scholarly journals Numerical Study on the Impact Instability Characteristics Induced by Mine Earthquake and the Support Scheme of Roadway

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Guang-jian Liu ◽  
Shan-lin Li ◽  
Zong-long Mu ◽  
Wen Chen ◽  
Lei-bo Song ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Mine ◽  
Numerical Study ◽  
Steel Strip ◽  
Near Field ◽  
Element Model ◽  
Static Stress ◽  
Impact Failure ◽  
Coal Rock ◽  
The Impact

Rockburst of deep roadway was induced by the superposition of mine earthquake disturbance and high static stress exceeding the limit strength of coal-rock mass. To study the roadway impact instability characteristics caused by mine earthquake disturbance and to propose an optimized support scheme, the discrete element model of the roadway structure was established based on the 1305 working face of the Zhaolou Coal Mine. The influence of mine earthquake amplitude and hypocenter location on the roadway was analyzed. The mesocrack evolution characteristics of the roadway were simulated and reproduced. Characteristics of stress field, crack field, displacement field, and energy field of the disturbed roadway with different support schemes were studied. The results showed that the greater the amplitude of the mine earthquake was, the severer the roadway impact failure was. The upper and left hypocenters had a significant influence on the roadway. The superposition of the high static stress and the dynamic stress due to the far-field mine earthquake resulted in the impact instability of coal-rock mass around the roadway, causing severe roof subsidence as well as rib and bottom heave. The evolution of tensile cracks caused the severe impact failure of roadway from a mesoscopic perspective. Using the flexible support to reinforce the roadway retarded the stress decline in roof and rib, improved the self-stability, reduced the number of near-field cracks, and decreased the displacement. Meanwhile, it allowed the roof and rib deformation, which was conducive to releasing elastic energy in surrounding rocks and reducing mine earthquake energy. The cracks and deformation in the floor were controlled by using the floor bolt. The optimal support scheme for a roadway to resist mine earthquake disturbance was proposed: “bolt-cable-mesh-steel strip-π-beam + floor bolt.” The research results have a specific guiding significance for the support of the coal mine roadway.

scholarly journals Numerical Study Of The Targeted Energy Transfer Between The Euler-Bernoulli Beam And A Nonlinear Energy Sink

2021 ◽  
Author(s):  
Mohi U. Rahamat Ullah
Keyword(s):  
Energy Transfer ◽  
Primary Structure ◽  
Numerical Study ◽  
Element Model ◽  
Impact Excitation ◽  
Nonlinear Stiffness ◽  
Targeted Energy Transfer ◽  
Stiffness Property ◽  
Energy Sink ◽  
The Impact

Targeted energy transfer (TET) refers to the spatial transfer of energy between a primary structure of interest and isolated oscillators called the energy sink (ES). In this work, the primary structure of interest is a slender beam modeled by the Euler-Bernoulli theory, and the ES is a single-degree-of-freedom oscillator with either linear or cubic nonlinear stiffness property. The objective of this study is to characterize the TET and the effectiveness of ES under impact and periodic excitations. By using the scientific computation package, MATLAB, numerical simulations are carried out based on excitations of various strength and locations. Both time and frequency domain characterizations are used. For the impact excitation, the ES with the cubic nonlinear stiffness property is more superior to the linear oscillator in that larger percentage of the impact energy can be dissipated there. The main energy transfer was found to be due to a 3- to-1 frequency coupling between the first bending mode and the ES. For the periodic excitation, however, both linear and nonlinear ES exhibit generally poorer performance than the case with the impact excitation. Future works should focus on the frequency-energy relationship of the periodic solution of the underlying Hamiltonian, as well as using finite element model to verify the simulation results.

Numerical Study on Influence of Joint Characters on Rock Mechanical Parameters

2011 ◽  
Vol 201-203 ◽  
pp. 2909-2912
Author(s):  
Yan Feng Feng ◽  
Tian Hong Yang ◽  
Hua Wei ◽  
Hua Guo Gao ◽  
Jiu Hong Wei
Keyword(s):  
Rock Mass ◽  
Compression Strength ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Deformation Modulus ◽  
Rock Joints ◽  
Structured Surfaces ◽  
Trace Length ◽  
The Impact

Rock mass is the syntheses composed of kinds of structure and structured surfaces. The joint characters is influencing and controlling the rock mass strength, deformation characteristics and rock mass engineering instability failure in a great degree. Through using the RFPA2D software, which is a kind of material failure process analysis numerical methods based on finite element stress analysis and statistical damage theory, the uniaxial compression tests on numerical model are carried, the impact of the trace length of rock joints and the fault throws on rock mechanics parameters are studied. The results showed that with the gradual increase of trace length,compression strength decreased gradually and its rate of variation getting smaller and smaller, the deformation modulus decreased but the rate of variation larger and larger; with the fault throws increasing, the compression strength first increases and then decreases, when the fault throw is equal to the trace length, the deformation modulus is the largest. When the joint trace length is less than the fault throw, the rate of the deformation modulus is greater than that of trace length, but the deformation modulus was not of regular change.

Numerical Study on Impact Response of Aircraft Sandwich Wing Made of Fiber-Metal Laminate Face-Sheets Subjected to Bird Strike

2012 ◽  
Vol 488-489 ◽  
pp. 8-13 ◽  
Author(s):  
S.M.R. Khalili ◽  
M. Assar ◽  
R. Eslami Farsani ◽  
I. Hajiyousefi
Keyword(s):  
Energy Absorption ◽  
Numerical Study ◽  
Metal Layer ◽  
Element Model ◽  
Fiber Types ◽  
Bird Strike ◽  
Impact Phenomena ◽  
Impact Responses ◽  
Fiber Metal ◽  
The Impact

Aircraft structures are frequently subjected to impacts from objects such as runway debris and birds. In new aircraft structural design, Fiber Metal Laminates (FMLs) play a significant role due to their excellent mechanical properties, particularly the impact properties. In this study, the aircraft sandwich wing with FML face-sheets are analyzed by finite element model for simulating the bird strike. The numerical simulations of bird strike impact are performed adopting a lagrangian approach to design the wing by MSC/PATRAN FE code. The numerical obtained results are compared with the results in the literature for validation of the model. The effect of fiber orientations, fiber types, metal types in FML face sheets in sandwich wing on impact responses are investigated. The impact responses are illustrated by displacement history, contact force history and energy absorption. According to these results, the sandwich panel with FML skin is suitable structure for energy absorption (that is the most important factor in impact phenomena). The lay-ups with titanium metal layer with aramid fibers are the best.

A numerical study of the influence of Z-pin parameters on the elastic properties of laminates

2020 ◽  
pp. 096739112097008
Author(s):  
Mengjia Li ◽  
Puhui Chen
Keyword(s):  
Elastic Properties ◽  
Composite Laminates ◽  
Numerical Study ◽  
Element Model ◽  
Fe Model ◽  
Insertion Angle ◽  
Benchmark Tests ◽  
Parametric Analyses ◽  
Longitudinal Modulus ◽  
The Impact

A finite element model with periodic boundary conditions was developed to investigate the influence of different Z-pin parameters including diameter, spacing, and insertion angle of Z-pin on the elastic properties of composite laminates. Benchmark tests were carried out to verify the FE model and a series of parametric analyses were subsequently performed. In general, all the elastic moduli, excluding the through-thickness modulus ( Ez), decreased while Ez increased nonlinearly with increasing Z-pin diameter and decreasing spacing. The reduction of Ey (transverse modulus) was approximately 40% of that of Ex (longitudinal modulus), while the reduction of Gxy is similar to that of Ex. Besides, Gxz and Gyz were reduced by approximately half of the reduction of Gxy. Although the impact of insertion angle was obvious on Ez, it was negligible on the other five moduli.

Stability Analysis about the Impact of Soft Rock to the Underground Cavern Group

2013 ◽  
Vol 706-708 ◽  
pp. 560-564
Author(s):  
Yi Huan Zhu ◽  
Guo Jian Shao ◽  
Zhi Gao Dong
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Stability Analysis ◽  
Soft Rock ◽  
Element Model ◽  
Underground Excavation ◽  
Power Station ◽  
Excavation Process ◽  
The Stability ◽  
The Impact

Soft rock is frequently encountered in underground excavation process. It is difficult to excavate and support in soft rock mass which has low strength, large deformation and needs much time to be out of shape but little time to be self-stabilized. Based on a large underground power station, finite element model analysis was carried out to simulate the excavation process and the results of displacement, stress and plasticity area were compared between supported and unsupported conditions to evaluate the stability of the rock mass.

scholarly journals Numerical Study on the Longitudinal Response Characteristics of Utility Tunnel under Strong Earthquake: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Guoyi Tang ◽  
Yumei Fang ◽  
Yi Zhong ◽  
Jie Yuan ◽  
Bin Ruan ◽  
...  
Keyword(s):  
Seismic Response ◽  
Strong Earthquake ◽  
Numerical Study ◽  
Soft Soil ◽  
Near Field ◽  
Element Model ◽  
Far Field ◽  
Response Characteristics ◽  
Longitudinal Response ◽  
Utility Tunnel

In this paper, the longitudinal seismic response characteristics of utility tunnel subjected to strong earthquake was investigated based on a practical utility tunnel project and numerical method. Firstly, the generalized response displacement method (GRDM) that was used to conduct this study was reviewed briefly. Secondly, the information of the referenced engineering and the finite element model was introduced in detail, where a novel method to model the joints between utility tunnel segments was presented. Thirdly, a series of seismic response of the utility tunnel were provided, including inner force and intersegment opening width. The results showed that (i) the seismic response of the utility tunnel under far-field earthquake may be remarkable and even higher than that under near-field earthquake; (ii) sharp variation of response may occur at the interface between “soft” soil and “hard” soil, and the variation under far-field earthquake could be much more significant. This research provides a reference for the scientific study and design of relevant engineering.

scholarly journals The influence of the fault zone width on land surface vibrations after the high-energy tremor in the “Rydułtowy-Anna” hard coal mine

2018 ◽  
Vol 36 ◽  
pp. 02007 ◽  
Author(s):  
Elżbieta Pilecka ◽  
Dariusz Szwarkowski
Keyword(s):  
Rock Mass ◽  
Fault Zone ◽  
Seismic Wave ◽  
Coal Mine ◽  
Land Surface ◽  
High Energy ◽  
Hard Coal ◽  
Surface Vibrations ◽  
The Impact ◽  
Damage Risk

In the article, a numerical analysis of the impact of the width of the fault zone on land surface tremors on the area of the “Rydułtowy – Anna” hard coal mine was performed. The analysis covered the dynamic impact of the actual seismic wave after the high-energy tremor of 7 June 2013. Vibrations on the land surface are a measure of the mining damage risk. It is particularly the horizontal components of land vibrations that are dangerous to buildings which is reflected in the Mining Scales of Intensity (GSI) of vibrations. The run of a seismic wave in the rock mass from the hypocenter to the area’s surface depends on the lithology of the area and the presence of fault zones. The rock mass network cut by faults of various widths influences the amplitude of tremor reaching the area’s surface. The analysis of the impact of the width of the fault zone was done for three alternatives.

scholarly journals Atmosphere and Ocean Modeling on Grids of Variable Resolution—A 2D Case Study

2014 ◽  
Vol 142 (5) ◽  
pp. 1997-2017 ◽  
Author(s):  
Peter D. Düben ◽  
Peter Korn
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Study ◽  
Element Model ◽  
Ocean Modeling ◽  
Local Error ◽  
Grid Refinement ◽  
Variable Resolution ◽  
Geostrophic Balance ◽  
The Impact

Abstract Grids of variable resolution are of great interest in atmosphere and ocean modeling as they offer a route to higher local resolution and improved solutions. On the other hand there are changes in grid resolution considered to be problematic because of the errors they create between coarse and fine parts of a grid due to reflection and scattering of waves. On complex multidimensional domains these errors resist theoretical investigation and demand numerical experiments. With a low-order hybrid continuous/discontinuous finite-element model of the inviscid and viscous shallow-water equations a numerical study is carried out that investigates the influence of grid refinement on critical features such as wave propagation, turbulent cascades, and the representation of geostrophic balance. The refinement technique the authors use is static h refinement, where additional grid cells are inserted in regions of interest known a priori. The numerical tests include planar and spherical geometry as well as flows with boundaries and are chosen to address the impact of abrupt changes in resolution or the influence of the shape of the transition zone. For the specific finite-element model under investigation, the simulations suggest that grid refinement does not deteriorate geostrophic balance and turbulent cascades and the shape of mesh transition zones appears to be less important than expected. However, the results show that the static local refinement is able to reduce the local error, but not necessarily the global error and convergence properties with resolution are changed. The relatively simple tests already illustrate that grid refinement has to go along with a simultaneous change of the parameterization schemes.

scholarly journals Geotechnical Study of The Impact of Groundwater Level For Slope Stability in Coal Mine

2019 ◽  
Vol 1 (1) ◽  
pp. 12-21
Author(s):  
Jioni Santo Frans ◽  
Muhammad Hafizh Nurfalaq
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
Safety Factor ◽  
Coal Mine ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Angle ◽  
Primary Data ◽  
The Impact

Rock mass has force equilibrium which can be disturbed due to changes in rock mass conditions, both by naturally as well as human activities. In response, rock masses could have instability to reach new equilibrium and trigger landslides. Unstable slopes will affect the safety, economic and social factors. Groundwater has its own problems in mining management. Pore water pressure can cause uplift force and reduce the strength of the rock mass forming slopes and affect the slope stability. The study area has groundwater level relatively close to surface and causes the slope to be in nearly saturated condition. This research aims to study of the effect of groundwater levels on the stability of coal mine slopes in the study area. The research method includes collecting primary data through field observations to collect related technical data and secondary data collection through literature studies. Slope stability analysis was carried out to obtain recommendations with a minimum Safety Factor of 1.30. The results showed the ground water level has an inverse relationship to Safety Factor value. The recommendation is  depressurisation using drain holes. The target of groundwater level reduction in the mine wall is RL+40 in the sidewall area and RL+65 in the highwall area. Another alternative is is by resloping the overall slope angle of the mine wall in the study area. The mine slope is recommended for layback with an overall slope angle of around 24 °.

scholarly journals Numerical Study Of The Targeted Energy Transfer Between The Euler-Bernoulli Beam And A Nonlinear Energy Sink

2021 ◽  
Author(s):  
Mohi U. Rahamat Ullah
Keyword(s):  
Energy Transfer ◽  
Primary Structure ◽  
Numerical Study ◽  
Element Model ◽  
Impact Excitation ◽  
Nonlinear Stiffness ◽  
Targeted Energy Transfer ◽  
Stiffness Property ◽  
Energy Sink ◽  
The Impact

Targeted energy transfer (TET) refers to the spatial transfer of energy between a primary structure of interest and isolated oscillators called the energy sink (ES). In this work, the primary structure of interest is a slender beam modeled by the Euler-Bernoulli theory, and the ES is a single-degree-of-freedom oscillator with either linear or cubic nonlinear stiffness property. The objective of this study is to characterize the TET and the effectiveness of ES under impact and periodic excitations. By using the scientific computation package, MATLAB, numerical simulations are carried out based on excitations of various strength and locations. Both time and frequency domain characterizations are used. For the impact excitation, the ES with the cubic nonlinear stiffness property is more superior to the linear oscillator in that larger percentage of the impact energy can be dissipated there. The main energy transfer was found to be due to a 3- to-1 frequency coupling between the first bending mode and the ES. For the periodic excitation, however, both linear and nonlinear ES exhibit generally poorer performance than the case with the impact excitation. Future works should focus on the frequency-energy relationship of the periodic solution of the underlying Hamiltonian, as well as using finite element model to verify the simulation results.

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