scholarly journals Study on Mining Pressure Control of Deep Coal Seam——Based on Artificial Fault Technology

2021 ◽  
Author(s):  
Xiaoding Xu ◽  
Yubing Gao ◽  
Manchao He ◽  
Qiang Fu ◽  
Xingjian Wei
Keyword(s):  
Mechanical Model ◽  
Abutment Pressure ◽  
Dynamic Pressure ◽  
Horizontal Distance ◽  
Rock Blasting ◽  
Distribution Law ◽  
Pressure Relief ◽  
Working Surface ◽  
Mining Pressure ◽  
Cutting Point

Abstract Based on the pressure transfer principle and stress distribution characteristics around a fault, introducing artificial fault technology to control the propagation of abutment pressure, and a mechanical model of abutment pressure under the influence of artificial fault was established. This new mechanical model can well fit the distribution law of mining stress after roof cutting. The pressure transfer mechanism of prefabrication support of rock blasting was analyzed, and the transfer trend of pressure and the mining stress of rock top was determined. It is of great significance to guide the implementation of the pressure relief work at the top of the stope. The study shows that the total energy of the system is conserved, the integrity of rock layer is destroyed by blasting, and the deformation and damage of pressure relief zone absorb a large amount of energy. Thus, the accumulated strain energy of abutment pressure region is released, and the influencing range of abutment pressure is reduced. As the horizontal distance from the cutting surface is farther away from the working surface, the smaller the stress difference on both sides of the cutting top, the less obvious the blocking effect of mining pressure. When the cutting point is closer to the working surface, the higher the peak value of abutment pressure due to the superposition of peripheral stress concentration caused by the cutting and peak of abutment pressure caused by mining. Then, the numerical simulation analysis was carried out, the results show that the technology of forming artificial fault by cutting the top can cut off the influence range of the mining pressure. It can effectively control the deformation of dynamic pressure tunnl. Finally, a practice of rock blasting pressure relief engineering was carried out, and the influencing range of abutment pressure of working face before blasting pressure reduction was reduced by 1/3 compared with that before the pressure relief.

scholarly journals Safe and Efficient Coal Mining Below the Goaf: A Case Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 864 ◽  
Author(s):  
Weidong Pan ◽  
Shaopeng Zhang ◽  
Yi Liu
Keyword(s):  
Abutment Pressure ◽  
Theoretical Calculations ◽  
Distribution Law ◽  
Working Face ◽  
Strata Behavior ◽  
Working Resistance ◽  
Behavior Characteristics ◽  
Theoretical Analyses ◽  
Important Significance

Mining at the fully mechanized working face below the goaf of the short-distance coal seam is influenced by the upper goaf. To address this problem, methods such as theoretical analyses, numerical simulation, and on-site measurement are used to study the strata behavior characteristics of the Ningxia Lingxin Coal Mine 051508 working face in this study. The roof weighting intervals of the working faces below the goaf and the non-goaf are obtained via theoretical calculations. The stoping processes of the working faces below the goaf and the non-goaf are simulated with FLAC3D to obtain the distribution law of the bearing pressure and plastic zones before the working face. Based on the statistical analysis of the measured working resistance of the supports and its distribution, the roof weighting interval of the working face mining below the goaf is obtained. The results show that the roof weighting interval and the advanced abutment pressure during mining at the working face below the goaf are smaller than those below the non-goaf, providing a reasonable theoretical basis for mining below the goaf, and having important significance for safe and efficient mining.

Measurement of High Amplitude Relief Valve Noise for Acoustically Induced Vibration and Comparison to Predictive Methods

2014 ◽  
Author(s):  
Neal Evans
Keyword(s):  
Dynamic Pressure ◽  
Maximum Flow ◽  
High Amplitude ◽  
Accurate Estimate ◽  
Relief Valve ◽  
Nitrogen Gas ◽  
Pressure Relief ◽  
Direct Measurements ◽  
Predictive Methods ◽  
Piping Systems

The prediction of acoustically induced vibration (AIV) failures in the design or redesign of piping systems requires an accurate estimate of the excitation source. Furthermore, the next generation of AIV analysis may require a physics-based noise-generation predictive technique, which entails the need for validation via direct measurements. The noise generated by a pressure relief valve (PRV) during a full-scale AIV blowdown test was measured inside a pipe downstream of the valve. A maximum flow rate of 33.5 kg/s was achieved using nitrogen gas through a 3×4″ relief valve generating a peak dynamic pressure level exceeding 650 kPa and sustained levels of 450 kPa (peak). Measurements are compared to existing noise calculation techniques which appear to under-predict the generated noise.

scholarly journals Study of An Innovative Approach of Roof Presplitting for Gob-Side Entry Retaining in Longwall Coal Mining

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3316 ◽  
Author(s):  
Xingyu Zhang ◽  
Liang Chen ◽  
Yubing Gao ◽  
Jinzhu Hu ◽  
Jun Yang ◽  
...  
Keyword(s):  
Longwall Mining ◽  
Design Method ◽  
Innovative Approach ◽  
Pressure Relief ◽  
Working Face ◽  
Longwall Coal Mining ◽  
Safety Production ◽  
Supporting Effect ◽  
Mining Pressure

Gob-side entry retaining (GER) is a hot issue with regard to saving resources and reducing the drivage ratio in longwall mining. This paper investigates an innovative approach of roof presplitting for gob-side entry retaining (RPGER). RPGER uses the directional cumulative blasting to split the roof in advance. The rock roof within the presplitting range caves in gob after mining. The caved gangue can become the natural rib of the gob-side entry and expands to be the natural supporting body for resisting the upper roof movement. A numerical model of RPGER was established by the discrete element method (DEM), which showed that the supporting effect by the expanded gangue was well functioning. The gob-side entry was in pressure-relief surroundings and featured in the lesser deformation. The roof presplitting design method was presented and validated with a field test. The test illustrated that RPGER reduced the mining pressure on the retained entry side. The expanded gangue on the entry side was gradually compacted. It is the compaction process that played the role of reliving mining pressure, and the compacted gangue became the effective rib of the gob-side entry. The retained entry in the pressure-relief surroundings would stabilize a lagging distance behind the working face. The gob-side entry after stabilization met the entry retaining and the safety production requirements. This work illustrates the mechanism of RPGER and validates its feasibility and efficiency.

scholarly journals Study on Surrounding Rock-Bearing Structure and Associated Control Mechanism of Deep Soft Rock Roadway Under Dynamic Pressure

2019 ◽  
Vol 11 (7) ◽  
pp. 1892 ◽  
Author(s):  
Dongdong Qin ◽  
Xufeng Wang ◽  
Dongsheng Zhang ◽  
Xuyang Chen
Keyword(s):  
Dynamic Pressure ◽  
Soft Rock ◽  
Friction Angle ◽  
Surrounding Rock ◽  
Control Effect ◽  
Pressure Relief ◽  
Reinforcement Scheme ◽  
Soft Rock Roadway ◽  
Bearing Structure ◽  
Rock Roadway

Providing support for deep soft rock roadways under dynamic pressure is a major technical challenge. In this study, the distribution characteristics of surrounding rock-bearing structure of such roadways were systematically examined using theoretical analysis and numerical simulation. Based on the control effect of different support methods on the surrounding rock-bearing structure; a reinforcement scheme for deep dynamic soft rock roadway was proposed and applied. The results indicate that: (1) by increasing the supporting strength of the internal bearing structure, cohesion, and internal friction angle of the surrounding rock, and by reducing the influence of mining, making the external bearing structure close to the roadway and reducing the thickness of the bearing structure, can improve the bearing capacity of the shallow surrounding rock in the roadway; (2) under the conditions of dynamic load and creep of the surrounding rock; the deformation of the rock increases significantly; external bearing structure is far away from the roadway, and thickness of the bearing structure increases; anchor cable support and floor pressure relief effect better control over the roof and the roadside deformation and floor heave, respectively; and the thickness of the corresponding external bearing structure is reduced by 30.84% and 41.50%, respectively; and (3) based on the application, the zonal reinforcement scheme of “fix cable to shed, floor pressure relief, deep-shallow composite grouting” is proposed and put into practice, with good results. The results of this study can provide theoretical support and reference for the determination of supporting parameters in deep roadways.

Study on Abutment Pressure Distribution Law of Fully-Mechanized Sublevel Caving Face in Extra-Thickness

2015 ◽  
Vol 1094 ◽  
pp. 405-409
Author(s):  
Lei Yu
Keyword(s):  
Pressure Distribution ◽  
Abutment Pressure ◽  
Distribution Law ◽  
Working Face ◽  
Sublevel Caving ◽  
Coal Wall ◽  
Pressure Peak ◽  
Cutting Height ◽  
Coal Seam Thickness ◽  
Peak Value

Based on field observation, analogy simulation and theoretical analysis, the abutment pressure distribution law of fully-mechanized sublevel caving face with extra-thickness was studied. The results showed that: Different instability type of the structure ‘Combined cantilever beam-articulated rock beam’ in fully-mechanized sublevel caving roof led to cyclical changes of abutment pressure; with an invariable coal seam thickness and increasing cutting height, abutment pressure peak value tended to stabilize after reaching the maximum, but as the working face advancing its location transferred to the front of coal wall working face and the influence region of abutment pressure increased; with an invariable cutting height and increasing once mining thickness, abutment pressure peak value decreased, and the distance between peak point and coal wall and the influence region increased. The results of the study would have some guiding role in extra-thickness fully mechanized mining’s safety and efficiency.

Study on distribution law of lead abutment pressure in fully mechanized caving face with large mining height

2014 ◽  
pp. 389-394
Author(s):  
Fu-Lian He ◽  
Zhi-Yang Liu ◽  
Tong-Da Li ◽  
Sheng-Rong Xie ◽  
Huan-Kai Wu ◽  
...  
Keyword(s):  
Abutment Pressure ◽  
Distribution Law ◽  
Large Mining Height ◽  
Mining Height

scholarly journals Analysis on Rock Burst Risks and Prevention of a 54 m-Wide Coal Pillar for Roadway Protection in a Fully Mechanized Top-Coal Caving Face

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zhihua Li ◽  
Ke Yang ◽  
Jianshuai Ji ◽  
Biao Jiao ◽  
Xiaobing Tian
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Influencing Factors ◽  
Abutment Pressure ◽  
Large Diameter ◽  
Coal Pillar ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Working Face ◽  
Coal Pillars

A case study based on the 401103 fully mechanized caving face in the Hujiahe Coal Mine was carried out in this research to analyze the rock burst risks in a 54 m-wide coal pillar for roadway protection. Influencing factors of rock burst risks on the working face were analyzed. Stress distribution characteristics on the working face of the wide coal pillar for roadway protection were discussed using FLAC3D numerical simulation software. Spatial distribution characteristics of historical impact events on the working face were also investigated using the microseismic monitoring method. Results show that mining depth, geological structure, outburst proneness of coal strata, roof strata structure, adjacent mining area, and mining influence of the current working face are the main influencing factors of rock burst on the working face. Owing to the collaborative effects of front abutment pressure of the working face and lateral abutment pressure in the goaf, the coal pillar is in the ultimate equilibrium state and microseismic events mainly concentrate in places surrounding the coal pillars. Hence, wide coal pillars become the regions with rock burst risks on the working face. The working face adopts some local prevention technologies, such as pressure relief through presplitting blasting in roof, pressure relief through large-diameter pores in coal seam, coal seam water injection, pressure relief through large-diameter pores at bottom corners, and pressure relief through blasting at bottom corners. Moreover, some regional prevention technologies were proposed for narrow coal pillar for roadway protection, including gob-side entry, layer mining, and fully mechanized top-coal caving face with premining top layer.

scholarly journals Influence of Upper Seam Extraction on Abutment Pressure Distribution during Lower Seam Extraction in Deep Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Feng Wang ◽  
Zeqi Jie ◽  
Bo Ma ◽  
Weihao Zhu ◽  
Tong Chen
Keyword(s):  
Coal Seam ◽  
Pressure Distribution ◽  
Abutment Pressure ◽  
Field Measurements ◽  
Pressure Relief ◽  
Deep Mining ◽  
Key Strata ◽  
Mining Safety ◽  
Seam Mining ◽  
Overlying Strata

Pressure-relief coal mining provides an effective way to decrease stress concentration in deep mining and ensures mining safety. However, there is currently a lack of research and field verification on the pressure-relief efficiency and influencing factors during upper seam extraction on the lower seam. In order to make up for this deficiency, in this study, field measurements were conducted in panel Y485, which has a maximum depth of 1030 m and is partially under the goaf of the upper 5# seam in the Tangshan coal mine, China, and evolution of advanced abutment pressure was analyzed. Numerical simulations were conducted to study of influence of key strata on advanced abutment pressure. Influence mechanisms of the upper seam extraction on the advanced abutment pressure distribution during lower seam extraction were revealed. The results indicate that the distribution of advanced abutment stress is influenced by the key strata in the overlying strata. The key strata above the upper coal seam were fractured due to the upper coal seam mining, and the advanced abutment stress was only influenced by the key strata between the two seams during lower coal seam mining. When key strata were present between two seams, the extraction of the lower seam still faces potential dynamic disasters after the extraction of the upper seam. In this case, it would be necessary to fracture the key strata between the two seams in advance for the purpose of mining safety. Key strata in the overlying strata of the 5# seam were fractured during extraction, and advanced abutment pressure was only influenced by the key strata located between the two mined seams. The influence distance of advanced abutment pressure in panel Y485 decreased from 73 m to 38 m, and the distance between the peak advanced abutment pressure and the panel decreased from 29 m to 20.5 m, achieving a pronounced pressure-relief effect.

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