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ABSTRACT: Jinchuan mine is the largest underground nickel mine in China, There is highly stressed surrounding rock in this mine. The problem of highly fractured roadway support in the mine is serious. In the paper, according to mechanical principle of imitation soil nail reinforcement on highly fractured roadway support, the coupling reinforcing technology of prestressed hollow rock bolt-TECCO wire mesh-grouting concrete is proposed. In this supporting system, the prestressed rock bolt perform as the deep roots of plants into shallow rock to reinforce deep stability of the bedrock, the wire mesh just like be the shallow roots of plants, and the random distribution of grouting is the branch roots of plants. The on-site support test shows that the technology of prestressed hollow rock bolt-TECCO wire mesh-grouting not only improves the strength and rigidity of the supporting structure, but also provides a “first softening” for highly stressed broken roadway. After 20 days of roadway support, the deformation rate of surrounding rock is less than 0.05mm/d, the largest subsidence of the roof of the roadway is 37.6mm, and the largest relative displacement of the two gangs is 62.8mm, which indicates that the support method can effectively control the deformation of the roadway.
- Asia > China (0.36)
- North America > United States (0.28)
- Research Report > New Finding (0.41)
- Research Report > Experimental Study (0.41)
- Energy > Oil & Gas > Upstream (0.49)
- Materials > Metals & Mining (0.49)
Research on Comprehensive Gas Control Model at First Mining Face of Lower Protective Seam in Seam Group with High Gas
Dai, Guanglong (School of Energy and Safety, Anhui University of Science and Technology, Province and MOE Joint Key Lab of Mine Safety and High Efficient Mining) | Qin, Ruxiang (School of Energy and Safety, Anhui University of Science and Technology, Province and MOE Joint Key Lab of Mine Safety and High Efficient Mining) | Guo, Laigong (School of Energy and Safety, Anhui University of Science and Technology) | Fu, Baojie (School of Energy and Safety, Anhui University of Science and Technology, Province and MOE Joint Key Lab of Mine Safety and High Efficient Mining) | Chen, Gongsheng (Huainan Mining Group Pan Yidong Mine) | Zhou, Yanan (Huainan Mining Group Pan Yidong Mine)
Abstract: Aiming at the problem of gas control in mining process of deep well and high gas low permeability coal seam group, raise the method of surface well, cross-measure boreholes in bed plate tunnel, gas drainage from holes along roof strike and goaf drainage pipe. According to the condition of protective seam, construct of “three dimensional” gas drainage pattern in coal seam, goaf and adjacent layer. The Application effect of first mining face of 1252 (1) in Pan Yidong Mine shows that release pure gas amount of protective layer bottom lane wear layer drilling pump reaches 42.09m/min,which is 44.45% for the extraction of total and gets notable effects. On surface well, it mainly is protective gas, its average concentration, 47.5%, is the highest. Gas drainage from holes along roof strike and goaf drainage pipe takes Mining goaf layer gas. Because of low concentration, it is only 9.09 m/min. Although its total poured gas reaches 105.8 m/min, it adapts vertical gas extraction mode, and different extraction way extracts different source of gas, and thus solves effectively the problem of low permeability of coal seam gas control. Introduction The main mining method of Huainan mining area is seam group mining. And with the increasing depth of mine, gas pressure and gas content are also increasing. Thus the coal and gas outburst happene easier. First mining face is the key, because a large amount of gas emits from neighboring layer during the stooping in first coal mining face. In order to avoid gas exceeding limit, we have to take effective control measures to ensure safe and efficient mine production . “The low permeability coal seam mining group first key seam relief - mining Mined side gas distribution and drainage technology, reveals the “Y” type ventilation goaf side pressure relief gas rich region, migration channel, gas distribution and pressure relief on gas migration law, put forward new technologies and new ways to stay roadway drilling method of coal and gas extraction” Yuan Liang studied. “The low permeability coal seam group with high gas pressure relief gas drainage mechanism and experimental, revealed the influence of mining roof and floor strata dynamic evolution of fractures and relief on gas migration law at first mining seam group key relief layer after mining area, found goaf side of vertical fractured zone, and bottom band bending subsidence expansion deformation bands within coal swell deformation, a significant increase in the permeability of the coal seam” Lu Ping studied. Pan Yidong Mine takes 1252 (1) First Coal Face as a under protective layer, with the mine influence, the relief gas from adjacent layer 13-1 coal seam will tumbles in 1252 (1) Mining goaf, causing a large amount of gas emission. The paper presents high gas seam group first mining face gas comprehensive control technology, and it can guide gas control in Huainan Mining engineering practice, and has important theoretical significance and practical value for Y-type ventilation Protective Layer Mining Face Gas Management.
Introduction Many times, traffic safety issues come to the forefront following an incident or near miss. However, safety professionals can take a more proactive view of site safety and efficiency by conducting road safety audits (RSA). These audits are especially helpful for large sites, such as office or educational campuses, large construction sites, petrochemical facilities and manufacturing locations. When coupled with lessons learned from public roadways, RSAs can be a useful tool for hazard mitigation. A road safety audit is a multi-disciplined examination of an existing or future roadway, performed by an independent, qualified team. The team should include professionals with experience developing roadways but who are not involved in the original development of the roadway being examined. The RSA focuses only on safety and considers all road users and environmental conditions, with the overall goal of focusing on the safe operation of roadways and crossings. An RSA tries to answer two primary questions:What parts of the road are a safety concern and to whom? How can those issues be eliminated or mitigated? Traffic safety is often focused on driver behavior and training, which are primarily administrative control solutions. By performing an RSA, an organization can focus higher on the Hierarchy of Controls by implementing engineering control solutions that are less reliant on driver actions. In many ways, an RSA draws on the Prevention through Design (PTD) concept of assessing risk and planning solutions before incidents occur. In keeping with the PTD concept, an RSA is most effective if it can be performed during conceptual and preliminary design—anticipating and eliminating hazards before they are introduced. But, regardless of when an RSA is performed, it can significantly reduce risk and improve efficiency. Similar to any other form of proactive risk assessment, an RSA identifies opportunities for improvement before an incident or near miss demands attention. Benefits of a Road Safety Audit vs. Traffic Safety Study While traffic safety on public roadways is managed through formal analysis and specifically designated countermeasures, it is impractical to approach private sites in the same manner. An RSA is a safety performance examination performed by a team of stakeholders. It qualitatively estimates and reports on potential road safety issues and identifies opportunities for improvements in safety for all road users.
Disaster-Causing Mechanism and Control Technology of Strong Rock Pressure in Fully Mechanized Caving Face of Steeply Inclined Coal Seam
Yang, Wenhua (xi’an University of Science and Technology / Key Laboratory of Western Mines and Hazard Prevention) | Lai, Xingping (xi’an University of Science and Technology / Key Laboratory of Western Mines and Hazard Prevention) | Wang, Ningbo (National Energy Group Xinjiang Energy Company) | Shan, Pengfei (xi’an University of Science and Technology / Key Laboratory of Western Mines and Hazard Prevention) | Zhang, Shuai (xi’an University of Science and Technology / Key Laboratory of Western Mines and Hazard Prevention) | Ren, Jie (xi’an University of Science and Technology / Key Laboratory of Western Mines and Hazard Prevention)
Abstract Under the condition of fully mechanized horizontal sublevel caving mining in steeply inclined and extra-thick seam, the problem of disaster caused by strong rock pressure is becoming increasingly prominent, which seriously restricts the safe production of the mine. It is urgent to study its mechanism to provide theoretical basis for the prevention and control of rock pressure. In this study, numerical simulation experiments are carried out to reveal the change characteristics of stress field, displacement field and plastic zone of the whole model after single slice mining in steep seam. Then, combined with the coal seam occurrence characteristics and mining methods, using the knowledge of mine pressure and rock mechanics, the structure model of stope overburden is obtained. The results show that under the complicated geological occurrence conditions of steeply inclined seams, it is difficult for roof strata to collapse in time under the condition of self-weight after mining, and a large area of roof suspension is formed. Under the combined action of transfer stress and bending stress of suspended roof, a triangular stress concentration area (SFC=2.5-3) is formed in the stope rock mass 6m-45m away from the roof roadway along the coal seam inclination, which makes the stress of roadway support system increase sharply and causes the occurrence of floor heave and side heave and other rock pressure phenomena. With the mining level extending to the deep, the stress concentration degree increases, and the rock pressure appearance also increases. When the stress reaches the ultimate tensile strength of roof strata, the roof collapses in a large area instantaneously, forming a strong rock pressure event. According to the structure and stress characteristics of overburden caving, the electromagnetic radiation intensity of coal and rock mass is obviously reduced by adopting multi-level roof blasting weakening technology of surface and underground, which reduces the stress concentration in coal and rock mass of working face, effectively controls the rock pressure problem of working face, and ensures the safety production of working face.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.99)
A BSTRACT: In order to investigate into mechanical characteristics of rock surrounding entry with using bolt support system technology to control rock stability in large dip coal seams (LDCS) whose obliquity are from 25° to 45°, self-design rotatable experimental frame of similar material simulation was used to build the 30° model of solid-side entry based on analyzing geological and technological conditions in Huainan coal mines. Excavating and mining induced stress development, deformation characteristics, and breakage modes of rock surrounding gateway in LDCS have been synthetically analyzed. Results show that, influenced by large dip, asymmetrical characteristic of stress redistribution and deformation is to be serious and strata behaviors, such as roof falling and breaking, high-rib heaving and caving, floor heaving, and low-rib collapsing etc., are to be shrewd. All above utmost extent lead it is more difficultly to implement bolt support to control gateway rock stability in LDCSs mining. The high-rib and roof of entry in solid coal are the key sections to control in bolt support implementing. Effecting and Acting mechanism by large dip on mechanical characteristics of surrounding rock and bolt support system are opened. And it is also very important to improve support material, optimize support parameters, and enhance excavating management. 1. INTRODUCTION Coal seam obliquity increasing results in asymmetrical structure of extracting roadway and adds it is difficult to control rock stability while bolt support system is implemented, which limits safely and high-efficiently mining LDCS whose obliquity is from 25° to 45°.Simulation material physical experiment has been an important method and usually used to investigate into deformation, failure, and extracting-induced & mining-induced stress redistribution of rock. Also, the method has been applied to study mechanical characteristics of rock surrounding roadway with bolt support system and played active roles in mining engineering [1-10].
- Research Report > New Finding (0.68)
- Research Report > Experimental Study (0.49)