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 Experimental Accuracy and Stability of Gas Outburst Experimental System

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yanbao Liu ◽  
Haitao Sun ◽  
Bo Wang ◽  
Linchao Dai ◽  
Jie Cao
Keyword(s):  
Simulation Experiment ◽  
Physical Simulation ◽  
Testing Machine ◽  
Test System ◽  
Experimental Simulation ◽  
Design Parameters ◽  
Test Machine ◽  
Gas Outburst ◽  
Similar Materials ◽  
Simulation Results

Gas outburst is an important issue in deep coal mining. At present, the gas-rock coupling change mechanism and intensity prediction of gas outburst are not clear. The research of gas outburst simulation experiment is particularly important. The State Key Laboratory of Gas Disaster Monitoring and Emergency Technology of China independently developed a large-scale coal and gas outburst physical simulation test system. However, the influence of the design parameters of the testing machine on the stability and accuracy of the simulation experiment is unclear. The article analyzes the energy conversion in the process of gas outburst through experimental simulation phenomena and results. The experimental simulation results show that the energy released by the CO2 gas in similar materials is the most important energy source. The cracks of similar materials increase the nominal volume of similar materials, and the deformation energy stored in similar materials slightly increases. The experimental simulation results are consistent with the actual situation on site. Combined with CAE simulation analysis, the displacement and pressure of the indenter of the experimental machine remained basically unchanged during the experiment, and the system did not produce resonance. Comprehensive analysis shows that the design of the test machine meets the simulation requirements.

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 Two-Dimensional Numerical Modeling of Flow in Physical Models of Rock Vane and Bendway Weir Configurations

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 458
Author(s):  
Drew C. Baird ◽  
Benjamin Abban ◽  
S. Michael Scurlock ◽  
Steven B. Abt ◽  
Christopher I. Thornton
Keyword(s):  
Numerical Modeling ◽  
Physical Model ◽  
Numerical Models ◽  
Hydraulic Performance ◽  
Physical Models ◽  
Protection Measures ◽  
Design Engineers ◽  
Model Study ◽  
Study Results ◽  
Wide Range

While there are a wide range of design recommendations for using rock vanes and bendway weirs as streambank protection measures, no comprehensive, standard approach is currently available for design engineers to evaluate their hydraulic performance before construction. This study investigates using 2D numerical modeling as an option for predicting the hydraulic performance of rock vane and bendway weir structure designs for streambank protection. We used the Sedimentation and River Hydraulics (SRH)-2D depth-averaged numerical model to simulate flows around rock vane and bendway weir installations that were previously examined as part of a physical model study and that had water surface elevation and velocity observations. Overall, SRH-2D predicted the same general flow patterns as the physical model, but over- and underpredicted the flow velocity in some areas. These over- and underpredictions could be primarily attributed to the assumption of negligible vertical velocities. Nonetheless, the point differences between the predicted and observed velocities generally ranged from 15 to 25%, with some exceptions. The results showed that 2D numerical models could provide adequate insight into the hydraulic performance of rock vanes and bendway weirs. Accordingly, design guidance and implications of the study results are presented for design engineers.

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.

The Proposal of Wall Thickness Management Criteria of T-Pipes

2012 ◽  
Author(s):  
Kiyoharu Tsunokawa ◽  
Taku Ohira ◽  
Naoki Miura ◽  
Yasumi Kitajima ◽  
Daisuke Yoshimura
Keyword(s):  
Numerical Simulation ◽  
Wall Thickness ◽  
Parametric Study ◽  
The Other ◽  
Wall Thinning ◽  
Study Results ◽  
Simulation Results ◽  
Design Construction

Although the reinforcement for openings is checked in accordance with design / construction standard when thinning was observed in T-pipes, this evaluation becomes too conservative or requires much time and effort. This paper describes additional parametric study results and proposes a guideline for thickness management of wall thinning T-pipes. On the other papers related to this project, the experiment and numerical simulation results are reported. This paper referred these results and performed further investigation.

Computational Fluid Dynamics Analysis of Two Parallel Rectangular Jets Using OpenFOAM

2016 ◽  
Author(s):  
Han Li ◽  
Huhu Wang ◽  
Yassin A. Hassan ◽  
N. K. Anand
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Stokes Equations ◽  
Laser Doppler Anemometry ◽  
Physical Models ◽  
Shear Stresses ◽  
Turbulence Characteristic ◽  
Computational Fluid Dynamics Analysis ◽  
Simulation Results

Two or multiple parallel jets are an important shear flow that widely existing in many industrial applications. The interaction between turbulence jets enables fast and thorough mixing of two fluids. The mixing feature of parallel jets has many engineering applications, such as, in Generation IV conceptual nuclear reactors, the coolants merge in upper or lower plenum after passing through the reactor core. While study of parallel jets mixing phenomenon, numerical experiments such as Computational Fluid Dynamics (CFD) simulations are extensively incorporated. Validation of varied turbulent models is of importance to make sure that the numerical results could be trusted and served as a guideline further design purpose. Many commercial CFD packages in the market such as FLUENT and Star CCM+ can provide the ability to simulate turbulent flow with predefined turbulence model, however, such commercial solvers may lack the flexibility that allow users build their own models for R&D purpose. The existing solvers in OpenFOAM are developed to fulfill both academic and industrial needs by achieving large-scale computational capability with a variety of physical models. Moreover, as an open source CFD toolbox, OpenFOAM grants users full control of the source code with complete freedom of customization. The purpose of this study is to perform CFD simulation using OpenFOAM for two submerged parallel jets issuing from two rectangular channels. Fully hexahedron multi-density mesh is generated using blockMesh utility to ensure velocity gradients are properly evaluated. A generalized-multi-grid solver is used to enhance convergence. Based on Reynolds-Averaged Navier-Stokes Equations (RANS), the realizable k-ε and k-ε shear stress transport (SST) are selected to model turbulent flow. Steady state Finite Volume solver simpleFoam is used to perform the simulation. In addition, data from experiments run in Thermal-Hydraulic Lab at Texas A&M University using particle image velocity (PIV) and Laser Doppler Anemometry (LDA) methods are considered in order to compare and validate simulation results. A number of turbulence characteristic such as mean velocities, turbulent intensities, z-component vorticity were compared with experiments. It was found that for stream-wise mean velocity profile as well as shear stresses, the realizable k-ε model exhibits a good agreement with experimental data. However, velocity fluctuation and turbulence intensities, simulation results showed a certain discrepancy.

Influence of Oriented Perforation Design on Refracture Reorientation: Simulation and Experiment

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Minhui Qi ◽  
Mingzhong Li ◽  
Tiankui Guo ◽  
Chunting Liu ◽  
Song Gao ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Large Scale ◽  
Simulation Models ◽  
Fracture Initiation ◽  
Simulation Method ◽  
Induced Stress ◽  
Study Results ◽  
Simulation Results ◽  
Fracturing Experiments ◽  
The Impact

The oriented perforating is the essential technique to guide the refracture reorientation, but the influence of the oriented perforation design on the refracture steering radius is still unclear. In this paper, the factors influencing the refracture reorientation were studied by simulation models and experiments. The effects of initial fracture, well production, and perforations on the refracture initiation and propagation were analyzed. Three-dimensional finite element models were conducted to quantify the impact of perforation depth, density, and azimuth on the refracture. The large-scale three-axis hydraulic fracturing experiments guided by oriented perforations were also carried out to verify the fracture initiation position and propagation pattern of the simulation results. The research results showed that perforations change the near-wellbore induced stress distribution, thus changing the steering radius of the refracture. According to the simulation results, the oriented perforation design has a significant influence on the perforation guidance effect and refracture characteristics. Five hydraulic fracturing experiments proved the influence of perforating parameters on fracture initiation and morphology, which have a right consistency between the simulation results. This paper presents a numerical simulation method for evaluating the influence of the refracture reorientation characteristics under the consideration of multiple prerefracturing induced-stress and put forward the oriented perforation field design suggestions according to the study results.

Harmonic Effects Analysis of Electronic Loads Controller Controller On Self Excited Induction Generator (SEIG) Operations

2017 ◽  
Vol 8 (2) ◽  
pp. 273
Author(s):  
Refdinal Nazir ◽  
Andi Pawawoi ◽  
Riska Amalia
Keyword(s):  
Laboratory Testing ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Induction Generator ◽  
Generator System ◽  
Load Current ◽  
Harmonic Currents ◽  
Study Results ◽  
Simulation Results ◽  
Order Components

<p>The aplication of Electonic Load Controller (ELC) on Self-Excited Induction Generator (SEIG) driven by renewable energy sources creates harmonic issues. This paper has analyzed the propagation of the harmonic current generated by the ELC in the generator system. Mathematical modeling and computer simulation is used to analyze the propagation of harmonic currents generated by ELC on the generator system. Laboratory testing has also been conducted to justify the simulation results. The study results showed that the propagation harmonic currents created by ELC on the stator widings of SEIG and main load side are rejected for high order components, and attenuated for lower order components. Consequently, the THD<sub>I</sub> of stator and main load current will be reduced significantly<em>.</em></p>

scholarly journals Study on heat transfer performance of geothermal pile-foundation heat exchanger in GSHP system

2019 ◽  
Vol 111 ◽  
pp. 06068
Author(s):  
Hezhi Zhang ◽  
Bo Xu ◽  
Zhenqian Chen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pile Foundation ◽  
Heat Transfer Performance ◽  
Physical Models ◽  
Transfer Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Cooling Period ◽  
Study Results

In order to study the heat transfer performance of geothermal pile-foundation heat exchanger in ground source heat pump system (GSHP), the physical models of pile-foundation heat exchanger and heat exchanger group were established. The heat transfer processes of pile-foundation heat exchanger and heat transfer performance was analyzed both in cooling and heating mode. To carry out the simulation of heat transfer process for 3×3 energy piles, an office building located in Nanjing was introduced. The all-year dynamic building load was calculated with DeST, including the cooling period from June to September, the heating period from December to March and two recovery periods. After ten year’s running, the average soil temperature increases in non-equilibrium condition. Study results are approximate to the actual situation and can be used as theoretical basis for the design and application of pile-foundation heat exchanger in GSHP system.

Numerical Simulation and Experimental Study of Jet Distance in Abrasive Waterjet Polishing

2012 ◽  
Vol 472-475 ◽  
pp. 2037-2042 ◽  
Author(s):  
Jia Qiang Peng ◽  
Dan Lu Song ◽  
Liang Chao Li
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Theoretical Basis ◽  
Process Research ◽  
Physical Models ◽  
Abrasive Waterjet ◽  
Workpiece Surface ◽  
Cutting Machine ◽  
Simplec Algorithm ◽  
Simulation Results

In this paper, it introduces the work principle of abrasive waterjet polishing (AWJP) and analyzes the jet distance to the influence of the AWJP under a certain pressure, with a numerical simulation and analysis to the jet distance based on jet mechanics and fluid dynamics. By establishing the physical models of the different jet distance of the AWJP and adopting the Realizable k-ε model and the SIMPLEC algorithm, it gains the jet flow field of the AWJP with different jet distance models and the distribution of turbulence intensity and pressure and velocity on the workpiece surface. The numerical simulation results of the different jet distance were analyzed and compared, according to the AWJP to the characteristic requirement of the jet. By doing the polishing experiment with a abrasive waterjet cutting machine, it verifies that the best polishing distance range of AWJP is from 10 times to 13 times of the nozzle diameter, which provides the theoretical basis for the process research of the AWPJ in the future.

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