Advanced Materials Research Vols. 962-965

Abstract: Due to the complex geological conditions of Nanshan mine east region, the outburst predict index overrun frequently in the process of high-dipping extremely thick coal seam rock cross-cut coal uncovering, this text designed and optimized the front explore borehole parameter to ascertain conditions of coal seam; Optimized gas drainage drilling parameters to improve the rate of extraction, reduced the blank tape; On the basis of the theory of mechanics, derivate the computational formula of minimum safety rock pillars, identified with the minimum thickness safety of rock pillars. Through the above measures, guaranteed debunking coal seams quickly and safely.

Abstract: In coal mines one of the most serious safety problems are endogenous fires. Given the specific mining conditions a number of self-heating and spontaneous combustion occurs in coal mining. These activities have a negative effect on the organization of mining operations and require a variety of interventions for their disposal and are a considerable economic burden. At the same time in case of suitable conditions threaten of their transition in the explosion exists. For the application of appropriate measures it is necessary to know the size of the risk of endogenous fires in the coal mine. The paper therefore describes a methodology for risk analysis of endogenous fire in a coal mine, taking into account all relevant factors of production.

Abstract: We conducted a numerical simulation of oxygen concentration in goaf using Comsol4.3b when the air volume in working face ranges from 500 m³/min to 900m³/min. The result show that with the air volume increasing the oxygen concentration boundary of 18% move to deep goaf in a small scale, while the boundary of 8% move to deep goaf in a large scale and show an exponential relationship, in other words air volume change greatly affect the 8% boundary. The boundary of maximum air leakage and air leakage 0.004% all display an exponential relationship with air volume. But the movement scale of air leakage boundary 0.004% is small. The width of oxidation zone increases obviously with air volume increasing and the relations formula is L_max= 100.4ln (Q)-25.55ln (Q)-410.4. Draw a conclusion that in ventilation management air volume should be reduced appropriately in order to reduce the width of oxidation zone and slow the speed of moving to deep goaf, thus control spontaneous combustion in goaf.

Abstract: The paper put forward allowable deformation of highway is the premise of the study on problems of highway influenced by coal mining subsidence. Base on the analysis of correlative regulations and highway characteristics, the research pointed out a certain deformation value is not suitable for judging the safety of highway influenced by coal mining subsidence and the criterion of allowable deformation with considering the structure and the material of highway must be established. Using curvature as the allowable deformation index, The paper derived the criterion formula of the allowable deformation of highway and calculated the allowable deformation interval of common highway in China. The achievement is useful for solving correlative problems in the future.

Abstract: In order to reduce the danger of single coal seams outburst during the tunneling in coal roadway and ensure the tunneling of coal seams, this text analyzed the mechanism of crossing drilling against outburst; studied the area measures of floor tunnel crossing and grid drainage boreholes in coal roadway, Designed and optimized the drilling technical parameters; Analyzed the relationship between the drainage concentration and scalar; Calculated the maximum overlying coal seam gas to spare scalar quantity is 224300 m³ ;Used a variety of indicators to investigate the effect of outburst prevention. It shows that Gas content and gas pressure have significant lower than drainage. After the drainage up to standard, all the sensitive indexes is not overrun, during the coal roadway tunneling, it does not appears dynamic phenomenon. Solve the problem of mining imbalances, guaranteed the safety driving of roadway.

Abstract: In order to study the feasibility of the ascending mining in Maiduoshan coal mine, the “two belts” of 6# coal should be predicting. Based on the analyzing of mine hydrogeological conditions, the three-dimensional numerical model is established by the FLAC3D, the scope of “two belts” by lower coal mining is predicted. The results shows that the fracture zone height of 6# coal less than the distance between 6# coal and 2# coal, and Maiduoshan coal mine meet the requirement of ascending mining. At the same time, combining the ratio method and balance analysis of surrouding rock, ascending mining is feasible in Maiduoshan coal mine.

Abstract: Given the irrationality and limitations in thick coal seam of the empirical formula of height of water flowing fractured zone , this article reveals the special thick seam fully mechanized mining damaging rules of overlying rock and determines the height of water flowing fractured zone with 3D finite element numerical simulation,according to the complex geological conditions and the special thick seam fully mechanized mining methods of Laohutai ore mining working face E5400 as an example. Results show that the destruction of repeated mining area of the overlying rock will have superposition effect and the superposition effect will increase with the development of mining; the fracture sharp of water fracture zones is in close proximity to the "arch". Simulation results and the actual detection height fitting is better, so it assesses the range of overburden water flowing fracture zones and rationality of the height.

Abstract: Full-pillar extraction by filled wide working face layout in strip mining resolved the course of surface deformation and moving into two period drew support from wide working face layout in partial mining, filling in roof falling zone and full-pillar extraction. It could carry point of reducing mining effect and protecting surface.This paper explained technical principle of full-pillar extraction by filled wide working face layout in strip mining, and analysed effect of wide working face partial mining and roof filling in falling zone in this technology, and researched the features of surface deformation and moving with this technology in a demonstration. Resources under buildings and Coal demand increased year by year with rapid development of economy and it speeding up depletion of common resources,therefor,coal seam under rivers,buildings and railways reasonable mining has important significance for improving recovery and relieving energy shortage.Coal seam under rivers,buildings and railways reserves reached 137.9Gt in State owned coal mine according to statistics, which coal seam under buildings makes 94.68Gt account 69% of the total and constraints mine development.To some degree,although traditional reduce subsidence mining technology settled pressed coal mining problems,but its extension limited by low recovery,the high cost,difficult to carry out and the difference with saving resources and high efficient.Full-pillar extraction by filled wide working face layout in strip mining resolved the course of surface deformation and moving into two period drew support from wide working face layout in partial mining,filling in roof falling zone and full-pillar extraction,which could carry point of reducing mining effect.It is one of the technological approaches to make high recovery,the low cost and high efficient in pressed coal mining.This paper analyzed wide working face in strip mining and filling effects in the strata movement control and researched the ground deformation features by an example with Full-pillar extraction by filled wide working face layout in strip mining.

Abstract: This paper put forward the technical ideas of tool pillar mining with stowing that is dividing mining and stowing into two stages and recycling pillars based on the first stage stowing body support roof by analyzing tool pillar faces characteristic with pillar and goaf septal arrangement. Due to the stope drift and pillar size are both small, the goaf should be timely stowing in order to ensure stability of pillars and stowing body, author introduced stowing and mining interval width and stowing body strength determined method in two stages. This paper calculated pillar load of the first stage and stowing body load of the second stage with enlarge pressure arch theory, determined stowing and mining interval width in two stages and stowing body strength in the first stage combined with safety factor. At last author determined the second stage stowing body strength according to the surface movement and deformation control requirement with numerical simulation.

Abstract: Significant geological factor of coal occurrence is layered structure of coal measures overburden rock, and bedrock sand-shale ratio is a key element of coal measures overburden rock layered structure. On the background of geological occurrence conditions of 2^-2 coal in Yushen coal mining area, the sandstone layer, sandstone average thickness and sand-shale ratio are taken as variables to build the 18 different types of layered structure models. On this basis, basic law of coal measures bedrock sand-shale ratios which is a key characteristic of layered structure impacting mining subsidence is mainly studied by using numerical simulation method. The results show that: firstly, in spite of any condition of sandstone layer coefficient subsidence coefficient always decrease with the increase of sand-shale ratios. However, the effect of sand-shale ratios on subsidence coefficient continuously decreased with the increasing of sandstone layer coefficient. Secondly, when the sandstone layer coefficient is less than 70%, the different sand-shale ratios have significant influence on the subsidence coefficient, and when the sandstone layer coefficient is more than 90%, subsidence coefficients corresponding to different sand-shale ratios show obvious convergence characteristics. The gap between each other is only 1%~2%. Thirdly, taking the subsidence coefficient corresponding to the sand-shale ratio is 6:4 as reference, the curves about the rate of decrease in subsidence coefficient is set up when the sand-shale ratio is 7:3 or 8:2, and the fitting equations are presented on the basis of Log3P1 mathematical model.