Study on Surface Settlement of Jinchuan Copper-Nickel Area in Time Series InSAR

15 Dec 2019 / by Li Qiang,Wang Weihong, Yang Ning, Han Dan, Zhou Wentao

Surface settlement problem in Jinchuan copper-nickel mine area, this paper applies SBAS-InSAR technology and time series D-InSAR technology, and uses multi-temporal Sentinel-1A interference image to study the ground settlement in this area.Timing D-InSAR technology and SBAS-InSAR technology are used for monitoring.After two results comparison and verification analysis, there are two obvious settlement funnels in the mining area, namely 5-7 rows and old pits in the West 2 mining area, and the maximum settlement rate in the 5-7 rows in the West 2 mining area is -13mm/year. The maximum line shape of the radar line of sight is 13mm, and the settlement area reaches 0.45km2. There is obvious settlement in the southeast of the old pit. The maximum rate of settlement is -85mm/year, and the maximum line shape of the radar line of sight is 78mm. The settlement area has reached 1.4km2 provides an important basis for the safe production of Jinchuan Copper-Nickel Mine.

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Conveying vs. trucking economics for medium sized applications

10 Dec 2019 / by R. Munson


This paper shows how easy it is to perform economic evaluations ofoverlandconveyorprojectsand summarizes rules of thumb that speed up theprocess.

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Determining Factors Affecting Thermal Comfort In Underground Coal Mine.

15 Nov 2019 / by Shibaji Dey and Netai Chandra Dey

Thermal comfort in underground mining is one of the important factors in daily mining operation so does its monitoring and measurement. In Indian mining condition there are very insignificant research investigations have been done therefore, for better productive mines, determination of thermal comfort is necessary. Thermal stress along with its comfort factors has been taken into consideration for this study. Two different thermal comfort indices i.e. predicted mean vote (PMV) and predicted percent of dissatisfied (PPD) are fixed as the indicators of thermal comfort. Total 20 participants are taken for the study to assess the thermal comfort during their regular mining shift hours. Correlation statistics is also applied for finding out the interrelationship between PMV, PPD, and different thermal comfort factors. The result shows several positive and negative correlation score of low to medium for most of the thermal stress factors. Among those, few factors are found with very strong correlation. A positive correlation between PMV and heat generation due to metabolism (r=0.99) has been found while strong negative correlations between PMV vs. heat exchange by convection in breathing(r=-0.88) and evaporative heat exchange in breathing(r=-0.99) have been identified. It can be concluded that not a few but several factors are responsible for alteration in thermal comfort. It is also found from mine A (r=0.60) and Mine B (r=0.53) data set that the PMV and PPD has a medium strong correlation. Identification of thermal comfort factors is important to frame appropriate workload and a proper thermal comfort model for workers.

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Mechanisms and control technology for roof caving of a roadway in a fold belt in Zhaogu No.2 coal mine, Jiaozuo city, Henan province, China

10 Nov 2019 / by Gao Xu

To prevent the roof caving of a mining roadway in the No. II1 coal seam in Zhaogu No. 2 Coal Mine, Jiaozuo City, Henan Province, China, we analysed mechanisms of roof caving of the roadway in geological tectonic belt in the coal mine by using comprehensive research methods, such as theoretical analysis, numerical simulation, and field testing. The results demonstrate that: (1) the No. II1 coal seam contains fault and fold structures and its bidirectional pressure ratio can reach about 3, which affects the shape and extent of the plastic zone in the roadway. (2) Based on the theory of a butterfly-shaped failure zone and numerical simulation, the shape of the plastic zone in the roadway was analysed. It is found that, when the plastic zone in surrounding rock of the roadway presents a butterfly-shaped distribution, large deformation occurs in the roadway when wings of the butterfly-shaped failure zone are just located in roof, floor, and two side walls of the roadway. (3) Due to the significant changes in the plastic zone, anchor bolts arenot long enough and anchor cables with limited elongation fail to support the roadway. Therefore, a scheme using long anchor bolts was proposed. The connected long bolts underwent significant elongation and are able to provide a continuous supporting force. This controls the deformation of surrounding rock, thus achieving good supporting effect.

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The Damage and Permeability Evolution Law of Coal Mass during Confining Pressure Relief

10 Oct 2019 / by Qingying Cheng , Bingxiang Huang

In order to research the damage and permeability evolution law of coal mass under fluid-solid coupling during confining pressure relief, the permeability coefficient determination test on coal samples with transient pressure pulse method has been conductedunder the condition of false triaxial and constant axial pressure. The experiment results indicated that the deformation of coal sample is mainly radial expansion deformation during confining pressure relief. When axial pressure is between uniaxial compressive strength and triaxial compressive strength, the typical curve of “confining pressure relief-volume strain” contains three stages: elastic deformation recovery, plastic deformation and failure stage.The damage and permeability coefficient variation has a confining pressure relief threshold. Below this threshold, permeability coefficient increases slowly and steady; above this threshold, it rises rapidly. It also has a inflection pointfor confining pressure relief. When confining pressure relief exceeds inflection point, coal sample gets macro rupture and permeability coefficient increases sharply.

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