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 Key Factors Affecting the Deformation and Failure of Surrounding Rock Masses in Large-Scale Underground Powerhouses

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Meng Wang ◽  
Jia-wen Zhou ◽  
An-chi Shi ◽  
Jin-qi Han ◽  
Hai-bo Li
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Affecting Factors ◽  
Key Factors ◽  
Underground Powerhouse ◽  
Deformation And Failure ◽  
Factors Affecting ◽  
Geological Conditions

The stability of the surrounding rock masses of underground powerhouses is always emphasized during the construction period. With the general trends toward large-scale, complex geological conditions and the rapid construction progress of underground powerhouses, deformation and failure issues of the surrounding rock mass can emerge, putting the safety of construction and operation in jeopardy and causing enormous economic loss. To solve these problems, an understanding of the origins and key affecting factors is required. Based on domestic large-scale underground powerhouse cases in the past two decades, key factors affecting the deformation and failure of the surrounding rock mass are summarized in this paper. Among these factors, the two most fundamental factors are the rock mass properties and in situ stress, which impart tremendous impacts on surrounding rock mass stability in a number of cases. Excavation is a prerequisite of surrounding rock mass failure and support that is classified as part of the construction process and plays a pivotal role in preventing and arresting deformation and failure. Additionally, the layout and structure of the powerhouse are consequential. The interrelation and interaction of these factors are discussed at the end of this paper. The results can hopefully advance the understanding of the deformation and failure of surrounding rock masses and provide a reference for design and construction with respect to hydroelectric underground powerhouses.

Establishment and Application of Microseismic Monitoring System to Deep-Buried Underground Powerhouse

2013 ◽  
Vol 838-841 ◽  
pp. 889-893
Author(s):  
Biao Li ◽  
Feng Dai ◽  
Nu Wen Xu ◽  
Chun Sha
Keyword(s):  
Rock Mass ◽  
Monitoring System ◽  
Wave Velocity ◽  
Microseismic Monitoring ◽  
Surrounding Rock ◽  
P Wave ◽  
Monitoring Method ◽  
Underground Powerhouse ◽  
Geological Conditions ◽  
The Stability

The right bank underground powerhouse of Houziyan hydropower station is a typical deep-buried type with high geostress and complicated geological conditions. To monitor and analyze the stability of surrounding rock mass during continuous excavation of the powerhouse excavation and locate the potential failure zones, an ESG (Engineering Seismology Group) microseismic monitoring system manufactured in Canada was installed in April, 2013. The wave velocity of the monitoring system was determined through fixed blasting tests. And the average location error is the minimum while P-wave velocity is 5700m/s, less than 10m and meeting the system request. By combining the temporal and spatial distribution regularity of microseimic events with field excavation, micro-crack clusters and potential instability zones were identified and delineated. The results will provide a reference for later excavations and supports of the underground powerhouse. Furthermore, a new monitoring method can also be supplied for the stability analysis of surrounding rock mass in deep-buried underground powerhouses.

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.

Research on Similar Materials for Rheological Test of Hard Rock Mass

2017 ◽  
Vol 744 ◽  
pp. 169-173
Author(s):  
Long Yun Zhang ◽  
Shang Yang Yang
Keyword(s):  
Rock Mass ◽  
Model Test ◽  
Rheological Behavior ◽  
Mechanical Model ◽  
Mechanical Tests ◽  
Surrounding Rock ◽  
Hydropower Station ◽  
Similar Material ◽  
Geological Conditions ◽  
Deep Rock

The analog material, used in the Geo-mechanical model test that is designed to study the unloading rheological behavior and failure characteristics of rock mass, must reflect the physico-mechanical behaviors of the actual rock mass. The surrounding rock of Meng-di-gou hydropower station is in complex geological conditions. With the excavation of the rock mass, the surrounding rock gradually unloading, and the property of the near rock mass. It is necessary to carry out Geo-mechanical model test to study the rheological properties of deep rock mass under complicated geological conditions. So the similar material, comprised of iron powder, barite powder, and quartz sands bound with a solution of alcohol and colophonium, is suggested to be improvable. Firstly, through more than 300 groups of mix proportion tests, the influence of different mix proportions of the ingredients are analyzed to obtain the optimal analog materials; Secondly, more than 1200 specimens are made into size Φ50mm×100mm; Lastly, physico-mechanical tests were conducted by using the specimens to test the mechanical property of the similar material, and the basic physico-mechanical parameters are obtained from the analog material. The results indicates that the property of the similar material matches well with that of the rock mass in site, so the similar material is suitable for the Geo-mechanical model test, and it can be used to test the unloading rheological behavior of rock mass of Meng-di-gou hydropower station.

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 Study on Pressure Relief Effect of Rock Mass with Different Borehole Parameters

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chao Peng ◽  
Wanrong Liu
Keyword(s):  
Acoustic Emission ◽  
Rock Mass ◽  
Rock Burst ◽  
Strength Reduction ◽  
Surrounding Rock ◽  
Reduction Degree ◽  
Occurrence Time ◽  
Pressure Relief ◽  
Research Results ◽  
Relief Effect

Rock burst is one of the disaster accidents that can easily happen in rock cavern engineering. At present, one of the most commonly used methods to control rock burst is borehole pressure relief technology. In this paper, the influence of drilling layout schemes on the pressure relief effect of surrounding rock mass is systematically studied. The research results show that the strength reduction degree, AE evolution characteristics, failure modes of rock samples with different borehole positions, boreholes spacing, boreholes dip angles, and boreholes layout forms are different. The strength reduction degree of rock sample with an inclined arrangement form is the largest, followed by the arrangement form being up three-flower layout or down three-flower layout. Using the inclined layout and three-flower layout can achieve better pressure relief effect of the surrounding rock mass. The research results are beneficial to the rock burst of surrounding rock of the cavern. The acoustic emission can effectively monitor the stability of the surrounding rock of the cavern. However, the threshold value and the occurrence time of the acoustic emission of the cavern instability changed after the cavern surrounding rock is drilled holes. If the borehole is arranged at the surrounding rock mass, the occurrence time of the cavern instability may be advanced.

Comparison Optimization Analysis of the Location of Power House under Complex Geological Structure

2006 ◽  
Vol 306-308 ◽  
pp. 1455-1460
Author(s):  
Jing Zeng ◽  
Qian Sheng ◽  
Qing Chun Zhou
Keyword(s):  
Rock Mass ◽  
Geological Structure ◽  
Surrounding Rock ◽  
Obvious Effect ◽  
Power House ◽  
Mass Comparison ◽  
Geological Conditions ◽  
Stability Of Surrounding Rock ◽  
Complex Geological Structure ◽  
The Stability

The power house of Yantan extended hydropower project, with complex geological conditions such as fault f211 below the power house and quartzite on top of it, is a huge underground cavern with large span and high wall. In order to evaluate the stability of the power house surrounded by such complex geological structure, the numerical simulation excavation of power house with different location schemes were studied by the elasto-plastic 2D FEM method. The deformation and evolutive process of the stress with the progress of excavation were analyzed. On the condition ensuring the whole stability of surrounding rock mass, comparison optimization analyses were conducted on the power house location scheme. The rational location scheme was demonstrated. The final analyses results show that: (1) The mechanical properties of quartzite and its relative location to the power house has no obvious influence to the stability of surrounding rock mass.(2) The f211 is the main bad geological structure which affect the stability of power house. (3) The case of moving 10m upward of power house is the most rational scheme for the whole stability of power house. (4) The Supporting measures, which would has an obvious effect in controlling the influence on the stability of surrounding rock mass by weak geological structure, are suggested at the out-crop of f211.

scholarly journals Investigation on the Vibration Effect of Shock Wave in Rock Burst by In Situ Microseismic Monitoring

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Mingshi Gao ◽  
Hongchao Zhao ◽  
Yichao Zhao ◽  
Xiaojun Gao ◽  
Xiangyu Wang
Keyword(s):  
Shock Wave ◽  
Experimental Study ◽  
Rock Burst ◽  
Monitoring System ◽  
Seismic Source ◽  
Microseismic Monitoring ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Geological Conditions

Rock burst is a physical explosion associated with enormous damage at a short time. Due to the complicity of mechanics of rock burst in coal mine roadway, the direct use of traditional investigation method applied in tunnel is inappropriate since the components of surrounding rock are much more complex in underground than that of tunnel. In addition, the reliability of the results obtained through these methods (i.e., physical simulation, theoretical analysis, and monitoring in filed application) is still not certain with complex geological conditions. Against this background, present experimental study was first ever conducted at initial site to evaluate the effect of shock wave during the rock burst. TDS-6 microseismic monitoring system was set up in situ to evaluate the propagation of shock wave resulting in microexplosions of roadway surrounding rock. Various parameters including the distance of epicentre and the characteristic of response have been investigated. Detailed test results revealed that(1)the shock wave attenuated exponentially with the increase of the distance to seismic source according to the equation ofE=E0e-ηl; particularly, the amplitude decreased significantly after being 20 m apart from explosive resource and then became very weak after being 30 m apart from the seismic source;(2)the response mechanics are characteristic with large scatter based on the real location of surrounding rock despite being at the same section. That is, the surrounding rock of floor experienced serious damage, followed by ribs, the roof, and the humeral angles. This in situ experimental study also demonstrated that microseismic monitoring system can be effectively used in rock burst through careful setup and data investigation. The proposed in situ monitoring method has provided a new way to predict rock burst due to its simple instalment procedure associated with direct and reasonable experimental results.

scholarly journals The effect of contact grouting on support load

2021 ◽  
Vol 6 ◽  
pp. 5-12
Author(s):  
Liskovets Aleksandr ◽  
Tatsienko Viktor ◽  
Gogolin Viacheslav
Keyword(s):  
Rock Mass ◽  
Layer Thickness ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Cement Grout ◽  
Hardened Cement ◽  
Support Design ◽  
Tight Contact ◽  
Geological Conditions ◽  
Arch Support

Introduction. The paper analyzes contemporary methods of frame support design in permanent workings and reveals that contact grouting has received little attention. Contact grouting makes the tight contact between the hardened cement grout and the surrounding rock possible, whereas it is impossible when applying concrete lagging. The paper employs analytical method of arch support, grouting layer, and the surrounding rock calculation considering their softening. Analytical formulae determining support load has been obtained. The formulae take into account strain and strength characteristics of the surrounding rock, hardened cement grout, and support. Support load was calculated under various values of the grouting layer thickness and linear strain modulus and the depth of mining. The dependencies between the support load and the indicated parameters have been obtained, which makes it possible to select the cement grout composition for various mining and geological conditions. Research objective is to determine the effect produced by grouting layer thickness and strain characteristics on arch support load value in order to check its strength in various mining and geological conditions. Methods of research are built upon the physically based analytical methods of geomechanics to solve the problem of interaction between the support, grouting layer, and surrounding rock mass. Results. The results of arched support load calculation are presented for various values of grouting layer thickness, its strain characteristics, and depth of mining. Conclusions. The presence of the grouting layer in the void behind the support has a significant effect on the methods of arch support design. The developed methods take account of the fact that a layer of soft rock develops in the rock mass between the grouting layer and undisturbed rock. When the rock is being broken, its volume in this layer increases, which, in its turn, results in support load transfer growth through the grouting layer. It has been determined that the increase in the hardened cement grout strain and grouting layer thickness reduces support load.

scholarly journals Failure Analysis and Control Measures of Deep Roadway with Composite Roof: A Case Study

2021 ◽  
Author(s):  
Yongliang LI ◽  
Renshu Yang ◽  
Shizheng Fang ◽  
Hai Lin ◽  
Shaojie Lu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Mechanical Response ◽  
Surrounding Rock ◽  
Control Measures ◽  
Shanxi Province ◽  
Efficient Production ◽  
Stable Layer ◽  
Failure Characteristics ◽  
Geological Conditions ◽  
Unstable Layer

Abstract There is great variation in the lithology and lamination thickness of composite roof in coal-measure strata; thus, the roof is prone to delamination and falling, and it is difficult to control the surrounding rock when developing roadway in such rock strata. In deep mining, the stress environment of surrounding rock is complex, and the mechanical response of the rock mass is different from that of the shallow rock mass. For composite-roof roadway excavated in deep rock mass, the key to safe and efficient production of the mine is ensuring the stability of the roadway. The present paper obtains typical failure characteristics and deformation and failure mechanisms of composite-roof roadway with a buried depth of 650 m at Zhaozhuang Coal Mine (Shanxi Province, China). On the basis of determining a reasonable cross-section shape of the roadway and according to the failure characteristics of the composite roof in different regions, the roof is divided into an unstable layer, metastable layer, and stable layer. The controlled unstable layer and metastable layer are regarded as a small structure while the stable layer is regarded as a large structure. A superimposed coupling support technology of large and small structures with a multi-level prestressed bearing arch formed by strong rock bolts and highly prestressed cable bolts is put forward. The support technology provides good application results in the field. The study thus provides theoretical support and technical guidance for ground control under similar geological conditions.

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