Advanced Materials Research Vol. 868

Abstract: The stability of tailing dams has recently become a hot issue on the engineering, and geo-synthetics curing processing applications are widely used. The influence of the tailings dam stability of geo-textile grid by calculating and analyzing with numerical simulation is studied. It reveals the mechanical behavior and the inherent law of the dam under different physical properties and different conditions of geo-grid. The force of reinforcement and the change law of ultimate load under different working conditions are systematically simulated by FLAC, and then analyze the formation process of sensitivity and fracture plane that influenced the ultimate load. The result shows: The failure surface is not such concentrated after joining the geo-textile grid and the safety factor increases 60%. The stability of the dam structure of tailing dam is effectively improved. Research has provided the basis for the structure stability of tailings dam's designing.

Abstract: The paper is aimed at introducing our research of mathematical modelling of mine ventilation roadway optimal cross-section and its solving method. As we know, a rational cross-section should be determined to satisfy each intake and return airflow roadway based on the analysis of the relationship between ventilation cross-section and capital construction costs, in addition to maintenance costs and ventilation power costs. Reasonable selection of ventilation roadway cross-section is important to economic. The least square method is reasonable to build mathematical model for ventilation roadway costs. On the basis of previous studies, the relationship of capital construction costs and maintenance costs were further analyzed. Finally, considering the capital construction, maintenance and ventilation power costs three costs, the mathematical model was more accurate. Through researching a single ventilation roadway costs variation with the size of cross-section, cross-section size determined by considering time variable of costs was optimal, and built by this size could reduce economic investment. Hereby, it provides a solving method for the whole process of ventilation networks roadway cross-section optimization.

Abstract: Based on extremely complex geological characteristics of metal mines, a mining model was built up, and from the micro - meso - macro point of view, relationship between rock AE and failure characteristics of overlying rock mass was studied and AE is divided into four stages. From the view of AE energy and distribution, the generation location, shape and size of caving of overburden rock was predicted. Through studies on the difference of goaf size, the author obtained the displacement variation and failure characteristics of metal mine overburden rock under tectonic stress, self-weight stress and dynamic mining conditions.

Abstract: For the accuracy of the inrush risk assessment of the problem, put forward in the mine inrush risk assessment using the entropy weight fuzzy comprehensive evaluation method to determine the index weight, through the membership function in fuzzy comprehensive evaluation to quantify the qualitative description of these factors, evaluated the henan jiaozuo mine inrush risk. The results show that the mine water inrush risk grade is "great", the actual mine water inrush accidents have occurred, prediction results conform to the actual situation, and safety evaluation value based on the principle of maximum membership degree is more than analytic hierarchy - fuzzy comprehensive evaluation to get , 0.0696. Thus, the method in the mine inrush prediction can objectively and accurately reflect the actual situation of mine inrush.

Abstract: Traditional microcomputer fault oscillograph cannot meet the requirements of coal mine substation to digital and networked. A double CPU and distributed coal mine fault oscillograph is presented, the device data acquisition unit of new fault oscillograph use high performance DSP chip TMS320LF2812 to complete signal acquisition and processing, and S3C2410 chip is used in data management unit to complete the data storage, display and communication function. Test results show that the new fault oscillograph could separately installed in each substation and has stable operation and high communication capacity advantages.

Abstract: With the rapid expansion of mining right circulation market in China, disorder, chaos and disputes occurs frequently. The relevant laws, regulations and policies, the construction of the service mechanism and the management are all lag behind. This paper analyzes the main reasons of the problems and the status of mining right market. The author then puts forward that to build a modern mining right circulation market, we should revise the laws, regulations and policy with the terms of the reality, establish modern information release platform, improve the intermediary institutions and strengthen management.

Abstract: Acoustic emission (AE) technique is a trend of non-contact technique forecasting coal and rock dynamic disaster.Coal and rock AE propagation attenuation exponent function on different AE frequencies, different quality factors and different propagation distance are acquired by theory and numerical simulation and actual experiment; the effect of AE sensor installation manners on coal and rock surface , coal and rock bottom and wave guide are studied, the results show that the effect of AE sensor installation manner on wave guide is better than on coal and rock surface ,equivalent to installation manner on coal and rock hole bottom. Based on above study results, actual rock bursts are successfully forecasted.

Abstract: Mathematical model based on elasticity is not suitable for soft seam hydraulic fracturing mechanism study because its intensity is small, Poisson's ratio is relatively large, and its prone to plastic deformation. Based on plastic mechanics, the theory of large deformation and fracture mechanics theory, hydraulic fracturing of soft coal seam is divided into three phases, namely, coal bed compaction, fracture initiation and crack propagation from the view of the deformation mechanism, the occurring and developing mechanism. The initiation pressure of soft seams considered strain softening character after plastic deformation is obtained on the basis of above. The result shows that the initiation pressure is related to elastic modulus, Poisson's ratio, the angle of internal friction and residual strength. Elastic modulus is inversely proportional to the initiation pressure, the greater its value, the smaller the initiation pressure; but Poisson's ratio, the angle of internal friction and the residual strength and fracture initiation pressure is directly proportional relationship, the greater its value, since the smaller the crack pressure.

Abstract: This paper introduces occurrence characteristics of coal bed methane in China, and analyses the influence of coal seam permeability on coal mine methane extraction. In addition, it presents the mechanism of increasing permeability by pressure relief. Lastly, the methane extraction technologies are discussed, and the applicable conditions of these technologies are analyzed. It is seen that choosing appropriate methane drainage technology, often in combination with several technologies including ground drilling, underground drilling, and pressure relief and permeability improving measures, is crucial for geological complex coal seam, especially low permeability soft coal seam.

Abstract: The east wing of the third new mine of Fengfeng Group co., LTD has been designed to construct about 2490m with a long service time, bad geological conditions and slowly driving speed. Through improving rock drivage construction techniques, the mine has taken measures of driving by three teams, a scientific construction organization of digging while spraying and a kind of advancing crossover operation method of after four in the first four. In addition, the mine also strengthens the management and takes scientific and reasonable scoring model and acceptance criteria. Through all these measures the mine has improved the driving speed effectively and make on the single lane rock drivage footage of more than 120 m good grades. The effect of roadway supporting and forming is of good quality and it has never had safety accidents. Whats more, the economic benefits and social benefits are obvious. It provides an important reference significance for similar quick rock drivage project.