Geotechnical structure interpretation from borehole wall imagery at Mamput Block, Central Kalimantan, Indonesia

Abstract

One of the considerations in mining excavation is geotechnical conditions especially structure orientation. Its observations can be done on the surface or through the drill core. However, if there is no free vertical plane on the surface and core observation, then it is difficult to find the direction of dip and strike, which then the televiewer technology is used. This study aims to reveal the structural conditions and to observe the strike and dip of rock layers using the High-Resolution Acoustic Televiewer (HIRAT) apparatus. This apparatus is an accurate and reliable method for recording structural data and has widely used in mining activity. Analysis of the structural conditions was carried out with a reading density of 0.20 m. The observations show that the discontinuity plane is generally trending to Northeast - Southwest, with a dip generally below 30°. The results of the structural interpretation of the borehole have various features that are bedding plane, filled fracture/joint, minor/major open joint, broken zone, and washout. This study gives many advantages especially in preparing data for project feasibility related to excavation, underground tunneling, or other constructions.

Discontinuity characterization of rock strata using borehole wall imagery and scanline

“…A high-resolution acoustic televiewer is the probe being used (HiRAT). By translating the travel time and amplitude of the ultrasonic signal sent from the borehole wall, this tool can transmit fracture structural conditions, bedding planes, and the orientation of these planes in the borehole [17]. The probe contains a sensor that can simultaneously scan the borehole wall and is packed as a fixed acoustic transducer and rotational acoustic mirror.…”