Coal Mining Excavation Research Articles

A Fractal and Numerical Simulation Coupled Study of Fracture Network during Coal Mining Excavation

This paper features a numerical study that is carried out by using discontinuous deformation method (DDA) and fractal geometry. The configurations of rock strata calculated by DDA were imported into a code that is written by using VC++ called “Fractal” to calculate the fractal dimension of the rock strata. As illustrated, a long wall mining case in China was presented. The relationship of the fractal dimension, excavation length, stress, and movement of strata were discussed. The evolution of fractal dimension can be considered as an index of instability or failure. The method proposed in this paper can be employed to predict the period weighting in long wall mining engineering.

Numerical model for the zonal disintegration of the rock mass around deep underground workings

Deep underground excavation can produce zonal disintegration in the surrounding rock under certain conditions. This phenomenon has mainly been studied in a qualitative manner using in situ investigations or laboratory experiments. Researchers have also derived analytical solutions, which resulted in the formation conditions for zonal disintegration. However, the analytic solutions developed to date are not suitable for practical engineering applications because of the stringent model requirements and complicated boundary conditions. To investigate the mechanism of zonal disintegration, a numerical method is proposed to model the phenomenon. The following concepts are incorporated into FLAC3D via its built-in FISH. First, coal mine (or tunnel) excavation is considered as a dynamic process. Second, the element failure criteria are developed based on the maximum tensile stress criterion and strain energy density theory. Third, the mechanical damage is modeled through a decrease in the multi-step elastic modulus, i.e., the nonlinear stress–strain behavior is approximated by the multi-linear elastic softening model. Two practical cases with zonal disintegration are simulated using the proposed method. Both simulations predict the same number of fractured zones at the same location as those obtained through in situ monitoring.

The Abrasive Resistance Study about the Cutting Picker 40Cr of Coal Cutter

The cutting pick is primarily used in footing excavation such as coal mining and roadway excavation, so the performance of cutting tooth directly affect the mining capacity, the driving efficiency, and the service life of the tool. The quality of domestic mining pick is lower than that abroad, especially the tooth body wear of the whole shearer picks accounts for half of its overall failure. Thus tooth body 40Cr was treated by various heat treatment processes in this experiment, so as to improve the hardness and wear resistance of cutting tooth, analysis the surface wear scar of morphology, research the wear mechanism, that made for reducing the consumption of cutting tooth, improving work efficiency, and easing the labor intensity of workers undergound.

Experimental study on the variation law of coal temperature during excavation in coal mines

By testing the temperature of the coal and the stress of the working surface, we got the variation law of coal temperature and coal stress during the excavation. The result shows that the activities of mining affect the coal temperature, the fluctuation of coal temperature and the coal stress is synchronous. During the smooth change of crustal stress, the coal temperature basically keeps unchanged, when the dynamic phenomenon appears, the coal temperature changes, as well the coal stress. Therefore, we can use the online coal temperature monitoring system to test the coal temperature of the working surface continuously, and it can provide basic information for forecasting coal mine power disaster before it happens.

A numerical solution to integrated water flows: Application to the flooding of an open pit mine at the Barcés river catchment – La Coruña, Spain

► We developed an integrated and lumped surface/groundwater numerical model. ► We developed and applied a new approach for actual evapotranspiration processes. ► We applied novel approaches for infiltration rates and overland flows processes. ► Interface and GIS developments manage simulated conditions and numerical results. ► Application allows mass conservation on deep water bodies with complex hydrogeology. This research and practical application is concerned with the development of a physically-based numerical model that incorporates new approaches for a finite element solution to the steady/transient problems of the joint surface/groundwater flows of a particular region with the help of a Geographic Information Systems to store, represent, manage and take decisions on all the simulated conditions. The proposed surface–subsurface model considers surface and groundwater interactions to be depth-averaged through a novel interpretation of a linear river flood routing method. Infiltration rates and overland flows generation processes are assessed by a sub-model which accounts for this kind of surface–groundwater interactions. Surface–groundwater interactions consider also novel evaporation and evapotranspiration processes as a diffuse discharge from surface water, non-saturated subsoil and groundwater table. The practical application regards the present flooding of the Meirama open pit, a quite deep coal mining excavation, with freshwater coming from the upper Meirama sub-basin, in the context of the water resources fate and use at the Barcés river catchment (∼87.9 km 2 ), Coruña, Spain. The developed model MELEF was applied to the complex geology of a pull-apart type sedimentary tertiary valley and the whole of the water resources of the Barcés River drainage basin, down to its outlet at the Cecebre Reservoir. Firstly, the model was adapted and calibrated during a simulation period of three and a half years (2006/2009) with the aid of the historically registered hydrological parameters and data. Secondly, the results predict the most likely forthcoming evolution of the present flooding of the Meirama open pit to reach therein a total depth level of almost 200 m, as regards the projected evolution of the water resources, climatology and usages.

Numerical Simulation of Coal Mining Excavation Based on Discontinuous Deformation Analysis

The movement and deformation of rock stratum occur when the excavation is carries out during the underground mining process. Rock is a continuous-discontinuous material so the continuum mechanics method may not handle the rock problem well. The discontinuous deformation analysis (DDA) method which discretizes the rock mass to block system can describe the large displacement and deformation of rock blocks, especially the rock stratum collapse. The DDA was employed in this paper to analysis a mining excavation process. The displacement field and stress field of rock stratum was computed. The result shows that the DDA can handle the mining excavation and the rock stratum movement and deformation problem well.

Stresses and displacements due to underground mining using a finite element procedure

A two dimensional finite element procedure is applied to simulate a coal mining excavation sequence. A procedure with linear solution steps is developed and applied to an idealized mountain cross-section with exceptionally thick coal seams and large dip angle. The results provide information on pillar pressure, floor and roof stability, displacement characteristics and surface subsidence.

Stability of access tunnels to coal mine excavation : Adam, G J; Braidford, W; Dudley, W R Proc Conference on Rock Engineering (Newcastle-upon-Tyne, 4–7 April 1977), P541–555

Stability of access tunnels to coal mine excavation : Adam, G J; Braidford, W; Dudley, W R Proc Conference on Rock Engineering (Newcastle-upon-Tyne, 4–7 April 1977), P541–555