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Rock Mech Rock Eng (2013) 46:341357 DOI 10.1007/s00603-012-0282-6
ORIGINAL PAPER
Comparison of Permeability and Groutability of Ostur Dam Site Rock Mass for Grout Curtain Design
S. M. Sadeghiyeh M. Hashemi R. Ajalloeian
Received: 30 December 2010 / Accepted: 10 June 2012 / Published online: 18 July 2012 Springer-Verlag 2012
Abstract The focus of this study is the empirical hydromechanical behaviour of the Ostur dam site rock mass. The area surrounding the dam mostly consists of diorite and andesite, with primary fractures and hydro-thermal veins. The hydromechanical behaviour of the rocks was determined using 500 water pressure tests at 5-m intervals. The hydrothermal veins and 2,739 discontinuities were studied and mapped along the dam axis. As a result, it was possible to design an optimum grout curtain for the dam axis. The empirical hydromechanical behaviour of the rock was studied to determine water ow and grout pressurised ow during the eld tests that were conducted on two representative A-series grouting operation boreholes (one borehole for each abutment). The secondary permeability index (SPI), Lugeon value (LU), rock quality designation (RQD) and cement take (CT) values are presented and compared in this article. It is concluded that permeability and groutability are mostly controlled by the spec-ications and characteristics of the veins, especially in shallow areas and lower depths. A procedure is proposed based on a comparison of the trends in the RQDSPI and LUCT, and it is suggested that the areas with diverging trends require no treatment and that those with converging trends require heavy treatment. Additional complementary
studies that were conducted during the construction stage have validated these results.
Keywords Hydromechanical behaviour Hydrothermal
veins Ostur dam Water pressure test Permeability
Groutability
1 Introduction
The sealing of dam foundations and abutments is required due to the geological conditions of rock masses (their lithology, the strength of the rock, their hydrothermal veins as primary discontinuities, their main joint sets as secondary discontinuities, the distribution of the discontinuities, the quality and strength of the joint-lling material) and their permeability conditions. The decision to install a grout curtain depends largely on the results of water pressure tests (WPTs), as introduced by Lugeon (Ewert 1997c).
The geological and permeability conditions of a rock mass may be evaluated based on laboratory, eld and...