scholarly journals Theoretical Calculation and Analysis on the Composite Rock-Bolt Bearing Structure in Burst-Prone Ground

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Liang Cheng ◽  
Yidong Zhang ◽  
Ming Ji ◽  
Mantang Cui ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Theoretical Calculation ◽  
Rock Burst ◽  
Mechanical Model ◽  
Surrounding Rock ◽  
Rock Bolt ◽  
Mining Engineering ◽  
Calculation Formula ◽  
Mining Depth ◽  
Rock Parameters ◽  
Bearing Structure

Given the increase in mining depth and intensity, tunnel failure as a result of rock burst has become an important issue in the field of mining engineering in China. Based on the Composite Rock-Bolt Bearing Structure, which is formed due to the interaction of the bolts driven into the surrounding rock, this paper analyzes a rock burst prevention mechanism, establishes a mechanical model in burst-prone ground, deduces the strength calculation formula of the Composite Rock-Bolt Bearing Structure in burst-prone ground, and confirms the rock burst prevention criterion of the Composite Rock-Bolt Bearing Structure. According to the rock burst prevention criterion, the amount of the influence on rock burst prevention ability from the surrounding rock parameters and bolt support parameters is discussed.

scholarly journals Migration Law of the Roof of a Composited Backfilling Longwall Face in a Steeply Dipping Coal Seam

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 188 ◽  
Author(s):  
Wenyu Lv ◽  
Yongping Wu ◽  
Liu Ming ◽  
Jianhui Yin
Keyword(s):  
Coal Seam ◽  
Inclination Angle ◽  
Mechanical Model ◽  
Surrounding Rock ◽  
Longwall Face ◽  
Mining Operations ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Migration Law

The artificial-caved rock composited backfilling approach can effectively restrain the dynamic phenomena in the coal seam and the associated roof and floor during mining operations, and can also improve the stability of the system of support and surrounding rock. In this study, based on the analysis of influencing factors affecting the surrounding rock movement and deformation of the composited backfilling longwall face in a steeply dipping coal seam, the roof mechanical model is developed, and the deflection differential equation is derived, to obtain the roof damage structure and the location of the roof fracture for the area without backfilling. The migration law of the roof under different inclination angles, mining depths, working face lengths, and backfilling ratios are analyzed. Finally, mine pressure is detected in the tested working face. Results show that the roof deflection, bending moment, and rotation drop with the increase of the inclination angle and backfilling ratio, whereas these parameters increase with greater mining depth and working face length. The roof failure location moves toward the upper area of the working face as the inclination angle and working face length increases, while it moves toward the center of the non-backfilling area with greater mining depth and backfilling ratio. Results from the proposed mechanical model agree well with the field test results, demonstrating the validity of the model, which can provide theoretical basis for a safe and efficient mining operation in steeply dipping coal seams.

scholarly journals Energy Distribution Law of Dynamic Failure of Coal-Rock Combined Body

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Guangbo Chen ◽  
Tan Li ◽  
Guohua Zhang ◽  
Pengcheng Teng ◽  
Bin Gong
Keyword(s):  
Energy Distribution ◽  
Rock Burst ◽  
Hard Rock ◽  
Engineering Practice ◽  
Calculation Formula ◽  
Rock Layer ◽  
Distribution Law ◽  
Energy Accumulation ◽  
Coal Rock ◽  
Bearing Structure

The rock burst must be generated by energy. In order to explore the distribution law of energy in coal-rock system, based on the structural characteristics of coal and rock and the mechanical characteristics analysis of coal-rock combined body model, the calculation formula of energy distribution was given before the damage of same diameter coal-rock combine body and nonsame-diameter coal-rock combined body; the uniaxial compression experiments were carried out on the combined body, and the energy distribution before the failure of the combined body was calculated by using the energy distribution calculation formula. The results show that the greater the difference in hardness between the components of the combined body, the stronger the outburst proneness; the energy mainly accumulates on the weak component before the combined body is destroyed, and the hard components act as a clamping device. When the soft layers and the hard rock layers are interbedded, the energy accumulation ability of the soft rock layer is stronger than that of the hard rock layer, and the weak rock layer is the main carrier of energy accumulation. According to this, from the perspective of energy accumulation layer, for the energy-bearing structure, direct release energy and indirect release energy two kinds of rock burst prevention and control concepts and corresponding antiburst measures were proposed. At the same time, engineering practice, microseismic monitoring, and on-site measurement were conducted in Junde Coal Mine. The results show that the blasting pressure relief for the weak coal seam and the hard roof destroys the energy-bearing structure formed by the fine sandstone-coal-fine sandstone and effectively releases the energy and has a remarkable antiscour effect.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

scholarly journals Characteristics Analysis and Modelling of a Pneumatic Underwater Launching System

2018 ◽  
Vol 232 ◽  
pp. 02005
Author(s):  
Bin Li ◽  
Song Guo ◽  
Wei Li ◽  
Deman Zhang ◽  
Nei Wang
Keyword(s):  
Theoretical Calculation ◽  
Calculation Formula ◽  
Numerical Work ◽  
Characteristics Analysis ◽  
Hydrodynamic Noise

Comprehensive characteristics of a pneumatic underwater launching system were analyzed and the simulation was carried out by simulink. The components of the pneumatic underwater launching system were introduced, and the theoretical calculation formula for the system was derived. A rated pressure of 3.5MPa and 5MPa was offered in the numerical work. Analyses in different piston height show good behaviors: Proper increase of piston-initial accumulator pressure is beneficial to reduce hydrodynamic noise, choose the appropriate pressure of accumulator. The hydrodynamic noise of the system can be significantly reduced by optimizing the structure of the double-acting cylinder, increasing the height of the piston and improving the structure of the piston.

Study on the Prediction Method of Tunnel Surrounding Rock Pressure Based on the Theory of Progressive Destruction

2012 ◽  
Vol 446-449 ◽  
pp. 1432-1436
Author(s):  
Suo Wang
Keyword(s):  
Rock Pressure ◽  
Characteristic Curve ◽  
Prediction Method ◽  
Surrounding Rock ◽  
Progressive Damage ◽  
Tunnel Excavation ◽  
Practical Engineering ◽  
Surrounding Rock Pressure ◽  
The Relationship ◽  
Rock Parameters

In order to predict tunnel surrounding rock pressure, this paper puts forward a series of dynamic numerical simulative model on the tunnel excavation. According to the change of rock damage in the construction program, it adjusts dynamically the mechanical material parameters of surrounding rock. So the model achieves the purpose which is controlling and simulating the process of tunnel progressive damage. In accordance with the numerical simulative results, it analyzes the relationship between the rock parameters with the plastic strain, radial displacement. Then this paper proposes a prediction method of tunnel surrounding rock pressure based on the theory of the progressive damage and method of characteristic curve. Finally, it compares the pressure on the numerical simulative models with on the site date, and it proves that the prediction method has practical engineering value.

scholarly journals A study of the mechanical structure of the direct roof during the whole process of non-pillar gob-side entry retaining by roof cutting

2020 ◽  
Vol 38 (5) ◽  
pp. 1706-1724
Author(s):  
Xiao Liu ◽  
Xinzhu Hua ◽  
Peng Yang ◽  
Zhiguo Huang
Keyword(s):  
Mechanical Model ◽  
Superposition Principle ◽  
Calculation Formula ◽  
Concentrated Load ◽  
Maximum Deformation ◽  
Whole Process ◽  
Roadway Support ◽  
The Relationship ◽  
Important Basis ◽  
Roof Deformation

The non-pillar entry (roadway) retained by roof cutting serves the two adjacent working faces. As compared with the conventional mining roadways, the roadway retained by roof cutting has a longer life cycle and receives more complicated influence from mining. Determining the location where the roof deformation and maximum deformation occur can provide an important basis for roadway support. Here, the direct roof of the roadway is studied by assuming it as an elastic deformation body. The stress features of the direct roof of the gob-side entry retained by roof cutting are analyzed, and the roof deformation is divided into five stages. The stress superposition principle is employed, and the equivalent concentrated load within the roadway is introduced. The mechanical model of the direct roof is established for the whole process of gob-side entry retaining by roof cutting. Next, the calculation formula for the concentration of direct roof at different positions is obtained for the whole process of gob-side entry retaining by roof cutting. The application scope of the calculation formula and the determination method of the key parameters are analyzed. The relationship between direct roof deformation of the roadway and stiffness of the support system is studied. The results show that the direct roof deformation has a symmetrical distribution about the midline. The maximum roof deformation occurs in the middle of the roadway, and it gradually decreases as the coal seam stiffness increases. During the example calculation, the maximum roof deformation is 280 mm for the gob-side entry retaining under primary mining. The measured maximum roof deformation is 320 m, and the error rate is 12.5%. It is then verified that the uniform mechanical model proposed in this study applies to the calculation of direct roof deformation in the gob-side entry retained by roof cutting.

scholarly journals Correction to: Stress and load-bearing structure analysis of the surrounding rock in a soft broken roadway

2020 ◽  
Vol 13 (23) ◽  
Author(s):  
Guangming Zhao ◽  
Chongyan Liu ◽  
Siming Kao ◽  
Xiaobo Zhang ◽  
Xiang Cheng
Keyword(s):  
Structure Analysis ◽  
Surrounding Rock ◽  
Load Bearing ◽  
Bearing Structure
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