Seismic Refraction Technique for Delineating Unstable Areas in Pit Slopes

Experimentation with seismic velocity measurements at Kennecott Copper Corp.'s Bingham mine disclosed that some recognized slide areas are characterized by low velocity profiles. A new traverse technique employed during the investigation allows rapid and precise measurements of a quantity referred to as "apparent velocity." This value is a weighted average of the actual velocity in the overbreak zone near the surface and in the intact rock at depth. The low points on the velocity profile are apparently the result of lower actual velocities and deeper overbreak in less competent material within the slide zones. Experience verifies the usefulness and practicality of the technique in delineating adverse areas prior to detectable failure. The technique may be employed as a rapid and economic means of slope stability surveillance in large open pit mines.