The effect of the alteration degree of ophiolitic melange on permeability and grouting

Knowledge of rock alteration can be used to give a reliable zonation of a d am foundation for grouting purposes. Rock alteration does affect both water -loss and the uptake of grout by the rock, and the existence of a close con nection between water-loss and grout consumption has been accepted for year s. However, the strength of this relationship is still debated and at the s ame time rock alteration is not considered to be possible indicator of grou t consumption. In this study, the effect of rock alteration upon permeabili ty and grout consumption has been investigated using the results of groutin g at the Yenihayat Dam in Turkey. Using a geological field study, the alter ation categories at the investigation area are identified, and zonation of the dam site according to these categories is made. The need for grouting w as determined with the help of these alteration categories and these conjec tures are tested using the results of injection work. Furthermore, the rela tionship between water-loss and grout take is investigated and a linear for mula with a moderate explanatory power is established by statistical analys is. The formula also has a physical interpretation. This study shows that z onation according to the alteration degree can be a useful approach for gro uting decisions. Similar studies at different sites and on different rock t ypes are needed to verify the validity of this approach. (C) 2000 Elsevier Science B.V. All rights reserved.