scholarly journals Experimental and Numerical Simulation of Coal Rock Impact Energy Index Based on Peridynamics

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Feng He ◽  
Tianjiao Ren ◽  
Song Yang ◽  
Hongjie Bian
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Uniaxial Compression ◽  
Elastic Deformation ◽  
Impact Energy ◽  
Elastic Energy ◽  
Deformation Energy ◽  
Energy Index ◽  
Actual Impact ◽  
Rock Bursts

In response to the increasing severity of the rock burst phenomenon and its relatively difficult prediction, peridynamics and indoor uniaxial compression experiments were used to calculate the changes of the internal elastic energy (t) and impact energy (c) for different rock masses during a loading process from an energy perspective. Two traditional indices for judging rock burst tendency—the rock elastic deformation energy index (WET) and the rock impact energy index (WCF)—were combined to define a new actual impact energy index (W) to more accurately determine the occurrence tendency of rock bursts. The LAMMPS software was used to simulate the internal energy changes of rock materials under pressure, and the results were compared with experimental results for verification. The results were as follows: (1) in the uniaxial compression experiments of different specimens, fine sandstone had the strongest impact resistance, followed by coarse sandstone, mudstone, bottom coal seam, and top coal seam, and the obtained material properties provide a reference for predicting the rock bursts of various rock types in practical engineering. (2) The values calculated using the actual impact energy index (W) and the simulation value were 1.75 and 1.77, respectively, which corresponded to a lower error than when the rock impact energy index (WCF) and the rock elastic deformation energy index (WET) were used individually. Thus, this index can better predict the rock burst. (3) The simulated specimen was subjected to a gradual increase in the internal stored elastic energy during compression, which gradually decreased after the ultimate compressive strength was exceeded. The degree of impact damage formed after macroscopic crushing occurred depended on its residual energy.

scholarly journals Mechanism of Rock Bursts Induced by the Synthetic Action of “Roof Bending and Rock Pillar Prying” in Subvertical Extra-Thick Coal Seams

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhenhua Wu ◽  
Peng-Zhi Pan ◽  
Jianqiang Chen ◽  
Xudong Liu ◽  
Shuting Miao ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Rock Burst ◽  
Roof Rock ◽  
High Energy ◽  
Coal Seams ◽  
Rock Bursts ◽  
Rock Pillar ◽  
Mining Depth ◽  
Rock Burst Mechanism

When studying the rock burst mechanism in subvertical extra-thick coal seams in the Wudong coal mine in Xinjiang, China, most studies focus on rock pillars, while the effect of the roof on rock bursts is usually ignored. In this paper, a rock burst mechanism in subvertical extra-thick coal seams under the control of a “roof-rock pillar” is proposed. A theoretical analysis is first performed to explain the effect of roof-rock pillar combinations on rock bursts in coal seams. Numerical modeling and microseismic analysis are implemented to further study the mechanism of rock burst. The main conclusions are as follows: 1) During the mining of the B3+6 coal seam, an obvious microseismic concentration phenomenon is found in both the roof and rock pillar of B3+6. The rock bursts exhibited obvious directionality, and its main failure characteristics are floor heave and sidewall heave, but there will also be some failures such as shoulder socket subsidence in some parts. 2) The stress transfer caused by rock pillar prying is the main reason for the large difference in rock burst occurrence near the vertical and extra thick adjacent coal seams under the same mining depth. 3) Under the same cantilever length, the elastic deformation energy of the roof is much greater than that of the rock pillar, which makes it easier to produce high-energy microseismic events. With an increasing mining depth, the roof will become the dominant factor controlling the occurrence of rock bursts. 4) The high-energy event produced by the rock mass fracture near the coal rock interface easily induces rock bursts, while the high-energy event produced by the fracture at the far end of the rock mass is less likely to induce rock burst. 5) Roof deformation extrusion and rock pillar prying provide high static stress conditions for the occurrence of rock bursts in the B3+6 coal seam. The superposition of the dynamic disturbance caused by roof and rock pillar failure and the high static stress of the coal seam is the main cause of rock burst in the B3+6 coal seam.

scholarly journals Experimental Study of the Influence of Moisture Content on the Mechanical Properties and Energy Storage Characteristics of Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Nan Liu ◽  
Chuanming Li ◽  
Ruimin Feng ◽  
Xin Xia ◽  
Xiang Gao
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Rock Burst ◽  
Elastic Energy ◽  
Coal Sample ◽  
Water Injection ◽  
Peak Stress ◽  
Peak Strain ◽  
Energy Index ◽  
The Impact

Rock burst occurs frequently as coal mining depth goes deeper, which seriously impacts the safety production of underground coal mines. Coal seam water injection is a technique commonly used to prevent and control such accidents. Moisture content is a critical factor tightly related to rock burst; however, an in-depth insight is required to discover their relationship. In this study, the influence of moisture content on the mechanical properties of coal and rock burst tendency is explored via multiple measurement techniques: uniaxial compression test, cyclic loading/unloading test, and acoustic emission (AE) test. These tests were performed on coal samples using the MTS-816 rock mechanics servo testing machine and AE system. The testing results showed that with the increase in moisture content, the peak strength and elastic modulus of each coal sample are reduced while the peak strain increases. The duration of the elastic deformation phase in the complete stress-strain curves of coal samples is shortened. As the moisture content increases, the area of hysteretic loop and elastic energy index W ET of each coal sample are reduced, and the impact energy index K E is negatively correlated with the moisture content, whereas dynamic failure time is positively correlated with the moisture content, but this variation trend is gradually mitigated with the continuous increase of moisture content. The failure of the coal sample is accompanied by the sharp increase in the AE ring-down count, whose peak value lags behind the peak stress, and the ring-down count is still generated after the coal sample reached the peak stress. With the increase in moisture content, the failure mode of the coal sample is gradually inclined to tensile failure. The above test results manifested that the strength of the coal sample is weakened to some extent after holding moisture, the accumulative elastic energy is reduced in case of coal failure, and thus, coal and rock burst tendency can be alleviated. The study results can provide a theoretical reference for studying the fracture instability of moisture-bearing coal and prevention of coal and rock burst by the water injection technique.

The Affection of Ke of Coal Seam on Strata Behavior

2013 ◽  
Vol 734-737 ◽  
pp. 858-862
Author(s):  
Wen Jie Wang ◽  
Hong Wei Wang ◽  
Zhao Hua Wang ◽  
Duo Xu
Keyword(s):  
Coal Seam ◽  
Impact Energy ◽  
Peak Position ◽  
Vertical Stress ◽  
Energy Index ◽  
Important Indicator ◽  
Stress Peak ◽  
Coal Wall ◽  
Strata Behavior ◽  
The Impact

Coal seam burst tendency is one of the main factors of rockburst. The impact energy index is an important indicator to evaluate bursting liability of coal. The research on the impact of coal seam impact energy index on the mining pressure behavior regularity is important for the rockburst prediction and prevention. This paper used FLAC3D numerical calculation software to simulate the mining process of seam workface with different Ke and studied the strata behavior regularity with different Ke. Calculations indicated that the vertical stress peak increased in the middle of the seam workface with Ke increasing and the peak position closer to face should implement the anti-impact measures. However, with Ke decrease, vertical stress superimposes at peak stress increases sharply, gradually increasing vertical stress peak distance away from the face and roadway coal wall and the peak position of moves away from face and roadway coal wall. Therefore, the stress in the roadway and face superimposed at the scour protection measures should be implemented.

scholarly journals Damage Evaluation for Rock Burst Proneness of Deep Hard Rock under Triaxial Cyclic Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Shuang You ◽  
Hongguang Ji ◽  
Zijian Zhang ◽  
Chenghan Zhang
Keyword(s):  
Cyclic Loading ◽  
Rock Burst ◽  
Elastic Energy ◽  
Failure Process ◽  
Damage Zone ◽  
High Stress ◽  
Energy Index ◽  
Dissipation Energy ◽  
Deep Mining ◽  
Cyclic Loading And Unloading

High stress and strong excavation disturbance are the main causes of dynamic disasters, rock burst in deep hard rocks, and are more frequent and violent than those in shallow, which seriously restricts the deep mining. Given rock burst encountered in deep mining of Lingnan metal mines, the optimized triaxial cyclic loading and unloading tests are designed to characterize the performance of rock failure and to evaluate the rock burst proneness. The correlation between elastic energy index and damage evolution is built, and rock burst proneness in each status is analyzed; furthermore, the dissipation energy in the failure process of deep rocks is explicated. In this paper, the law that the elastic energy index via damage increases is drawn. In terms of the dynamic disaster conditions in the deep rock, the identification approach for the damage zone of the rock burst is established.

scholarly journals Experimental Study on the Effect of Advancing Speed and Stoping Time on the Energy Release of Overburden in an Upward Mining Coal Working Face with a Hard Roof

2019 ◽  
Vol 12 (1) ◽  
pp. 37 ◽  
Author(s):  
Feng Cui ◽  
Yanbin Yang ◽  
Xingping Lai ◽  
Chong Jia ◽  
Pengfei Shan
Keyword(s):  
Coal Seam ◽  
Energy Release ◽  
Rock Burst ◽  
Response Ratio ◽  
Working Face ◽  
Significant Difference ◽  
Loading And Unloading ◽  
Microseismic Events ◽  
Microseismic Event ◽  
The Impact

In order to study the influence of advancing speed and stoping time of a coal face on the scale and frequency of rock burst, the energy release characteristics of an overburden fracture under six advancing speeds and four stoping times are studied by theoretical analysis and similar simulation experiments. The distribution characteristics of microseismic events before and after stoppage are compared, and the load/unload response ratio is introduced to analyze the relationship between the synergistic effect of advancing speed and stoping time and the characteristics of microseismic events in coal and rock mass. The mechanism of rock burst induced by the advancing speed and stoping time effect in the working face is studied, and the coordinated regulation and mitigation of advancing speed and stoping time are analyzed and completed. The results show that the effect of advancement speed and stoping time is very important to the energy release of overburden. The energy released by microseismic events during stoping is exponentially related to the advancing speed. The change of advancing speed causes the change of microseismic event characteristics, reflecting the evolution process of overburden structure and its energy. During stoping, the secondary microseismic events disturbed by mining occur frequently, leading to the significant difference of energy released by microseismic events during stoping. After stoping, the microseismic energy is more than four times higher than that during the stop period, and the risk of coal seam impact is high during the stope period. The synergetic change of advancement speed and stoping time changes the cycle of energy accumulation and release. The response ratio of loading and unloading considering the effect of advancement speed and stoping time is established by using the corresponding ratio of loading and unloading, and the impact risk of the coal seam is quantitatively analyzed. Based on the monitoring and analysis of microseismic events, the safety mining index of coordinated control with the energy of a single microseismic event of 180 J is established, and the best advancing speed of the working face is determined to be 4 m/d. According to the corresponding ratio of loading and unloading, the reasonable stoping time of different advancing speeds and the corresponding advancing speed of different stoping times after the resumption of mining are determined, so as to provide a reference for the safe and efficient mining of similar rock burst mines.

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 Mechanism of Rock Burst Revealed by Numerical Simulation and Energy Calculation

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Wenlong Zhang ◽  
Nianjie Ma ◽  
Ji Ma ◽  
Chen Li ◽  
Jianju Ren
Keyword(s):  
Numerical Simulation ◽  
Force Field ◽  
Rock Burst ◽  
Elastic Energy ◽  
Computational Method ◽  
Energy Calculation ◽  
Monitoring And Control ◽  
Mass Release ◽  
The Difference ◽  
And Control

We propose a new computational method to calculate the storage elastic energy value of surrounding rocks based on numerical simulation and theoretical calculation. By calculating the difference value in energy under different force states and comparing them with the energy level when rock burst occurs, we get the mechanism of rock burst: when roadway and surrounding rocks are in the condition of large ratio bias force field, certain triggering stress causes mass release of the elastic energy of surrounding rocks around the roadway, and when the energy reaches a certain level, rock burst will occur. We also put forward the specific force field conditions and triggering stress values of rock burst, which is of great guiding significance for the mechanism disclosure, monitoring, and control of rock burst.

Research on Bursting Liability and its Preventive Measures of -906m Deep Coal and Rock in Zhuji Coal Mine

2012 ◽  
Vol 170-173 ◽  
pp. 428-433 ◽  
Author(s):  
Dong Ming Guo ◽  
Hua Jun Xue ◽  
Li Juan Li ◽  
Jun Long Xue ◽  
Gui He Li
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Water Injection ◽  
Elastic Strain Energy ◽  
Hole Drilling ◽  
Energy Index ◽  
Deep Mining ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
The Impact

Rock burst is a common mine dynamic phenomenon in the world, and the research on bursting liability of coal and rock is the foundation of rock burst’s prevention and treatment. This paper has a research on bursting liability of coal and rock of 11-2 coal seam which is the main coal seam of Zhuji coal mine, and through the research and analysis of coal seam burst energy index(bursting energy index, elastic strain energy index, duration of dynamic fracture) and rock seam burst energy index(bending energy index), this paper given that seam and rock in deep mining section of Zhuji coal mine has bursting liability, put forward a series of countermeasures such as the previous water injection, hole-drilling method, blasting distressing to the coal seam with the impact disaster for deep mining in Zhuji coal mine.

scholarly journals Numerical Investigation of Influences of Drilling Arrangements on the Mechanical Behavior and Energy Evolution of Coal Models

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Tong-bin Zhao ◽  
Wei-yao Guo ◽  
Feng-hai Yu ◽  
Yun-liang Tan ◽  
Bin Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Mechanical Behavior ◽  
Rock Burst ◽  
Test Results ◽  
Energy Index ◽  
Energy Evolution ◽  
Compression Tests ◽  
Influencing Mechanism ◽  
Drilling Method

Destress drilling method is one of the commonly used methods for mitigating rock bursts, especially in coal mining. To better understand the influences of drilling arrangements on the destress effect is beneficial for rock burst mitigation. This study first introduced the rock burst mitigation mechanism of the destress drilling method and then numerically investigated the influences of drilling arrangements on the mechanical properties of coal models through uniaxial compression tests. Based on the test results, the energy evolution (i.e., the energy dissipation and bursting energy indexes) influenced by different drilling arrangements was analyzed. When the drilling diameter, the number of drilling holes in one row, or the number of drilling rows increases, the bearing capacity of specimens nonlinearly decreases, but the energy dissipation index increases. In addition, the drilling diameter or the number of drilling holes in one row affects the failure mode weakly, which is different from that of the number of drilling rows. Consequently, the bursting energy index decreases as increasing the drilling diameter or the number of drilling holes in one row, but as increasing the number of drilling rows, the variation law of bursting energy index is not obvious. At last, the influencing mechanism of drilling arrangement on the rock burst prevention mechanism of the destress drilling method was discussed and revealed.

Sign in / Sign up

Export Citation Format

Share Document