Identification of Rock Mass Critical Discontinuities While Borehole Drilling

Abstract

Modern technologies need more mineral resources for energy generation, metallurgical products, chemicals, and many other uses. These resources are usually extracted from the Earth’s crust. Many engineering underground-space infrastructures are left after mining activity, with their very interesting features such as very large storage capacities (e.g., for hydrocarbons, hydrogen, radioactive, or other waste), and long-term geomechanical stability. Our original experiments were carried out in the conditions of an underground metal ore mine where typical mobile drilling rigs, additionally equipped with a set of sensors for recording signals as effects of rock–drill interaction were used for the research testing. A series of boreholes with diameters of Ø38 and lengths of up to 9 m in the rock medium were drilled in the “weak” and “strong” rock masses, and the frequency spectra of their signals were analyzed with the use of the fast Fourier transform (FFT) and short-time Fourier transform (STFT) algorithms. According to the proposed idealized theoretical model of the disturbance and the distinctive acceleration value of the drilling characteristic, the location of the critical discontinuities in the roof of the excavation were recognized. The most important advantage of the proposed method is the quantity and objective monitoring method for detection of a critical rock mass defect (discontinuity) that is significant for the potential functionality of underground workings as a potential energy storage room and their reinforcement.

Assessment of the Stability of Bev Lhd Loader

“…In various scientific and research centers, work is carried out on the wear of cutting tools [2], bolt load [3,4], mining methods [5] or dynamic simulations, etc. [6,7,8,9]. CAD/CAE programmes are applied, theoretical models and tests stands are developed The works concern calculations and testing of an artificial bottom of a mining shaft [10], the use of neural networks in simulations [11], numerical simulations of the mining process [12] or numerical analyzes according to appropriate standards [13].…”

Implementation of the Displacement Discontinuity Method in Geotechnical Case Studies

“…The DDM method is a helpful tool for a fast and accurate assessment of the stability of underground excavations provided that the location and orientation of joints need to be determined. A useful monitoring technique for identifying a crucial rock mass defect (joint) that could impact the functionality of underground excavations is presented in the work of Radosław et al [11]. (b) The second problem considered here was the effect of internal pressure on the circular opening that simulates hydraulic fracturing, a method that finds applications in hydrocarbon exploitation and wellbore stability.…”

“…The existence of joints and faults is a significant risk for underground excavation design, and a special technique for detecting such discontinuities is presented in the paper of Radosław et al [11]. Many studies have applied various techniques, such as numerical solution methods [12][13][14], to determine instabilities around underground openings.…”

Geomechanical Characterization of the Rock Mass along a Deep Vertical Borehole

“…Many methods have been developed to describe the condition of the rock mass, in terms of both the conditions of maintaining underground workings and possible natural hazards. Progress in the field of technology allows the search for new techniques for the ongoing monitoring of rock masses, especially in the context of ensuring the stability of underground structures [2].…”

“…Recently, Ref. [2] proposed a simplified theoretical model of a single rock mass discontinuity (strata separation), explaining the expected change (anomaly) in the characteristics when the drill rod passes through critical places.…”