Numerical Experiments of Drilling Pressure Relief Preventing Roadway Rock Burst

2013 ◽  
Vol 353-356 ◽  
pp. 1583-1587 ◽  
Author(s):  
Yan Liang Wen ◽  
Guo Jian Zhang ◽  
Zhi Qiang Zhang
Keyword(s):  
Rock Mass ◽  
Rock Burst ◽  
High Stress ◽  
Simulation Software ◽  
Control Technique ◽  
Pressure Relief ◽  
Main Factors ◽  
Rock Burst Mechanism ◽  
Research Situation ◽  
Relief Effect

Based on rock burst mechanism and the present research situation of control technique, pressure relief process of drilling to rock burst roadway is modeled by numerical simulation software, the contrast and analysis of stress field of surrounding rock are put up with and without pressure relief. The results of the calculation indicate that after drilling high stress area on the both sides of the roadway reduces obviously, but stress peak increases and its position is not converted into the deep areas evidently. It is the energy of the high stress area that makes the rock mass between the drillings failure, which achieves the purpose of pressure relief. Drilling diameter and space between drillings are main factors influencing pressure relief effect. The major the drilling diameter and the smaller the space between boreholes, the more complete the rock mass between the drillings failure and the better the pressure relief effect.

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.

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

scholarly journals Analysis of pressure relief effect of borehole in rock burst mine

2021 ◽  
Author(s):  
Pengbo Xu ◽  
Junjie Shao ◽  
Dong Fan ◽  
Jianghua Chang ◽  
Ning Zhang
Keyword(s):  
Rock Burst ◽  
Pressure Relief ◽  
Relief Effect

scholarly journals Mechanism of Rock Bursts Induced by the Synthetic Action of “Roof Bending and Rock Pillar Prying” in Subvertical Extra-Thick Coal Seams

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhenhua Wu ◽  
Peng-Zhi Pan ◽  
Jianqiang Chen ◽  
Xudong Liu ◽  
Shuting Miao ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Rock Burst ◽  
Roof Rock ◽  
High Energy ◽  
Coal Seams ◽  
Rock Bursts ◽  
Rock Pillar ◽  
Mining Depth ◽  
Rock Burst Mechanism

When studying the rock burst mechanism in subvertical extra-thick coal seams in the Wudong coal mine in Xinjiang, China, most studies focus on rock pillars, while the effect of the roof on rock bursts is usually ignored. In this paper, a rock burst mechanism in subvertical extra-thick coal seams under the control of a “roof-rock pillar” is proposed. A theoretical analysis is first performed to explain the effect of roof-rock pillar combinations on rock bursts in coal seams. Numerical modeling and microseismic analysis are implemented to further study the mechanism of rock burst. The main conclusions are as follows: 1) During the mining of the B3+6 coal seam, an obvious microseismic concentration phenomenon is found in both the roof and rock pillar of B3+6. The rock bursts exhibited obvious directionality, and its main failure characteristics are floor heave and sidewall heave, but there will also be some failures such as shoulder socket subsidence in some parts. 2) The stress transfer caused by rock pillar prying is the main reason for the large difference in rock burst occurrence near the vertical and extra thick adjacent coal seams under the same mining depth. 3) Under the same cantilever length, the elastic deformation energy of the roof is much greater than that of the rock pillar, which makes it easier to produce high-energy microseismic events. With an increasing mining depth, the roof will become the dominant factor controlling the occurrence of rock bursts. 4) The high-energy event produced by the rock mass fracture near the coal rock interface easily induces rock bursts, while the high-energy event produced by the fracture at the far end of the rock mass is less likely to induce rock burst. 5) Roof deformation extrusion and rock pillar prying provide high static stress conditions for the occurrence of rock bursts in the B3+6 coal seam. The superposition of the dynamic disturbance caused by roof and rock pillar failure and the high static stress of the coal seam is the main cause of rock burst in the B3+6 coal seam.

scholarly journals Numerical Simulation and Analysis of Tunnel Failure Mode by Stochastic Fracture Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fukun Xiao ◽  
Lei Xu ◽  
Gang Liu ◽  
Zhiyuan Hou ◽  
Le Xing
Keyword(s):  
Numerical Simulation ◽  
Rock Burst ◽  
Monte Carlo Model ◽  
High Stress ◽  
Tectonic Stress ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Structural Plane ◽  
Dip Angle ◽  
The Stability

The dip angle, length, spacing, and fracture distance of rock fissure affect the morphology of roadway after collapse. The numerical simulation software CDEM is used to simulate the morphology of roadway collapse. The Monte Carlo model is used to simulate different types of crack models in two-dimensional plane and generate different crack models. The effects of crack angle, crack length, fracture distance, and spacing on the deformation of surrounding rock are analyzed. The influence of different rock burst on the failure strap-fall modes of fissure roadway and roadway in different sections is analyzed, and the stability law of roadway is studied. Under the condition of high stress, the roadway shape has little influence on the distribution of the principal stress difference of surrounding rock, but the equivalent excavation radius determines the distribution of the plastic zone of surrounding rock. The larger the ineffective reinforcement zone is, the larger the deformation around the roadway will be. The decrease of the angle between the structural plane and the vertical stress increases the failure range of the roadway under the gravity burst pressure. Under the horizontal tectonic stress type rock burst, when the structural plane inclination angle is 0°, the two-sided caving body fills the roadway and the roof caving range becomes smaller.

scholarly journals Numerical simulation study on rheological failure characteristics of rock mass under high stress

2020 ◽  
Vol 192 ◽  
pp. 04003
Author(s):  
Liming Qiu ◽  
Xueqiu He ◽  
Dazhao Song ◽  
Zhenlei Li
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Failure Process ◽  
High Stress ◽  
Sudden Change ◽  
Confining Pressure ◽  
Simulation Software ◽  
The Body ◽  
Failure Characteristics ◽  
Rock Failure Process

This paper uses the RFPA numerical simulation software to establish a numerical model of the rheological failure of the rock mass under stress. Rheological failure characteristics of the body was researched, and the results shows: (1) The rupture sequence of rock rupture is from the corner to the middle. When the rock loses stability under pressure, the rock often ruptures from the corner. The corner gradually collapses and cracks. Then the cracks spread to the middle of the rock. Many cracks extending from the corners are in the rock. The central part intersects each other and eventually causes the rock to break. (2) Rock samples of different lithologies have different stress values when they break under the same confining pressure. From the experimental process, we know that granite>sandstone>mudstone. Therefore, the higher the strength of the rock, the harder the rock will be broken. (3) The weaker the plasticity at rupture, the stronger the brittleness and the stronger the sudden change of rupture. In the deep mining process, the greater the confining pressure, the more obvious the rheological characteristics of the rock, and the greater the total energy released during the rock failure process.

Numerical Simulation of Preventing Rock Burst with Hydraulic Cutting

2012 ◽  
Vol 524-527 ◽  
pp. 637-641 ◽  
Author(s):  
Yao Cheng ◽  
Yu Lin Ma ◽  
Yong Li Zhang
Keyword(s):  
Numerical Simulation ◽  
Rock Burst ◽  
High Stress ◽  
Element Model ◽  
Pressure Relief ◽  
Deep Mining ◽  
Before And After ◽  
Mining Pressure ◽  
Slot Cutting ◽  
The Finite Element Model

Rock burst become increasingly serious in deep mining. Pressure relief will be realized with hydraulic cutting in the coal seam, and rock burst could be substantial prevented. The finite element model of hydraulic cutting is established, the variation of stresses around the slot before and after hydraulic cutting are found by Ansys software. The results of numerical simulation show: The influence circle of differential pressure with hydraulic cutting is about 5 meters. In the circle the stresses fall down 81%. The pressure relief is best when the pitch of holes is 8 meters with multi-slot cutting. The surface high stress area is significantly reduced after slotting and the stress concentration zone transferred to the deep. Reasonably direction of cutting travel determined pressure relief, and the cutting distance could influence directly the dimension and scope of pressure relief. The simulation results provide a theoretical foundation and technical reference for preventing rock burst with hydraulic cutting.

scholarly journals Study on the Key Technology of Controlling the Instability of Deep High-Stress Coal and Rock Mass and Relieving the Danger

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhijing Zhang ◽  
Jianghong Zuo ◽  
Dongji Lei
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Rock Fracture ◽  
Mine Safety ◽  
Detection Accuracy ◽  
Pressure Relief ◽  
Rock Body ◽  
Thick Coal Seam ◽  
Before And After ◽  
Relief Effect

In order to solve the problem of stress concentration and gas overrun in the process of uncovering high gas and thick coal seam, combined with the occurrence characteristics of coal seams in Wuyang Coal Mine, the measures of “hydraulic and mechanical cavity making + steel screen pipe + surrounding rock grouting” are adopted to establish a method for mutual verification of multiple effect test indexes of residual stress, residual gas content, coal seam moisture content, and microseismic signal characteristics, and the three-dimensional accurate analysis of the influence range of hydraulic cavitation is effectively realized. By comparing and analyzing the gas extraction amount, the surrounding borehole stress change and the microseismic monitoring signals before and after the application of hydraulic cavitation technology are studied. The results show the following. (1) The pressure relief effect of the hydraulic cavity on surrounding coal decreases with the increase of distance, and the pressure relief effect is most obvious at 1.0∼2.5 m, in the range of 2.5–3.5 m around the hydraulic drilling hole, the duration, rate, and amplitude of pressure relief are reduced compared with those in the range of less than 2.5 m, while in the range of more than 3.5 m, the effect of pressure relief is very weak. (2) During the period of hydraulic cavitation release hole, the radius of water supply to coal seam is within 1.5 m, which accounts for 79% of coal wall area. (3) It is also a process where the stress distribution in the coal and rock body needs to be rebalanced before and after hydraulic caverning, which is often accompanied by microfracture of coal and rock mass. The analysis shows that, before hydraulic caverning, the waveform of coal and rock fracture signal has a short duration, large amplitude, and obvious signal mutation, and the dominant frequency of the signal is about 250 Hz, with large total energy. After hydraulic caverning, the intensity of coal and rock fracture events is greatly reduced. The research results can effectively identify the influence range of hydraulic cavitation, improve the detection accuracy and efficiency of hydraulic cavitation range, effectively predict and warn the hidden danger of mine safety, and provide a reference for the work of similar mines.

scholarly journals Analysis of the Influence of Upper Protective Layer Mining on the Effect of Pressure Relief and Protection of Coal and Rock Masses between the Lower Overburden Layers

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Jiaxin Dang ◽  
Min Tu ◽  
Xiangyang Zhang ◽  
Qingwei Bu
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Expansion Ratio ◽  
Pressure Relief ◽  
Protection Effect ◽  
Protective Seam ◽  
Coal Wall ◽  
Seam Mining ◽  
Protective Seam Mining ◽  
Relief Effect

Protective seam mining is an effective gas pressure relief method in deep mining. Effective theoretical calculation methods in the current studies on the prediction of pressure relief protection effect of interbed coal and rock masses and their distribution laws are lacking. Thus, the evaluation and research with respect to pressure relief effect in protective seam mining relatively lag behind. This situation restricts the engineering feasibility evaluation and decision making in the protective seam mining. Therefore, the influence of upper protective seam mining on the pressure relief protection effect of coal and rock mass between underlying beds was investigated in this study. On the basis of an analysis of concrete engineering projects, a mechanical model was constructed for the pressure relief protection effect of upper protective seam mining on the coal and rock mass between underlying beds. The distribution equation of pressure relief expansion ratio in the underlying protected seam was also derived. The influence laws of main influencing factors on the pressure relief protection effect of the protected seam were revealed as well. In the end, the pressure relief effect was analyzed and verified for the protected seam before and after mining through numerical simulation and similarity simulation test. The pressure relief effect of upper protective seam mining on the coal and rock mass between underlying beds and the distribution characteristics were deeply explored in this study, which could provide a theoretical reference for the decision making in the gas extraction engineering design and pre-evaluation of extraction effect. Results show that the effective pressure relief zone (expansion rate>0.3%) of the protected seam beneath the goaf is located within the range of approximately 40 m from the coal wall to the rear part. It also presents an approximate “Λ-shaped distribution characteristic,” that is, it experiences migration and evolution with the advancement in the working face. Moreover, the peak pressure relief lags behind the coal wall on the working face by nearly 10–20 m. In the numerical simulation, the expansion ratio in the goaf also presents an approximate “Λ-shaped distribution.” Its effective pressure relief zone is the 50 m range from the coal wall to the rear part of the goaf, and the peak value lags behind the coal wall by around 15 m. The theoretical results and numerical simulation results are basically consistent with the physical experiment results. The expansion rates are 1.25%, 1.268%, and 1.32%, respectively. The elastic modulus E of coal seam and interbed spacing H are the main influencing factors of the swelling deformation and are negatively correlated with the expansion ratio. In the actual mining process, E and H of the protected layer can be measured to infer the expansion deformation of the protected layer.

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