scholarly journals Study on the Modification of Confining Rock for Protecting Coal Roadways against Impact Loads from a Roof Stratum

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1331
Author(s):  
Haiyang Yi ◽  
Zhenhua Ouyang ◽  
Xinxin Zhou ◽  
Zhengsheng Li ◽  
Jianqiang Chen ◽  
...  
Keyword(s):  
Rock Burst ◽  
Dynamic Stress ◽  
Earth Pressure ◽  
Modified Method ◽  
Coal Roadway ◽  
Geological Conditions ◽  
Roof Stratum ◽  
Grouting Reinforcement ◽  
Vibration Wave ◽  
Stress Damage

Promoting the ability of anti-bursting of the confining rock of a coal roadway is of significant importance to the safe production of a coal mine. In particular, in deep-buried coal mines, highly frequent rock burst occurs due to large earth pressure and complex geological conditions, which needs serious improvement. This paper investigated a type of confining rock modified method, which can modify the physical properties of the surrounding rock and form a crack region and a reinforced region by blasting and grouting reinforcement. Based on a set of physical model experiments and numerical modeling, the results of a comparative analysis between a normal roadway and the modified roadway in the static stress redistribution, dynamic stress, damage evolution, and energy dissipation suggest that the modified confining rock is capable of protecting the coal roadway against rock burst from roof stratum, obviously reducing and transferring the concentered static–dynamic stress out of the cracked region, dissipating the dynamic energy by plastic damage in the cracked region, and keeping the integrity of the reinforced region. In addition, the velocity of the dynamic stress vibration wave at the surface of the modified coal roadway is obviously reduced, which is beneficial for decreasing the movement of cracked rock blocks and protecting the lives and goods in the coal roadway.

scholarly journals Numerical Simulation of the Effect of Dynamic Stress on the Rock Surrounding a Mine Roadway

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jun-hua Xue ◽  
Ke-liang Zhan ◽  
Xuan-hong Du ◽  
Qian Ma
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Rock Burst ◽  
Dynamic Stress ◽  
Simulation Method ◽  
Mining Areas ◽  
Geological Conditions ◽  
Mine Roadway ◽  
The Stability ◽  
Two Sides

In view of the damage of dynamic stress to the rock surrounding a mine roadway during coal mining, based on the actual geological conditions of Zhuji mine in Huainan, China, a UDEC model was established to study the influences of the thickness and strength of the direct roof above the coal seam and the anchorage effect on the stability of the roadway. The failure mechanism and effect of the dynamic stress on the rock surrounding a mine roadway were revealed. Under dynamic stress, cracks appear near the side of the roadway where the stress is concentrated. These cracks rapidly expand to the two sides of coal and rock mass. At the same time, the coal and rock mass at the top of the roadway fall, and finally, the two sides of coal and rock mass were broken and ejected into the roadway, causing a rock burst. However, when the same dynamic stress is applied to the roadway after supports are installed, there is no large-deformation failure in the roadway, which shows that, under certain conditions, rock bolting can improve the stability and seismic resistance of the surrounding coal and rock mass. Furthermore, by simulating the failure of surrounding rock with different strengths and thicknesses in the immediate roof, it is found that the thinner the roof, the greater the influence of the dynamic stress on the roadway; the stronger the roof is, the more likely the rock burst will occur with greater intensity under the same dynamic stress. A numerical simulation method was used to analyze the factors influencing rock bursting. The results provide a theoretical basis for research into the causes and prevention of rock bursts in deep mining areas.

scholarly journals Numerical Analysis of Soil Improvement for a Foundation of a Factory Using Stone Columns Made of Different Types of Coarse-grained Materials

2019 ◽  
Author(s):  
Jakub Stacho ◽  
Monika Sulovska
Keyword(s):  
Numerical Analysis ◽  
Accurate Determination ◽  
Soil Improvement ◽  
Coarse Grained ◽  
Stone Columns ◽  
Modified Method ◽  
Geological Conditions ◽  
Deformation Properties ◽  
Final Settlement ◽  
The Impact

Stone columns made of coarse-grained materials and crushed stone are one of the most-used technologies for soil improvement all over the world. Stone columns improve the strength and deformation properties of subsoil and reduce the time required for the consolidation of fine-grained soils. The impact of the improvement depends on the properties of the original subsoil as well as the properties of the coarse-grained materials used for the stone columns. The article deals with the effects of the properties of coarse-grained materials for stone columns on the settlement and consolidation times of improved subsoil for the foundation of a factory. Numerical modeling as a 2D task was performed using Plaxis geotechnical software. The numerical analysis included two methods of modeling stone columns in a plane strain model, i.e., one method often used by practical engineers in the region of Slovakia, and one modified method, which allowed for a more accurate determination of the final settlement and consolidation time. The method modeled stone columns as continuous walls, and the compaction of the soil between the stone columns was taken into account. The results showed that the type of coarse-grained material can significantly affect the final settlement and time of consolidation. Stone columns made of quarry stone were suitable in the given geological conditions regardless of the design of the mesh, while stone columns made of pebble gravel were suitable only with a mesh of 1.5 x 1.5 m.

Deep Well of Coal Roadway Bolt-Cable Mechanism Analysis and its Engineering Application

2012 ◽  
Vol 226-228 ◽  
pp. 1094-1097 ◽  
Author(s):  
Bai Xiao Tang ◽  
Yong Wei Wang
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
Engineering Practice ◽  
Construction Technology ◽  
Mechanism Analysis ◽  
Small Aperture ◽  
Deep Well ◽  
Coal Roadway ◽  
Geological Conditions ◽  
Support Cost

Cable Anchor Supporting mechanism theory analysis, combined with high geostress, composite roof and complex geological conditions, the deep well under conditions of coal roadway by small aperture, anchor on the form of the structure and high prestressed construction technology, engineering practice shows that the technology is simple and applicability,is deep well solve the high stress soft rock tunnel, large sections into bifurcation point supports of the effective way of the problem. Not only reduces the support cost, reduce the workload of the Lane repair, and also greatly reduce the labor intensity of construction personnel, improve the reliability of the engineering safety. Accumulated experience, has broad application prospects for the deep well under the conditions of the other coal mine soft rock roadway

scholarly journals Experimental Methods to Assess the Effectiveness of Soil Conditioning with Foam in Fully Weathered Granite

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Liming Tao ◽  
Zhongtian Chen ◽  
Jian Cui ◽  
Huiwu Wang ◽  
Yong Fang
Keyword(s):  
Test Procedure ◽  
Earth Pressure ◽  
Optimization Methods ◽  
Test Method ◽  
Pressure Balance ◽  
Foaming Agents ◽  
Application Range ◽  
Weathered Granite ◽  
Geological Conditions ◽  
Foam Properties

The application range of the earth pressure balance (EPB) shield has been expanded due to advances in optimization methods, one of which is the application of foam conditioning. This method is widely used in EPB tunnelling owing to its strong applicability in different hydrological and geological conditions. When applying the foam conditioning method under different circumstances, it is necessary to optimize the conditioning parameters. Therefore, it is necessary to propose a test procedure for evaluating foam properties and the conditioning effect. This paper proposes a procedure to assess foaming agents by the mixing test and microscopic observation of the foam and a procedure that combines the slump test, compression test, and shear test to assess the foam-conditioned soil and determine the optimal parameters of conditioning. The test method is introduced and performed on fully weathered granite from Guangzhou Metro Line 21. The test results demonstrate that the foam injection ratio and pressure and type of the foaming agent all influence the performance of the conditioned soil. Moreover, the suggested conditioning scheme is proposed, and the application of the scheme can improve the tunnelling efficiency.

Study on Soil Conditioning and Key Construction Parameters of EPB TBM Advancing in Sand-Pebble Layer of Beijing Metro

2011 ◽  
Vol 90-93 ◽  
pp. 2138-2142 ◽  
Author(s):  
Hua Jiang ◽  
Yu Sheng Jiang ◽  
Mao Lan Huang ◽  
Xin Nie
Keyword(s):  
Plastic Flow ◽  
Earth Pressure ◽  
Soil Condition ◽  
Pressure Balance ◽  
Soil Conditioning ◽  
Geological Conditions ◽  
Before And After ◽  
Epb Tbm ◽  
Earth Pressure Balance ◽  
Low Efficiency

Mechanical properties of sand-pebble layer is very unstable, it is unfavourable for TBM excavation. For the reasons of poor soil conditioning and low plastic flow of muck, EPB TBM tunnel construction in sand-pebble layer of Beijing metro has exposed variety of issues: continuous dynamic earth pressure balance is hard to established, mud cake is formed frequently in earth chamber, key construction parameters such as thrust, torque, advance speed can not be controlled in reasonable scopes, which lead to low efficiency of TBM construction. Taking“Xi-Liu”of line 10 lot 11 as an research object, the mechanical characteristics of sand-pebble layer and construction problems of TBM advancing are analyzed, variety of soil conditioning measures are used for improving plastic flow of muck and minimizing construction influence induced by poor geological conditions, meanwhile contrast studies on key construction parameters before and after soil conditioning are carried out. The results indicate that effect of soil condition plays very significant roles in controlling TBM construction parameters and improving advancing efficiency.

scholarly journals A Control Method of Rock Burst for Dynamic Roadway Floor in Deep Mining Mine

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Zhimin Xiao ◽  
Jun Liu ◽  
Shitan Gu ◽  
Mingqing Liu ◽  
Futian Zhao ◽  
...  
Keyword(s):  
Rock Burst ◽  
Control Method ◽  
Tectonic Stress ◽  
Surrounding Rock ◽  
Floor Rock ◽  
Deep Mining ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Working Face ◽  
Geological Conditions

Roadway floor rock burst is an important manifestation of rock bursts in deeply buried mines. With the increase of mining depth and mining intensity, rock burst disasters in the roadway floor such as floor heaves are becoming more serious. The article investigated the roadway floor severe heave caused by floor rock burst during excavation of the No. 3401 working face, which was controlled by an anticlinal structure and deep mining in Shandong Mine, China. Firstly, by analyzing geological conditions of the working face, roadway support parameters, and characteristics of coal and rock, it was revealed that high tectonic stress and high crustal stress were main causes of the floor rock burst. Secondly, based on the Theory of Mechanics and Theory of Energy, the energy conversion process in the roadway floor was discussed, and the rock burst condition caused by elastic energy in the roadway floor was analyzed. The failure characteristics of roadway-surrounding rock were also inspected, using a borehole recorder. The roof and sidewalls of roadway mainly contained fissures and cracks, whereas cracks and broken areas are distributed in the roadway floor. Finally, based on the deformation and failure characteristics of roadway-surrounding rock, a method termed “overbreaking-bolting and grouting-backfill” was proposed to control roadway floor rock burst. The method was tested in the field, and the results showed that it could effectively control the deformation of roadway floor and rock burst, guaranteeing the stability of roadway floor. This impact control method for the roadway floor can provide a reference for the prevention and control of roadway rock burst in mines with similar geological conditions.

scholarly journals Preliminary Discussion on Comprehensive Research Method for Rock Burst in Coal Mine Based on Newton’s Second Law

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Jianping Zuo ◽  
Hongqiang Song ◽  
Yunqian Jiang ◽  
Shankun Zhao ◽  
Meilu Yu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Rock Burst ◽  
Research Method ◽  
Surrounding Rock ◽  
Research Progress ◽  
Field Energy ◽  
Second Law ◽  
Preliminary Discussion ◽  
Geological Conditions ◽  
Newton's Second Law

Rock burst is one of the major dynamic disasters that directly threaten production safety in coal mines. According to the current research, the occurrence of rock burst can be described by the generalized Newton’s second law with three elements which are research object, force condition, and motion state. These three elements refer to the coal and rock mass in the mining area, concentrated static and dynamic loads, and dynamic instability of surrounding rock, respectively. On this basis, a comprehensive rock burst research method involving the three elements of Newton’s second law was proposed, which especially focuses on the investigation into geological conditions of mining areas. The research procedure of this method specifically includes the detailed exploration of engineering geological bodies, the classification and stability evaluation of surrounding rock, the measurement and inversion of in situ stress, the evolution analysis of mining-induced stress field, energy field, and fracture field, the study of multiscale failure mechanism of coal and rock mass, the establishment of theoretical failure model of coal and rock mass, the real-time monitoring and warning in potentially dangerous areas, and the reasonable prevention and control in key risk zones. As a preliminary discussion, the significant research progress in each aspect mentioned above has been reviewed and the feasible research directions of rock burst are presented in this paper.

scholarly journals The Study on Large-Diameter Drilling Prevention Method of Rock Burst in the Xinxing Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Gao Xu ◽  
Zuo Minghui ◽  
Shu Yanmin
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Plastic Zone ◽  
Rock Burst ◽  
Large Diameter ◽  
Practical Implementation ◽  
Physical Parameters ◽  
Mine Pressure ◽  
Working Face ◽  
Geological Conditions

Based on the engineering background, the 41051 working face of the 65th coal mine in Qitaihe Xinxing Mine was regarded as the engineering background, by using of the comprehensive research methods such as theoretical analysis and calculation, FLAC3D numerical simulation, physical parameters of coal and rock in laboratory, and the field industrial measurement, to research on the large drilling relieving rock burst mechanism and parameter setting in reasonable. The distribution of stress and plastic zone in drilling surrounding rock and its influence parameters are clarified, and the distribution of the “butterfly plastic zone” and the mutation condition of the “butterfly plastic zone” in trigger stress state are explored. On the basis, combined with theoretical analysis and numerical simulation, studying the rock burst prevention and treatment mechanism in large drilling, through the statistics of the Xinxing mine pressure characteristics, the measurement of the physical parameters of coal and rock and the test of ground stress finding is that the coal satisfies “Three hard” condition in Xinxing mine and is affected by larger horizontal tectonic stress. Combined with the real geological conditions, the layout parameters of relief pressure large drilling are simulated, and the result shows that the drilling of 600 diameters and 10 m pitch of hole and throughout the working face is reasonable, and the effect is obvious about pressure relief. For the practical implementation, the electromagnetic radiation monitoring is used to evaluate the effect in field; to comprehensive analysis, the relief pressure large drilling has obvious control effect to the 41051 workface rock burst.

Application of Grouting Reinforcement Technology in Pingshan Shaft Station

2014 ◽  
Vol 580-583 ◽  
pp. 1347-1351
Author(s):  
Liang Tian ◽  
Jing Yi Xi ◽  
Jian Liu ◽  
Xiao Dong Liu ◽  
Feng Shang ◽  
...  
Keyword(s):  
Roof Rock ◽  
Soft Rock ◽  
Difficult Problem ◽  
Surrounding Rock ◽  
Ground Pressure ◽  
Geological Conditions ◽  
Floor Heave ◽  
Cable Force ◽  
Grouting Reinforcement ◽  
Roadway Support

Support of soft rock is a big challenge in all mines at home and abroad. Soft rock is of different kinds of rheological property for geological conditions, mine ground pressure and so on. It brings about really difficult problem to roadway support. In order to ensure safety application and prolong usage, shaft station need to be reinforced. Sight instrument was used to analyze broken conditions. The results show that the broken depth in roof rock is 5~6 m, and greater than 4 m in sidewalls. According to failure characters and sight results, we determine that rock of shaft station belongs to high geo-stress and jointed soft rock. On this basis, technology of grouting reinforcement combined with cable anchor support is carried out. Monitoring results of surface convergence and cable force show that bearing capacity of surrounding rock increases obviously, roadway contraction and floor heave are well controlled.

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.

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