitudes. A displacement of 10 M in geophone location was sufficient to notice a power loss above the variance error, but because the machine power was not constant with time, power needed to be normalised before comparison was made between records made at different times. It was possible to filter the tunnelling machine noise spectrum from the compressor and background noise.

• Corporate Authors:

  Imperial College of Science & Technology, England

  Department of Geology, Geophysics Section
  London SW7 2BP,   England 
• Authors:
  • Dash, B P
  • Thenuwara, A
• Publication Date: 1977-11

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 21 p.

Subject/Index Terms

• TRT Terms: Amplitude (Physics); Damping (Physics); Drilling; Electromagnetic spectrum; Environment; Equipment; Forecasting; Frequency (Electromagnetism); Geology; Geophysics; Location; Mathematical analysis; Measuring instruments; Noise; Physical properties; Properties of materials; Rocks; Seismicity; Sound; Surveying; Surveying; Tunneling; Tunnels
• Uncontrolled Terms: Seismic investigations; Site investigation
• Old TRIS Terms: Rock properties
• ITRD Terms: 6988: Amplitude; 6471: Analysis (math); 6155: Apparatus (measuring); 5559: Damping; 3871: Drilling; 2455: Environment; 3674: Equipment; 132: Forecast; 6997: Frequency; 4053: Geology; 5742: Geophysics; 9061: Location; 5925: Properties; 4154: Rock; 5722: Site investigation; 6748: Sound; 6776: Spectrum; 3374: Tunnel
• Subject Areas: Bridges and other structures; Construction; Environment; Geotechnology; Materials; Public Transportation; I41: General Soil Surveys;

Filing Info

• Accession Number: 00377141
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Report/Paper Numbers: Monograph
• Files: ITRD, TRIS
• Created Date: Aug 30 1983 12:00AM