Research on Drill Pipe Fracture Mechanism of Pressure Relief in Thick Coal Seam

2016 ◽  
Vol 13 (12) ◽  
pp. 9313-9316
Author(s):  
Yan Li ◽  
Mingzhong Gao ◽  
Yunhai Cheng
Keyword(s):  
Coal Seam ◽  
Fracture Mechanism ◽  
Drill Pipe ◽  
Pressure Relief ◽  
Thick Coal Seam

scholarly journals Study of Gob-Side Entry Retaining Technology with Roof Cutting under Upper Roadway Condition

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xingen Ma ◽  
Manchao He ◽  
Xuewei Sun ◽  
Jianfeng Li ◽  
Gang He ◽  
...  
Keyword(s):  
Coal Seam ◽  
Surrounding Rock ◽  
Pressure Relief ◽  
Application System ◽  
Thick Coal Seam ◽  
Working Face ◽  
Geological Conditions ◽  
Key Technologies ◽  
Releasing Effect ◽  
System Designs

Gob-side entry retaining technology with roof cutting (GERRC) has been widely used in flat and near-flat coal seam conditions, but its application under inclined coal seam is still very deficient. In order to further improve the application system of GERRC and overcome the application difficulties under special geological conditions, this paper takes the 43073 working face of Yixin coal mine as an example to research the GERRC with upper roadway under gently inclined thick coal seam. Firstly, the difficulties in the upper entry retaining with inclined coal seam are analyzed and the corresponding key technologies and system designs are put forward. Subsequently, the roof cutting and upper entry retaining are designed in detail according to geological conditions of test working face, and the roof cutting and pressure releasing effect is analyzed by numerical simulation to expound the stress distribution and pressure releasing mechanism of surrounding rock. Finally, the upper entry retaining field test is carried out to verify the feasibility and applicability of the technology and related designs. Through field monitoring, it is found that the weighting step increases significantly, the weighting strength decreases effectively on the roof cutting side, and the pressure relief effect is obvious. Meanwhile, the maximum roof to floor convergence is 361 mm and the maximum shrinkage of both sides is 280 mm, so the retained entry can meet the reuse requirement of adjacent working face.

scholarly journals Engineering Practice of Ultra-high Pressure Hydraulic Slotting and Pressure Relief Pumping in Through Layer Hole

2021 ◽  
Vol 236 ◽  
pp. 01029
Author(s):  
Siqian Li
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
High Efficiency ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Thick Coal Seam ◽  
Ultra High Pressure ◽  
Drainage Rate ◽  
Gas Control

In order to solve the problems of low gas drainage rate and long drainage time in thick coal seam with low permeability, ultra-high pressure hydraulic slotting pressure relief and permeability enhancement technology was applied in the test. The practice shows that after adopting the ultra-high pressure hydraulic slotting, the gas drainage rate is greatly improved, the time for reaching the standard of drainage is shortened, and the difficult problem of gas control in the mining face of thick coal seam is solved, which provides technical guidance for high-efficiency gas control in thick coal seam with similar conditions in mining area.

scholarly journals Reasonable Arrangement of High-Level Orientation Extraction Boreholes of Pressure Relief Gas in Overlying Strata under High-Strength Fully Mechanized Mining in Low-Gas-Thick-Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Han Gao ◽  
Xuanping Gong ◽  
Xiaoyu Cheng ◽  
Rui Yu ◽  
Hui Wang
Keyword(s):  
Coal Seam ◽  
Gas Flow ◽  
High Strength ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Gas Field ◽  
Thick Coal Seam ◽  
Gas Accumulation ◽  
Working Face ◽  
Gas Control

In order to solve the problem of pressure relief gas control under high-strength fully mechanized top-coal caving in low-gas-thick-coal seams, this paper studies the evolution of overburden structures and the distribution characteristics of fissure fields during the initial and stable period of working face by physical simulation and numerical analysis. The mathematical model of coupling between mining fracture field and pressure relief gas field is established. The results reveal the distribution characteristics of pressure relief gas field that considers mining-induced fissure field. According to the distribution of mining gas accumulation area, the high directional long boreholes have been put forward to control the pressure relief gas in goafs, and the effect has been tested. The results show that the initial pressure and three periodic pressures occurred from the cutting hole to 135 m in the initial mining period of the working face. The height of collapse zone developed to 22 m, and fracture height developed to 75 m. The development height of caving zone is stable at 25∼27 m, and the development height of fissure zone is stable at 75∼95 m. The process and distribution of pressure relief gas flow in goaf are obtained by solving the numerical model of pressure relief gas flow in mining fissure field. The gas accumulation area is located within 25∼55 m from return laneway and 25∼50 m from the roof of coal seam. After the implementation of high directional long drilling gas drainage technology in the initial mining period and the stable mining period, good results have been obtained in the gas control, where the average concentration of gas extraction is 5.8%, the average gas flow rate is 0.71 m3/min, and the gas concentration in upper corner and return air is less than 0.8%. The results can provide a reference for pressure relief gas control under similar conditions.

scholarly journals Study on first caving fracture mechanism of overlying roof rock in steep thick coal seam

2015 ◽  
Vol 25 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Bei Zhang ◽  
Shenggen Cao
Keyword(s):  
Coal Seam ◽  
Fracture Mechanism ◽  
Roof Rock ◽  
Thick Coal Seam

scholarly journals Study on the “Pressure Relief and Yielding Support” Joint Prevention and Control Technology for the Weak Impact Roadway in the Extremely Thick Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zengde Yin ◽  
Jinxiao Liu ◽  
Wenbin Sun ◽  
Kebao Guo ◽  
Feng Zhang
Keyword(s):  
Coal Seam ◽  
Prevention And Control ◽  
Surrounding Rock ◽  
Control Technology ◽  
Pressure Relief ◽  
Thick Coal Seam ◽  
Roadway Support ◽  
Yielding Support ◽  
And Control ◽  
The Impact

Weak impact occurs during roadway excavation in some extremely thick coal seams in China. Although this hazard is not enough to destroy the roadway, it will cause fracturing and large deformation of the roadway surrounding rock, resulting in the fracturing of bolts and anchor cables and bringing great difficulties to roadway support. In the hope of solving this problem, firstly, the reason for impact occurrence in the roadway of the extremely thick coal seam is analyzed from the perspective of energy. Then, the surrounding rock fracture evolution in such a roadway is explored by means of numerical simulation, microseism, and borehole observation. Furthermore, the “pressure relief and yielding support” joint prevention and control technology is proposed and applied to Yili No. 1 Coal Mine. The field engineering application results show that the joint prevention and control technology can effectively reduce the impact energy and ensure the stability of the roadway surrounding rock in the extremely thick coal seam. The research findings can provide a theoretical foundation for the roadway support of the same type.

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 Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

Analysis of Pressure Relief Effect on the Protective Layer of Hard Roof and Extra-Thickness Coal Seam Mining

2018 ◽  
Vol 37 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Zhongchang Wang ◽  
Wenrui Bian
Keyword(s):  
Coal Seam ◽  
Protective Layer ◽  
Pressure Relief ◽  
Hard Roof ◽  
Seam Mining ◽  
Relief Effect
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