Determination of Engineering Geological Conditions of A Plant-Site: A Case Study in an Open Pit Mine in Çine, Aydın

Abstract

A plant will be constructed between the Alipasa and Sarıkısık feldspar open-pit mines in Karpuzlu-Çine (Aydın) to conduct the works of crushing-grinding and flotation. An investigation was carried out to determine engineering geological conditions at and below the plant-site using scan-lines, geophysical measurements, and three inclined borehole data. Geological structure and ground conditions including geotechnical data such as discontinuity frequency and spacing, RQD% and CR% acquired from the drill hole exploration and geophysical survey are determined. Along the inclined drill holes, true discontinuity spacing values computed for each core run represent the most intersected discontinuities. In these calculations, determination of the acute angles between the axes of drill holes and strikes of the discontinuity sets are important as much as the investigation of fracture distributions in the subsurface. For this reason, the stereographic projection techniques were used to determine the true acute angle in this work. The purpose of the investigation is to identify and mitigate difficulties caused by ground conditions. The rock conditions comprise heavily jointed and weathered metamorphic rocks and the ability of these to support the foundations is considered. It was determined that the bearing capacity values obtained from the geotechnical computations considering RQD values agree with the ones acquired from the geophysical measurements, except the weakness zones (sheared zones). It was also determined that the values of allowable bearing pressure based on the geotechnical works are more conservative than the ones from the geophysical measurements. When all results are considered, the ratio between the allowable bearing capacity (qa) values acquired from geotechnical and geophysical measurements is close to 0.65.