scholarly journals Study on Overburden Rock Movement and Stress Distribution Characteristics under the Influence of a Normal Fault

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Quansen Wu ◽  
Peng Kong ◽  
Quanlin Wu ◽  
Xinggang Xu ◽  
Xingyu Wu ◽  
...  
Keyword(s):  
Rock Burst ◽  
Coal Pillar ◽  
Local Deformation ◽  
Overburden Rock ◽  
High Position ◽  
Rock Bursts ◽  
Fault Activation ◽  
Working Face ◽  
Prediction And Prevention ◽  
Geological Conditions

Fault activation triggers local deformation and dislocation, releasing a large amount of energy that can easily cause mining disasters, such as rock bursts and roadway instability. To study the changing characteristics of overburden structures and the evolution law of mining-induced stress as panel advances towards a fault from a footwall, two similar models were established, namely, a simulation experimental model and a numerical simulation model. In addition, the relationship among mining, mining stress, and rock bursts induced by fault activation was investigated. The results of this study reveal that when the working face is 30 m away from the fault, the high-position rock mass near the fault turns to the goaf where the fault is activated, and the two walls display relatively obvious dislocation. During the process of footwall panel mining to the fault, the abutment stress of the coal pillar tends to increase initially, followed by a decrease. When the working face is 20 m away from the fault, the abutment stress ahead of the working face reaches its maximum. When the width of the coal pillar is within the range of 10–40 m, the coal pillar accumulates a large amount of energy, and the working face affected by the fault easily induces a rock burst. Before fault activation, disturbances arising from the mining activities destroy the equilibrium stress environment of the rock system surrounding the fault, and the fault continuously accumulates energy. When the accumulated energy reaches a certain threshold, under the action of normal stress or shear stress, the fault will be activated, and a large amount of energy will be released, which can easily induce a rock burst. The research results in this paper provide a scientific basis for the classification, prediction, and prevention of rock bursts under similar geological conditions.

scholarly journals Influence of Different Advancing Directions on Mining Effect Caused by a Fault

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Lishuai Jiang ◽  
Pu Wang ◽  
Pengqiang Zheng ◽  
Hengjie Luan ◽  
Chen Zhang
Keyword(s):  
Rock Burst ◽  
Physical Simulation ◽  
Hanging Wall ◽  
Physical Models ◽  
Rock Bursts ◽  
Fault Activation ◽  
Study Results ◽  
Similar Materials ◽  
Simulation Results

To study the correlation among advancing direction, strata behaviors, and rock burst induction, two physical models utilizing similar materials are established. Subsequently, the influence of advancing direction on the mining effect, caused by a fault, is studied. Moreover, the rock bursts affected by faults with different mining directions are compared and analyzed. The results show that the overlying structure varies notably, affected by fault cutting and fault dip, and the fault-affected zone and the cause of induced rock burst differ with different mining directions. However, regardless of mining directions, the overlying structure of the hanging wall is stable and fault activation is not obvious, while that of the footwall is relatively active and fault activation is violent; the risk of rock burst on the footwall is larger than that of mining on the hanging wall. Finally, an engineering case regarding two rock bursts in panel 6303 is used to verify some physical simulation results to a certain extent. Study results can serve as a reference for face layout and prevention of rock bursts under similar conditions.

scholarly journals An Approach to Dynamic Disaster Prevention in Strong Rock Burst Coal Seam under Multi-Aquifers: A Case Study of Tingnan Coal Mine

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7287
Author(s):  
Xinxin Zhou ◽  
Zhenhua Ouyang ◽  
Ranran Zhou ◽  
Zhenxing Ji ◽  
Haiyang Yi ◽  
...  
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Water Inrush ◽  
Coal Seams ◽  
High Position ◽  
Integrated Method ◽  
Working Face ◽  
Strong Rock ◽  
And Control

In order to prevent the multi-dynamic disasters induced by rock burst and roof water inrush in strong rock burst coal seams under multi-aquifers, such as is the case with the 207 working face in the Tingnan coal mine considered in this study, the exhibited characteristics of two types of dynamic disasters, namely rock burst and water inrush, were analyzed. Based on the lithology and predicted caving height of the roof, the contradiction between rock burst and water inrush was analyzed. In light of these analyses, an integrated method, roof pre-splitting at a high position and shattering at a low position, was proposed. According to the results of numerical modelling, pre-crack blasting at higher rock layers enables a cantilever roof cave in time, thereby reducing the risk of rock burst, and pre-crack blasting at underlying rock layers helps increase the crushing degree of the rock, which is beneficial for decreasing the caving height of rock layers above goaf, thereby preventing the occurrence of water inrush. Finally, the proposed method was applied in an engineering case, and the effectiveness of this method for prevention and control of multi-dynamics disasters was evaluated by field observations of the caving height of rock layers and micro-seismic monitoring. As a result, the proposed method works well integrally to prevent and control rock burst and water inrush.

scholarly journals Study on the Mechanism and Control of Rock Burst of Coal Pillar under Complex Conditions

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Xingping Lai ◽  
Huicong Xu ◽  
Jingdao Fan ◽  
Zeyang Wang ◽  
Zhenguo Yan ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Rock Burst ◽  
Coal Mine ◽  
High Stress ◽  
Coal Pillar ◽  
Vertical Stress ◽  
Body Area ◽  
High Stress Concentration ◽  
Solid Coal ◽  
Working Face

In order to explore the mechanism of coal pillar rock burst in the overlying coal body area, taking W1123 working face of Kuangou Coal Mine as the engineering background, the full mining stage of W1123 is simulated by FLAC3D. It is found that the high stress concentration area has appeared on both sides of the coal pillar when W1123 does not start mining. With the advance of the working face, the high stress concentration area forms X-shaped overlap. There is an obvious difference in the stress state between the coal pillar under the solid coal and the coal pillar under the gob in W1123. The concrete manifestation is that the vertical stress of the coal pillar below the solid coal is greater than the vertical stress of the coal pillar below the gob. The position of the obvious increase of the stress of the coal pillar in the lower part of the solid coal is ahead of the advancing position of the working face, and the position of the obvious increase of the stress of the lower coal pillar in the gob lags behind the advancing position of the working face. At the same time, in order to accurately reflect the true stress environment of coal pillars, the author conducted a physical similarity simulation experiment in the laboratory to study the local mining process of the W1123 working face, and it is found that under the condition of extremely thick and hard roof, the roof will be formed in the gob, the mechanical model of roof hinged structurer is constructed and analyzed, and the results show that the horizontal thrust of roof structure increases with the increase of rotation angle. With the development of mining activities, the self-stable state of the high stress balance in the coal pillar is easily broken by the impact energy formed by the sudden collapse of the key strata. Therefore, the rock burst of coal pillar in the overlying coal body area is the result of both static load and dynamic load. In view of the actual situation of the Kuangou Coal Mine, the treatment measures of rock burst are put forward from the point of view of the coal body and rock mass.

scholarly journals A Control Method of Rock Burst for Dynamic Roadway Floor in Deep Mining Mine

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Zhimin Xiao ◽  
Jun Liu ◽  
Shitan Gu ◽  
Mingqing Liu ◽  
Futian Zhao ◽  
...  
Keyword(s):  
Rock Burst ◽  
Control Method ◽  
Tectonic Stress ◽  
Surrounding Rock ◽  
Floor Rock ◽  
Deep Mining ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Working Face ◽  
Geological Conditions

Roadway floor rock burst is an important manifestation of rock bursts in deeply buried mines. With the increase of mining depth and mining intensity, rock burst disasters in the roadway floor such as floor heaves are becoming more serious. The article investigated the roadway floor severe heave caused by floor rock burst during excavation of the No. 3401 working face, which was controlled by an anticlinal structure and deep mining in Shandong Mine, China. Firstly, by analyzing geological conditions of the working face, roadway support parameters, and characteristics of coal and rock, it was revealed that high tectonic stress and high crustal stress were main causes of the floor rock burst. Secondly, based on the Theory of Mechanics and Theory of Energy, the energy conversion process in the roadway floor was discussed, and the rock burst condition caused by elastic energy in the roadway floor was analyzed. The failure characteristics of roadway-surrounding rock were also inspected, using a borehole recorder. The roof and sidewalls of roadway mainly contained fissures and cracks, whereas cracks and broken areas are distributed in the roadway floor. Finally, based on the deformation and failure characteristics of roadway-surrounding rock, a method termed “overbreaking-bolting and grouting-backfill” was proposed to control roadway floor rock burst. The method was tested in the field, and the results showed that it could effectively control the deformation of roadway floor and rock burst, guaranteeing the stability of roadway floor. This impact control method for the roadway floor can provide a reference for the prevention and control of roadway rock burst in mines with similar geological conditions.

scholarly journals Study on Characteristics of Mining Earthquake in Multicoal Seam Mining under Thick and Hard Strata in High Position

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Shuli Wang ◽  
Guangli Zhu ◽  
Kaizhi Zhang ◽  
Lei Yang
Keyword(s):  
Rock Burst ◽  
Research Work ◽  
High Energy ◽  
Microseismic Monitoring ◽  
Temporal And Spatial Distribution ◽  
High Position ◽  
Main Research ◽  
Working Face ◽  
Mining Safety ◽  
Seam Mining

Rock burst has become one of the most serious world’s problems in coal resources mining, and fracture and movement of thick and hard strata in high position is the main reason to induce strong mining earthquake and rock burst. Multicoal seam mining of 10302 working face in Baodian coal mine is selected as an engineering background, which has thick and hard strata in high position. Using SOS microseismic monitoring system to collect microseismic events and date during multicoal seam mining, characteristic and difference of microseismic in multicoal seam mining under thick and hard rock in high position is analyzed systematically. The main research work is as follows: reveal temporal and spatial distribution and evolution law of microseismic and analyze difference and correlation of microseismic in multicoal mining under thick and hard strata in high position, especially the relationship between mining earthquake with high energy and fracture and movement of thick and hard strata in high position. With the characteristics of microseismic, rock burst mechanism and difference induced by thick and hard strata in high position are discussed. The research and achievement could make guidance to multicoal seam mining safety under thick and hard strata in high position.

scholarly journals Research on Reasonable Width of Coal Pillars of Non-equal Width Isolated Working Face Heading Goaf in Deep Mine

2021 ◽  
Author(s):  
weili yang ◽  
Quande wei ◽  
Zhonghui Wang ◽  
Zhizeng Zhang ◽  
Xiaocheng Qu ◽  
...  
Keyword(s):  
Rock Burst ◽  
Critical State ◽  
Research Result ◽  
High Stress ◽  
Coal Pillar ◽  
Stress Monitoring ◽  
Equilibrium Relation ◽  
Deep Mine ◽  
Working Face ◽  
Coal Pillars

Abstract Setting reasonable coal pillar is a key to ensure safe mining of island coal face heading goaf in deep mine. With determination of reasonable width of coal pillars of non-equal width isolated working face 3201 in worked-out area in one mine in Shandong as the engineering background, a research was conducted on the mechanism of rock burst induced by and the reasonable width of coal pillars of isolated working face in worked-out area and the main conclusions are as follows: (1) the coal pillars of isolated working face 3201 in worked-out area changed from pillars with goaf on two sides→pillars with goaf on three sides→pillars with goaf on four sides, resulting in evolution of overlying strata from pre-mining static “┒-shaped” structure→“C-shaped” structure→“O-shaped” structure and corresponding spatial stress from “saddle-shaped” profile→“platform-shaped” profile→“arch-shaped” profile; (2) the rock burst was induced by coal pillars, because the high stress on coal pillars at critical state of a rock burst was greater than their comprehensive strength and induced a rock burst due to sudden instability; (3) by establishing a bearing and load model of coal pillars at critical state of a rock burst and based on the equilibrium relation, an method for estimating reasonable width of coal pillars of isolated working face in worked-out area in deep mine was derived and applied to the isolated working face 3201 in worked-out area, thus comprehensively determining that the width of coal pillars should be 130m. The field stress monitoring verified the reasonability. The research result is of great significance to prevention of rock burst induced by coal pillars of isolated working face in worked-out area in deep mine.

scholarly journals Analysis on Rock Burst Risks and Prevention of a 54 m-Wide Coal Pillar for Roadway Protection in a Fully Mechanized Top-Coal Caving Face

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zhihua Li ◽  
Ke Yang ◽  
Jianshuai Ji ◽  
Biao Jiao ◽  
Xiaobing Tian
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Influencing Factors ◽  
Abutment Pressure ◽  
Large Diameter ◽  
Coal Pillar ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Working Face ◽  
Coal Pillars

A case study based on the 401103 fully mechanized caving face in the Hujiahe Coal Mine was carried out in this research to analyze the rock burst risks in a 54 m-wide coal pillar for roadway protection. Influencing factors of rock burst risks on the working face were analyzed. Stress distribution characteristics on the working face of the wide coal pillar for roadway protection were discussed using FLAC3D numerical simulation software. Spatial distribution characteristics of historical impact events on the working face were also investigated using the microseismic monitoring method. Results show that mining depth, geological structure, outburst proneness of coal strata, roof strata structure, adjacent mining area, and mining influence of the current working face are the main influencing factors of rock burst on the working face. Owing to the collaborative effects of front abutment pressure of the working face and lateral abutment pressure in the goaf, the coal pillar is in the ultimate equilibrium state and microseismic events mainly concentrate in places surrounding the coal pillars. Hence, wide coal pillars become the regions with rock burst risks on the working face. The working face adopts some local prevention technologies, such as pressure relief through presplitting blasting in roof, pressure relief through large-diameter pores in coal seam, coal seam water injection, pressure relief through large-diameter pores at bottom corners, and pressure relief through blasting at bottom corners. Moreover, some regional prevention technologies were proposed for narrow coal pillar for roadway protection, including gob-side entry, layer mining, and fully mechanized top-coal caving face with premining top layer.

scholarly journals The Study on Large-Diameter Drilling Prevention Method of Rock Burst in the Xinxing Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Gao Xu ◽  
Zuo Minghui ◽  
Shu Yanmin
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Plastic Zone ◽  
Rock Burst ◽  
Large Diameter ◽  
Practical Implementation ◽  
Physical Parameters ◽  
Mine Pressure ◽  
Working Face ◽  
Geological Conditions

Based on the engineering background, the 41051 working face of the 65th coal mine in Qitaihe Xinxing Mine was regarded as the engineering background, by using of the comprehensive research methods such as theoretical analysis and calculation, FLAC3D numerical simulation, physical parameters of coal and rock in laboratory, and the field industrial measurement, to research on the large drilling relieving rock burst mechanism and parameter setting in reasonable. The distribution of stress and plastic zone in drilling surrounding rock and its influence parameters are clarified, and the distribution of the “butterfly plastic zone” and the mutation condition of the “butterfly plastic zone” in trigger stress state are explored. On the basis, combined with theoretical analysis and numerical simulation, studying the rock burst prevention and treatment mechanism in large drilling, through the statistics of the Xinxing mine pressure characteristics, the measurement of the physical parameters of coal and rock and the test of ground stress finding is that the coal satisfies “Three hard” condition in Xinxing mine and is affected by larger horizontal tectonic stress. Combined with the real geological conditions, the layout parameters of relief pressure large drilling are simulated, and the result shows that the drilling of 600 diameters and 10 m pitch of hole and throughout the working face is reasonable, and the effect is obvious about pressure relief. For the practical implementation, the electromagnetic radiation monitoring is used to evaluate the effect in field; to comprehensive analysis, the relief pressure large drilling has obvious control effect to the 41051 workface rock burst.

scholarly journals Study on Dynamic Behavior Law and Microseismic Monitoring in Stoping Process of Roadway with High Gas and Wide Coal Pillar

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Baobin Gao ◽  
Chuangnan Ren ◽  
Qun Dong ◽  
Liwei Chen
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Dynamic Characteristics ◽  
Coal Pillar ◽  
Microseismic Monitoring ◽  
Coal Industry ◽  
Gas Pressure ◽  
Pillar Width ◽  
Working Face ◽  
Microseismic Activity

In order to study the dynamic characteristics and microseismic distribution in the mining process of roadway with high gas and wide coal pillar, combined with the two dynamic events of N2105 working face in Yuwu Coal Industry, theoretical analysis and field measurement research were carried out. According to the theory of structural mechanics and geomechanics, the causes of dynamic appearance are analyzed. Combined with the specific situation, the influence of mining depth, coal pillar width, gas pressure, and content on the dynamic performance is analyzed. Stress monitoring and microseismic monitoring are carried out on one side of coal seam. The results show that, with the increase of the mining distance, the backside roof of the goaf is prone to unbalanced fracture due to the lack of lateral stress, and the impact pressure generated is used for the reserved protective coal pillar behind the goaf, causing the floor heave of coal seam. The combined stress generated by the anticlinal structure below the working face interacts with the abutment pressure of the working face to produce superposition effect, which promotes the occurrence of dynamic appearance. The critical depth of rock burst in Yuwu Coal Industry is about 600m. The increase of coal elastic energy caused by roof subsidence is more uniform with the increase of coal pillar width. The decrease of gas pressure in coal seam promotes the rock burst disaster. The vertical stress of coal seam at one side of the working face shows different evolution characteristics along the trend and strike. The vertical stress of coal seam in the lateral range of 53 m is adjusted to different degrees and tends to be stable until 300 m behind the working face. The active microseismic area in the middle of the working face was located 50 m in front of the working face, and the microseismic activity continued to 30–50 m behind the working face. The active microseismic area at the side of the roadway was located 30 m in front of the working face, and the microseismic activity continued to 100–180 m behind the working face. The inflection point, where the stress in the elastic area of coal pillar increases sharply, corresponds to the active microseismic area, which indicates that the dynamic characteristics in the mining process of roadway with high gas and wide coal pillar are related to the distribution law of microseismic. This study has a certain guiding significance for optimizing the width of reserved coal pillar, monitoring the coal seam stress/microseismic, and understanding the dynamic disaster of coal and rock under complex conditions.

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