Using Photogrammetric Methods for Mapping Geological Structures and Predicting Pitwall Kinematics at the Persus Mine, Ayanfuri of Ghana
Abstract
Mapping geological structures in a mine is crucial for exploration and exploitation of the ore of that mine, helping in determination of the life span of the mine. In very unstable areas, the traditional method is usually inaccurate, time consuming and very risky. In this study a novel approach of photogrammetric principles was adopted for geological structural mapping at Persus mine. The geological structures of the pit walls were captured using Nikon D7000 camera and processed using SiroVision Version 5.1.11.0 software; and the kinematics analysis was done using Dips Version 5.103 software. In all, three individual mosaics were created using stereo models of the faces forming a composite image. The structural mapping was performed using SiroJoint a component of SiroVision. A total of 50 joints were mapped on the photographs. The orientation of the Dip and Dip directions were determined by plotting the mapped structures in Stereonet. This also helped to determine the areas of low to high concentrations using the Frictional Angle, Pit Slope, Daylight Envelope and the Critical Point. The strength of the intact rock was 54 MPa and it falls in the range of 50-100 MPa hence rate 7. The space of discontinuity was 1.9 m which lies between 0.6-2.0 and was given a rating value of 15; condition of discontinuity of the face thus slightly weathered and rated 25. The various rating values were put together giving the total rating value of 52 which helped to define the class and the description within which the rock was found. The cohesion of the rock mass lies between 200-300 kPa and the frictional angle between 25-30 degrees. SET 1 and 2 were kinematically stable but SET 3 is unstable, therefore sliding and hence failure is possible.
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