Assessment of Foundation Rocks of the Proposed Makhol Dam in the Northern Salah- Alddin, Iraq

Abstract

This study was done as an assessment of the foundation rocks of the proposed Makhol dam in the northern Salah- Aiddin Governorate, Iraq. This study consists of field, laboratory, and office work. It was noticed in the field that the thirteen (13) different rock mass units comprised along the dam axis. Three rock mass classification systems were adopted (used) in the evaluation: Rock Mass Rating, Dam Mass Rating, and Geological Strength Index. The DMRSTA (RMR related to dam stability) values for the right bank range between 36.97- 73.8. These values indicate good stability of foundation rocks of the right part with the presence of some instability of primary effect (not serious effect) in unit no.3 (Fatha Formation), and the DMRSTA values of the left bank range between 44.97– 61.7 These values indicate no instability for the foundation rocks on the left bank for all rock mass units. The RMRBD89 values range between 37– 73.3. These values reveal that the foundation rocks are desirable and can be excavated for rockfill and earth fill dams, but for the gravity dam, the rock mass unit 3, must be excavated to the desirable RMRBD89 value in the case of a gravity dam, and indicate that the foundation rocks do not require grouting when the type of dam is earth fill. Some rock mass units require grouting (spot grouting), especially for the rock mass unit 3 when the type of dam is Rockfill, and require systematic grouting, especially when the type of dam is Gravity. The Roc Lab software was used for the purpose of determining the mechanical properties of all rock units through the Hook-Brown failure criterion.