APPLICATION OF 3D SCANNING TECHNIQUES FOR ASSESSING THE ENGINEERING GEOLOGICAL PROPERTIES OF FRACTURED ROCKMASSES

The engineering performance of fractured rockmasses containing various joints and faults are mainly controlled by the rock discontinuities, which significantly affects the overall stability of the rock slopes and underground openings. Generally, investigation of engineering geological properties of rock fractures are conducted adopting scanline methods or window mapping techniques. However, these procedures are often time-consuming, and moreover contain subjective judgements resulting in biased conclusions. In this study, the engineering geological properties of fractured rockmasses are collected using the 3D scanning techniques widely applied in civil engineering projects to enhance the reliability of field data analysis. The system utilizes both stereo photographs from disgital SLR cameras as well as 3D imagery from laser scanners to generate accurate 3D models using image processing techniquesto extract geotechnical data. The main purpose of this study is to assess the stability of underground openings, in terms of the factor of safety and the yield zone size within the rockmass. The 3D model of the groundwater flow is constructed from detailed knowledge of the geologic conditions, and effects of the water pressure on the overall stability are considered. Some numerical codes are adopted to construct the hydrogeologic model of a undeground limestone mine, and the rate of groundwater inflow and resulting porewater pressure distribution are estimated. Finally, three-dimensional stability of the mine openings is analyzed using the effective stress developed within the rock mass. A practical guidelines for designing the room and pillar layout for the underground limestone mines are provided from the assessment of the hydro-mechanical characteristics of fractured rock masses.