井田地质构造对煤层瓦斯赋存控制作用的研究

阳煤集团新景矿在3#煤层采掘时频繁发生煤与瓦斯突、喷出现象,严重威胁着矿井安全生产和3#煤层的正常开采。论文基于地质构造影响煤层瓦斯赋存的原理,分析地质构造对煤层瓦斯、煤体结构及瓦斯突、喷出的控制作用,为防治矿井瓦斯灾害,保障煤矿安全生产提供地质基础。

0403工作面运输巷掘进期间煤与瓦斯防突治理

煤与瓦斯突出作为煤矿突出矿井灾难之一,文章介绍了正明煤业公司防治煤与瓦斯突出的经验和方法。

瓦斯抽放系统负压自动放水器的研制与应用

在煤与瓦斯突出矿井中的瓦斯抽采工作尤为重要,现用的自动放水器效率低,造成煤层水进入抽采管路后排出不及时,会使管路有效截面缩小造成抽采效果降低等问题,为解决这一问题,在矿用负压自动放水器工作原理的基础上进行研制,通过对零部件的设计和材料的更换使其维护简单、实用性强,有效地解决了瓦斯抽采管路积水的问题。

瓦斯抽放系统负压自动放水器的研制与应用

在煤与瓦斯突出矿井中的瓦斯抽采工作尤为重要,针对现用的自动放水器效率低,造成煤层水进入抽采管路后排出不及时,就会使管路有效截面缩小,抽采效果降低等问题,在矿用负压自动放水器工作原理的基础上进行研制,通过对零部件的设计和材料的更换使其维护简单、实用性强,有效地解决了瓦斯抽采管路积水的问题。

赵庄矿3~#煤层突出危险性预测敏感指标优选

针对赵庄矿3#煤层实际地质采矿条件,确定4种主要突出危险预测敏感指标;通过现场试验及各种指标敏感性的对比分析,得出钻屑法对赵庄3#煤层突出危险性敏感性相对较高;根据钻屑法指标预测结果实现了矿井安全掘进。

基于颗粒压缩实验的破碎比功测定研究

为了更好的表征煤体强度特性,根据黎金格的新表面学说,提出了1种基于颗粒压缩实验的破碎比功测定方法;基于该方法,对阳泉矿区原生煤和不同类型构造煤的破碎比功进行了系统性测定。测定结果表明:阳泉矿区构造煤的破碎比功介于18.14~87.39 J/m2,比原生煤(约1 098.46 J/m2)低1~2个数量级;同时,碎粒煤的破碎比功(64.26~87.39 J/m2)明显大于糜棱煤(约18.14 J/m2),为糜棱煤的3.54~4.82倍。

囊袋式“两堵一注”带压封孔工艺材料的自主创新与应用

针对煤与瓦斯突出矿井中影响煤矿安全生产重要因素之一就是瓦斯的治理工作,采用抽采的方式来防治瓦斯事故是最有效的措施,在瓦斯抽采过程中采用囊袋式"两堵一注"带压封孔工艺,操作简便、快捷,技术先进,封孔效果好,但是施工的钻孔分布数量多,封孔工艺材料消耗量大,购买成本高,通过自主研发加工封孔工艺材料,节约成本得到了显著效果。

Coal and gas outburst dynamic system

Coal and gas outburst is an extremely complex dynamic disaster in coal mine production process which will damage casualties and equipment facilities, and disorder the ventilation system by suddenly ejecting a great amount of coal and gas into roadway or working face. This paper analyzed the interaction among the three essential elements of coal and gas outburst dynamic system. A stress-seepage-damage coupling model was established which can be used to simulate the evolution of the dynamical system, and then the size scale of coal and gas outburst dynamical system was investigated. Results show that the dynam- ical system is consisted of three essential elements, coal-gas medium （material basis）, geology dynamic environment （internal motivation） and mining disturbance （external motivation）. On the case of CI 3 coal seam in Panyi Mine, the dynamical system exists in the range of 8-12 m in front of advancing face. The size scale will be larger where there are large geologic structures. This research plays an important guid- ing role for developing measures of coal and gas outburst prediction and prevention.

Advances in gas content based on outburst control technology in Huainan, China

The sudden and violent nature of coal and gas outbursts continues to pose a serious threat to coal mine safety in China. One of the key issues is to predict the occurrence of outbursts. Current methods that are used for predicting the outbursts in China are considered to be inadequate, inappropriate or impractical in some seam conditions. In recent years, Huainan Mining Industry Group(Huainan) in China and the Commonwealth Scientific and Industrial Research Organisation(CSIRO) in Australia have been jointly developing technology based on gas content in coal seams to predict the occurrence of outbursts in Huainan. Significant progresses in the technology development have been made, including the development of a more rapid and accurate system in determining gas content in coal seams, the invention of a sampling-while-drilling unit for fast and pointed coal sampling, and the coupling of DEM and LBM codes for advanced numerical simulation of outburst initiation and propagation. These advances are described in this paper.

Principle and engineering application of pressure relief gas drainage in low permeability outburst coal seam

With the increase in mining depth, the danger of coal and gas outbursts increases.In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas.Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained.The practice in the Panyi coal mine has shown that, after mining the C11coal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated.The result was that we achieved a safe and highly efficient mining operation of the C13 coal seam.

A coupled DEM and LBM model for simulation of outbursts of coal and gas

An outburst of coal and gas is a major hazard in underground coal mining. It is generally accepted that an outburst occurs when certain conditions of stress, coal gassiness and physical-mechanical properties of coal are met. Outbursting is recognized as a two-step process, i.e., initiation and development. In this paper, we present a fully-coupled solid and fluid code to model the entire process of an outburst. The deformation, failure and fracture of solid （coal） are modeled with the discrete element method, and the flow of fluid （gas and water） such as free flow and Darcy flow are modeled with the lattice Boltzmann method. These two methods are coupled in a two-way process, i.e., the solid part provides a moving boundary condition and transfers momentum to the fluid, while the fluid exerts a dragging force upon the solid. Gas desorption from coal occurs at the solid-fluid boundary, and gas diffusion is implemented in the solid code where particles are assumed to be porous. A simple 2D example to simulate the process of an outburst with the model is also presented in this paper to demonstrate the capability of the coupled model.

Application of the catastrophe progression method in predicting coal and gas outburst

Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensive evaluation index system and a coal and gas outburst prediction model.In addition,we performed a standard transformation for each index system;based on the degree the various indices affect the risk of an outburst,to make the data dimensionless.Based on the outburst data from eight mines,we determined catastrophe progression values and verified these values.The results show that:1) converting multi-dimensional problems into one-dimensional problems using this catastrophe progression method can simplify the steps of predicting coal and gas outbursts;2) when pre-determined catastrophe progression values are used to predict coal and gas outbursts,the predicting accuracy rate can be as high as 87.5%;3) the various coal mines have different factors inducing outbursts with varying importance of these factors and 4) the catastrophe progression values,calculated based on these factors,can be used effectively to predict the risk of outbursts in coal mines.

Coal and gas outburst mechanism of the “Three Soft” coal seam in western Henan

Based on the particularities of gas outbursts,i.e.,low gas bearing capacity and low gas pressure in the "Three Soft" coal seam in western Henan,we applied the theories of plate tectonics and regional structural evolution to investigate the mechanism of this seam and its impact on the coal seam gas formation.Our investigation revealed that coal and gas outbursts are distributed in a strip in a NW direction,with a number of high-penetration mines scattered towards the south side and low-gas mines largely located on the north side.We analyzed the statistics of 38 gas explosions and the rock-coal sturdiness number coefficient f of 167 sampling sites in the region and found the gas outburst mechanism that features a "low indicator outburst phenomenon".The mechanism is characterized by structural coal as its core,a low gas bearing capacity,low gas pressure and sturdiness coefficient f mostly less than 0.3.Our research results provide a theoretical foundation for effective control of gas disasters.

Bayesian discriminant analysis for prediction of coal and gas outbursts and application

Based on the principle of Bayesian discriminant analysis, we established a model of Bayesian discriminant analysis for predicting coal and gas outbursts. We selected five major indices which affect outbursts, i.e., initial speed of methane diffusion, a consistent coal coefficient, gas pressure, destructive style of coal and mining depth, as discriminating factors of the model. In our model, we divided the type of coal and gas outbursts into four grades regarded as four normal populations. We then obtained the corresponding discriminant functions through training a set of data from engineering examples as learning samples and evaluated their criteria by a back substitution method to verify the optimal properties of the model. Finally, we applied the model to the prediction of coal and gas outbursts in the Yunnan Enhong Mine. Our results coincided completely with the actual situation. These results show that a model of Bayesian discriminant analysis has excellent recognition performance, high prediction accuracy and a low error rate and is an effective method to predict coal and gas outbursts.

Effect of an electrostatic field on gas adsorption and diffusion in tectonic coal

The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree of damage is different, were selected from Tongchun, Qilin, and Pingdingshan mines. Using a series of experiments in an electrostatic field, we analyzed the characteristics of gas adsorption and diffusion in tectonic coal. We found that gas adsorption in coal conforms to the Langmuir equation in an electrostatic field. Both the depth of the adsorption potential well and the coal molecular electroneg- ativity increases under the action of an electrostatic field. A Joule heating effect was caused by changing the coal-gas system conductivity in an electrostatic field. The quantity of gas adsorbed and AP result from competition between the depth of the adsorption potential well, the coal molecular electronegativ- ity, and the Joule heating effect. △P peaks when the three factors control behavior equally. Compared with anthracite, the impact of the electrostatic field on the gas diffusion capacity of middle and high rank coals is greater. Compared with the original coal, the gas adsorption quantity,△P, and the gas diffusion capacity of tectonic coal are greater in an electrostatic field. In addition, the smaller the particle size of tectonic coal, the larger the△P.

Coal damage mechanism in the developing process of coal and gas outburst

Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the concentrated tensile stress appearing nearthe endpoint of the pores.Fractures in coal,gas pressure,ground stress and the tensilestrength of the coal matrix are the major controlling factors of this kind of damage.When theground stress releases abruptly and the gas pressure is high,tensile failure will occur aroundthe endpoint of the small pores due to gas pressure,and the coal may be broken up like powder;this is called pulverization.Otherwise,when the gas pressure is low,the tensile stress canonly occur around the endpoint of the large pores and fractures due to gas pressure,the fracturesin coal extend and link together,the fracture extension direction is statistically perpendicularto the direction of the minor principal stress.This kind of damage is shown as the stratifiedspall around the outburst hole.

Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

Propagation law of shock waves and gas flow in cross roadway caused by coal and gas outburst

In order to study the propagation law of shock waves and gas flow during coal and gas outburst,we analyzed the formation process of outburst shock waves and gas flow and established the numerical simulation models of the roadways with 45°intersection and 135°intersection to simulate the propagation of outburst gas flow and the process of gas transport.Based on the analysis of the simulation results,we obtained the qualitative and quantitative conclusions on the characteristics and patterns of propagation and attenuation of outburst shock waves and gas flow.With the experimental models,we investigated the outburst shock waves and gas flow in the roadways with the similar structures to the simulated ones.According to the simulation results,when the angle between the driving roadway and the adjacent roadway increased,the sudden pressure variation range in adjacent roadway and the influencing scope of gas flow increased and the sudden pressure variation duration decreased.The intersection between the driving roadway and the adjacent roadway has no effect on airflow reversal induced by the shock waves and gas flow.

Pore characterization of different types of coal from coal and gas outburst disaster sites using low temperature nitrogen adsorption approach

To characterize the pore features of outburst coal samples and investigate whether outburst coal has some unique features or not, one of the authors, working as the member of the State Coal Mine Safety Committee of China, sampled nine outburst coal samples(coal powder and block) from outburst disaster sites in underground coal mines in China, and then analyzed the pore and surface features of these samples using low temperature nitrogen adsorption tests. Test data show that outburst powder and block coal samples have similar properties in both pore size distribution and surface area. With increasing coal rank, the proportion of micropores increases, which results in a higher surface area. The Jiulishan samples are rich in micropores, and other tested samples contain mainly mesopores, macropores and fewer micropores. Both the unclosed hysteresis loop and force closed desorption phenomena are observed in all tested samples. The former can be attributed to the instability of the meniscus condensation in pores,interconnected pore features of coal and the potential existence of ink-bottle pores, and the latter can be attributed to the non-rigid structure of coal and the gas affinity of coal.

Determination of indices and critical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine

Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine. According to a characteristic analysis and a summary of the rules of coal and gas outbursts in the No.8 coal seam of a Hua- inan mine, we have investigated their effect on coal and gas outbursts in terms such as ground stress, gas, and coal structure. We have selected gas parameters and determined the critical values of each of the fol- lowing indices： gas content as 7.7 m^3/t, tectonic coal as 0.8 m thick, the absolute gas emission as 2 m3/min, the rate of change as 0.7 m3/min, the gas desorption index of a drilling chip KI as 0.26 mL/（g min^1/2） and the values of desorption indexes Ah2 as 200 Pa. From a verification of the production, the results indicate that application of each index and their critical values significantly improve the level of safety in the pro- duction process, relieve the burden upon the mine, save much labor and bring clear economic benefits.