Fracture System and Rock-Mass Characterization by Borehole Camera Surveying: Application in Dimension Stone Investigations in Geologically Complex Structures

Abstract

The successful exploration of dimension stone mainly depends on the quality, size, and shape of extractable blocks of dimension stone. The investigated area is in the Pelješac Peninsula (Croatia), in the External Dinarides orogeny, built from thick carbonate succession, characterized by relatively small deposits of high-quality dimension stone. These conditions demand challenging geological investigations in the “pre-quarry” phase to find optimal quarry location. The size and shape of dimension stone blocks are mainly controlled by fracture pattern systems. In the rugged, covered terrains, it is very hard to obtain a satisfactory amount of fracture data from the surface, so it is necessary to collect them from the underground. Borehole camera technology can visualize the inner part of the rock mass and measure the fracture characteristics. The main conclusions are as follows: (1) the digital borehole camera technology provides a quick, effective, and low-cost geological survey of fractured rock mass; (2) statistical fracture distribution parameters, P10, fracture spacing, Volumetric Joint Count (Jv) based on borehole wall survey can reflect the integrity of rock mass, providing a solid decision-making base for further investment plans and dimension stone excavation method.

Optimization of mining works for the purpose of obtaining and installing the dimension stone of a uniform appearance

“…Taking into account the type of rocks, spatial distribution and dominant (prevailing) discontinuities (stratification, faults and joints), mining works are carried out so that the front of the mining works follows the line of deposit strike where the direction of progress is vertical or parallel to the dominant discontinuities (joints that have the character of a maximum and submaximum), [9], [20].…”

Microstructure, Geometry and Hydrogeology of the fracture network of the Boda Claystone Formation

“…Recently, borehole video logging technology (borehole camera, optical and acoustic televiewer-BHTV) has been widely used in geological and hydrogeological research and nuclear waste research to measure fracture characteristics in boreholes. The fracture orientation (dip direction and dip), spatial parameters, and P10 linear fracture intensity could be easily determined using these methods (Pavičić et al, 2021). Acoustic borehole televiewers give a picture of the interior of a borehole by measuring the acoustic amplitude and return time of an ultrasonic signal emitted by a borehole logging tool.…”