Shivakumar Karekal

University of Wollongong | UOW · School of Civil Mining and Environmental Engineering

Salt-induced weathering is a common phenomenon in stone relics, and its traditional artificial evaluation of severity is greatly affected by subjective consciousness and lacks systematic standards. Here, we propose a hyperspectral evaluation method for quantifying salt-induced weathering on sandstone surfaces in laboratory tests. Our novel approach...

This paper presents the optimum auxiliary fan(s) location to control air recirculation in dead-end workings where diesel-powered vehicles operate. Investigations were conducted with various secondary fan locations from the dead-end crosscut with varying the intake air quantities using a 30 m3/s capacity twin 75 kW auxiliary fan and 45 m3/s capacity...

Cutter spacing is one of the important mechanical parameters that influence the cutting efficiency of tunnel boring machines (TBMs). A methodology was developed to optimize the cutter-spacing for efficient mechanical breaking, which improves the cutting efficiency of the jointed rock mass. In the beginning, 18 indentation tests were carried out on...

A new concept of critical shear strain ετcritical of rock joint under cyclic loading is presented, and the role of ετcritical in evaluating the sliding potential of rock joint is highlighted. A series of cyclic triaxial tests was conducted on a cylindrical rock joint specimen with a replicated rough surface representing a joint roughness coefficien...

In case of earthquakes and crustal movement, the concentration of impounding load over a large region of crust can cause disturbances to the stratum. In order to quantitatively investigate crack initiation, propagation and coalescence processes of jointed stratum based on thermal variations caused by concentrated load, a series of indentation tests...

Geological discontinuities govern the strength and deformation of rock mass and play an important role in the stability of geotechnical excavations, such as tunnels, caverns, slopes, and mines. In this paper, the failure mechanism of a tunnel in the vicinity of a fault zone is investigated by physical model tests with dimensions of 3 m × 2.4 m × 0....

We investigate herein the scale effect and anisotropy of jointed rock mass (JRM) from the perspective of acoustic emission (AE) characteristics and estimate the size of the representative element volume (REV). First, we propose an AE calculation based on the discrete element method (DEM) and use the statistical results of joint planes to generate a...

Argillization is commonly observed as excavating in mudstone stratum by tunnel boring machine. In addition to the operational and geological parameters studied by previous researchers, this phenomenon also has significant influence on the performance of tunnel boring machine, such as penetrate rate, advance rate, and utilization rate. In general, w...

The reliability of disc cutters has a significant influence on the safety and working efficiency of tunnel boring machines (TBMs). To investigate the reliability of disc cutters under different geological and operational conditions, we conducted a series of novel rolling cutting tests on intact and jointed sandstone blocks using different dip angle...

Abstract: This paper presents a detailed study of DPM dispersion in unventilated dead-end cross-cuts in an underground mine. The dispersion and dilution of DPM was measured in dead-end with time when the air is flowing in the main gallery. Parametric studies were conducted by varying the dead-end cross-cut lengths (10 m, 15 m, 20 m and 25 m), varyi...

This paper presents an air-void detection technique for air-coupled radar, which emits electromagnetic waves to interrogate an air-void inside a medium or between two media. The reflections from the air-medium interfaces are usually corrupted by air-coupling, antenna ringing, and internal reflections, rendering air-void detection very difficult or,...

The study is aimed at developing a new algorithm for back analysis of rock mass parameters based on the observed displacements of tunnel excavations under coupled stress-seepage field problems which are generally encountered in hydraulic tunnel projects. The back-analysis algorithm is developed by incorporating the Levenberg-Marquardt optimization...

In this paper, an attempt is made to model Diesel Particulate Matter (DPM) flows generated by Load Haul Dumpers (LHDs) and trucks in an underground mine environment for different DPM flow and intake air flow directions and exhaust pipe directions. Field experiments were conducted and used to validate the computational fluid dynamics (CFD) models an...

Diesel-operated man-riding vehicle and Load Haul Dumpers (LHD) are commonly used in underground mines. These vehicles are used to minimize the miners' travel time between working sections and loading operations. An inevitable side effect of using these diesel-operated vehicles is the generation and dispersion of diesel particulate matter (DPM). Thi...

Diesel-operated vehicles are commonly used by personnel in underground mines. Although these vehicles facilitate travel within the mine, their main disadvantage is that they generate diesel particulate matter (DPM), a known carcinogenic agent. This calls for research to control the spread of DPM in underground mines in order to ensure the safety of...

This paper presents a detailed study of DPM dispersion in unventilated dead-end cross-cuts in an underground mine. The dispersion and dilution of DPM was measured in dead-end with time when the air is flowing in the main gallery. Parametric studies were conducted by varying the dead-end cross-cut lengths (10 m,15 m, 20 m and 25 m), varying cross-cu...

Multi-seam coal mining comprises of a large number of working sections. A well-organized ventilation system is necessary to supply adequate air quantities to all working sections and to dilute diesel particulate matter (DPM) within the statutory limits. In this paper, an attempt has been made to optimize fan(s) operating points in a multi-seam mine...

The influence of structural anisotropy on time-dependent behaviour of foliated metamorphic greenschist collected from deep underground tunnel (−1300 m) in China was investigated to acquire the fundamental knowledge of the long-term mobility of greenschist in nature. Considering the structural anisotropy, greenschist samples with different inclinati...

In this paper, an attempt has been made to model DPM flow patterns in the vicinity of man riding vehicle(s) operating in a coal mine environment. The DPM flow patterns are modelled using the techniques of computational fluid dynamics (CFD) and validated using field experimental measurements. The models show that if the vehicle is stationary, DPM pa...

Highwall mining involves driving a series of parallel entries with web pillars in between. These entries are driven by using a continuous miner with attached conveying system to extract locked up coal behind the highwall slope when the open cut coal mine reaches its ultimate limit. These entries are driven unmanned, unventilated and unsupported. Th...

Hydraulic fracture networks (HFN) can be significantly affected by the anisotropy that is caused by bedding planes in shale. In this paper, a transverse isotropic model was built based on the parallel bond model (PBM) and smooth joint model (SJM) in the discrete element method (DEM) to simulate hydraulic fracturing. First, based on the micro charac...

The influence of different bit profiles on possible fracture modes was investigated using Finite Element Method. The International Association of Drilling Contractors (IADC) classification was used to design 14 types of profiles. The formation model was built, with given bit size, formation properties, meshing method and boundary conditions, etc. M...

The influence of different bit profiles on possible fracture modes was investigated using Finite Element Method. The International Association of Drilling Contractors (IADC) classification was used to design 14 types of profiles. The formation model was built, with given bit size, formation properties, meshing method and boundary conditions, etc. M...

Polycrystalline Diamond Compact (PDC) cutters have been popularly used in recent times due to their resistance against mechanical and thermal wear. This paper was focused on interface geometries between the substrate and the diamond table. Various types of interfaces were designed, to investigate how different interface geometries influence distrib...

Highwall mining operation involves driving a series of parallel unsupported, unmanned and unventilated excavations into a coal seam exposed at the open pit Highwall using a remotely operated continuous miner with attached conveying system. These parallel excavations are separated by web pillars of pre-designed width which are critical to the Highwa...

Characterization of the overburden rock mass and identification of the top surface of the coal are of critical importance in any open cut coal mining operation, because they play a major role in achieving better coal recovery and better performance in drilling and blasting and in the design of highwall slopes. Among various techniques for identifyi...