scholarly journals Investigation of Unstable Failure Potential of a Shear Slip Using DEM at an Underground Mine

2021 ◽  
pp. 59-83
Author(s):  
Xu Ma ◽  
Ping Zhang
Keyword(s):  
Shear Stress ◽  
Underground Mining ◽  
Joint Model ◽  
Underground Mine ◽  
Geological Mapping ◽  
Shear Displacement ◽  
Mining Operations ◽  
Unstable Failure ◽  
Shear Slip ◽  
Set Up

Geological structures and discontinuities subjected to the perturbations posed by mining operations in underground mining can be re-activated and cause fault-slip rockbursts. This study investigates geomechanical stability in terms of shear slip behavior along discontinuities using 3DEC with focusing on sudden changes of shear stress and shear displacement. A direct shear test is performed using a continuously yielding joint model to examine the evolution of shear stress and shear displacement on this joint. Further, this continuously yielding joint model is applied in major discontinuities of an underground mine to examine whether an unstable shear slip behavior exists, which is represented by a significant shear stress decrease and a shear displacement increase. By referring to geological mapping of this mine, four cases are developed and each case is set up with one type of major discontinuities with identically simulated mining operations. Results imply that the amplitude of shear stress decrease and shear displacement increase along discontinuities substantially increases with the depth due to higher virgin stresses and mining-induced stresses at greater depths. The discontinuity parallel to the interface between footwall and orebody is the least safe case and subjects to the largest potential of triggering seismic events. Keywords: Shear slip behavior, Unstable failure, Mining-induced seismicity, Continuously yielding joint model, DEM.

scholarly journals Sistem Dewatering Air Panas Tambang Bawah Tanah Toguraci PT. Nusa Halmahera Minerals

2019 ◽  
Vol 1 (1) ◽  
pp. 35-46
Author(s):  
Jimmy Bob Suroto ◽  
Ramdhan Rabbani ◽  
Anas Abdul Latif ◽  
Presentia Biserva Aesh
Keyword(s):  
Underground Mining ◽  
Water Drop ◽  
Water Discharge ◽  
Underground Mine ◽  
Hot Water ◽  
Underground Mines ◽  
Water Cooling ◽  
Mining Operations ◽  
Mining Front ◽  
Drill Holes

The development of the Toguraci Underground Mine was begun in 2011 with the ore production started in 2012. The amount of water continued to increase in the Underground Mine at the beginning of 2014 which became problem that effected the activities of mining. The increase of hot water Toguraci underground mining effected to the safety for workers who are exposed to hot water, ventilation problems and equipment that are submerged in hot water. Tuguraci mine has two dewatering systems, namely dewatering systems on the surface and dewatering systems in underground mines. The handling of surface water comes from pumping underground to surface where water discharge is around 400 L / s with the temperatures ranging from 70°C while water treatment in underground mines includes decreasing water heading levels and pumping water from underground mines to the surface. The increase water entering heading development and stoping can be overcome by changing the surface dewatering system by using water cooling, while underground mining is done by changing the pipeline from the polypipe to the steel pipe and to reduce water entering the mining front is doned by drill holes for installing submersible pumps and replacing Oddesse pump to the Schlumberger pump which is more resistant to high temperature hot water, as long as mining operations take place 48 borehole drilling has been done with 11 borehole flowrate below 5 l / s and 37 borehole with flow rate above 5 l / s, and a water drop of around 77 meters

A Heparin-coated Circuit Maintains Platelet Aggregability in Response to Shear Stress in an In Vitro Model of Cardiopulmonary Bypass

1998 ◽  
Vol 80 (09) ◽  
pp. 437-442 ◽  
Author(s):  
I. Hioki ◽  
K. Onoda ◽  
T. Shimono ◽  
H. Shimpo ◽  
K. Tanaka ◽  
...  
Keyword(s):  
Shear Stress ◽  
Cardiopulmonary Bypass ◽  
Membrane Skeleton ◽  
Platelet Glycoprotein ◽  
Platelet Surface ◽  
Platelet Aggregability ◽  
Vitro Model ◽  
Platelet Defects ◽  
Set Up

SummaryAlterations in platelet aggregability may play a role in the pathogenesis of qualitative platelet defects associated with cardiopulmonary bypass (CPB). We circulated fresh heparinized whole blood through tubing sets coated with heparin (C group, n = 10) and through non-coated sets (N group, n = 10) as a simulated CPB circuit. Shear stress (108 dyne/cm2)-induced platelet aggregation (hSIPA), plasma von Willebrand factor (vWF) activity and platelet glycoprotein (GP) Ib expression were measured, before, during, and after this in vitro set up of circulation. In the two groups, the extent of hSIPA significantly decreased during circulation and was partially restored after circulation. Decreases in the extent of hSIPA were significantly less with use of heparin-coated circuits. There was an equivalent reduction in plasma vWF activity, in the two groups. Expression of platelet surface GP Ib decreased significantly during circulation and recovered after circulation. Reduction of surface GP Ib expression during circulation was significantly less in the C group than that in the N group. Decrease in surface GP Ib expression correlated (r = 0.88 in either group) with the magnitude of hSIPA, in the two groups. The progressive removal of surface GP Ib was mainly attributed to redistribution of GP Ib from the membrane skeleton into the cytoskeleton. Our observations suggest that use of heparin-coated circuits partly blocks the reduction of hSIPA, as a result of a lesser degree of redistribution of GP Ib.

scholarly journals Geological CO2 quantified by high-temporal resolution stable isotope monitoring in a salt mine

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Alexander H. Frank ◽  
Robert van Geldern ◽  
Anssi Myrttinen ◽  
Martin Zimmer ◽  
Johannes A. C. Barth ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Underground Mining ◽  
Stable Carbon Isotope ◽  
Underground Mines ◽  
Background Concentration ◽  
High Temporal Resolution ◽  
Salt Mine ◽  
Gas Migration ◽  
Mining Operations ◽  
Anthropogenic Contributions

AbstractThe relevance of CO2 emissions from geological sources to the atmospheric carbon budget is becoming increasingly recognized. Although geogenic gas migration along faults and in volcanic zones is generally well studied, short-term dynamics of diffusive geogenic CO2 emissions are mostly unknown. While geogenic CO2 is considered a challenging threat for underground mining operations, mines provide an extraordinary opportunity to observe geogenic degassing and dynamics close to its source. Stable carbon isotope monitoring of CO2 allows partitioning geogenic from anthropogenic contributions. High temporal-resolution enables the recognition of temporal and interdependent dynamics, easily missed by discrete sampling. Here, data is presented from an active underground salt mine in central Germany, collected on-site utilizing a field-deployed laser isotope spectrometer. Throughout the 34-day measurement period, total CO2 concentrations varied between 805 ppmV (5th percentile) and 1370 ppmV (95th percentile). With a 400-ppm atmospheric background concentration, an isotope mixing model allows the separation of geogenic (16–27%) from highly dynamic anthropogenic combustion-related contributions (21–54%). The geogenic fraction is inversely correlated to established CO2 concentrations that were driven by anthropogenic CO2 emissions within the mine. The described approach is applicable to other environments, including different types of underground mines, natural caves, and soils.

scholarly journals Time-Dependent Response of a Recycled C&D Material-Geotextile Interface under Direct Shear Mode

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3070
Author(s):  
Fernanda Bessa Ferreira ◽  
Paulo M. Pereira ◽  
Castorina Silva Vieira ◽  
Maria de Lurdes Lopes
Keyword(s):  
Shear Stress ◽  
Stress Relaxation ◽  
Shear Displacement ◽  
Time Dependent ◽  
Shear Behaviour ◽  
Displacement Rate ◽  
Shear Mode ◽  
Direct Shear ◽  
Constant Displacement ◽  
Shear Box

Geosynthetic-reinforced soil structures have been used extensively in recent decades due to their significant advantages over more conventional earth retaining structures, including the cost-effectiveness, reduced construction time, and possibility of using locally-available lower quality soils and/or waste materials, such as recycled construction and demolition (C&D) wastes. The time-dependent shear behaviour at the interfaces between the geosynthetic and the backfill is an important factor affecting the overall long-term performance of such structures, and thereby should be properly understood. In this study, an innovative multistage direct shear test procedure is introduced to characterise the time-dependent response of the interface between a high-strength geotextile and a recycled C&D material. After a prescribed shear displacement is reached, the shear box is kept stationary for a specific period of time, after which the test proceeds again, at a constant displacement rate, until the peak and large-displacement shear strengths are mobilised. The shear stress-shear displacement curves from the proposed multistage tests exhibited a progressive decrease in shear stress with time (stress relaxation) during the period in which the shear box was restrained from any movement, which was more pronounced under lower normal stress values. Regardless of the prior interface shear displacement and duration of the stress relaxation stage, the peak and residual shear strength parameters of the C&D material-geotextile interface remained similar to those obtained from the conventional (benchmark) tests carried out under constant displacement rate.

A Review of Technical Potential for Coal Production and Coal Degasification – A Conventional Source of Methane – In Nigeria

2003 ◽  
Vol 14 (1) ◽  
pp. 59-67
Author(s):  
Adepo Jepson Olumide ◽  
Ayodele Charles Oludare ◽  
Balogun Olufemi
Keyword(s):  
Coal Seam ◽  
Fossil Fuels ◽  
Underground Mining ◽  
Simple Calculation ◽  
Gas Content ◽  
Gelling Agent ◽  
Coal Bed ◽  
Natural State ◽  
Mining Operations ◽  
Inorganic Matter

Coal, a solid fuel in its natural state has been identified as one of the world's major fossil fuels. It is a compact, stratified mass of mummified plant debris interspersed with smaller amounts of inorganic matter buried in sedimentary rocks. The use of coal as an energy source can be dated back to the prehistoric times. Methane is associated with many if not all coal seams, and is the dreaded “fire damp” responsible for many pit explosions. Coal mines are designed to vent as much methane as possible. It is present in the pores of coal under pressure, released during mining operations and can be extracted through vertical well bores. This paper highlights the fact that pipeline- quality methane can be extracted economically from coal seems before and during underground mining operations. The stimulation method involves hydraulic fracturing of the coal seam by using water, sand and, a gelling agent in a staged and alternating sand/and no sand sequence. The purpose is to create new fractures in the coal seam(s). The cleating of the coal helps to determine the flow characteristics of the coal formation and is vital in the initial productivity of a coal-methane well. The simple calculation of gas-in-place is achieved by multiplying the gas content of the coal by net coal thickness, the density, and the aerial extent of the drainage. The method is claimed to be suitable for use in Nigeria and potential sites for coal bed methane extraction in Nigeria are identified.

scholarly journals Development of a Novel Underground Mine Reconnaissance Robot

2021 ◽  
Author(s):  
◽  
Nick Thompson
Keyword(s):  
Underground Mining ◽  
Operating Time ◽  
Underground Mine ◽  
Positive Pressure ◽  
Rough Terrain ◽  
Planetary Gearbox ◽  
Brushless Dc ◽  
Mine Environment ◽  
Locomotion System ◽  
Lip Seals

<p>Despite advancements in safety technology, underground mining disasters kill hundreds of people each year. Typically after a disaster, a manned response team will enter the hazardous mine to ascertain its condition and rescue any survivors. A robotic entry platform could significantly reduce the risk to the response teams and the time taken to recover any survivors. However, existing mine search and rescue robots have had limited success in past disasters. Two primary aspects caused the failure of the existing platforms; poor rough terrain ability and lack of ingress protection for the harsh mine environment.  HADES, a novel underground mine reconnaissance robot is developed to address these issues. A lightweight yet robust chassis is manufactured from fibreglass. To allow HADES to operate in the potentially explosive atmosphere, the chassis is protected with a positive pressure gas system, designed to meet the ANZ60079.29 standard. This chassis is sealed against the mine environment with a series of O-rings and lip seals. Whegs are used as the primary locomotion method and are driven with a planetary gearbox and a brushless DC motor. To further improve a rough terrain capability of the locomotion system the rear arm of the chassis is mounted on an actuated pivot, increasing the rough terrain capability of HADES.  To ensure the operator can successfully assess and navigate the mine, HADES carries a comprehensive set of environmental and navigation sensors. The internal electronics and locomotion systems are powered with six Li-Po batteries that achieve an operating time of six hours and an expected range of 25 km.  HADES is 780x800x400 mm and is mostly sealed to the IP68 standard. The locomotion system is robust and can traverse the majority of the terrain expected in an underground mine. Loss of traction is the only problem encountered with the Wheg design. However, this can be easily fixed by changing the tip shape of the Wheg.</p>

Comprehensive Assessment of Working Conditions and Occupational Disease Rates at Mining and Metallurgical Enterprises

2021 ◽  
pp. 114-119
Author(s):  
A.G. Chebotarev ◽  
D.D. Sementsova
Keyword(s):  
Ferrous Metallurgy ◽  
Working Conditions ◽  
Occupational Diseases ◽  
Underground Mining ◽  
Working Environment ◽  
Aluminum Production ◽  
Dump Truck ◽  
Mining Operations ◽  
Production Factors ◽  
Aluminum Smelters

The paper presents the results of hygienic assessment of the working environment and work process factors at surface and underground ore mining operations, ferrous metallurgy plants and aluminum production facilities. It has been established that workers are affected by a complex of production factors (dust, toxic substances, noise, vibration, unfavorable micro climate, etc.), the level of which often exceeds the hygienic standards. The workplace conditions of the primary jobs at these enterprises in 60-80% of cases are classified as hazardous, i.e. Class 3 of various hazard degrees. The incidence of occupational diseases remains high, especially in underground mining and at aluminum production plants. The specific features of mining and metallurgical operations and the severity of unfavorable production factors determine the structure of occupational morbidity. Occupational respiratory diseases are most common among workers in the ferrous metallurgy industry and account for 70.3% in total. Vibration-induced pathologies are most frequently diagnosed among excavator, bulldozer and dump truck operators, and account for 52.9% of all the diagnosed occupational diseases. Hearing organ pathology in the form of neurosensory loss of hearing among workers of mining and metallurgical enterprises ranges from 10.2% (aluminum smelters) to 22.7% (ferrous metallurgy plants) in the occupational morbidity structure. Chronic intoxication with fluorine compounds at aluminum smelters was diagnosed in 68.1% of cases. The results obtained confirm the pressing need to improve the working conditions, introduce preventive measures based on the primary prevention principles, and reduce the risk factors of health problems among the workers.

Analysis on the Steady-state Performance and Losses of a Bent-axis Type Hydraulic Motor Used in Heavy Earth Moving Machinery

2021 ◽  
Author(s):  
Ajit Kumar Pandey ◽  
Amit Kumar ◽  
Nitish Kumar
Keyword(s):  
Steady State ◽  
Electric Motor ◽  
Underground Mining ◽  
Operating Conditions ◽  
Constant Speed ◽  
Working Environment ◽  
Variable Load ◽  
Mining Equipment ◽  
Mining Operations ◽  
Design Guideline

Hydraulic components play a significant role in the mining and construction equipment. It is responsible for smooth change in the output speed, torque, and power of the machine. The hydrostatic drive powered by a constant speed electric motor is widely used in the propel system of the mining equipment. Regulation of the displacements of the pump and the hydro-motor of the drive facilitates the control of the straight running and steering of the machines. In the present scenario, better efficiency and ease of control are the critical aspects to be considered in the design and selection of the hydraulic pump and motor used in underground mining operations. The bent axis hydro-motor is one such equipment that is an electro-hydraulic component that can work in an adverse working environment. The present study deals with the performance analysis of fixed displacement bent axis hydro-motor at different operating parameters such as different temperatures, sizes, viscosity at different loads, and drive speed. For analysis, the hydraulic drive consists of a variable displacement pump rotated by a constant speed electric motor and a fixed displacement hydro-motor. The regulation of the pump displacement controls the speed of the drive. Manually controlled hydrostatic drive propels the said machine against variable load demands. The present work investigates the performances of the hydro-motor used in the mining and construction machine through detailed modeling and experimentations. The steady-state performances are analyzed in terms of slip, torque losses and efficiency of the hydro-motor. The study finds the design guideline to operate the hydrostatic drive using such motors in a reasonable efficiency zone. The model is validated for various operating conditions of the equipment by comparing the predicted results with the test results. The outcome of the present work will be expedient for the preliminary design and assortment of similar hydraulic component used in the mobile, mining equipment.

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