Assessment of Rock Slope Instability of the Proposed Galat Sufar Open Pit Mine, River Nile State, Sudan

In this study, a proposed Galat Sufar open pit mine, river Nile state, Sudan has been approved through mining design processes. However, the area situated within highly tectonic region with different rock masses. This study is aimed to assess surface and sub-surface conditions of the rock masses and identify the expected rock failures. In this study, Televiewer survey and core logging methods are performed for sub-surface investigation. The limited surface exposure of the rock masses lead to the big differences from those recorded from the oriented core samples. Two shear planes and three joint sets constitute the discontinuity properties of surface rock masses, while two foliation planes (S₁: 86°/059° and S₂: 78°/292°) and four joint sets (J₁:89°/244°; J₂:12°/076°; J₃: 71°/287° and J₄:74°/158°) were recognized from drilled boreholes. In order to determine appropriate bench face angle for the weathered and fresh rock masse kinematic analysis technique was adopted using dip software. The kinematic scenarios performed at 20° and 10°-slope direction intervals, while bench face angles is calculated for 50°, 55° and 60° at the pit border for the top weathered rock masses and 70°, 75° and 80° for the sub surface one. The results show that the southern part of the proposed mine represents the highest risk with toppling failure for the top weathered rock masses, while low planar and toppling failure risk values recorded for the sub-surface rock masses. Finally, this study recommended that during mine development inherent site investigation must be continued to examine the stability of rock masses for the expected slope failure especially the southern part of the proposed mine.