Volume 32, N. 3

September-December 2009

Grouting of TBM Rock Tunnel for the Pinalito Hydroelectric Plant, Dominican Republic

Case Study

Volume 32, N. 3, September-December 2009 | DOWNLOAD PDF (4 downloads)


The Pinalito main hydroelectric tunnel, with a length of 11 km, is located in Cordillera Central mountain range, Dominican Republic. This mountain tunnel has been mined through extremely fractured andesitic-basaltic and rhyolitic tuffs. These rocks are been subjected to shear and collisional displacements between Caribbean and North America plates since middle Eocene. As a result, geological and hydrogeological conditions along the tunnel alignment are rather complicated. This paper presents the main aspects and results employed in order to overcome an unexpected water bearing incompetent rock zone, approximately eleven meters wide, that cross the tunnel alignment at Sta. 5+237.40. Ground treatment was well succeeded and took six months to be concluded. Procedures adopted took into account three steps, respectively: (1) geological drilling; (2) drainage; and (3) spilling and grouting injections.

Keywords: Grouting, Pinalito Hydroelectric Tunnel, TBM, Water bearing incompetent rock zone, Dominican Republic,

Submitted on April 17, 2008.
Final Acceptance on November 11, 2008.
Discussion open until April 30, 2009.
DOI: 10.28927/SR.323143