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Estimation of the situation in the mining output area
Published in G. N. Panagiotou, T. N. Michalakopoulos, Mine Planning and Equipment Selection 2000, 2018
P.I. Ponomarenko, A.A. Askarov
When planning the realization of the workings, the ways of their supporting and protection are chosen on the basis of the analysis of mine and geological conditions along the route of the designed working. Usually, the designers take data about the seam characteristics and enclosing rocks from the geological reports made by the geologists according to the prospecting holes. The drilling of those holes is expensive. Therefore, they are drilled in each 100 meters. That distance is too great value in the conditions of the mining operations, especially in the medium with thin stratification. The practical data testify to the fact that rocks can undergo the essential changes on the plot of such length. Sometimes one rock of the roof or ground can be replaced with another one, and their thickness is widely changed. The discrepancy of real mine and geological conditions to the predicted ones leads to the mistaken technical decisions when choosing the ways of supporting.
Laboratory-Ageing of Geomembranes in Municipal Landfill Leachates
Published in T. H. Christensen, R. Cossu, R. Stegmann, Landfilling of Waste: Barriers, 2020
Olivier Artières, François Goussé, Eric Prigent
Chemical and mechanical stresses can combine to affect the polymer's service life. The combined stress on semicrystalline polymeric materials can cause stress cracks (Landreth, 1988). This phenomenon is now well known for polyethylene geomembranes and is one of the disadvantages of this material (Halse et al., 1988; Peggs & Carlson, 1988). These failures often occur in the seam areas, due to residual stresses after seaming and also due to the overlapping geometry of the seams (Halse et al, 1988). Cracks and strain due to residual stress increase the diffusion of chemicals in the polymer material leading to chain die breaks.
Planning Experimental Investigations
Published in F.P. Glushikhin, G.N. Kuznetsov, M.F. Shklyarskii, V.N. Pavlov, M.S. Zlotnikov, Modelling in Geomechanics, 2022
F.P. Glushikhin, G.N. Kuznetsov, M.F. Shklyarskii, V.N. Pavlov, M.S. Zlotnikov
Let us analyse these graphs. For the case under consideration all the four unknown factors have a significant influence on convergence. Two of them—depth of location and thickness of seam—tend to increase it while the other two—strength and rigidity of the surrounding rocks—tend to decrease it. The depth at which the mine working is located has the strongest influence on the process under investigation. An empirical expression is fitted for each of the graphs. These hold good with all other factors at their average value.
On the dependence of predictive models on experimental dataset: a spontaneous combustion studies scenario
Published in International Journal of Mining, Reclamation and Environment, 2021
Khadija Omar Said, Moshood Onifade, Bekir Genc, Abiodun Ismail Lawal, Jibril Abdulsalam, Joseph Muchiri Githiria, Samson Bada
Geological factors include seam width, seam slope, organic matter, and presence of geological structures. The physical-chemical properties that influence the self-heating of coal include the presence of moisture, ash, carbon, organic sulphur, oxygen, temperature, and volatile contents [11,55]. In surface mines, coal exposed by cracks promotes its oxidation due to exposure to oxygen found in the air. For underground mines, unmined coal left for support or in roofs, mining techniques, coal seam dimensions, multiple seam mining, and ventilation design are the major causes of coal fires. Environmental variables influencing this phenomenon include humidity, direction, and speed of airstreams, gaseous concentrations, rain, and solar heat. The heat from external sources such as frictional heat from moving parts in mines causes sparks due to short-circuiting can also trigger coal burning.
A review of spontaneous combustion studies – South African context
Published in International Journal of Mining, Reclamation and Environment, 2019
A number of factors considerably influence the advance of low-temperature oxidation of coal. The factors include the oxygen concentration and temperature [30], inherent moisture content [31], the presence of particle minerals [32] and surface area [33]. The reaction can also be influenced by the proportion of each maceral composition [34,35], coal rank (Vitrinite reflectance) [35] and volatile and chemical composition of coals [36]. Factors such as geological, environmental, mining, physical and chemical conditions affect the process of self-heating and combustion in coal. Geological factors include seam thickness, seam gradient, organic matters and geological discontinuities (fissures, joint, cracks and faults). In open cast mines, the quantity of coal left on the coaling bench, micro- and macro-cracks in benches and outcrops are the key factors affecting self-heating, while in underground mines, parameters such as pillar and roof conditions, rate of advance, ventilation system and airflow, panel dimension, mining method, multi-seam working, ratio of coal extraction are the mining factors influencing coal self-heat. Environment parameters include air pressure, relative humidity, wind speed and direction, oxygen concentration, moisture and sun radiation. External factors such as discarding of hot ash, frictions of conveyor belt, electrical short circuits and ignition also affect spontaneous combustion. The physical and chemical parameters influencing coal spontaneous combustion includes moisture, volatile matter, ash, carbon, oxygen, organic sulphur, weathering, bacteria, temperature, ventilation, conductivity and ozone [13,15,37,38].
Discrete element analysis of deformation features of slope controlled by karst fissures under the mining effect: a case study of Pusa landslide, China
Published in Geomatics, Natural Hazards and Risk, 2023
Qian Zhao, Zhongping Yang, Yuanwen Jiang, Xinrong Liu, Fangpeng Cui, Bin Li
Taking the Pusa collapse as the geological prototype for numerical simulation research, a two-dimensional discrete element numerical model of the mountain before collapse is established along the main sliding direction at a scale of 1:1, as shown in Figure 3. In accordance with the test and calculation requirements of the technical specification ‘standard for test methods of engineering rock mass’ (GB/T 50266-2013), laboratory tests are carried out on various types of rock and coal seam samples collected on site. The density, bulk modulus, shear modulus, cohesion, internal friction angle and tensile strength of various materials are obtained by density test, uniaxial compression test, triaxial compression test and uniaxial tensile test, collated in Table 2. The determination of parameters for joints and rock interfaces is based on the field survey and engineering analogy method (Table 3), the main references are Zhong et al. (2020), Xiong et al. (2021), and Cui et al. (2022). Universal Distinct Element Code (UDEC) is a two-dimensional numerical program based on the distinct-element method for discontinuum modeling. UDEC simulates the deformation response of a discontinuous medium, represented as a combination of discrete blocks, subjected to either static or dynamic loading. It has been widely used in the study of progressive failure of rock slope, permeability characteristics of rock mass, and size-time effects of rock strength (Israelsson 1996). A variety of post-processing graphics can be displayed and output in UDEC, such as stress nephograms, displacement nephograms, joint state nephograms, seepage nephograms. It is also possible to set up different output items and extract specific values for each data in a certain range (points, lines and surfaces) before the nephogram is output. Coal and rock materials are regarded as elastoplastic materials and Mohr-coulomb plasticity failure criteria is adopted; the joints and the discontinuity surface between the rock strata are applied with the point contact-coulomb slip model in the UDEC. During the numerical calculation, the gravity g = 9.8 N/kg is set.