scholarly journals Numerical Simulation of Mechanical Characteristics of Roadway Surrounding Rock under Dynamic and Static Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Ce Jia ◽  
Sheng Li ◽  
Chaojun Fan ◽  
Jinbao Tang
Keyword(s):  
Plastic Zone ◽  
Stress Wave ◽  
Static Loading ◽  
Mechanical Characteristics ◽  
Surrounding Rock ◽  
Wave Disturbances ◽  
Cubic Polynomial ◽  
Simulated Condition ◽  
Distribution Of Stress ◽  
The Impact

Mechanical characteristics of roadway surrounding rock under different stress wave disturbances are the key to design roadway supporting scheme. In this study, the 2802 transportation roadway in Zhangcun Coal Mine is selected as the engineering background. The distribution of stress, displacement, and plastic zone in surrounding rock under the impact of different stress waves is studied. Results show that the stress and displacement of the roof, floor, and coal walls present fluctuating change with time during the stress wave loading process. With the increase of disturbing intensity of stress wave, the resistance ability for stress wave disturbance of the roof is lower than that of the floor, while the resistance ability of two sides is the same. The volume of plastic zone in roadway surrounding rock was calculated by the self-compiled FISH code. The relationship between the plastic zone volume and the stress wave disturbing intensity in different states is explored. The cubic polynomial relationship between the volume and the disturbing intensity in the state of shear_past and tension_past is obtained. Under the simulated condition, the disturbing intensity of stress wave has the greatest influence on the increase of shear_past volume when it equals 11 MPa. While the disturbing intensity of stress wave has the greatest influence on the increase of tension_past volume, it equals 7 MPa. Meanwhile, the relation between stress wave disturbing intensity and surrounding rock stress and displacement is obtained respectively. The achievements provide a theoretical base for roadway surrounding rock support under dynamic and static loading.

scholarly journals Failure behavior of the surrounding rock of jointed rock masses in a gold mine under impact disturbance

2021 ◽  
Author(s):  
Peng Li ◽  
Yunquan Wu ◽  
Meifeng Cai
Keyword(s):  
Stress Wave ◽  
Shear Failure ◽  
Jointed Rock ◽  
Surrounding Rock ◽  
Tensile Failure ◽  
Tensile Shear ◽  
Underground Engineering ◽  
Impact Stress ◽  
The Stability ◽  
The Impact

Abstract The impact disturbance has an important influence on the safety of underground engineering openings. In this paper, based on the in-situ stress measurement and structural plane investigation, the model of jointed rock roadway was established using the discrete element method (3DEC) to study the instability and failure characteristic of roadway surrounding rock with dominant joint planes under impact disturbance and to further analyze the influence of different buried depths, impact stress wave peaks, and stress wave delays on the stability of the surrounding rock. The results show that the stability of the surrounding rock is poor, and the whole convergence deformation of the surrounding rock occurs under the impact stress wave. There are three failure modes in the surrounding rock: tensile-shear failure, tensile failure, and shear failure. Tensile-shear failure mainly occurs in a small range close to the roof and floor of the roadway and the free surfaces of the two sides, and tensile failure occurs locally, while shear failure mainly occurs along the joint plane outside this range. Moreover, the greater the buried depth and stress wave peak value, the more serious the deformation of the surrounding rock. With the increase of stress wave delay, the deformation of the surrounding rock shows complex characteristics. In addition, the impact failure mechanism of the surrounding rock in jointed rock masses was discussed. The research results have important guiding significance for the prevention and control of underground engineering cavern disasters.

scholarly journals Damage Evolution and Circumferential Strain Distribution Characteristics of the Bolt-Supported Cavern under Multiple Explosion Sources

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Taotao Wang ◽  
Ansheng Cao ◽  
Weiliang Gao ◽  
Guangyong Wang ◽  
Xiaowang Sun
Keyword(s):  
Tensile Stress ◽  
Stress Wave ◽  
Strain Distribution ◽  
Damage Evolution ◽  
Circumferential Strain ◽  
Circumferential Stress ◽  
Surrounding Rock ◽  
Distribution Characteristics ◽  
Finite Element Software ◽  
The Impact

The impact of multiple explosion sources on the safety of the underground cavern is enormous. Based on a similarity model test, the finite element software LS-DYNA3D was utilized to analyze the damage evolution and circumferential strain distribution characteristics of the bolt-supported cavern under the seven combinations of concentrated charge explosion sources in three places, including the side of the vault, side arch, and sidewall. The accuracy of the simulation results is verified by comparing them with test results. The research results indicate that the damage of the surrounding rock is mainly caused by the tensile stress wave reflected from the free surfaces and the superposition of the tensile stress wave. The damage of the surrounding rock in the cases of multiple explosion sources is not a simple superposition of that in the cases of a single explosion source. The peak circumferential stress and damage of the surrounding rock in the middle of two explosion sources are significantly greater than that of the cases of the corresponding single explosion source. In the seven cases, the peak circumferential strain of the cavern wall changes from tensile to compressive from the vault to the spandrel. When the explosion occurs on the sidewall, the peak circumferential strain of the floor is tensile.

The Comparative Study on the Impact of Tunnel Excavation with Footage Different CRD to Testability of Surrounding Rock

2011 ◽  
Vol 243-249 ◽  
pp. 3417-3422
Author(s):  
Lin Po Shi ◽  
Bin Song Jiang ◽  
Yao Qiang Zhao
Keyword(s):  
Plastic Zone ◽  
Formation Control ◽  
Plastic Zone Size ◽  
Surrounding Rock ◽  
Zone Size ◽  
Control Effect ◽  
Tunnel Excavation ◽  
Rock Stability ◽  
The Comparative Study ◽  
The Impact

This article used Geotechnical Engineering General Software FLAC3D to simulate the tunnel CRD method under 1.5m, 2.0m, 2.5 m, 3.0 m footage separately and analysis the influence to the tunnel surrounding rock stability in the different footage construction. This paper selected a real tunnel project as the research object and analysis comparatively the rule and characteristic of various methods of tunnel surrounding rock displacement, stress distribution and the plastic zone size through simulated computing the different footage construction. The results show that,Ⅰ.Considered from the surrounding rock stress control that the 1.5m footage adjacent formation stress adjustment effect is best, next is 2.0m, 2.5 m, 3.0 m;Ⅱ.Considered from the plastic zone size that the 1.5m footage control effect is best, next is in turn 2.0m, 2.5 m, 3.0 m;ⅢConsidered from the surrounding rock displacement control that 1.5 meter footage adjacent formation control effect is best, but 2.0 meter, 2.5 meters and 3.0 meter phase differences are not big.

Study on the Impact of Stability around Tunnel Surrounding Rock in Construction Program

2012 ◽  
Vol 170-173 ◽  
pp. 1520-1523
Author(s):  
Sheng Ji Jin ◽  
Zhe Shu ◽  
Da Sheng Zhang ◽  
Zi Xin Liu
Keyword(s):  
Plastic Zone ◽  
Group Process ◽  
Surrounding Rock ◽  
The Body ◽  
Tunnel Effect ◽  
Tunnel Construction ◽  
Tunnel Excavation ◽  
The Stability ◽  
Rock Tunnel ◽  
The Impact

In order to analyze the different construction program under the tunnel surrounding rock stress, strain and plastic zone changes, we take water tunnel group of nuclear power plant as basic project and the application of software FLACIS3D numerical simulation.The results show that: During the tunnel excavation and support group process, the different rock tunnel construction program can produce different stress, displacement and plastic zone extended range of distribution and other aspects.To interval-type excavation program,although previously disturbing effect of the excavation of the tunnel construction and tunnel excavation of rock, it can generate less impact on the stability of surrounding rock. For the latter excavation of the tunnel, the tunnel project area affected by the first digging,the stress can be released, the stability of the first excavation of the tunnel effect is also small.Comparing to sequential and parallel program-type excavation program, the use of interval-style group of rock tunnel excavation will help stabilize the body.

scholarly journals Evaluando el rendimiento en la tabla de golpeo del makiwara

2012 ◽  
Vol 5 (2) ◽  
pp. 111
Author(s):  
Paul K. Smith ◽  
Timothy Niiler ◽  
Peter W. McCullough
Keyword(s):  
Static Loading ◽  
Mechanical Characteristics ◽  
Initial Step ◽  
Impact Characteristics ◽  
The Impact ◽  
Different Levels

No studies quantifying the impact characteristics of makiwara boards are available in the published literature. Logically, an initial step in determining the validity of the makiwara to develop karate technique would be to assess the mechanical characteristics of various types of makiwara board designs. It was, therefore, the purpose of this study to determine the stiffness of selected tapered board and stacked board makiwara training devices using static loading techniques to assess their suitability for practitioners of different levels. When our results are viewed in terms of progression of training, it would appear that a novice would be more suited to the more compliant ash stacked design and the expert more suited to the stiffer oak tapered design.

scholarly journals Research and Analysis on the Supporting Structure of the Second Lining of the Tunnel in the Phyllite Stratum

2020 ◽  
Vol 198 ◽  
pp. 02014
Author(s):  
Wei Zhiquan ◽  
Huang Baisheng ◽  
Yang Lu ◽  
Wei Yonghao ◽  
Qiu Jianqiao
Keyword(s):  
Plastic Zone ◽  
Surrounding Rock ◽  
Supporting Structure ◽  
Geological Conditions ◽  
Lining Structure ◽  
Calculation Results ◽  
Main Period ◽  
Secondary Lining ◽  
The Stability ◽  
The Impact

The reasonable construction of the secondary lining structure of the tunnel is an important link to ensure the stability of the surrounding rock of the tunnel. Taking a phyllite stratum tunnel project in Jiangxi as the background, the Flac3D finite difference software was used to numerically simulate and analyze the supporting structure of the secondary lining. The impact of support timing on surrounding rock stress. The calculation results show that with the progress of the construction step, the main period of the displacement of the vault is after the excavation of the upper section of the tunnel before the upper section support; The plastic zone of the surrounding rock changes obviously, especially above the tunnel, and finally the plastic zone develops to the ground; the stress of the surrounding rock shows a decreasing trend with the increase of the time of the secondary lining. The research results can provide certain guiding significance for the construction of the second lining of the tunnel under similar geological conditions.

scholarly journals Dynamic Response Mechanism of Impact Instability Induced by Dynamic Load Disturbance to Surrounding Rock in High Static Loading Roadway

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 971
Author(s):  
Jiazhuo Li ◽  
Penghui Guo ◽  
Heng Cui ◽  
Shikang Song ◽  
Wentao Zhao ◽  
...  
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Rock Burst ◽  
Dynamic Load ◽  
Static Loading ◽  
Energy Criterion ◽  
Mining Area ◽  
Surrounding Rock ◽  
Load Disturbance ◽  
Distortion Energy

Deep high static loading roadway is extremely prone to rock burst under dynamic load disturbance. The “force-energy criterion” for the failure of surrounding rock in such deep roadways and the “energy criterion” for the rock burst was established by considering the stress and energy evolution characteristics of rock burst under this circumstance. Under the engineering background of the main roadway in No.1 mining area of Gaojiapu Coal Mine in Binchang Mining Area, Shaanxi Province, China, the partial stress field and distortion energy field of surrounding rock in the main roadway and the spatial-temporal evolution laws under dynamic load disturbance were simulated and analyzed by using a built-in dynamic module of FLAC3D. Results show that after the dynamic load disturbance, the partial stress and distortion energy are concentrated in the shallow part at two walls of the roadway in the early phase. With the continuous propagation of dynamic load stress wave, the partial stress and distortion energy are transferred to the deep part. The sudden high-energy release occurred in the peak zone of partial stress, leading to the plastic failure of coal and rock mass. Subsequently, the distortion energy was fully accumulated in the original plastic zone and transferred from shallow surrounding rocks to the deep surrounding rocks in the roadway, where the partial stress and distortion energy of coal and rock mass reached the yield conditions. Thus, the original plastic zone was sharply expanded, thereby forming a new plastic zone. The coal and rock mass experienced an approximately static failure when no residual energy (ΔU) was found in it. When ΔU > 0, the rock mass experienced dynamic failure, and ΔU was mainly the volume transformation energy, which is approximately one-half of the total elastic strain energy. ΔU was transformed into the initial kinetic energy of broken coal and rock mass. Thus, the coal and rock mass are burst out. In severe cases, this condition was manifested by the rock burst in the main roadway. An optimization scheme of prevention and control measures for rock burst was proposed on the basis of the above conclusions. The microseismic activity laws before and after the unloading were compared, and a good effect was achieved. The research results can lay a theoretical foundation for predicting and preventing rock bursts in coal mines by actively regulating the disaster-pregnant environment and mitigating the disaster-inducing conditions.

Trajectory and Crystallography of Crack Growth in Austenitic Steel after LCF Tests

2013 ◽  
Vol 592-593 ◽  
pp. 793-796 ◽  
Author(s):  
Tamaz Eterashvili ◽  
Temur Dzigrashvili ◽  
Manana Vardosanidze
Keyword(s):  
Plastic Zone ◽  
Austenitic Steel ◽  
Low Cycle Fatigue ◽  
Propagation Direction ◽  
Cycle Fatigue ◽  
Slip Bands ◽  
Structure Changes ◽  
Microcrack Propagation ◽  
Distribution Of Stress ◽  
The Impact

Analysis of microcrack and mesocrack formation in austenitic steel thin filmsprepared after low-cycle fatigue (LCF) testsfrom bulk samples is presented using TEM techniques. Location, orientation and interaction of microcracks with microstructure components of the steel were determined. Plastic zone ahead of mesocrack tip and the structure changes in it were analyzed. Crystallography of slip bands and deformation twins and their relation with the microcrack propagation direction were also determined. The impact of grain anisotropy and inhomogeneous distribution of stress relaxation ahead of mesocrack tip in plastic zone were considered. Influence of sizes of mesocracks [ and microcracks and their relation with the trajectory and crystallography of propagation are also discussed.

Dynamic Phenomenon in Coal Mine Roadway Boundary and Supporting Adjustment in Bursting Condition

2014 ◽  
Vol 1073-1076 ◽  
pp. 2071-2077
Author(s):  
Peng Bo Li ◽  
Jin An Wang ◽  
Ke Lv
Keyword(s):  
Plastic Zone ◽  
Surrounding Rock ◽  
Point Of View ◽  
Anchor Bolt ◽  
Anchor Cable ◽  
Mine Roadway ◽  
Changing Trend ◽  
Roadway Support ◽  
The Impact ◽  
Good Support

The boundary magnification phenomenon was achieved in the coal mile surrounding rock, the displacement of surrounding rock was gradually increased, then more gentle in the plastic zone and sharply increase in the broken zone. The overall process of the displacement of surrounding rock exhibited graded changing trend; when the impact came, the broken zone had connected fissures caused by stretch of waves. It eventually increased the degree of damage in the boundaries of the broken zone and roadway. Accordingly, roadway support parameters were adjusted appropriately. From the energy point of view, the length of the anchor bolt was extended properly and that of the anchor cable was reduced properly. The adjusted length of the anchor bolt and cable well matched the size of the broken zone and plastic zone in roadway on site. There was a very good support effect. Anchor production process was also considered to improve gradient strength of materials which can better adapt to the rock burst environment.

Impact Load Buffering Method Based on Stress Wave Attenuation Principle

2019 ◽  
Vol 11 (02) ◽  
pp. 1950019 ◽  
Author(s):  
Lin Gan ◽  
He Zhang ◽  
Cheng Zhou ◽  
Lin Liu
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Dynamics Simulation ◽  
Scanning System ◽  
Isolation Method ◽  
Element Analysis ◽  
System A ◽  
High Emission ◽  
The Impact

Rotating scanning motor is the important component of synchronous scanning laser fuze. High emission overload environment in the conventional ammunition has a serious impact on the reliability of the motor. Based on the theory that the buffer pad can attenuate the impact stress wave, a new motor buffering Isolation Method is proposed. The dynamical model of the new buffering isolation structure is established by ANSYS infinite element analysis software to do the nonlinear impact dynamics simulation of rotating scanning motor. The effectiveness of Buffering Isolation using different materials is comparatively analyzed. Finally, the Macht hammer impact experiment is done, the results show that in the experience of the 70,000[Formula: see text]g impact acceleration, the new buffering Isolation method can reduce the impact load about 15 times, which can effectively alleviate the plastic deformation of rotational scanning motor and improve the reliability of synchronization scanning system. A new method and theoretical basis of anti-high overload research for Laser Fuze is presented.

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