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' the basic friction angle and "P was the surface roughness angle (Hoek and Bray, 1977). <br />' The surface roughness angle is the angle between the basic plane of the joint and the <br />planes representing the surface of ripples or undulations of the joint surface. This value <br />was based on our research of the subject, including published data from various <br />sources, and was a reasonable estimate given that no actual laboratory testing and field <br />' measurements had been performed. <br />' As a result of the 2003 geotechnical investigation, 20 rock samples were selected for <br />direct shear testing in order to better define the strength of the rock (L&A, 2003). The <br />test results produced only a basic friction angle, ?, and results indicated that the basic <br />friction angle of the discontinuities ranged from 13.7° to 49.3° with a mean value of 28°. <br />' These results do not include the two direct shear tests conducted on samples with clay <br />material along the foliation plane, which produced an average friction angle of 5°. <br />Since the 2003 geotechnical investigation, the graphical, three-dimensional kinematic <br />' analysis of wedge stability in the pit walls has been carried out using a basic friction <br />angle of 28° plus a surface roughness angle of 5° (total of 33°). <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />1 -7-