Advanced Materials Research Vols. 524-527

Abstract: According to the analysis of the sum of squared residuals (SSE), this paper have defined the discriminant function and SSE change rate and discussed the discrimination standards and parameter calculation method of weighted forecasting model. Based on the balance of overall SSE and partial SSE, the parameters and forecasting model can be calculated by the value scope of SSE change rate. Through the discriminant and analysis of the mining safety incident weighted forecasting model, the derived model can have a high recent forecasting accuracy, thus it can provide reliable basis for safety management decision making. Discriminant function and SSE change rate have extensive applicability and can be used as a discrimination standard of the security system prediction model.

Abstract: Based on the overburden three caving feature, the deformation of mining rock process was devided and the criterion of gradual transformation of each stages deformation were given. Then , combined the thin-plate theory, the differential models were derived for rock deformation in level and similar to level bured condition. The boundary condition of each models and exchange condition between different models were put forward and the gradual mechanics model was set up.The subsidence model before roof collapse was solved by Navier double trigonometric series and the deflection surface expression of rock deformation was put forword. At last, the reliability and practicality of the models was verified by engineering examples.

Abstract: The roadway bolt supporting with easy-breaking roof is a complex systematic problem, and the success or failure of roadway bolt supporting is determined by pre-stress level in some sense. To well recognize the bolt supporting effect under different pre-stress level, the laneway which has cracky roof is taken to systematically analysis the changing situation of roadway’s stress and deformation by using 2-dimension finite difference code -FLAC2D.The theoretical analysis and practical observation results show that high pre-stress scheme is the best way to improve the roadway surrounding rock strength and to control the cracky roof roadway’s deformation. It has some references to engineering design, construction and maintenance for similar soft rock mines.

Abstract: Based on the low permeability raw coal samples of coal seams of Daichiba coal mine of Guangwang group, we study the change of permeability under different stress states by a self-developed three-axis penetration device. It is proved by experiments that the permeability of coal sample increases rapidly along with the growing of the pressure at the procedure of loading at lower actual stress levels whose rules of changes is the function of negative exponent. In the process of unloading, rate of permeability increase slowly with the reduction of effective stress. It will greatly improved when the effective stress drops to a certain level, and this conformed to power function law. As the influence of coal seam gas permeability solid coupling factors is very complex, the normalized treatment for the factors has done by defining pressure-sensitive effect coefficient of coal samples permeability. Based on the results of the test to establish the relationship between pressure sensitive effect index and effective stress, this relationship reflects the trend of the coal sample permeability changes in the effective stress. And derive a functional relationship based on the coal sample of the pressure-sensitive effect index of permeability and effective stress.

Abstract: In order to improve production safety and the gas utilization in highly gassy coal mines, based on thin seam, poor gas permeability and low gas content in thin seams in Laoyingyan mine, the migration paths and abundant region of pressure-relieved gas in gob was studied by means of the strata displacement theory as well as movement regularity of gob gas. Simultaneous production system of coal mining and gas drainage was established in Laoyingyan mine, comprehensive gas drainage methods was adopted such as gas drainage method of highly-located roof crossing hole and the gas drainage method from gob. The results showed that gas drainage volume is 7.2m3/min, gas drainage efficiency was 36.3%, the phenomenon of gas-over-limit was eliminated. It was implemented that the gas resource safe, high efficient and green simultaneous coal mining and gas drainage under the premise of safe production of coal resources.

Abstract: The collapse of the hard roof rocks was characterized by its sudden and entire breakage and falling during the mining of the shallow-thick coal seams in Datong district. In this paper, structural mechanics methods was used to study the collapse mechanism of the hard roof rocks. The results showed that when some of the coal pillars lost their load bearing capacity, the pressure of the surronding rocks would be transferred to the left ones which were also to be damaged due to the extra load, and this would cause a domino effect of the adjacent pillars’s failure, and eventually cause the entire collapse of the hard roof rocks.

Abstract: Longtime existence of the mined-out region brings enormous security potential risk to the residents living in ore area. The model of the mined-out region underground has been established and calculated, and the effect of mined-out region on ground subsidence has been analyzed. The analysis result shows that the deformation of the roof of the mined-out region has significant influence on the ground surface and measures must be carried out immediately. Finally, the rational measures for treating the mined-out region are given to ensure the smooth and safe operation of the follow-up mining.

Abstract: Pressed ventilation in heading face is actually turbulent jet ventilation. In the blind drift, the air ducts are usually laid on one side of the drifting tunnel forming the wall-attached jet along the side of the tunnel and in order to dilute and pour out harmful gas and dust, and create an backflow at the same time, the airflow of the ventilation jet must reach at the head of the tunnel. Therefore, the forced ventilation in heading face is actually restrained wall attached jet ventilation in confined space.

Abstract: The paper main introduce the principle of integrated pillarlesss coal production and methane extraction technology, the gas flow characteristics of stope and the coal production and methane extraction technology. In order to solve the mine production replacement problems under the high stress and high gas conditions in the deep mine, integrated pillarlesss gob-side entry retaining in return airway and "Y" type ventilation industrial trial were conducted. The integrated pillarlesss entry retaining could keep the road in a support pressure reduced area. The back filled mass could be effective to isolate the gas in the goaf and the application of "Y" type ventilation could highly reduce the gas content in the top corner.

Abstract: Atmospheric pressure changes on the fully mechanized top-coal caving has very significant effect to gas emission produce, through discussion to the mine gas emission source,and analysis the actual measured data.Get the result:with the rise of the ground atmospheric pressure ,the mine gas emission is absolutely reduced,and gas changes in return flow is after atmospheric pressure changes 0.5-1h later. Summarized measures to the gas emission suddenly increased.To the coal mine has guiding significance for production safety.