scholarly journals Study on Catastrophe Theory of Activation-Induced Prominence of Faults under Dynamic Disturbance

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Yujun Zuo ◽  
Hao Wang ◽  
Meilu Yu ◽  
Xiaoxiao Dou ◽  
Zhonghu Wu ◽  
...  
Keyword(s):  
Catastrophe Theory ◽  
External Input ◽  
Surrounding Rock ◽  
Coal And Gas Outburst ◽  
External Energy ◽  
Dynamic Disturbance ◽  
Gas Outburst ◽  
Prediction And Prevention ◽  
Mining Disturbance ◽  
The Stability

In view of the phenomena of coal and gas outburst induced by fault activation under dynamic disturbance, a mechanical model of faults and surrounding rock mechanics was established based on the theory of fold catastrophe. Moreover, the dynamic disturbance factors were introduced and analyzed to analyze the influencing factors of outburst coal rock outburst. Through theoretical analysis, it shows that the thinner the fault medium is, the more energy the external input is required for system instability, and the external energy can reflect the stability of the system. When the width of fault media is fixed, the stronger the mining disturbance, the less energy the external input is required for system instability; on the contrary, the weaker the mining disturbance is, the more energy the external input is required for system instability. In addition, through the equation of conservation of kinetic energy, it can be seen that the stronger the mining disturbance, the greater the critical value of the surrounding rock thickness. The paper introduces the dynamic disturbance parameters through the catastrophe theory and analyzes the influence of the existence of faults on coal and gas outburst in detail, which provides a new theoretical basis for the prediction and prevention of coal and gas outburst disasters.

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

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.

scholarly journals Analysis of the Occurrence Mechanism for Coal and Gas Outburst Based on Multiple Discriminant Indices

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Hai Rong ◽  
Hongwei Zhang ◽  
Bing Liang ◽  
Weihua Song
Keyword(s):  
Coal Mine ◽  
Regional Distribution ◽  
Geological Structure ◽  
Coal And Gas Outburst ◽  
Prevention Measures ◽  
Distribution Law ◽  
Risk Levels ◽  
Gas Outburst ◽  
Prediction And Prevention ◽  
Occurrence Mechanism

In order to reveal the occurrence mechanism of coal and gas outburst and optimize the measures to prevent the disaster, a coal mine in Henan Province was undertaken as the research background. Based on the geological and mining conditions of the coal mine, the gas geological analysis method is applied to determine the outburst occurrence and to classify the risk levels. A multifactor pattern recognition method is used to determine the risk probability of the dynamic disasters such as coal and gas outburst. The relationship between geological structure, rock mass stress, and mine dynamic hazards is determined using geo-dynamic division method and FLAC3D numerical simulation. The occurrence and manifestation characteristics of the dynamic hazards are determined. COMSOL Multiphysics software is used to evaluate the original prevention measures and to optimize the measures. The research results determine the main influencing factors and regional distribution law of coal and gas outburst, which is of great significance to the risk prediction and prevention of dynamic disasters such as coal and gas outburst.

A new method for coal and gas outburst prediction and prevention based on the fragmentation of ejected coal

Fuel ◽  
2021 ◽  
Vol 287 ◽  
pp. 119493
Author(s):  
Chaolin Zhang ◽  
Enyuan Wang ◽  
Jiang Xu ◽  
Shoujian Peng
Keyword(s):  
Coal And Gas Outburst ◽  
New Method ◽  
Gas Outburst ◽  
Prediction And Prevention

Characteristics of Coal and Gas Outburst within Gas Geological Units in Qidong Mine

2013 ◽  
Vol 734-737 ◽  
pp. 45-51
Author(s):  
Ai He Chen ◽  
Dong Ji Lei ◽  
Yu Gui Zhang
Keyword(s):  
Magmatic Rock ◽  
Coal And Gas Outburst ◽  
Gas Content ◽  
Coal Bed ◽  
Burial Depth ◽  
Gas Outburst ◽  
Prediction And Prevention ◽  
Gas Occurrence ◽  
Tectonic Coal ◽  
Geological Units

The precise mechanism of the coal and gas outburst is still unresolved, but productive practices in Qidong mine have testified that the coal and gas outburst accidents are predominantly associated with the belt of geological structure, the zone of tectonic coal occurrence and the area of the stress concentration. So it is very important to study characteristics of coal bed gas geology for coal bed gas prediction and prevention. Using gas-geology theory and method, the research focused on the factors of coal and gas outburst, such as coal bed gas occurrence, stress distribution, tectonic coal occurrence and magmatic rock presence within Qidong mine. The result shows that: Qidong mine district could be divided into 4 geological units by 3 faults as the boundary, the faults of Weimiao fault, F2, and F5; there are different conditions and main controlling factors of coal bed gas occurrence within four geological units. The unit I of geology: coal bed gas occurrence conditions are simpler, mainly contacted with the coal burial depth; the unit II: the conditions are more complex, predominantly associated with fault structures; the unit III: as a result of the presence of igneous intrusions, coal bed gas content in unit III is the highest within the whole mine; the unit IV: major factor of the conditions is the fold caused by strata uplift, which also leads to a large number of gas emissions. 25 coal and gas outburst accidents all occurred within the unit II of geology.

scholarly journals Coal and Gas Outburst Affected by Law of Small Fault Instability during Working Face Advance

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Jianyun Lin ◽  
Yujun Zuo ◽  
Kai Zhang ◽  
Wenjibin Sun ◽  
Biao Jin ◽  
...  
Keyword(s):  
Fault Zone ◽  
Coal And Gas Outburst ◽  
Face Advance ◽  
Movement Rate ◽  
Gas Outburst ◽  
Working Face ◽  
Prediction And Prevention ◽  
Small Fault ◽  
Coal And Gas Outbursts ◽  
Overburden Strata

To analyze the effect of small faults in the working face on coal and gas outbursts, the coal and gas outburst accident in the 21431 working face was studied with the 3DEC numerical simulation method, and the main research contents were the change laws of both stresses at the small fault and the overburden strata movement rate in the small fault zone of which the drop height and the strike were designed into different groups. The results show that the risk of small fault slip increases with the advancing working face. In addition, there is a positive correlation between the risk and the small fault throw. The movement rate of overburden strata in the small fault zone increases along with the rising of the small fault throw, which increases the energy transferred to the coal seam from the surrounding rock under the effect of the small fault. Hence, the effect of small faults on the working face on coal and gas outbursts was positively correlated with the small fault throw. Under the influence of a small fault strike, the closer it is to the small fault along the dip distance at the same working face, the greater the risk will be of a coal and gas outburst. And the bigger the small fault strike is, the greater is the stress concentration degree in front of the working face and the more the elastic energy is stored and the greater is the possibility of an outburst. The paper analyzes the influence of small faults on coal and gas outbursts in the working face, which has reference significance for the prediction and prevention of coal and gas outburst disaster in the working face.

scholarly journals Stability Control of a Goaf-Side Roadway under the Mining Disturbance of an Adjacent Coal Working Face in an Underground Mine

2019 ◽  
Vol 11 (22) ◽  
pp. 6398
Author(s):  
Houqiang Yang ◽  
Changliang Han ◽  
Nong Zhang ◽  
Changlun Sun ◽  
Dongjiang Pan ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Stability Control ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Key Strata ◽  
Coal Recovery ◽  
Working Face ◽  
Underground Coal Mines ◽  
Mining Disturbance ◽  
The Stability

Goaf-side roadway driving could not only notably reduce the loss of coal resources and improve the coal recovery rates, but also greatly mitigate the imbalance between excavation speed and production needs, which are able to prolong the service life of the mine and are pivotal to sustainable and efficient development of underground coal mines. However, it is difficult to control the stability of the goaf-side roadway, especially under mining disturbance of another adjacent coal working face. In order to control the stability of the goaf-side roadway, Haulageway 1513 in the Xinyi Coal Mine of China, under mining disturbance, theoretical analysis, numerical simulation, and engineering practice were carried out to reveal the mechanism of overburden key strata fracture, stress distribution, and deformation characteristics of the surrounding rock of the goaf-side roadway due to mining disturbance. Results showed that some key strata above Goaf 1512 did not fracture due to the influence of the strata caving angles. However, these key strata would fracture and break into rock blocks when suffering from mining disturbance of the adjacent coal working face, which changed the stress distribution and increased the deformations of the surrounding rock of the goaf-side roadway. The combined techniques of pressure relief and bolt support were proposed and carried out to control the stability of the goaf-side roadway. Engineering practice indicated that the maximum deformations of the roof and sidewall-to-sidewall were 220 mm and 470 mm, respectively. The deformations of the goaf-side roadway under mining disturbance were efficiently controlled.

scholarly journals Stability Analysis of Roadway Groups under Multi-Mining Disturbances

2021 ◽  
Vol 11 (17) ◽  
pp. 7953
Author(s):  
Yuantian Sun ◽  
Ruiyang Bi ◽  
Qingliang Chang ◽  
Reza Taherdangkoo ◽  
Junfei Zhang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Coal Pillar ◽  
Stability Control ◽  
Surrounding Rock ◽  
Key Strata ◽  
Working Face ◽  
Roadway Stability ◽  
Mining Disturbance ◽  
Mining Face ◽  
The Stability

The roadway stability has been regarded as the main challenging issue for safety and productivity of deep underground coal mines, particularly where roadways are affected by coal mining activities. This study investigates the −740 m main roadway in the Jining No. 2 Coal Mine to provide a theoretical basis for the stability control of the main deep roadway affected by disturbances of adjacent working activities. Field surveys, theoretical analyses, and numerical simulations are used to reveal mechanisms of the coal mining disturbance. The field survey shows that the deformation of roadway increases when the work face advances near the roadway group. Long working face mining causes the key strata to collapse based on the key strata theory and then disturbs the adjacent roadway group. When the working face is 100 m away from the stop-mining line, the roadway group is affected by the mining face, and the width roadway protection coal pillar is determined to be about 100 m. Flac3D simulations prove the accuracy of the theoretical result. Through reinforcement and support measures for the main roadway, the overall strength of the surrounding rock is enhanced, the stability of the surrounding rock of the roadway is guaranteed, and the safe production of the mine is maintained.

STUDY OF THE STRENGTH REDUCTION DDA METHOD AND ITS APPLICATION TO MOUNTAIN TUNNEL

2012 ◽  
Vol 09 (03) ◽  
pp. 1250041 ◽  
Author(s):  
CAICHU XIA ◽  
CHONGBANG XU ◽  
XU ZHAO
Keyword(s):  
Catastrophe Theory ◽  
Reduction Method ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Surrounding Rock ◽  
Strength Reduction Method ◽  
Tunnel Design ◽  
The Stability ◽  
Mountain Tunnel ◽  
Dda Method

The stability of tunnel surrounding rock is the mainly concerned content during tunnel design and construction procedure. It is one of the main tasks for researchers to accurately estimate the stability of tunnel surrounding rock. Generally, determined by its engineering geological features, surrounding rock of mountain tunnel is cut by joints into discontinuous blocks, which can be more accurately analyzed by discontinuum-base numerical methods, e.g., the discontinuous deformation analysis (DDA) method. In addition, progress of deformation and failure of tunnel surrounding rock is often a nonlinear catastrophe behavior, so that it is feasible to determine the tunnel stability by the catastrophe theory. The strength reduction method can be used to simulate failure progress development in its computation procedure by reducing the strength parameters. Based on the DDA method, the strength reduction method and the catastrophe theory are adopted to study the stability of tunnel surrounding rock. Firstly, the strength reduction method is used to obtain the function of displacement and the reduction factor varies, and then the catastrophe theory is used to judge the critical state of surrounding rock based on the function curve. The reduction factor at this critical point is defined as the stability safety factor of the tunnel. Thus the stability status of the surrounding rock can be determined. Jinjishan multiple-arch tunnel is a big span tunnel with eight traffic lanes, which is a very important project of the second phase project of Fuzhou city airport. This method is put into application of this project to guarantee safety of the tunnel.

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