Combined the mechanism of gob-side entry retaining by roof cutting pressure relief and the geological conditions of Jiaozishan coal mine, the influence of gob-side entry retaining from the depth of blasting bore in the process of roof cutting pressure relief was studied by the method of FLAC3D numerical simulation. When the depth of blasting bore was 4m, it was most significant that the surrounding rock stress of roadway transferred to the roadway deep; meanwhile, the surrounding rock deformation was also the minimum. And the result was applied to an industrial practice in the intake airflow roadway of the 9706 working face. When the working face was mined, the surrounding rock deformation was basically identical between the coalside entry in front of the working face and the gob-side entry behind the working face, which met the requirements of retaining roadway and production in the next working face. It successfully reduced the difficulty of protecting roadway and the loss of coal pillar, and achieved remarkable economic and social benefits.
Keywords: Roof cutting pressure relief; gob-side entry retaining; numerical simulation; surrounding rock control; ground pressure monitoring
Basalt and granite quarries. In one of limestone quarry, expansion of quarry is planned.With increase in limestone production, optimum blasting performance in terms of fragmentation and gradation is critical. Limestone is identified as weathered, highly weathered and massive limestone based on previous exploration. Based on geological strength index, limestone is classified as blocky, very blocky, blocky/seamy and disintegrated. Further observation is required on geological discontuities for all quarry faces. This paper evaluates technological options of unmanned aerial vehicle (UAV) with photogrammetry and Lidar technology with digital images for recording and storing data of geological discontinuities.
Keywords: Geological strength index, UAV with photogrammetry, Lidar technology with digital images
This paper proposed an approach of Bayesian inference in structural equation modelling (SEM) to evaluate the accident causation in underground coal mines in India. The statistics on accident events and reportable incidents has not shown the corresponding levels of improvement. In the area of major hazards control, the mining industry has emphasized mainly on past experiences and lessons learnt. However, the conventional risk management processes are not able to achieve the goal of zero accident potential (ZAP) due to a tonne of reasons. Bayesian inference SEM is necessary to develop the models and the coefficient of parameter estimation. The Markov Chain Monte Carlo sampling in the form Gibbs sampling was applied for sampling from the posterior distribution. The results revealed that all coefficients of SEM parameters are statistically significant. The Bayesian error statistics reveals that this model provides an approach to reduce accidents in underground coal mines of India.
Keywords: Mine safety, structural equation modelling, Bayesian inferences
There is a strong fluid-solid coupling effect during the process of coal seam pulse water infusion. Based on the basic principle of liquid-solid coupling, the dynamic damage evolution rule during coal seam pulse water infusion is simulated through secondary development of ABAQUS software. During this process the mathematical model of the strain accumulation model due to the periodic changes of pulse water pressure is embedded in SOIL module of ABAQUS software discussed in this paper, in order to obtain the dynamic damage evolution rule of coal seam around the pulse water infusion hole. It provides a new quantitative method of determining coal seam pulse water infusion parameters and location. The law of different parameters of pulse water infusion on the dynamic damage evolution of coal around the infusion hole is gotten. Numerical simulation results show that, during the process of coal seam high pressure pulse water infusion, the stress field and flow field are mutual influence and mutual restriction. The coupling of the stress and flow field have impact on the physical and mechanical properties of coal in front of the working face, these factors promote each other and prevent coal and gas outburst effectively. The coal damage quantity increases significantly with the water infusion time prolonging under constant water infusion pressure and frequency. The coal damage quantity increases significantly with the water infusion pressure increasing under constant water infusion time and frequency. The coal damage quantity increases significantly with the water infusion frequency increasing under constant water infusion pressure and time. So the pulse water infusion time needs to ensure a better effect of preventing coal and gas outburst is gotten. Meanwhile the pulse water infusion pressure needs to improve under the existing technical conditions. The frequency of pulse water infusion needs to improve under the existing technical conditions. This research results contribute to obtain accurate dynamic distribution law of damage fields around water infusion holes. It provides theoretical basis for optimizing pulse water infusion in technological parameters design and raising water infusion effect.
Keywords: Coal seam water infusion, pulse, liquid-solid coupling, dynamic damage evolution, flow
The wind power converts kinetic energy in wind to generate electricity. This is done by using wind turbines. The exhaust air driven out to atmosphere by the mine ventilation fan has the potential to drive the wind turbines. The wind turbines will subsequently generate electricity which can be used to lighten the lights of streets, office complex, pumping water etc. The paper deleneates the concept followed by experimental investigations.
Keywords: Wind power, Mine ventilation fan, Wind turbines
With the help of a mine planning and design software Surpac, a geological database was created into which the coordinates and alignment of the borehole points and their constituents along with their individual grades were fed into. The deposit which has been studied is a bauxite ore. From this database, the boreholes were displayed graphically in the software GUI. Further, surface generation using the points was done that facilitated for the manual task of sectioning of individual borehole row sets. After sectioning all the hole sets, a solid model representation of the ore deposit was generated, validated and its volume and tonnage were determined with the input of its specific gravity which is known as reserve estimation. Moreover, the borehole data was composited using downhole compositing method and statistical trends of individual constituents of bauxite were studied. Block modelling was done with the help of downhole composite and the volume of the total block model was also calculated. The anomalies in the volumes between solid model and block model was discussed. The grades of individual constituents of bauxite, i.e. Al2O3, Fe2O3, SiO2 and TiO2 were determined for a particular block using Inverse Square Distance method (ISDM) and were found out to be 44%, 28.28%, 2.21% and 2.02% respectively. For the same block, the grade of Al2O3 was determined using three different grade measurement techniques, i.e. Nearest Neighbour, ISDM and Ordinary Kriging and were found out to be 41.4%, 44% and 41.37% respectively. The grades were compared to proper reasoning and concluded accordingly.
Keywords: Geological database, solid model, block model, Surpac software, reserve estimation, grade measurement