This article describes elements of the Casecnan Multipurpose Project in the Philippines, which became fully operational in 2002. It includes a nearly completely unlined 24-km pressure tunnel excavated by drill and blast and TBM, enabling comparison of the effectiveness of the two approaches in terms of how efficiently the headrace tunnel carries water. This is an irrigation and hydroelectric power network in the northern part of Luzon Island. It adds 400GWh/year in power and irrigates 31,000 hectares of agricultural land. It involves intercepting and diverting two rivers, sending them into storage basins, followed by desilting basins before entering the transbasin tunnel that has an upper nearly horizontal drive and a lower drive that is inclined. Both are essentially unlined, with only a few hundred meters of steel lining at crucial points. The upper drive is located in mainly competent rock, while the lower one passes through highly variable soils. Longitudinal cross-sections and tunnel cross- sections are included. A challenge was to minimize head losses over such a large tunnel system. Friction losses from roughness of the interior are the main concern, and this was an opportunity to compare losses from drill and blast with TBM excavation losses. Models were used to compute anticipated losses and cut costs of smoothing portions of the drive beyond what would be needed to meet project demands.

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  • Corporate Authors:

    Polygon Media Limited

    Tubs Hill House, London Road
    Sevenoaks, Kent TN13 1BY,   United Kingdom 
  • Authors:
    • Bremen, R
  • Publication Date: 2003-5


  • English

Media Info

  • Features: Figures; Photos; References;
  • Pagination: p. 16-19
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00962207
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Files: BTRIS, TRIS
  • Created Date: Sep 2 2003 12:00AM