scholarly journals Optimization and Practice for Partition Pressure Relief of Deep Mining Roadway Using Empty-Hole and Deep-Hole Blasting to Weaken Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Baobao Chen ◽  
Changyou Liu ◽  
Fengfeng Wu
Keyword(s):  
Large Diameter ◽  
Elevation Angle ◽  
Failure Behavior ◽  
Deep Hole ◽  
Pressure Relief ◽  
Deep Mining ◽  
Safe Level ◽  
Drilling Parameters ◽  
Decoupling Coefficient ◽  
Stress Boundary

Rockbursts are among the most harmful dynamic disasters, threatening the personnel safety and mine operation. In order to alleviate stress concentration of roadsides and prevent rockbursts, the large-diameter boreholes and deep-hole blasting are employed for partition pressure relief in the deep mining roadway. Combined with failure behavior and stress distribution of the coal, the multilevel division of risk degree for roadsides stress is determined. Based on the orthogonal test of borehole pressure relief in the general danger partition, the response degree of quantitative indexes to main factors influencing the pressure relief effect is considered. The optimal drilling parameters of 120.0 mm diameter, 20.0 m depth, 1.0 m hole spacing, and 5° elevation angle are obtained, determining the stress boundary of safe pressure relief with boreholes. At higher dangerous stress divisions, the optimized blasting parameters through numerical simulation could be obtained as follows: 15.0 m depth, 1.3 decoupling coefficient, and 2.0 m hole spacing, and meanwhile, a stress relief partition of crisscross cracks with 0.61 m height is formed. The roadsides stress could be well controlled within the safe level. Then, an optimal combination of pressure relief is applied to different stress partition of roadsides, and the effectiveness is validated by field test, which proves remarkably applicable for engineering.

scholarly journals A Preliminary Study on the Design Method for Large-Diameter Deep-Hole Presplit Blasting and Its Vibration-Isolation Effect

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Shuangshuang Xiao ◽  
Hongsheng Wang ◽  
Guowei Dong
Keyword(s):  
Vibration Isolation ◽  
Design Method ◽  
Blast Hole ◽  
Large Diameter ◽  
Field Testing ◽  
Open Pit ◽  
Vibration Velocity ◽  
Deep Hole ◽  
Charge Mass ◽  
Presplit Blasting

Presplit blasting can reduce vibration and back impact induced by cast blasting, thus resulting in a smooth bench slope. To design reasonable presplit blasting parameters, this research investigated the formation of presplit faces based on the explosion mechanics and revealed the cracking mechanism of presplit blasting. According to the stress distribution in the vicinity of the blast holes under the action of explosive stress waves and blasting gas, we deduced theoretical formulae for parameters including charge mass in blast holes, hole spacing, and distance from presplit blast holes to cushion holes. On this basis, a method was proposed for the design of large-diameter deep-hole presplit blasting. Field testing was conducted by setting different spacing for presplit blast holes, to monitor the blasting-induced vibration. The results showed that appropriate hole spacing can reduce the particle vibration velocity and the attenuation index of blasting-induced vibration changed slightly while the attenuation coefficient decreased significantly; the formed presplit faces were smooth and had a high half-cast factor. Finally, the reasonable hole spacing for presplit blasting, distance from presplit blast hole to the cushion hole, and the charge mass in blast holes in the Heidaigou open-pit coal mine were determined, respectively.

Design and Siting for Large Diameter Well Type Repositories

2003 ◽  
Author(s):  
Sergey Dmitriev ◽  
Lev Prozorov ◽  
Aleksey Tkachenko ◽  
Andrey Guskov ◽  
Svetlana Korneva
Keyword(s):  
Large Diameter ◽  
Activity Level ◽  
Intermediate Level ◽  
Construction Technology ◽  
Actual Problem ◽  
Near Surface ◽  
Drilling Rig ◽  
Safe Level ◽  
Central Russia ◽  
Geological Conditions

RADON enterprises are historically responsible in Russia for institutional waste of low and intermediate activity level. MosNPO RADON is a leading organization for 16 enterprises of RADON system, established in the early 60-s, only 14 from which are now in operation and have about 10% of their repositories available for upcoming waste. Construction of new repositories and selection of new perspective sites is very actual problem for RAW management in Russia now. Traditionally near surface repositories are considered to be acceptable for storage or even disposal of low and intermediate level waste (LILW), which decay to safe level in some hundreds of years. Forty years experience in LILW isolation using near surface repositories at Russian RADON facilities has shown that a lot of operational and natural factors impact on the engineered barriers and may cause failure of the isolation (freezing-thawing cycles, construction works). In addition construction of new old-type repositories requires more area. Since 1997 development and testing of Large Diameter Wells (LDW) as a new type of repositories for low and intermediate level waste is carried out at Zagorsk site. MosNPO RADON specialists developed the LDW construction technology with the aim to use such wells for LILW isolation in moraine clays. The diameter of LDW-type repository may range from 1 to 5 m depending on drilling rig capabilities and performance parameters of host rock. The depth of well (repository) depends on geological parameters and hydro-geological conditions at the site. These features affect on the siting process by additional geological and hydro-geological requirements. In result of preliminary studying of Central Russia two regions were found to be perspective for construction of LDW-type repositories.

Investigation on Deep Hole Trepanning of TC10 Titanium Alloy

2019 ◽  
Author(s):  
Xiaolan Han ◽  
Zhanfeng Liu
Keyword(s):  
Titanium Alloy ◽  
Tool Wear ◽  
Titanium Alloys ◽  
Process Parameters ◽  
Thrust Force ◽  
Large Diameter ◽  
Manufacturing Cost ◽  
Deep Hole ◽  
Technical Problems ◽  
Material Utilization

Abstract Titanium alloy is a typical hard-to-machine material, and has a relatively expensive material price. For deep-hole tubes made of titanium alloys, the material utilization rate of direct deep-hole drilling is relatively low, especially for large diameter holes. Deep-hole trepanning provides an effective method that reduces manufacturing cost and improves the material utilization which is used on larger diameter bars. In this paper, deep-hole trepanning tests are carried out on the TC10 titanium alloys to resolve the key technical problems. The thrust force and torque, tool wear, and chip morphology are analyzed based on the different process parameters. The results show that appropriate process parameters can remove the chips easily and reduce the thrust force and tool wear. The titanium alloy deep-hole trepanning has a good drilling effect and solves the problem of drilling deep, large diameter holes in titanium alloy tubes, which has practical significance for reducing production cost and improving material utilization.

Study on Deep Hole Drilling Process and Cutting Performance

2020 ◽  
Vol 866 ◽  
pp. 42-53
Author(s):  
F.Q. You ◽  
R. Zhang ◽  
Yong Guo Wang
Keyword(s):  
Finite Element ◽  
Reference Value ◽  
Drilling Process ◽  
Deep Hole ◽  
Drilling Force ◽  
Finite Element Software ◽  
Drilling Temperature ◽  
Drilling Parameters ◽  
Simulation Results ◽  
Twist Drills

In deep hole machining, drilling parameters for twist drills have an important impact on tool life and economic efficiency. In order to explore the influence of drilling parameters on twist drills, this paper established a drilling model for twist drill 45 steel, orthogonal experiments were designed. AdvantEdge FEM finite element software was used to simulate the drilling force, torque and drilling temperature. The drilling force, torque and drilling temperature were analyzed by using the finite element simulation value as the orthogonal experimental value. In order to ensure that the simulation results have certain reference value, the drilling experiment was carried out in order to ensure the simulation results have reference value. Finally, the optimal combination of drilling parameters was obtained.

scholarly journals Mechanism and Control of Roadway Floor Rock Burst Induced by High Horizontal Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Dongming Guo ◽  
Xinchao Kang ◽  
Zhiying Lu ◽  
Qiyu Chen
Keyword(s):  
Rock Burst ◽  
Prevention And Control ◽  
Large Diameter ◽  
Horizontal Stress ◽  
Steel Tube ◽  
Pressure Relief ◽  
Floor Rock ◽  
Concrete Filled Steel Tube ◽  
Rock Burst Risk ◽  
And Control

According to the characteristics of rock burst of high horizontal stress roadway floor, the rock burst mechanism of roadway floor was studied with the background of south track roadway Xing’an mine. Based on the deflection theory and energy principle of the slab, the mechanical model of the floor of the roadway under high horizontal stress was established, the stress and energy criteria of rock burst occurred in the floor of the roadway were deduced, the prevention and control measures of the floor pressure relief with large diameter borehole and concrete-filled steel tube pile support were put forward, and the key parameters were determined. By establishing a numerical model, the evolution law of plastic zone, horizontal stress, and elastic strain energy density of roadway floor with or without support is contrastively analyzed. The results show that the effective means to prevent and control the floor rock burst is to cut off the stress transfer path by weakening the hard floor to reduce floor energy accumulation so as to reduce the floor rock burst risk. Based on the above research, field tests were carried out, and the microseismic monitoring results showed that the floor pressure relief of large diameter boreholes and concrete-filled steel tube pile support effectively relieved the floor rock burst and guaranteed the safety and efficiency of roadway excavation. This technology can provide a reference for the prevention and control of floor rock burst of similar roadways.

scholarly journals Study on the Evolution Law of Overburden Breaking Angle under Repeated Mining and the Application of Roof Pressure Relief

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4513 ◽  
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xingping Lai ◽  
Jiantao Cao ◽  
Pengfei Shan
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Theoretical Calculation ◽  
Simulation Experiment ◽  
Elevation Angle ◽  
Theoretical Formula ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Physical Similarity ◽  
Working Face

Aiming at the serious problems caused by coal mine mining activities causing the rock burst accidents, this paper is based on rock mechanics and material mechanics to establish the key layer breaking by the double-key layer beam breaking structural mechanics model of a single working face and double working face under repeated mining. The theoretical calculation formula of the angle was used as the theoretical basis for the elevation angle of the pre-reloading hole of the hard roof. The rationality and reliability of the formula were verified by the physical similarity simulation experiment and the 3 Dimension Distinct Element Code numerical simulation experiment, revealing the rock formation under the influence of repeated mining. The results show that the derived key layer breaking angle formula is suitable for the theoretical calculation of the breaking angle of the key layer of a single coal seam when the repeated disturbance coefficient is λ = 1; when it is λ = 2, it is suitable for the repeated mining of the short-distance double-coal mining. The rationality and reliability of the theoretical formula of the breaking angle of the double key layer of single coal seam and double coal seam were verified by the physical similarity simulation experiment. Through the 3DEC numerical simulation results and theoretical calculation results, the W1123 working face hard top pre-cracking pressure relief drilling elevation angle was 78°. The drilling peeping method was used to verify the results. The results show that the theoretical formula of the critical layer breaking angle is well applied in engineering practice.

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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