Evaluation of tunnel support based on seismic velocity before excavation

The tunnel support for rock before construction has been designed mainly based on the seismic velocity from geophysical prospecting. In Japan, a ground classification mainly according to seismic velocity is initially essential to use standard design method for support pattern of mountain tunnel. However there are a lot of cases which ground conditions estimated from seismic data before tunnel excavation are quite different from actual ground conditions during excavation. In this study, first attempt was made to compare the extent of support pattern between in design and in construction. Furthermore, to make clear of difference on seismic velocities between before excavation and after construction, many records including seismic prospecting data on actual tunnel wall and from site investigation before excavation were studied. From these data, deferential extents of both seismic velocities on various ground classification were obtained. It is finally concluded that it is necessary to incorporate some reduction factors of seismic velocity into field seismic velocity before excavation when applying to tunneling support design. From this study, following outcome are drawn: (1) A modification rate of tunnel support from design is depending on geological conditions, especially on the origin of rock. (2) A modification rate increases with the oldness of rock origin, especially in sedimentary rock. (3) A reduction ratio of seismic velocity between in tunnel wall and in field before excavation is shown that this ratio of sedimentary rocks is larger than that of plutonic rocks. It is concluded that when tunnel support is designed based on seismic velocity, it is necessary to take more cautions on estimating sedimentary rocks. (A). "Reprinted with permission from Elsevier". For the covering abstract see ITRD E124500.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/08867798
• Authors:
  • ITO, T
  • AKAGI, W
  • SHIROMA, H
  • NAKANISHI, A
  • KUNIMURA, S
• Publication Date: 2004-7

Language

• English

Media Info

• Pagination: 513-4
• Serial:
  • TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY. UNDERGROUND SPACE FOR SUSTAINABLE URBAN DEVELOPMENT. PROCEEDINGS OF THE 30TH ITA-AITES WORLD TUNNEL CONGRESS SINGAPORE, 22 - 27 MAY 2004
  • Volume: 19
  • Issue Number: 4-5
  • Publisher: Elsevier
  • ISSN: 0886-7798

Subject/Index Terms

• TRT Terms: Conferences; Evaluation and assessment; Excavation; Geology; Tunnels
• ITRD Terms: 8525: Conference; 9020: Evaluation (assessment); 5155: Excavation (process); 4053: Geology; 3374: Tunnel
• Subject Areas: Bridges and other structures; Design; Geotechnology; I25: Design of Tunnels;

Filing Info

• Accession Number: 01011661
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Dec 19 2005 3:23PM