scholarly journals Research on Evaluation Index and Application of Rockburst Risk in Deep Strip Mining

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bangyou Jiang ◽  
Hongguang Ji ◽  
Long Fu ◽  
Shitan Gu ◽  
Tong Zou ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Coal Mine ◽  
Coal Pillar ◽  
Width Ratio ◽  
Strip Mining ◽  
Index Method ◽  
Research On Evaluation ◽  
Mechanics Model ◽  
Evolution Characteristics ◽  
Comprehensive Index Method

The practice shows that deep strip mining induces rockburst disaster easily. Accurately evaluating rockburst risk of the strip coal pillar is of great significance for ensuring the safety of deep strip mining. In this paper, the catastrophe mechanics model was used to analyze the abrupt instability condition of strip coal pillar. And the three indicators that are the medium stiffness ratio (k) of the elastic and plastic zone in the coal pillar, the plastic zone width ratio (aY), and the elastic deformation index (Uq) of core zone were put forward with considering the geometry size of coal pillar. Based on the 3202 panel of Gucheng Coal Mine, the evolution characteristics of rockburst risk of coal pillar under different mining widths and coal pillar widths were studied by numerical simulation. The evaluation result shows that the strip coal pillar of the 3202 panel is in danger of strong rockburst, which is more in line with the actual situation than the results of the traditional rockburst tendency identification test and comprehensive index method. These three indicators can be regarded as important indicators to evaluate the rockburst risk in the strip mining engineering field. Based on that, the design principle of strip mining in Gucheng Coal Mine was put forward, which is considered an important reference for similar cases.

Research on Evaluation of the Pipeline Direct Drinking Water Quality With Improved Comprehensive Index Method

Epidemiology ◽  
2011 ◽  
Vol 22 ◽  
pp. S87-S88
Author(s):  
Huang Lihong ◽  
Chen Renjie ◽  
Wu chuan ◽  
Wang Lifang ◽  
Cheng Deguang ◽  
...  
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Drinking Water Quality ◽  
Index Method ◽  
Research On Evaluation ◽  
Comprehensive Index ◽  
Comprehensive Index Method

scholarly journals Structure Partition and Reasonable Width Determination of Waterproof Coal Pillar in Strip Mining

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 3) ◽  
Author(s):  
Rui Wang ◽  
Jian-biao Bai ◽  
Shuai Yan ◽  
Gui-qiang Pan ◽  
Dong Zhang ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Coal Mine ◽  
Water Pressure ◽  
Coal Pillar ◽  
Mine Pressure ◽  
Failure Zone ◽  
Core Zone ◽  
Zone Width ◽  
Elastic Core ◽  
Pressure Failure

Abstract Retaining a waterproof coal pillar is the most effective water conservation method for a roadway close to the gob, and determining a reasonable width of the waterproof coal pillar has been a common problem among mining scholars for a considerably long time. Based on the mining of the 15208 mining face in Xinjing Coal Mine, the structure of waterproof coal pillar is divided into a mine-pressure-influenced plastic zone, an effective waterproof elastic core zone, and a water pressure failure zone. The mine-pressure-influenced plastic zone width is determined by using the limit equilibrium theory, the parabolic strength theory, and the separation variable method. The effective waterproof elastic core zone width is determined by the semi-inverse solution method, and the water pressure failure zone width is determined by considering the infiltration and softening of water. After that, combined with the previous theoretical analysis of engineering examples, the theoretical value of waterproof coal pillar width is obtained. In addition, the physical shape distribution of the waterproof coal pillar is measured by ultrasonic detection technology. The results are consistent with the field measured results. The correctness of the model is verified. Finally, the rationality of the model is verified by comparing with the previous classical models. The research results are applied to the design of the waterproof coal pillar in Xinjing Coal Mine, which could provide a theoretical basis for determining the width of the waterproof coal pillar located close to a gob.

scholarly journals Investigation on Rock Strata Fracture Regulation and Rock Burst Prevention in Junde Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Fengnian Wang ◽  
Gan Li ◽  
Chi Liu
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Coal Pillar ◽  
Energy Concentration ◽  
Pressure Relief ◽  
Rock Stratum ◽  
Mechanics Model ◽  
Bending Elasticity ◽  
Mine Roadway ◽  
Rock Strata

Through the establishment of structural mechanics model, this paper analyzes the fracture of super thick rock stratum. Through the model, it can be seen that the fracture of low-level super thick rock stratum produces large elastic energy release and dynamic load, which is easy to produce disasters such as rock burst. The numerical calculation shows that under the influence of low hard and thick rock stratum, the leading area of coal mine roadway will produce energy concentration, and the coal pillar will also produce energy accumulation. Thick rock stratum is in bending state and has large bending elasticity. Coal pillar has large compression elasticity, which is the main reason for rock burst. The accumulation of elastic properties of overburden and rock burst caused by coal pillar energy storage can be effectively controlled by using advanced presplitting blasting, coal seam drilling pressure relief, and strengthening support.

scholarly journals Research on the Influence of Slurry Filling on the Stability of Floor Coal Pillars during Mining above the Room-and-Pillar Goaf: A Case Study

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Zhu Li ◽  
Guorui Feng ◽  
Jiaqing Cui
Keyword(s):  
Plastic Zone ◽  
Coal Mine ◽  
Body Height ◽  
Coal Pillar ◽  
Northwest China ◽  
Engineering Practice ◽  
Working Face ◽  
The Stability ◽  
Safe Mining ◽  
Upward Mining

Room-and-pillar mining is a commonly used mining method in previous practice in northwest China mining area. Due to priority selection of high-quality resources, coal mines in northwest China generally have to face upward mining above goaf. Thus, the stability of a floor coal pillar influenced by mining activities plays an essential role in upward mining above goaf. The results indicated that a floor coal pillar kept stable before coal excavation in the no. 6107 working face in the Yuanbaowan coal mine; however, the plastic zone in the floor coal pillar expanded sharply and the elastic core zone reduced suddenly on the influence of abutment pressure. Finally, the floor coal pillar supported failure. Accordingly, the paper proposed a floor coal pillar reinforcing technique through a grout injection filling goaf area. As physically limited by a different-height filling body on the double sides, the plastic zone scope and horizontal displacement and loading capacity of the floor coal pillar were studied, working out that the critical height of the filling body should be about 6 m which can ensure safe mining when upward mining above goaf. Case practice indicated that the fractures induced by mining in the floor coal pillar, filling body, and floor can be restrained effectively when the filling body height is 6 m, which can ensure floor coal pillar stability and safe mining of the no. 6107 working face in the Yuanbaowan coal mine. The research can provide theoretical and technical guidance for upward mining above goaf and have a critical engineering practice value.

Study on Fractal Elastic Damage Constitutive Law for Concrete Material under Static Load

2011 ◽  
Vol 138-139 ◽  
pp. 1269-1273
Author(s):  
Ming Xie ◽  
Shan Suo Zheng
Keyword(s):  
Fracture Surface ◽  
Damage Mechanics ◽  
Constitutive Law ◽  
Uniaxial Test ◽  
Fractal Characteristic ◽  
Mechanics Model ◽  
Evolution Characteristics ◽  
Mesoscopic Level ◽  
Fractal Characteristics ◽  
Stochastic Properties

The stochastic properties and discreteness of macroscopic property for concrete appear on mechanical property and fracture surface. In consideration of stochastik and discreteness of fracture surface, a class of mesoscopic damage mechanics model of concrete based on spring model, are put forward to understand the real damage evolution characteristics of concrete at the level of constitutional law. A kind of spring-slipper model is introduced to reflect the elastic-plastic damage behavior. It has been confirmed that fracture surface of concrete has self-affine fractal characteristic only on a certain spatial scale, but the actual fracture surface of concrete is a stochastic surface with multi-fractal characteristics. Uniaxial test was operated, combined with the Computerized Tomography test of concrete, to study the evolution of crack surface from mesoscopic level to macroscopic level. Compared with the existing damage constitutive law and experimental results preliminarily, the feasibility of fractal damage constitutive law is verified.

Principle of Well-Net Design for Coalbed Methane Exploitation in Coal Mine Area

2014 ◽  
Vol 543-547 ◽  
pp. 3967-3973
Author(s):  
Bao Shan Han
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Design Theory ◽  
Surface Condition ◽  
Coal Pillar ◽  
Negative Influence ◽  
In Situ Stress ◽  
Well Location

There are abundant CBM (Coalbed Methane) in China. These CBM has caused a remarkable problem to the coal-mining in China. In order to improve the structure of Chinese energy and eliminate the risk of coal mine gas, the relevant industries and sections have implemented many explorations in CBM enriched areas. With great achievements, there are many important problems in the actions of CBM exploitation. The disadvantageous interaction of the surface CBM well and the later coal mining has been ignored at all. There are many disadvantages and defects. To solve these problems and eliminate or weaken the disadvantageous, the scientific and reasonable design of surface CBM well location is an important step. With the thinking of surface condition, coal mining plan, the arrangement of coal mine laneway, the direction and scale of the in-situ stress, and thinking more about the negative influence to and of surface CBM well, according to the theories of mining dynamics, mining engineering, mining geomechanics, and the CBM engineering, the design theory of the surface CBM well net can be studied. Finally, the arrangement principle of CBM product well in coal field is presented. The existing or future coal pillar will be a critical location for the surface CBM well location.

Comparative Study on Indoor Air Quality Evaluation Method

2012 ◽  
Vol 178-181 ◽  
pp. 267-271
Author(s):  
Xing Yang Leng ◽  
Ping Jiang
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Index Method ◽  
Comprehensive Evaluation Method ◽  
Comprehensive Index Method ◽  
Grey Relational

This paper reviewed six kinds of indoor air quality (IAQ) evaluation methods, by which the same IAQ status were evaluated. Besides, the relations and distinctions of six methods were also analyzed. The results indicate that the evaluation results of different methods on the same sample are not identical. Fuzzy comprehensive evaluation method, pollution loss rate method and comprehensive index method are relatively accurate, and improved grey relational analysis method has the largest error.

Research on the Spatial Effect of Green Economic Efficiency in China from the Perspective of Informatization

2020 ◽  
Author(s):  
Xinbao Tian ◽  
Chuanhao Yu
Keyword(s):  
Industrial Structure ◽  
Spillover Effect ◽  
Coordination Mechanism ◽  
Green Economy ◽  
Spatial Econometric ◽  
Index Method ◽  
Spatial Spillover ◽  
Regional Coordination ◽  
Comprehensive Index Method ◽  
Spatial Spillover Effect

Abstract Background: Green economy has been paid more and more attention in the information age. Informatization plays an important role in the development of green economy by the transmission of industrial structure rationalization and upgrading. Because of the spatial mobility of information, it is necessary to study the spatial spillover effect of information on the efficiency of green economy. In this paper, the non-radial directional distance function and the comprehensive index method are used to evaluate the efficiency of green economy and informatization respectively. On this basis, the spatial characteristics of the two are analyzed. Finally, the spatial econometric model is used to analyze the spatial impact of informatization on the efficiency of green economy. Results: The following findings can be drawn: (i)The spatial distribution of the green economy efficiency and informatization are unbalanced; (ii) There is a significant spatial spillover effect in the efficiency of green economy; (iii) The development of informatization plays an important impact on the efficiency of green economy. Conclusions: It can be seen that informatization plays an important role in the development of green economy, so we can get the following suggestions: (i) Developing green economy according to different conditions of different places. (ii) Establishing regional coordination mechanism of green economic development. (iii) Using informatization to promote the development of green economy.

Evaluation of Water Quality of Rural Drinking Water and Countermeasure Research in Luquan City

2013 ◽  
Vol 773 ◽  
pp. 815-818
Author(s):  
Fang Hong Li ◽  
Xu Li Liang
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Site Investigation ◽  
Water Type ◽  
Water Safety ◽  
Index Method ◽  
Countermeasure Research ◽  
Investigation Area ◽  
Drinking Water Safety ◽  
Comprehensive Index Method

The rural drinking water safety is an important issue for people's livelihood. For Luquan city, of Hebei province in China, drinking water was sampled through site investigation, and the water quality was analyzed used comprehensive index method. The results show that: the water type is IV in the investigation area, which is not suitable for drinking in a long time. The corresponding measures were proposed combined with the real conditions, which could provide theoretical guidance and policy reference for improvement of rural drinking water management mechanism.

scholarly journals Expansionary Evolution Characteristics of Plastic Zone in Rock and Coal Mass Ahead of Excavation Face and the Mechanism of Coal and Gas Outburst

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 984
Author(s):  
Hongtao Liu ◽  
Linfeng Guo ◽  
Xidong Zhao
Keyword(s):  
Plastic Zone ◽  
Mechanical Analysis ◽  
Coal And Gas Outburst ◽  
Analysis Model ◽  
Change Of Direction ◽  
Gas Outburst ◽  
Evolution Characteristics ◽  
Prediction And Prevention ◽  
Coal And Gas Outbursts ◽  
Scientific Challenge

Factors leading to coal and gas outbursts are complicated, and the accuracy of predicting outbursts remains difficult to achieve. Therefore, coal and gas outburst risk are still a scientific challenge in the fields of mining, geology, safe engineering, and rock mechanics. Theories explaining and predicting coal and gas outbursts associated with restored strain and gas energy are hot topics. Based on numerical modelling, the evolution of a plastic zone ahead of an excavation face with change of direction and magnitude of regional pre-mining stress field were analyzed. A mechanical analysis model for the expansionary evolution process of the plastic zone ahead of the excavation face was constructed, and the expansionary evolution characteristics of plastic zone ahead of the excavation face were analyzed. The physical and mechanical process and basic conditions for the initiation and development of coal and gas outbursts induced by evolution of plastic zone were discussed. The research provides some new insights into the mechanism, prediction, and prevention of goal and gas outbursts.

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