scholarly journals Research on the Mechanism of Main Roof Advanced Breaking and Supporting Technology When Long-wall Face Passing Through Abandoned Roadways

2021 ◽  
Author(s):  
Pan Weidong ◽  
Deng Cang ◽  
Li Boyang ◽  
Zhang Kunming ◽  
Gao Shan
Keyword(s):  
Underground Mining ◽  
Coal Pillar ◽  
Main Roof ◽  
Simulation Method ◽  
Critical Value ◽  
Ground Pressure ◽  
Restricted Problems ◽  
Mining Condition ◽  
Support Force ◽  
The Stability

Abstract Unlike general long-wall mining, the roof activity is more intense when long-wall face passes through the abandoned roadway. Technically, the coal pillar between the abandoned roadway and the long-wall face will suddenly fail with a certain critical value of its width, leading to the roof breaks in advance and other production-restricted problems because of the support loss, which will be a great threat to underground mining activities. In order to guarantee a safe mining condition, therefore, it is greatly necessary to uncover how the roof breaks in advance and how to cope with it. From the stability maintaining of the key block perspective, this paper took for research that the 12404-1 long-wall face of Wulanmulun coal mine, China. The critical value of the coal pillar’s width was determined to be about 5m by theoretical analysis, likely, the appropriate support force of the abandoned roadway’s roof is about 4020KN per meter. Meanwhile, a numerical simulation method was adopted to study the ground pressure when the long-wall face passing through the abandoned roadway. Correspondingly, a compound supporting technology involving the roof presplit technique, anchor cable supporting and pumping pillar supporting were proposed for the roof of the abandoned roadway, and it practically worked well.

scholarly journals Study on Overburden Stability and Development Height of Water Flowing Fractured Zone in Roadway Mining with Cemented Backfill

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yu Dong ◽  
Yucheng Huang ◽  
Jifang Du ◽  
Fei Zhao
Keyword(s):  
Empirical Formula ◽  
Mechanical Model ◽  
Fractured Rock ◽  
Coal Pillar ◽  
Main Roof ◽  
Mechanical Analysis ◽  
Overburden Rock ◽  
Fractured Zone ◽  
The Stability ◽  
Rock Beam

In order to explore the stability of overburden rock and the development height of water flowing fractured zone in roadway filling mining, based on the movement and deformation mechanism of overburden rock, the mechanical analysis of overburden stability and failure was carried out, and the mechanical model of main roof rock beam was established, and the ultimate span and limit deflection of rock beam fracture were deduced. Combined with the mechanical model of the main roof fractured rock, the basis for the judgment of overburden failure developing to fractured zone is given in this paper. Taking a coal mine roadway backfill under water-bearing stratum as an example, based on the equivalent mining height, the theoretical calculation and analysis are carried out on the stability of overburden rock and the height of water flowing fractured zone. The reliability of the theoretical analysis is verified compared with the empirical formula and the numerical simulation results. The results showed that the water flowing fractured zone developed to the bottom of no. 7 glutenite, with a height of 32.5 m, slightly less than the calculation result of the empirical formula. The thickness of the waterproof coal pillar was 39.8 m, which was much less than the distance from the aquifer to the coal seam and can be mined safely.

scholarly journals Stability Analysis of the Entry in a New Mining Approach Influenced by Roof Fracture Position

2019 ◽  
Vol 11 (22) ◽  
pp. 6349
Author(s):  
Jun Yang ◽  
Hongyu Wang ◽  
Yajun Wang ◽  
Binhui Liu ◽  
Shilin Hou ◽  
...  
Keyword(s):  
Coal Pillar ◽  
Main Roof ◽  
Surrounding Rock ◽  
Fracture Position ◽  
Solid Coal ◽  
Rock Structure ◽  
Temporary Support ◽  
Coal Wall ◽  
Pillar Mining ◽  
The Stability

Non-coal pillar mining with roadway formed automatically (RFANM) is a new mining approach, which demonstrates revolutionary significance because it does not require making roadway before mining and coal pillar retaining. In order to explore the stability of the surrounding rock structure in RFANM, the deformation of the surrounding rock was theoretically analyzed and simulated based on three different fracture positions of the main roof. It was concluded that reasonable control of temporary support strength in roadway is of great importance to control the deformation of the entry. The deformation process of surrounding rock under different fracture positions in RFANM was simulated by using the Universal Discrete Element Code (UDEC). The results of the numerical simulation showed that the main roof was fractured at the solid coal side or gob side; the deformation of the roadway was small. The fracture condition of the main roof at the gob side required a higher effect of roof slitting or temporary support from the roadway. Through drilling and peeping at the retained roadway, it was judged that the main roof was broken inside the coal wall. Field monitoring results revealed that the deformation of the roadway can be effectively controlled.

scholarly journals Accident Analysis in Relation to Main Roof Structure When Longwall Face Advances toward a Roadway: A Case Study

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Chang Liu ◽  
Zengqiang Yang ◽  
Peilin Gong ◽  
Kai Wang ◽  
Xiaoqiang Zhang ◽  
...  
Keyword(s):  
Sharp Increase ◽  
Coal Pillar ◽  
Main Roof ◽  
Mechanical Analysis ◽  
Longwall Face ◽  
Good Effect ◽  
Key Factors ◽  
Roof Structure ◽  
Similar Simulation Experiment ◽  
The Stability

Practices show that hydraulic supports crushing accidents or roadway supports failure often take place when a longwall face advances toward an abandoned roadway or a predriven equipment recovery room. Therefore, a 2D similar simulation experiment is conducted to reveal the loading mechanism. The result shows that when the workface advances close to roadways, the main roof breaks ahead of the workface and leads to instability of higher strata. These two changes induce a sharp increase of the load on supports and lead to an accident. Thus, more attention should be paid to the advanced fracture. Therefore, mechanical analysis is used to explain the advanced fracture. Results show that the failure of coal pillar being excavated induces a sharp increase in the main roof’s hanging length. Once the hanging length reaches the limit, the advanced fracture takes place. Therefore, the stability of the coal pillar and the hanging length of roof strata are two key factors that may induce an accident. To prevent the a similar supports crushing accident, the partial backfilled technology which partly backfills the abandoned roadway in height and length to maintain the stability of the coal pillar is put forward and put into practice. The field test shows a good effect.

Study of the Effect of Mining with Transition from Open-Pit to Underground and without Protective Coal Pillar on Slope Stability

2014 ◽  
Vol 1010-1012 ◽  
pp. 1475-1481
Author(s):  
Shi Guo Sun ◽  
Yanan Yi ◽  
Lu Jin ◽  
Jia Huan Shi
Keyword(s):  
Slope Stability ◽  
Slope Failure ◽  
Underground Mining ◽  
Coal Pillar ◽  
Simulation Method ◽  
Mining Area ◽  
Control Measures ◽  
Open Pit ◽  
Rock Body ◽  
Mining Scheme

As this mining area has a shallow coal seam and a dump, therefore, the mining for the deep resources uses the method of transition from open-pit to underground without protective coal column. In this paper, the numerical simulation method is used to analysis the surface subsidence and slope stability from the two different mining schemes which are from inside to outside, and from outside to inside, in order to obtain the optimization of mining scheme. And settlement and slope stability of rock body are further analyzed from two aspects of fully exploit from the tendency and from toward, the result of an overall slip slope failure caused by underground mining is found. So that in the process of exploitation, corresponding prevention and control measures to the slope safety has been put forward, ensuring smooth production.

Numerical Simulation of Ground Pressure Activity Caused by Orebody Mining under Road

2012 ◽  
Vol 462 ◽  
pp. 407-412
Author(s):  
Zong Hong Zhou ◽  
Ke Peng Hou ◽  
Feng Yu Ren
Keyword(s):  
Numerical Simulation ◽  
Underground Mining ◽  
Ground Deformation ◽  
Hanging Wall ◽  
Simulation Method ◽  
Wall Rock ◽  
Control Measures ◽  
Road Transportation ◽  
The Road ◽  
Ground Pressure

There is the Jinggu-Minle road to cross through the No. 3 ore clusters in Songjiapo copper mine. The surface ground deformation and strata movement caused by underground mining will threaten the road transportation safety, which doesn’t allow collapse. Using numerical simulation method, the ground pressure activity and deformation, movement mechanism of strata were analyzed under different mining methods. Moreover, some control measures such as reserving insulating pillar and point pillars were put forward to maintain the stability of mined-out areas and the surface road. An optimal mining scheme was recommended. The results showed that the mining process of No. 3 ore clusters can’t cause direct failure to road, and the failure of hanging wall rock will have indirect influence to the road with the lapse of time. Reserving the insulating pillar, top pillar and point pillars can effectively reduce the plastic area range of hanging wall and strata failure in the mining process. The results can provide theoretical basis for the actual mining design and rock strata control.

Optimization of Stope Structural Parameters in Phosphorite Mine and its Stability Analysis

2014 ◽  
Vol 580-583 ◽  
pp. 1268-1272 ◽  
Author(s):  
Xiang Xing Li ◽  
Ke Gang Li
Keyword(s):  
Structural Parameters ◽  
Simulation Method ◽  
Surrounding Rock ◽  
Room And Pillar Mining ◽  
Rock Stability ◽  
Mining Depth ◽  
Ground Pressure ◽  
Pillar Mining ◽  
Phosphate Deposit ◽  
The Stability

A mine plans to exploit the low dip thin phosphate deposit by room-and-pillar mining. But a township highway is just above the orebody, and its distance is only 80m, in order to better control the ground pressure in stopes and ensure the operation security, the size of room and pillar must be reasonably designed to maintain the stability of stopes and surrounding rock. The 3D-σ numerical simulation method was applied to analyze the surrounding rock stability in different stope structure parameters. The results show that when holding the size of pointed prop unchanged, the surrounding rock stability would decline with the increase of room width and pillar spacing, for security, the mining plan, the pointed prop is 3×3 m, the stope width and pillar spacing is not more than 9 m, were considered to be one of the optimal. In addition, it is important to emphasize that if the mining depth exceeds 300m, some methods, such as decreasing the spacing of stope and pointed props or increasing the pillar size, need to be taken to avoid the stope instability caused by greater ground pressure.

scholarly journals Study on the Stability of Coal Pillars Under the Disturbance of Repeated Mining in a Double-Roadway Layout System

2021 ◽  
Vol 9 ◽  
Author(s):  
Shuaigang Liu ◽  
Jianbiao Bai ◽  
Xiangyu Wang ◽  
Guanghui Wang ◽  
Bowen Wu ◽  
...  
Keyword(s):  
Coal Pillar ◽  
Simulation Method ◽  
Calculation Model ◽  
Internal Damage ◽  
Damage Area ◽  
Technical Parameters ◽  
Supporting Structure ◽  
Transportation Capacity ◽  
Combined Control ◽  
The Stability

The double-roadway layout system, which is extensively applied in large mines, has the potential to significantly balance excavation-mining and improve mine ventilation and transportation capacity. However, the coal pillar in the double-roadway layout system is easily destabilized due to the disturbance of repeated mining, which has a significant impact on the safety and reliability of coal mines. This paper takes the coal pillar and its supporting structure of the double-roadway layout system as the research object, establishes a UDEC trigon numerical calculation model, and systematically corrects the input parameters, while explaining the excavation method of roadways and the simulation method of the supporting structure element. The numerical simulation results show that under the conventional support intensity conditions, the internal damage of the coal pillar during the excavation period is about 20%, while the internal damage to the coal pillar develops to 55% throughout the first-panel mining. During the disturbance of repeated mining, the damage in the coal pillar increased to 90%, and the coal pillar was already in a state of failure. Under the combined control of rock bolts and counter-pulled anchor cables, the coal pillar damage does not change significantly during the excavation and first-panel mining. During the disturbance of repeated mining, the damage of the coal pillar is reduced to 63%. There is a certain low damage area in the coal pillar, which can ensure the stability of the coal pillar and its supporting structure as a whole. Furthermore, the on-site monitoring results show that the maximum value of the floor-to-roof and rib-to-rib convergence of a W1310 tailgate during the repeated mining disturbance stage is 730 and 620 mm, respectively. The findings of this study give an approach to—as well as estimated values for the design of, including its “small structure” control technical parameters—the double-roadway layout system.

Stability Evaluation and Safety Monitoring of Pressure in Yichang Phosphorus Mine

2012 ◽  
Vol 170-173 ◽  
pp. 589-592
Author(s):  
Yun Xiao ◽  
Xian Fu Li ◽  
Bin Tian ◽  
Jia Guo Wang
Keyword(s):  
Underground Mining ◽  
Element Model ◽  
Automatic Monitoring ◽  
Test Collection ◽  
Stability Evaluation ◽  
Automatic Monitoring System ◽  
Ground Pressure ◽  
Mining Conditions ◽  
The Stability ◽  
Matter Element Model

The disasters dynamics and security of phosphate are important problems in Phosphorus ore-deposit mining. So monitoring in unstable, hazardous areas and goaf can effectively focus on the activities of ground pressure. Based on mine-site exploration, engineering test, collection of physical and mechanical parameters for ore, research of geology and mining conditions, the main controlling factors of ground pressure were identified. Combining practical projects, the fuzzy matter-element model of stability evaluation on ground pressure in empty areas was built and analyzed, which showed the good agreement with the evaluation results and measured values. At the same time, based on the stability of underground mining partition, automatic monitoring system of phosphate was constructed, which may provide some useful advices for the safety study of ground pressure in phosphate rock mass.

Microseismic Monitoring and Disasters Control of a Large Range of Underground Mining

2012 ◽  
Vol 616-618 ◽  
pp. 320-325
Author(s):  
Xian Wei Luo ◽  
Feng Gao
Keyword(s):  
Large Range ◽  
Underground Mining ◽  
Mining Area ◽  
Microseismic Monitoring ◽  
Field Application ◽  
Ground Pressure ◽  
Ore Body ◽  
Mining Condition ◽  
Disaster Monitoring ◽  
And Control

In order to minimize the threat of ground pressure disasters, this paper introduces the work of microseismic monitoring based on analyzing a large range of mining condition of No.92 ore body of Tongkeng Tin Mine. A system of microseismic and ground pressure disaster monitoring in the range of No.92 ore body mining area is established by using three 12-channel of rock accoustic emission equipments and a 24-channel microseismic monitoring system, combined with ordinary surrounding rock pressure and displacement monitoring instruments. Data acquisition, analysis and treatment are automatically. Field application shows that many ground pressure activities are monitored effectively by analyzing the rock acoustic emission at different energy and the moving law of overlying strata. The technology provides a reliable support to early warning and control of ground pressure disasters.

scholarly journals Rock pressure relief is the basic alternative for sustainable underground mining

2021 ◽  
Vol 280 ◽  
pp. 08020
Author(s):  
Victor Nazimko ◽  
Ludmila Zakharova ◽  
Alexey Kusen ◽  
Syd Peng
Keyword(s):  
Longwall Mining ◽  
Underground Mining ◽  
Computer Code ◽  
Stress Relief ◽  
Coal Seams ◽  
Mining Depth ◽  
Steady Growth ◽  
Ground Pressure ◽  
The Stability ◽  
Basic Alternative

Retreat longwall mining is the most productive system for underground extraction of tabulated deposits. However, the steady growth of the mining depth dramatically increased the ground pressure in chain pillars protecting the longwall entries. Therefore, several coal industries have tried to shift to pillarless mining and practiced maintenance of the head or tail entry behind the longwall in the stress relief zones using the backfill bodies in the thin coal seams. We modernized the pillarless variant of the retreat longwall system introducing the third roadway, which is driven in the consolidated goaf behind the moving longwall in a stress relief zone. We used a computer code FLAC3D to simulate stress redistribution during pillarless extraction of adjacent panels that assisted to determine optimal parameters of mining layout. This modernized technology provides for sustainable mining due to enhancement of transport, ventilation, safety conditions, and a comfortable environment because of the stability of the underground roadways, which serve the high productive longwalls.

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