ROCK MASS CHARACTERIZATION OF WADI-MUJIB DAM SITE, CENTRAL JORDAN

This paper assesses the rock mass characterisation of the dam site and reservoir area of Wadi Mujib in central Jordan by means of the rock m ass classification systems rock mass rating (RMR) and the Barton tunne lling index (Q). The linear relationships between the RMR and Q rating s obtained from both borecores and scanlines are quite similar and ind icate good correlation. The results obtained showed that the foundatio n rocks are of good geomechanical quality, whereas the geomechanical q uality of the rock masses constituting the dam abutments exhibit fair quality. The improvement of rock mass quality towards the foundation a rea was also proved by a seismic refraction survey, which indicated th at the foundation rocks are characterised by high longitudinal velocit ies compared with the dam abutment rocks. Therefore, the foundation ro cks are favourable for the construction of both concrete gravity and f ill type dams. However, based on the rock mass conditions of the dam a butments and, in addition, other factors that affect the selection of the dam type (such as seismicity) it would be preferable to construct a rockfill dam, due not only to the aforementioned conditions but also to the availability of construction material around the dam site.