scholarly journals Research on Deformation Characteristics and Control Technology of Soft Rock Roadway under Dynamic Disturbance

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Chuan-Wei Zang ◽  
Yang Chen ◽  
Miao Chen ◽  
Hong-Mo Zhu ◽  
Chen-Ming Qu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Dynamic Load ◽  
Static Load ◽  
Load Condition ◽  
Soft Rock ◽  
Propagation Distance ◽  
Long Term Stability ◽  
Load Intensity ◽  
And Control

In the mining process of an underground coal mine, the dynamic load often causes great damage to the roadway and affects the normal mining of coal mine. In this paper, the deformation of surrounding rocks under static load and different disturbance intensities is studied by numerical simulation. The results show that under the same static load condition, the greater the dynamic load strength is, the more obvious the roadway roof displacement subsidence is. With the increase in dynamic load propagation distance, the amplitude of the dynamic load waveform decreases gradually. Under the same disturbance load intensity, the variation of roadway displacement with different disturbance load frequencies is studied. According to the influence of dynamic load on the deformation of the roadway, a combined support plan of shotcrete anchor net and reinforcement anchor cable is proposed. Finally, the rationality of the optimized support scheme is verified by numerical simulation and field results. The results show that the combined support scheme can effectively increase the strength of the broken soft rock and reduce the deformation of the surrounding rock. At the same time, it releases the expansion energy generated by the mutual compression and deformation of the rock layers, effectively maintaining the long-term stability of the roadway.

scholarly journals Study on Occurrence Mechanism of Coal Pillar in L-Shaped Zone during Fully Mechanized Mining Period and Prevention Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zeng-qiang Yang ◽  
Hong-mei Wang ◽  
De-quan Sun ◽  
Xian-jian Ma ◽  
Ming-bao Xu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Rock Burst ◽  
Dynamic Load ◽  
Static Load ◽  
Coal Pillar ◽  
Simulation Software ◽  
In Situ Investigation ◽  
Simulation Results ◽  
Occurrence Mechanism

In order to study the occurrence mechanism of rock burst in L-shaped zone during a fully mechanized mining period, the No. 705 working face which is located in Baojishan Colliery is taken as a typical engineering background. By means of in situ investigation, theoretical analysis, numerical simulation, in situ tests, and relevant monitoring methods, the occurrence mechanism of rock burst and corresponding prevention technology are studied. The results show that a coal pillar with some confining pressure in the L-shaped zone is established by FLAC3D numerical simulation software, and the numerical simulation results indicate that the change in static load has a greater effect than dynamic load on coal pillar unstable failure; the static load plays a role in storing energy, and dynamic load plays a role in inducing rock burst; the bolt-mesh-cable support and high-pressure water jet unloading combined technology is put forward to prevent rock burst in roadways, and the numerical simulation results show that stress distribution of surrounding rock meets the model of strong-soft-strong (3S) structure, and the moment distribution is reasonable. In the follow-up mining, a limit value of coal fines is used to determine that this measure is a reasonable method to prevent rock burst. The study conclusions provide theoretical foundation and new guidance for preventing rock burst by synergistic effect technology in roadways.

scholarly journals Research on Fault Activation Law in Deep Mining Face and Mechanism of Rockburst Induced by Fault Activation

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Lyu Pengfei ◽  
Bao Xinyang ◽  
Lyu Gang ◽  
Chen Xuehua
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Coal Pillar ◽  
Fault Structure ◽  
Fault Activation ◽  
Fault Type ◽  
Stress Behavior ◽  
Mining Face ◽  
And Control ◽  
The Impact

To effectively monitor and control the severe mining-induced rockburst in deep fault area, the fault activation law and the mechanical essence of rockburst induced by crossing fault mining were studied through theoretical analysis, microseismic monitoring, field investigation, and other methods; numerical simulation was employed to verify the obtained fault activation law and the mechanical nature. First, the distribution of microseismic sources at different mining locations and the fault activation degree were analyzed. According to the microseismic frequency and the characteristics of the energy stage, the fault activation degree was divided into three stages: fault stress transfer, fault pillar stress behavior, and fault structure activation. It was determined that the impact disaster risk was the strongest in the stage of the fault pillar stress behavior. Based on the periodic appearance law of microseisms in fault area, three types of conceptual models of fault-type rockburst were proposed, and the rockburst carrier system model of “roof-coal seam-floor” in the fault area was established. The mechanical essence of fault-type rockburst was obtained as follows: under the action of fault structure, the static load of the fault coal pillar was increased and superimposed with the active dynamic load of the fault, leading to high-strength impact disaster. Finally, the prevention and treatment concepts of fault-type rockburst were proposed. The monitoring and prevention measures of fault-type rockburst were taken from two aspects: the monitoring and characterization of fault rockburst and weakening control of the high static load of the fault coal pillar and dynamic load of fault activation. The proposed concepts and technical measures have been verified in the working face 14310 of Dongtan Coal Mine with sound results. The research results have a guiding significance for the prevention and control of rockburst in a similar mining face under crossing fault mining.

Research of the Permafrost Dynamic Load Direct Shear Apparatus

2013 ◽  
Vol 405-408 ◽  
pp. 454-459
Author(s):  
Ying Hui Cui ◽  
Jian Kun Liu ◽  
Peng Lv
Keyword(s):  
Numerical Simulation ◽  
Power Systems ◽  
Engineering Design ◽  
Control Systems ◽  
Dynamic Load ◽  
Dynamic Parameters ◽  
Direct Shear ◽  
Direct Shear Apparatus ◽  
And Control ◽  
Measurement And Control

The dynamic parameters of the permafrost are very important for engineering design, also using in the numerical calculation. The dynamic parameters directly affect the correctness of engineering design and numerical simulation. Beijing Jiaotong University developed a novel dynamic load direct shear apparatus to measure these parameters. In the paper, it is analyzed Power systems, measurement and control systems of the dynamic load direct shear apparatus, and gave a verification experiment, the results show that dynamic load direct shear apparatus can complete its purpose.

scholarly journals Mechanism of Coal Burst and Prevention Practice in Deep Asymmetric Isolated Coal Pillar: A Case Study from YaoQiao Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Chengchun Xue ◽  
Anye Cao ◽  
Wenhao Guo ◽  
Songwei Wang ◽  
Yaoqi Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Prevention And Control ◽  
High Stress ◽  
Coal Pillar ◽  
Support Pressure ◽  
Mining District ◽  
Coal Pillars ◽  
And Control ◽  
The Impact

Coal pillar bursts continue to be a severe dynamic hazard. Understanding its mechanism is of paramount importance and crucial in preventing and controlling its occurrence. The extreme roadway deformations from the asymmetric isolated coal pillars in the central mining district of YaoQiao Coal Mine have responded with frequent intense tremors, with risky isolated coal pillar bursts. The theoretical analysis, numerical simulation, and field measurements were done to research the impact of spatial overburden structure and stress distribution characteristics on the isolated coal pillar area, aiming to reveal the mechanism of coal pillar burst leading to the practice of prevention and control in the asymmetric isolated coal pillar area. The study shows that the overburden structure of the asymmetric is an asymmetric “T” structure in the strike-profile, and the stress in the coal pillar is mostly asymmetric “saddle-shaped” distribution, with the peak stress in the east side of the coal pillar, and the coal pillar is a “high stress serrated isolated coal pillar.” Numerical simulation results showed that the support pressure in the isolated coal pillar area on the strike profile was asymmetrically “saddle-shaped” distribution. The peak vertical stress in the coal pillar area continued to rise and gradually shifted to the mining district's deep part. As a result, the response of the roadway sides to the dynamic load disturbance was more pronounced. They developed a coal burst prevention and control program of deep-hole blasting in the roof of asymmetrical isolated coal pillar roof and unloading pressure from coal seam borehole. Monitored data confirmed that the stress concentration was influential in the roadway’s surrounding rock in the asymmetric isolated coal pillar area, circumventing coal pillar burst accidents. The research outcomes reference the prevention and control of coal bursts at isolated working faces of coal pillars under similar conditions.

scholarly journals Coal Burst Induced by Horizontal Section Mining of a Steeply Inclined, Extra-Thick Coal Seam and Its Prevention: A Case Study from Yaojie No. 3 Coal Mine, China

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Zhengyi Wang ◽  
Linming Dou ◽  
Guifeng Wang
Keyword(s):  
Coal Mine ◽  
Dynamic Load ◽  
Abutment Pressure ◽  
Static Load ◽  
Horizontal Section ◽  
Static Loads ◽  
Thick Coal Seam ◽  
Working Face ◽  
Limiting Load ◽  
Coal Bursts

At present, coal bursts in working faces of steeply inclined coal seams (SICSs) have rarely been investigated, and current research focuses on the influences of roof breaking and instability of overlying structures in goaf on coal bursts; however, the stress state of coal masses in working faces being subjected to coal bursts is rarely researched. To overcome the above defects, a model for analysing stresses on coal masses in horizontal section of SICSs was established based on the coal burst that occurred in LW5521-20, Yaojie No. 3 Coal Mine, Lanzhou, Gansu Province, China. Moreover, the mechanism underpinning such a coal burst in SICSs was analysed based on the superposition mechanism of dynamic and static loads. The results show that the side abutment pressure near the roof and floor under the horizontal sections of SICSs is asymmetrically distributed in the vertical direction in which the peak of side abutment pressure near the roof is closer to the working face and therefore is taken as the source of static loads for coal bursts in working faces. When the superimposed dynamic load caused by hanging roof breaking and high static load borne in the coal masses is larger than the critical load for coal burst inception, a coal burst will occur. Furthermore, the superimposed dynamic load induced by coal bursts on the support and the initial static load on the supports are larger than their limiting load, which leads to support collapse and eventually causes dynamic failure of the working face. The coal burst in working faces in horizontal sections of SICSs can be prevented by using deep-hole presplit blasting in a hard roof, destress blasting in coal masses, and support optimisation of working faces, showing a favourable preventative effect.

scholarly journals The Mechanical Criterion of Activation and Instability of Normal Fault Induced by the Movement of Key Stratum and Its Disaster-Causing Mechanism of Rockburst in the Hanging Wall Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Lyu Pengfei ◽  
Lu Jiabin ◽  
Wang Eryu ◽  
Chen Xuehua
Keyword(s):  
Coal Mine ◽  
Static Load ◽  
Hanging Wall ◽  
Coal Pillar ◽  
Normal Fault ◽  
Fault Slip ◽  
Fault Activation ◽  
Key Stratum ◽  
Two Factors ◽  
And Control

Coal mine rockburst is closely related to the complex geological structure. Understanding the criterion of the fault activation instability and the disaster-causing mechanism of rockburst under the influence of mining is the theoretical premise and important guarantee of safe and efficient coal mining. In this paper, based on the theory of key stratum, the mechanical model of fault slip instability in the normal fault during the hanging wall mining was established, and the instability criterion was derived. It is concluded that the fault slip instability of the hanging wall is mainly controlled by two factors: (1) the distance between coal seams and key stratum and (2) the distance between working face and fault. Moreover, these two factors have an inverse relation to the occurrence of rockburst. Subsequently, three conceptual models of rockburst induced by the fault stress transfer, stress concentration of coal pillars, and fault structural instability were proposed. Based on the rock mechanics theory, the rockburst carrier system model of “roof-coal seam-floor” near the fault was established. The mechanical essence of fault rockburst was obtained as follows: under the action of fault, the static load of fault coal pillar was increased and superimposed with the fault activation dynamic load, leading to high-strength rockburst disaster. Based on the occurrence mechanism of fault rockburst, the monitoring and prevention concept and technical measures were proposed in three aspects, including the monitoring and control of fault activation dynamic loads, the monitoring of high static load in fault coal pillar and stress release, and the strengthening roadway support. These prevention and control measures were verified in the panel 103down02 of the Baodian Coal Mine in engineering, and the effectiveness of these measures was proved.

Numerical Simulation of Rock Bolt Deformation under Dynamic Load

2013 ◽  
Vol 441 ◽  
pp. 443-447
Author(s):  
Zhong Wei Li
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Dynamic Load ◽  
Static Load ◽  
Local Effect ◽  
Simulation Software ◽  
Rock Bolt

This paper used LS-DYNA simulation software to simulate rock bolt breaking position, displacements at different locations and the plastic deformation under dynamic load. Major drew the following conclusions: plastic deformation of the bolt away from breaks 600mm is only 1/20 compared with breaks; deformation of the rock bolt increased as the distance away from dynamic load applied position reduced, rock bolt deformation under dynamic load has a local effect; rock bolt deformation under dynamic load and rock bolt deformation under static load had essentially different.

Validation of SST 300 bearing casing for SST 200 bearing casing in static load condition

2011 ◽  
Vol 3 (7) ◽  
pp. 277-278
Author(s):  
Jinesh Shah ◽  
◽  
Mohammad Azim Aijaz ◽  
Pratik Kikani ◽  
Sagarkumar Shah ◽  
...  
Keyword(s):  
Static Load ◽  
Load Condition

Dynamic Load-balancing and Control for Server-Side Rendering on Ajax-GIS

2013 ◽  
Vol 133 (4) ◽  
pp. 891-898
Author(s):  
Takeo Sakairi ◽  
Masashi Watanabe ◽  
Katsuyuki Kamei ◽  
Takashi Tamada ◽  
Yukio Goto ◽  
...  
Keyword(s):  
Load Balancing ◽  
Dynamic Load ◽  
Dynamic Load Balancing ◽  
Server Side ◽  
And Control

Effect Analysis of Nitrogen Injection on the Variation of “Oxidation Zone” in Coal Mine Gob Based on Numerical Simulation

2016 ◽  
Vol 9 (1) ◽  
pp. 47-54
Author(s):  
Jing Shen ◽  
Mingran Chang
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Effect Analysis ◽  
Mine Fire ◽  
Nitrogen Injection ◽  
The Difference ◽  
Residual Coal

One of the main reasons for coal mine fire is spontaneous combustion of residual coal in gob. As the difference of compaction degree of coal and rock, the underground gob can be considered as a porous medium and divided into “three zones” in accordance with the criteria. The “three zones” are “heat dissipation zone”, “oxidation zone” and “choking zone”, respectively. Temperature programming experiments are taken and numerical simulation with obtained experimental data is utilized to analyze the distribution of “three zones” in this paper. Different width and depth of “oxidation zone” are obtained when the inlet air velocity is changed. As the nitrogen injection has inhibition effect on spontaneous combustion of residual coal in gob, nitrogen is injected into the gob. The widths of “oxidation zone” are compared before and after nitrogen injection. And ultimately the optimum location and volume of nitrogen injection are found out.

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