Permeability of Savcibey Dam (Bilecik) axis location and design of grout curtain

Abstract

This study comprise the design of the planned grout curtain in Savcibey Dam (Söğüt/Bilecik) in order to provide impermeability along the dam axis. Within the context of field studies, engineering geology map was generated, ground investigation drilling was realized and permeability tests were performed. Within the field studies, the joint conditions of the geological units (Triassic aged Bozüyük Metamorphic schists) under the dam axis and its effect on permeability was observed considering the positions of the discontinuities with regard to the dam axis location. Orientation of discontinuities generally have strikes changing between N - S and NNE - SSW. 5 boreholes on dam axis, 2 boreholes on cofferdam, 3 boreholes on diversion tunnel and 2 boreholes on spillway total 245 m ground investigation borehole were drilled. In order to determine the permeability profile of dam axis and design the grout curtain, Lugeon tests in Bozüyük Metamorphic units observed in dam axis, falling head permeability tests in alluviums observed in thalveg and slope debris observed in right abutment were performed. Lugeon tests realized in Bozüyük Metamorphic units show that the unit is generally permeable and partly low permeable. Alluvium and slope debris are highly permeable. In addition, drilling works realized in dam axis shows that the augmentation of the weathering degree cause an increase of permeability in Triassic aged Bozüyük Metamorphic schists. As a result of these studies information about the permeability of Savcibey Dam was collected and the grout curtain hole was designed. Accordingly, it is predicted that approximately 40 m depth of grout curtain from the stripping excavation with the depth of 1.50 m would prevent the possible leakages.