Advanced Materials Research Vols. 524-527

Abstract: In order to solve the serious damage and repeat revision problem of high stress soft rock roadway in deep -950 level of Tangshan coal mine, based on the theory of the maximum stress level, together with the actual measurement of geostress and the laboratory mechanical parameters of rock-core and computer numerical simulation, the high strength combined support technology and supporting parameters are determined and the engineering test has been done. The engineering test results show that the parameter determination of high strength combined support technology, which based on the actual measurement of geostress, can effective solve the support issue of high stress soft rock roadway and provide useful experience for similar engineering problems.

Abstract: Thirty-eight groundwater samples from three deep seated aquifers (the Quaternary, the Coal bearing and the Taiyuan Fm aquifers) had been collected from three coal mines in northern Anhui Province, China for analyzing their major ions, and the statistical methods (correlation, cluster and discriminant analysis) had been processed for evaluating the source of ions and relationship between aquifers. The results suggest that: (1) the chemical signatures of the groundwater are mainly controlled by dissolution of plagioclase, K-feldspar and calcite; (2) the aquifers had been mixed with each other, especially the mixing between the Quaternary aquifer and the Taiyuan Fm aquifer. Discriminant analysis has produced two functions and a diagram, which can be used for water source discrimination.

Abstract: We had the digital analysis study on side slope stability in order to deduce the calculation process of side slope safety factor with Janbu method and calculate the side slope safety factor of Jianshan iron mine, and put forward the effective management measures ,which achieved the ideal result

Abstract: To address the issue of high gas emissions in mining gassy coal seams in underground coal mines, the concept of a three-entry panel layout with a retained goaf-edge gateroad and a “Y” type ventilation system is introduced in this paper. With the layout and ventilation system, distribution characteristics of methane concentration in the panel goaf is analyzed, technologies of gas drainage with boreholes drilled from the retained goaf-edge gateroad and into stress-relieved overlying and underlying seams are described, and an application case of such layout in a coal mine is also presented in this paper.

Abstract: In this paper, the mine subsidence in Luanchuan county, Henan Province is investigated using time-series InSAR technique. 9 ALOS PALSAR images from May 11, 2008 to November 17, 2010 were used to generate 21 interferograms with vertical baselines less than 2000m. The results show that average subsidence velocity in Lanchuan mining area is 0 ~-59mm/year. The subsidence velocity in the north is faster than that in the south and the east faster than the west. Subsidence taken place mainly in Lengshui, Chitudian and Shizimiao Town with a velocity over -35mm/year.

Abstract: Aim to analyze the development trend of ground fissures, new type of deformation monitoring device was developed. The device was used to measure the deformation of ground fissures in metal mine. The results showed it was feasible to monitoring the three-dimensional deformation. This study could provide reference for the similar condition mine.

Abstract: In recent years, with the rapid development of highway, high-speed railway and other large cross-section tunnel engineering, a large number of waste rocks are piled up and induce various security issues which affect people's production and living environment seriously. The actual capacity of the LQS tunnel waste rocks dump has been far more than its design dimensions, and brings about a certain extent potential safety hazard to some expressway projects in Sichuan Province. Utilizing FLAC3D and its Mohr-Coulomb criterion establish 2D model, and analyzes displacements, and calculate its safety factor, estimate the slope stability and destructiveness of the waste rocks dump. The calculation results are coincide with the actual damage situation well. In order to improve the slope stability of LQS tunnel waste rocks dump, the influence degree of its wall height, moisture ratio, and slope ratio of safety factor will be analyzed, sequentially confirm the critical value of every factor, and find out the prominent factors. The numerical analysis on the slope stability of multi-step waste rocks dump with retaining wall will be the basis of similar sites.

Abstract: Assuming that the flow of water and gas in the coal seam fracture system to follow Darcy flow law, according to multiphase fluid flow mechanics and porous media fluid mechanics theory, this paper establishes gas-water dual media in the coal seam hydraulic extrusion coupled seepage model. Make use of this model simulates the main technical parameter injection pressure of the coal seam hydraulic extrusion, and compared to actual injection pressure of Huai river mining area, the results are in agreement. This model provides a reference to optimize the main techinical parameters of the coal seam hydraulic extrusion.

Abstract: Rock burst become increasingly serious in deep mining. Pressure relief will be realized with hydraulic cutting in the coal seam, and rock burst could be substantial prevented. The finite element model of hydraulic cutting is established, the variation of stresses around the slot before and after hydraulic cutting are found by Ansys software. The results of numerical simulation show: The influence circle of differential pressure with hydraulic cutting is about 5 meters. In the circle the stresses fall down 81%. The pressure relief is best when the pitch of holes is 8 meters with multi-slot cutting. The surface high stress area is significantly reduced after slotting and the stress concentration zone transferred to the deep. Reasonably direction of cutting travel determined pressure relief, and the cutting distance could influence directly the dimension and scope of pressure relief. The simulation results provide a theoretical foundation and technical reference for preventing rock burst with hydraulic cutting.

Abstract: In view of the condition of driving roadway in the West Wing mining area in Pan Yidong mine: the -805m jitty and belt conveyor uphill would meet within the coal seams group, and the coal seams group will be opened successively at the two locations. According to uncovering coal difficulty, the method of off-site and reverse uncovering coal to be used to open the coal seams group. At first, opening the coal group in -805m jitty, and then excavating respectively coal seams group up or down in the opposite direction, finally the uncovering coal is finished. One-fourth times was reduced compared to the traditional plan of uncovering coal, achieving a win-win of good economic and security benefits.