Serkan Saydam

Load Transfer Behavior of Fully Grouted Cable Bolts Reinforced in Weak Rocks Under Tensile Loading Conditions

To enable a better understanding of the load transfer performance of fully grouted cable bolts, a new laboratory short encapsulation pull test (LSEPT) unit has been designed and constructed. With this unit, both peak and residual capacity can be assessed over a relatively large pull-out displacement range of 100 mm. Various cable bolt failure modes, including relative slippage along the cable/grout and grout/rock interface, can be studied. Both a modified and a plain strand cable bolt confined in a material having a low strength of 8 MPa were tested. Within this testing process, the impact of the design of the bearing plate was considered that was found to alter the failure mode of the modified cable bolt. Other factors are considered, including the influence of borehole diameter, cable surface geometry, and sample strength on the axial performance of cable bolts.

Unified Size-Effect Law for Intact Rock

AbstractA suite of laboratory testing was performed on Gosford sandstone samples having a range of sizes, including point-load and uniaxial compressive tests. A unified size-effect law (USEL), based on the work by Zdenek Bazant, involving fracture energy as well as fractal theories, was introduced. It was shown that USEL correlates well with the ascending and descending uniaxial compressive strength trends obtained from Gosford sandstone as well as five other rock types reported by Brian Hawkins. Fractal characteristics found to be the primary mechanism for ascending strength trends and surface flaws could be considered as a secondary mechanism. The influence of the contact area on the size-effect behavior of point-load results was investigated using a new approach. This approach was novel in the way it incorporated the load contact area. Determination of the point-load strength index using this new approach led to opposite size-effect trends compared with those observed using a conventional point-load st...

Experimental study for reducing gas inflow by use of thin spray-on liners in underground coal mines

Abstract This paper presents an investigation of the potential use of thin spray-on liners (TSLs) in underground coal mines as a gas management tool. The coal samples used were taken from a coal mine in Australia. Three different TSLs were examined. The experiments include single phase gas flow tests through intact and treated dry coal samples. Experimental observations indicate that TSLs can reduce gas permeability of coal by up to three orders of magnitude. However, the degree of the impact depends strongly on the type of TSLs. Further, the initial permeability of coal and TSL thickness also affect the efficiency of the process. There is a linear relation between the efficiency of the TSLs in controlling gas flow and their adhesion strength to the coal sample.

Failure of the threaded region of rockbolts in underground coal mines

Abstract HSAC 840 steel rockbolts were examined, all of which had failed in service through the threaded region exterior to the rock face by brittle fracture transverse to the bolt axis. The bolts had been in service in an Australian coal mine in which the groundwater had a pH of 7·5–8·5 and a relatively high bicarbonate level of 515–2200 mg l−1. All failures had occurred within the region comprising the domed washer and the end plate. The majority of the bolts showed a small thumbnail-shaped discoloured region 1.5-4.5 mm in length at the fracture origin, as is characteristic of stress corrosion cracking (SCC) in rockbolts. In half of these bolts, SCC had initiated immediately at the root of the thread, but in the other half of the bolts, SCC had initiated from a small pre-existing crack that had been produced in the thread as a result of a prior bending load.

Application of thin spray-on liners to enhance the pre-drained coal seam gas quality

Gas drainage has been the most common technique for gas management in underground coal mines. This method involves drilling holes into a virgin coal seam to allow the gas bleed off from the coal into the drainage holes. A major problem with the underground gas drainage is the air leakage around the gas drainage hole that cannot be blocked off by the sealing material. The air leakage will cause the low concentration of the drained gas and decrease the efficiency of the gas drainage hole, which may further lead to many other risks, such as spontaneous combustion, gas combustion and gas explosions. A thin spray-on liner is defined as a chemical-based layer or coating (3–5 mm) that is sprayed onto the rock surface to support mining excavations. Since their introduction, thin spray-on liners have received some success as a ground support tool for underground mining. Besides ground support, thin spray-on liners also show some potential to be used as a gas management tool in underground coal mines due to their relatively low permeability. This paper describes a field trial of using thin spray-on liners for enhancing the gas drainage efficiency by blocking the fractures around the drainage holes. The project involves spraying a thin spray-on liner onto the area surrounding gas drainage holes whereby the thin spray-on liner acts as a thin membrane decreasing the permeability of coal. This restricts the air migrating through the coal seam and diluting the gas from the drainage holes. The key benefits associated with the application of TSLs are the increase in the methane purity and the decrease in the air contamination. In-situ adhesion tests were conducted in parallel with the gas tests, and the results revealed that the TSL tested could be implemented for underground coal mine applications as the main failure mode is the internal failure of the coal substrate.

Modification to Radial Strain Calculation in Rock Testing

The complete uniaxial or triaxial stress–strain behavior of a rock sample can be achieved in compressive testing using a servo-controlled testing system. Initially, the load-deformation data is recorded during an experiment, and then to eliminate the scale dependency of force, this data are converted to the stress–strain curve for final reporting. It has been found that because of the particular design of the current sample instrumentation system used to measure the circumferential or lateral deformation during the uniaxial or triaxial compressive tests, a modification is required to be included in the conventional method of radial strain calculation. As a result, a new analytical solution has been developed to improve the accuracy of the radial strain calculation. The modification procedure differs depending on whether the test-sample diameter is greater or less than 50 mm. A comparative study was conducted based on visual observation and quantitative analysis to show the variation in a number of rock parameters including elastic modulus, Poissons ratio, peak stress, critical strain, residual stress strain, softening fracture energy, and residual stress when this modification was implemented. For a 50-mm-diameter sample, which is the suggested size for rock testing according to the International Society for Rock Mechanics, the effect of this modification on the parameters obtained from the post-peak region, such as critical strain, residual stress strain, and softening fracture energy varied from 5 % to 9 %. It was concluded that the impact of this modification procedure is more significant with smaller-diameter samples used in rock testing.

An integrated economics model for ISRU in support of a Mars colony - initial status report

The aim of this effort is to develop an integrated set of risk-based financial and technical models to evaluate multiple Off-Earth Mining (OEM) scenarios. This quantitative, scenarioand simulation-based tool will help identify combinations of market variables, technical parameters, and policy levers that will enable the expansion of the global economy into the solar system and return economic benefits. Human ventures in space are entering a new phase in which missions formerly driven by government agencies are now being replaced by those led by commercial enterprises – in launch, satellite deployment, resupply of the International Space Station, and space tourism. In the not-too-distant future, commercial opportunities will also include the mining of asteroids, the Moon, and Mars. This investigation will examine the role of OEM in a growing space economy. (In this investigation, the term ‘mining’ is taken to embrace minerals, ice/water, and other in situ resources.) OEM can be the engine that drives the space economy, so it would be useful to understand what OEM market conditions and technology requirements are needed for that economy to prosper. These specific elements will be studied in the wider context of creating an economy that could ultimately support a sustainable Mars Colony. Such a colony will need in situ resources not only for its own survival, but to prosper and grow, it must create viable business ventures, essentially by fulfilling the demand for in situ resources from and on Mars. This investigation will focus on understanding the role and economic prospect for OEM associated with the Human Colonization of Mars (HCM).

Environmental influence on mesh corrosion in underground coal mines

Abstract The effect of corrosion on different steel mesh types was examined in a Controlled Mine Environment laboratory which recreated underground mine environmental conditions. Corrosion rates of mesh at different testing conditions were calculated and weld strengths of the corroded mesh were examined. Mesh specimens in ‘dry’ conditions had no significant corrosion effects over 12 weeks. However, ‘wet-dry cycle’ mesh specimens exhibited significant corrosion rapidly, with estimated corrosion rates of around 0.01 mm/yr for galvanised mesh, whether sprayed once or three times daily, 0.70 mm/yr for three times daily sprayed black mesh and 0.48 mm/yr for once daily sprayed black mesh. The mesh corrosion mechanism was dramatically changed by wet-dry cycle. The results are indicative of the behaviour of installed mesh.

Publication strategies for academic career development in mining engineering

Abstract Academics in mining engineering around the world are expected to publish their research as part of their career development. Different schools have different strategies and expectations for publishing and evaluating the value of the publication. Using an online survey, we asked members of the Society of Mining Professors (SOMP) to indicate in which publication types they publish the most (refereed journals; non-refereed journals; refereed conferences; non-refereed conferences); to list the names of top refereed journals in which their research work has been published; to tell whether their universities count conference publications in the same way as journal publications; to explain how they measure the quality of a journal; to give the factors that contribute to the decision to submit their papers to any particular journal; if their universities consider “number of citations” of publications and “h-index” when a faculty member goes through the promotion process; and whether their universities use any kind of metrics to rank contribution as principal author and/or co-author of a publication. The results of this research may be used by SOMP members, particularly junior academic staff members, in planning publication activities and strategies that would support their academic career development.

Using Moodle — An open source leaning management system in Australian Mining Engineering Education

Learning Management Systems (LMS) including Moodle and Blackboard are now almost ubiquitous in many K-12 and Higher Education institutions. They represent a suite of technologies, tools, and processes that, when implemented and utilised skillfully, can have a very positive impact on the ability to provide a quality teaching and learning environment. The University of New South Wales (UNSW), School of Mining Engineering in Australia has successfully implemented the open source Moodle as the sole LMS in both undergraduate and postgraduate programs. This paper presents an overview of the existing approach to learning and based on this experience, provides recommendations for the future advanced implementation of Moodle.