Evaluation of permeability and groutability in rock mass of ostur dam site

Abstract

Dams are constructed to control the surface runoff. One of the important points involved in grouting operation and cut off curtain design is the geological and hydrogeological investigation of the site and evaluation of its groutability. The commonly method used for determination of permeability coefficient is water pressure test (WPT). The test includes measurement of water pressure (P) and discharge (Q) pumped in the drilled boreholes and its graphical representation as (P-Q) diagrams which can be interpreted to give rock mass hydromechanical behaviour. Based on the test designation, in Ostur dam site, 400 water pressure tests were conducted and analyzed. Results of these tests are used to determine the type of hydrogeomechanical behaviour. In the other hand, the test grouting was also conducted in continuation of the (WPT) operation and the results have shown that the bedrock of this dam is impermeable, with very low groutability potential. However, the shallow part of rock mass is partly affected due to weathering. The type of flow in these parts is identified as turbulent. From the other side, the rock mass is also intersected in deep parts by hydrothermal veins. The flow type in these parts is different from the shallow parts. © ISRM International Symposium - 5th Asian Rock Mechanics Symposium 2008, ARMS 2008. All rights reserved.