scholarly journals Research of Roof Anchorage Rock Beam Bearing Structure Model of Extra-Large Width Open-Off Cut and Its Engineering Application in a Coal Mine, China

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Shengrong Xie ◽  
Qing Zhang ◽  
Dongdong Chen ◽  
En Wang ◽  
Junchao Zeng ◽  
...  
Keyword(s):  
Influencing Factors ◽  
Coal Mine ◽  
Roadway Stability ◽  
Geological Conditions ◽  
Longwall Panel ◽  
Stress Changes ◽  
Backfill Mining ◽  
Large Width ◽  
Bearing Structure ◽  
Rock Beam

The stability of the extra-large width open-off cut of a longwall panel has been a major concern in underground solid backfill mining. In this study, a numerical model was built with FLAC3D for analyzing the characteristics of the effective prestressed field distribution in the extra-large width open-off cut roof in Xingdong coal mine, China. The numerical results obtained in this study demonstrate that an anchorage rock beam bearing structure (ARBBS) can be formed. Additionally, the ARBBS model was also constructed. The analytical expression of the maximum shear stress (MSS) in the model was obtained under the functions of composite influencing factors. Then, the MSS evolution laws in ARBBS with different thicknesses and spans were investigated using MATLAB software. The stress changes in ARBBS with a span of 15 m were compared and analyzed under the functions of single and composite influencing factors. The cooperative control principle of the roof ARBBS and two rib anchorage bearing structures was also clarified. Accordingly, a combined support scheme for an 11.5 m-wide open-off cut was proposed. The field applications demonstrated that the scheme successfully controlled the failure and deformation of the surrounding rock, thus contributing to the fast development of the open-off cut and the quick and timely installations of the backfill mining equipment. This validated the results of the ARBBS model. This study is expected to provide helpful references for other extra-large width open-off cut or roadway stability investigations and rock support design under similar engineering and geological conditions.

scholarly journals Dynamic Monitoring of the Water Flowing Fractured Zone during the Mining Process under a River

2018 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Shuai Chang ◽  
Zhen Yang ◽  
Changfang Guo ◽  
Zhanyuan Ma ◽  
Xiang Wu
Keyword(s):  
Water Flow ◽  
Coal Mine ◽  
Water Inrush ◽  
Unconfined Aquifer ◽  
Coal Extraction ◽  
Fractured Zone ◽  
Transient Electromagnetic ◽  
Geological Conditions ◽  
Longwall Panel ◽  
Flow Mechanisms

The hydrogeological conditions of coal mines in China are quite complex, and water inrush accidents occur frequently with disastrous consequences during coal extraction. Among them, the risk of coal mining under a river is the highest due to the high water transmissivity and lateral charge capacity of the unconfined aquifer under the river. The danger of mining under a river requires the accurate determination of the developmental mechanisms of the water flowing fractured zone (WFFZ) and the water flow mechanisms influenced by the specific geological conditions of a coal mine. This paper first used the transient electromagnetic (TEM) method to monitor the development of the WFFZ and the water flow mechanisms following the mining of a longwall face under a river. The TEM survey results showed that the middle Jurassic coarse sandstone aquifer and the Klzh unconfined aquifer were the main aquifers of the 8101 longwall panel, and the WFFZ reached the aquifers during the mining process. Due to the limited water reserves in the dry season, the downward flowing water mainly came from the lateral recharge in the aquifer. The water inrush mechanisms of the 8101 longwall panel in Selian No.1 Coal mine were analyzed based on the water flow mechanisms of the aquifer and the numerical simulation results. This provides theoretical and technical guidance to enact safety measures for mining beneath aquifers.

scholarly journals A Case Study on Large Deformation Failure Mechanism of Coal given Chamber and Invention of a New Wall-Mounted Coal Bunker in Xiashijie Coal Mine with Soft, Swelling Floor Rock

2017 ◽  
Author(s):  
Xingkai Wang ◽  
Wenbing Xie ◽  
Shengguo Jing ◽  
Jianbiao Bai ◽  
Zhili Su
Keyword(s):  
Failure Mechanism ◽  
Coal Mine ◽  
Numerical Models ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Floor Rock ◽  
Geological Conditions ◽  
Floor Heave ◽  
The Stability ◽  
Bearing Structure

Serious damage caused by floor heave in the coal given chamber of a vertical coal bunker is one of the challenges faced in underground coal mines. Engineering practice shows that it is more difficult to maintain the coal given chamber (CGC) than a roadway. More importantly, repairing the CGC during mining practice will pose major safety risks and reduce production. Based on the case of the serious collapse that occurred in the bearing structure of the CGC at the lower part of the 214# coal bunker in Xiashijie mine, China, this work analysed (i) the main factors influencing floor heave and (ii) the failure mechanism of the load-bearing structure in the CGC using FLAC2D numerical models and expansion experiment. The analysis results indicate that: the floor heave, caused mainly by mine water, is the basic reason leading to the instability and repeated failure of the CGC in the 214# coal bunker. Then a new coal bunker, without building the CGC, is proposed and put into practice to replace the 214# coal bunker. The FLAC3D software program is adopted to establish the numerical model of the wall-mounted coal bunker (WMCB), and the stability of the rock surrounding the WMCB is simulated and analysed. The results show that: (1) the rock surrounding the sandstone segment is basically stable. (2) The surrounding rock in the coal seam segment, which moves into the inside of the bunker, is the main zone of deformation for the entire rock mass surrounding the bunker. Then the surrounding rock is controlled effectively by means of high-strength bolt–cable combined supporting technology. According to the geological conditions of the WMCB, the self-bearing system, which includes (i) H-steel beams, (ii) H-steel brackets, and (iii) self-locking anchor cables, is established and serves as a substitute for the CGC to transfer the whole weight of the bunker to stable surrounding rock. The stability of the new coal bunker has been verified by field testing, and the coal mine has gained economic benefit to a value of 158.026174 million RMB over three years. The new WMCB thus made production more effective and can provide helpful references for construction of vertical bunkers under similar geological conditions.

Similarity simulation study on displacement and stress changes response to coal mining in Longdong coal mine, China

2020 ◽  
pp. qjegh2020-111
Author(s):  
Kai Huang ◽  
Long Xu ◽  
Fusheng Zha ◽  
Zhitang Lu ◽  
Jiwen Wu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Water Inrush ◽  
Coal Pillar ◽  
Working Face ◽  
Field Investigations ◽  
Geological Conditions ◽  
Stress Changes ◽  
Continuous Mining ◽  
The Stability

The complicated geological conditions, including the Fault Sun, in East No. 2 mining sub-area of the Longdong coal mine will influence the stability of strata during mining, leading to serious geological hazards. To circumvent this issue, a similarity simulation experiment was designed and performed in this study, in which the failure characteristics and evolution of displacement and stress within the strata were investigated, and the optimum width of a waterproof coal pillar was determined. The results showed that, as the working face progressed, the coal seam roof gradually deformed, from initial caving of the immediate roof to complete movement and curved subsidence of the entire roof. Significant changes in displacement and stress within the coal seam roof were recorded, and these increased during continuous mining activity. Displacement and stress difference on either side of the fault gradually increased and reached remarkable values with increase in mining distance. On the basis of the experiment results, water inrush is believed to be caused by the interaction between mining and the fault, and, as calculated from parameters collected in field investigations, a waterproof coal pillar of 50 m width should be established to prevent Fault Sun activation, thereby reducing the risk of water inrush from neighbouring aquifers.

scholarly journals Evolution of Interior and Exterior Bearing Structures of the Deep-Soft-Rock Roadway: From Theory to Field Test in the Pingdingshan Mining Area

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4357
Author(s):  
Qingxian Huang ◽  
Xufeng Wang ◽  
Xuyang Chen ◽  
Dongdong Qin ◽  
Zechao Chang
Keyword(s):  
Field Test ◽  
Soft Rock ◽  
Field Measurements ◽  
Mining Area ◽  
Surrounding Rock ◽  
Roadway Stability ◽  
Geological Conditions ◽  
Soft Rock Roadway ◽  
Bearing Structure ◽  
Rock Roadway

Pingdingshan mining area is one of the typical deep mining areas in China, and most of the mines in this area are troubled by the difficulties of the deep-soft-rock roadway support. Based on the concept of synergistic interactions of the interior and exterior bearing structure of the surrounding rock and, considering the specific geological conditions of the research site, we establish the mechanical model of the interior and exterior bearing structure of the roadway. Based on numerical simulation, we reveal the influence of main factors, such as support strength and mechanical characteristics, of surrounding rock on the distribution and evolution of the interior and exterior bearing structure. We found that increasing the support strength and mechanical parameters of surrounding rock can make the exterior bearing structure close to the roadway enhance the bearing characteristics of the interior and exterior bearing structure and improve the roadway stability. The distribution characteristics of the interior and exterior bearing structure of the roadway under six different support strengths and six different grouting parameters were systematically investigated by field measurements. According to the field test results, an effective strategy for controlling the deep-soft-rock roadway is proposed, which provides a good reference for surrounding rock control of the deep-soft-rock roadway in the Pingdingshan mining area and mines with similar mining conditions.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

scholarly journals Substantiation of Safe Conditions During Undermining of Hydraulic Waste Disposal

2018 ◽  
Vol 41 ◽  
pp. 01007
Author(s):  
Yuriy Kutepov ◽  
Aleksandr Mironov ◽  
Maksim Sablin ◽  
Elena Borger
Keyword(s):  
Rock Mass ◽  
Waste Disposal ◽  
Coal Mine ◽  
Water Body ◽  
Water Inflow ◽  
Open Pit ◽  
Coal Seams ◽  
Geological Conditions ◽  
Mine Workings ◽  
Mine Dump

This article considers mining and geological conditions of the site “Blagodatny” of the mine named after A.D. Ruban located underneaththe old open pit coal mine and the hydraulic-mine dump. The potentially dangerous zones in the undermined rock mass have been identified based onthe conditions of formation of water inflow into mine workings. Safe depthof coal seams mining has been calculated depending on the type of water body – the hydraulic-mine dump.

Study on Stability for Intersection of Deep Soft Rock Roadway

2011 ◽  
Vol 243-249 ◽  
pp. 2666-2669
Author(s):  
Zhan Jin Li ◽  
Yang Zhang ◽  
Xue Li Zhao
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Intersection Problem ◽  
The Third ◽  
Geological Conditions ◽  
Control Stability ◽  
Soft Rock Roadway ◽  
Crossing Point ◽  
Coupling Support ◽  
Rock Roadway

With the depth increasing continuously, more complicated of geological conditions, will make intersection in deep soft rock roadway is very difficult to support. In order to solve the intersection problem of difficult to support, combined with the third levels of the Fifth Coal Mine of Hemei, the coupling supporting design—anchor-mesh-cable + truss to control stability of crossing point—is proposed. Based software of FLAC3D, simulate the program applicable in deep soft rock roadway intersection. Application results show that the coupling support technology of anchor-mesh-cable + truss can effectively control the deformation of intersection in deep soft rock roadway.

scholarly journals A Cross-Sectional Epidemiological Survey of Work-Related Musculoskeletal Disorders and Analysis of Its Influencing Factors among Coal Mine Workers in Xinjiang

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xianting Yong ◽  
Fuye Li ◽  
Hua Ge ◽  
Xuemei Sun ◽  
Xiaofan Ma ◽  
...  
Keyword(s):  
Musculoskeletal Disorders ◽  
Influencing Factors ◽  
Coal Mine ◽  
Job Burnout ◽  
Work Related ◽  
Annual Prevalence ◽  
Short Period ◽  
Work Related Musculoskeletal Disorders ◽  
Years Of Service ◽  
Mine Workers

This study is to investigate the prevalence of work-related musculoskeletal disorders (MSDs) and the influencing factors among coal mine workers employed in on-site operations. The job burnout scale and MSD scale were implemented to investigate a random sample of 1,500 coal mine workers working in on-site operations in Xinjiang, China. In total, 1,325 valid questionnaires were collected, with a recovery rate of 88.33% (1,325/1,500). The rate of job burnout was 90%, of which 39.8% were categorized as mild burnout, 43.8% as moderate burnout, and 6.4% as severe burnout; the average job burnout score was 50.77±11.93. The annual prevalence of MSDs was 65.6%, with the highest annual prevalence in the waist (50.7%), followed by the neck, shoulder, and knee, and the lowest prevalence in the elbow (18.8%). Of the areas of the body affected by work-related MSDs, the highest proportion of requests for leave of absence was related to the waist, accounting for 25.7% of requests, while the lowest proportion (13.4%) was related to the wrist. In addition, the incidence of MSDs increased with the years of service. The lowest incidence of MSDs was associated with the two-shift and three-group working pattern. The prevalence of MSDs in the neck and waist was higher in women than in men. The prevalence of MSDs in various body parts increased with the years of service. Moreover, multiple logistic regression indicated that three shifts with four groups (OR=1.096, 95% CI: 0.832-1.445), working more than 10 years (OR=3.396, 95% CI: 2.369-5.748), working more than 20 years (OR=3.008, 95% CI: 1.419-6.337), significant bending (OR=2.062, 95% CI: 1.400-3.038), forward neck tilting (OR=1.572, 95% CI: 1.071-2.281), maximum force operation within a short period of time (OR=1.7222, 95% CI: 1.164-2.547), repeated movement of upper arms or fingers (OR=1.495, 95% CI: 1.034-2.161), slip or fall incidents (OR=1.124, 95% CI: 1.039-1.216), work under conditions of cold or temperature variations (OR=1.911, 95% CI: 1.342-2.720), mild burnout (OR=1.492, 95% CI: 1.016-2.191), moderate burnout (OR=1.852, 95% CI: 1.267-2.708), and severe burnout (OR=2.001, 95% CI: 1.145-3.496) were risk factors for MSDs. In conclusion, there is a high annual prevalence of MSDs among the coal mine workers employed in on-site operations in Xinjiang, China. Measures to reduce this prevalence are required.

scholarly journals A Fiber Bragg Grating Borehole Deformation Sensor for Stress Measurement in Coal Mine Rock

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3267 ◽  
Author(s):  
Wusheng Zhao ◽  
Kun Zhong ◽  
Weizhong Chen
Keyword(s):  
Optical Fiber ◽  
Coal Mine ◽  
Stress Measurement ◽  
Mechanical Load ◽  
Field Tests ◽  
Test Accuracy ◽  
Stress Monitoring ◽  
Stress Changes ◽  
Term Performance

A borehole deformation sensor for long-term stress monitoring in coal mine rock based on optical fiber Bragg gratings (FBGs) is presented. The sensor converts borehole deformation into optical fiber strain by using four rings. For each ring, two FBGs are bonded with the ring to measure the borehole deformation, and a reference FBG free from mechanical load is introduced to remove the temperature effect. Two simple checks on the test data can be performed to improve the test accuracy. Laboratory and field tests were conducted to validate the accuracy and long-term performance of the sensor. The results show that the sensor is capable of measuring stress in rock with good accuracy, and it performs well over a long period of time in coal mines. The developed sensor provides an approach for the long-term monitoring of stress changes in coal mine rock.

scholarly journals Reference P-wave velocity in coal seams at great depths in Jastrzebie coal mine

2019 ◽  
Vol 133 ◽  
pp. 01011
Author(s):  
Jakub Kokowski ◽  
Zbigniew Szreder ◽  
Elżbieta Pilecka
Keyword(s):  
Wave Velocity ◽  
Coal Mine ◽  
Velocity Model ◽  
P Wave ◽  
Coal Seams ◽  
Data Set ◽  
Seismic Profiling ◽  
Reference Velocity ◽  
P Wave Velocity ◽  
Geological Conditions

In the study, the determining of the reference velocity of the P-wave in coal seams used in seismic profiling to assess increases and decreases in relative stresses at large depths has been presented. The seismic profiling method proposed by Dubinski in 1989 covers a range of depth up to 970 m. At present, coal seams exploitation in Polish coal mines is conducted at greater depths, even exceeding 1200 m, which creates the necessity for a new reference velocity model. The study presents an empirical mathematical model of the change of the P-wave velocity in coal seams in the geological conditions of the Jastrzebie coal mine. A power model analogous to the Dubinski’s one was elaborated with new constants. The calculations included the results from 35 measurements of seismic profiling carried out in various coal seams of the Jastrzebie mine at depths from 640 to 1200 m. The results obtained cause changes in the result of calculations of seismic anomalies. Future validation of the proposed model with larger data set will be required.

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