scholarly journals The Spatiotemporal Characteristics of Coupling Effect between Roof and Backfill Body in Dense Backfill Mining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xinyuan Zhao ◽  
Xinwang Li ◽  
Ke Yang ◽  
Zhen Wei
Keyword(s):  
Coupling Effect ◽  
Coal Pillar ◽  
Simulation Test ◽  
Spatiotemporal Characteristics ◽  
Coupling Behavior ◽  
Backfill Mining ◽  
Similar Simulation Test ◽  
Body Support ◽  
Observation Results ◽  
Similar Simulation

Backfill mining has become an important part of coal mine green mining technology. In this paper, the spatiotemporal characteristics of coupling effect between the roof and dense backfill body were analyzed by theoretical analysis and similar simulation test, and Xingtai Mine in China was taken as an engineering case for verification. The results show that the larger subsidence of the roof is, the stronger the supporting capacity of the backfill body is, and the interaction between the two is more obvious, thus showing a coupling effect. This coupling effect presents a regular variation with the increase of backfill distance and time, that is, the coupling degree of roof and backfill body is high in the middle of goaf and low in the vicinity of the coal pillar in spatial distribution, and the coupling behavior of roof and backfill body continues to occur slowly with time. Through the monitoring of stress and displacement in the engineering site and the analysis of borehole observation results, the spatiotemporal coupling effect between roof subsidence and backfill support is fully verified. The research results are of great significance to the control of surrounding rock in backfill mining, the study of the mechanical aging characteristics of backfilling materials, and the optimization of backfill body support performance.

Strata Behaviors of Fully-Mechanized Sublevel Caving Face Based on Similar Simulation Test

2013 ◽  
Vol 734-737 ◽  
pp. 638-643
Author(s):  
Hua Wen Lv
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Test Model ◽  
Simulation Test ◽  
Slow Increase ◽  
Working Face ◽  
Sublevel Caving ◽  
Pressure Peak ◽  
Similar Simulation Test ◽  
Similar Simulation

in view of research situations of the fully mechanized sublevel caving, the similar simulation test model for fully mechanized sublevel caving was presented. During the top-coal caving process, variation of top-coal subsidence and abutment pressure were measured. Consequently, the ground pressure behavior of fully mechanized sublevel caving was analyzed. The following conclusions can be reached: (1) top coal subsidence experiences the process of slow increase, trend to aggressive and sharp increase; (2) undulate change as well as decay after reaching the peak of abutment pressure is appeared with the advance of working face, strata behaviors of main roof displays smoothly; (3) on account of cushion above hydraulic support, influence of dynamic load during periodic weighting such as rock burst can be eased and abutment pressure peak moves forward, consequently, strata behaviors in the working face presents smoothly.

scholarly journals Physical Modeling of the Controlled Water-Flowing Fracture Development during Short-Wall Block Backfill Mining

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Yun Zhang ◽  
Yongzi Liu ◽  
Xingping Lai ◽  
Jianming Gao
Keyword(s):  
Coal Pillar ◽  
Similarity Criterion ◽  
Test Results ◽  
Control Effect ◽  
Physical Similarity ◽  
Wall Block ◽  
Fracture Development ◽  
Backfill Mining ◽  
Backfill Materials ◽  
Overlying Strata

Abstract Short-wall block backfill mining (SBBM) technology is an effective method to solve the environmental problems in the mining process. Based on the technical characteristics of SBBM technology and the physical similarity criterion, the physical similarity models for comparing the control effects of water-flowing fracture (WFF) development using short-wall block cave mining (SBCM) and SBBM were established, and the deformation and the WFF development of overlying strata above gob were monitored. The test results determined that the composite materials of 5 mm thick pearl sponge+5 mm thick sponge+10 mm thick paper+6 mm thick board were adopted as the similar backfill materials by comparing the stress-strain curves between the similar backfill materials and the original gangue sample. When the backfilling body was filled into the gob, it would be the permanent bearing body, which bore the load of the overlying strata accompanied with the protective coal pillar. At the same time, the backfilling body also filled the collapse space of overlying strata, which was equivalent to reduce the mining height, and effectively reduced the subsidence and failure height of the overlying strata. Compared with SBCM, the test results showed that the maximum vertical deformation, the height of water-flowing fractured zone, and activity range of overlying strata using SBBM were reduced by 91.4%, 82.5%, and 64.9%, respectively. SBBM had a significant control effect on strata damage and WFF development, which could realize the purpose of water resource protection in coal mines.

scholarly journals Application of Roadway Backfill Mining in Water-Conservation Coal Mining: A Case Study in Northern Shaanxi, China

2019 ◽  
Vol 11 (13) ◽  
pp. 3719 ◽  
Author(s):  
Yihe Yu ◽  
Liqiang Ma
Keyword(s):  
Water Resources ◽  
Coal Mining ◽  
Groundwater Level ◽  
Water Conservation ◽  
Coal Pillar ◽  
Normal Growth ◽  
Mining Area ◽  
Backfill Mining ◽  
Northern Shaanxi ◽  
The Stability

The mining induced subsidence and strata deformation are likely to affect the stability of the aquiclude, resulting in loss of water resources in the mining area. In order to reduce the disturbance of coal mining to the overlying strata and to preserve the water resources in the coal mining area, the roadway backfill mining (RBM) method was trialed in Yuyang coal mine in Northern Shaanxi, China. Based on pressure arch theory and ultimate strength theory, a mechanical model was developed to analyze the stability of coal pillars. Then the maximum number of vacant roadways between the mining face and the backfilling face was determined according to the stability of coal pillar and filling body. The method to calculate aquiclude subsidence and deformation was also proposed. Furthermore, as indicated by FLAC3D numerical simulations, the maximum tensile stress subjected by the aquiclude was 0.14 MPa, which is smaller than its tensile strength; the horizontal deformation was 0.24 mm/m, which is also smaller than the critical deformation of failure. Field monitoring data demonstrated a maximum of 2.76 m groundwater level drop in the mining area after mining. The groundwater level was determined to be 4.45~10.83 m below surface, ensuring the normal growth of surface vegetation and realizing the water-conservation coal mining (WCCM).

Experimental Study on Wide Strip Mining with Similar Simulation under Deep-Lying Seams

2013 ◽  
Vol 295-298 ◽  
pp. 3318-3322
Author(s):  
Bao Bin Gao ◽  
Lin Li ◽  
Hui Gui Li
Keyword(s):  
Coal Pillar ◽  
Material Model ◽  
Mining Area ◽  
Scientific Basis ◽  
Ground Movement ◽  
Strip Mining ◽  
Key Strata ◽  
Wide Strip ◽  
Subsidence Basin ◽  
Similar Simulation

The ground movement laws due to wide strip mining under deep-lying seams has been studied with the experiment of similar material model, and the results of experiment could analysis qualitatively that it is feasible for wide strip mining under deep-lying seams. Taking 25 mining area of Hemei 9th mine as geologic background, the model of wide strip mining under deep seams has been made, which was used to study on the deformation of overburden and the ground movement laws. The results of experiment show that the properties and thickness of strata play a control role on the deformation, and the key strata play a core role; the deformation was dispersed with wide strip mining. When the width of strip mining and protective coal pillar are scientific and reasonable, the purpose of increasing the width of strip mining under the condition of controlling deformation could be achieved, and the entire mining area would be formed a flat subsidence basin. These achievements provide a scientific basis for solving the problem for the ground buildings protection in the conditions of wide strip mining under deep-lying seams, and that also provide some references for further studying on the method of wide strip mining under deep-lying seams.

scholarly journals Research on the Reasonable Coal Pillar Width and Surrounding Rock Supporting Optimization of Gob-Side Entry under Inclined Seam Condition

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Li-li Jiang ◽  
Zeng-qiang Yang ◽  
Gang-wei Li
Keyword(s):  
Stress Field ◽  
Control Mechanism ◽  
Coupling Effect ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Control Technology ◽  
Pillar Width ◽  
Monitoring Methods ◽  
Anchor Cable ◽  
Surrounding Rock Control

In order to study the optimal coal pillar width and surrounding rock control mechanism of gob-side entry under inclined seam condition, the 130205 return air entry adjacent to 130203 gob in Yangchangwan No. 1 well is taken as a typical engineering background. By means of engineering background analysis, theoretical analysis based on inside and outside stress field, numerical simulation by FLAC3D software, and in situ industrial test and relevant monitoring methods, the optimal coal pillar width and surrounding rock control technology are obtained. The results show that the influence range of inside stress field is about 12.2∼12.8 m based on theoretical calculation result; under the influence of 10 m coal column, the overall deformation of the roadway is relatively small and within the reasonable range of engineering construction, so the width of the coal pillar along the return air roadway is set to 10 m which is more reasonable; the cross-section characteristics of special-shaped roadway lead to asymmetric stress distribution and fragmentation of surrounding rock, and then the asymmetric surrounding rock control technology under the coupling effect of roof prestressed anchor + high-strength single anchor cable + truss anchor cable support is proposed. The monitoring results of this support method are effective for the maintenance of gob-side entry, and the study conclusions provide new guidance for the surrounding rock control mechanism of gob-side entry under inclined seam conditions.

scholarly journals Stability of Coal Pillar and Roof Movement Characteristics in Roadway Backfill Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Hai Lin ◽  
Renshu Yang ◽  
Yongliang Li ◽  
Shizheng Fang
Keyword(s):  
Mechanical Model ◽  
Maximum Stress ◽  
Coal Pillar ◽  
Engineering Practice ◽  
Alternate Bearing ◽  
Local Pressure ◽  
Immediate Roof ◽  
Backfill Mining ◽  
Coal Pillars ◽  
The Stability

In order to explore the stability of coal pillar and the characteristics of roof movement during the process of roadway backfill mining (RBM), the 301 backfilling test working face of Ordos Chahasu coal mine is taken as the background. Based on the expansive pressure arch theory, the evolution process of the stope expansive pressure arch in RBM is studied; by establishing a mechanical model for the stability of coal pillars, the interactions between the height, width, and the maximum number of branches are obtained. When the width and height of the branch are both 5 m, the optimal number of the branches is obtained. Then, by establishing a mechanical model for the subsidence of the immediate roof, the process of the immediate roof subsidence is divided into three stages, namely, the formation stage of the local pressure arch, the merge stage of the pressure arch, and the expansion stage of the pressure arch. In addition, using the numerical method, the alternate bearing process of coal pillars and filling bodies and the change of the maximum supporting stress are studied, and the evolution of the pressure arch bearing structure above the stope and the staged subsidence characteristics of the roof are analyzed. The on-site test showed that the coal pillar has a good stability during the mining process. The maximum stress of the coal pillar is 16.5 MPa, and the maximum stress of the filling body is 9 MPa. The maximum settlement of the immediate roof is 102 mm, indicating that the roof control effect is good. This research will play an important role on engineering practice.

The Application Research on Backfill Mining Technology of Gangue for Coal Pillar Mining in Xingtai Mining Village

2010 ◽  
Vol 156-157 ◽  
pp. 225-231 ◽  
Author(s):  
Li Ma ◽  
Zi Wei Ding
Keyword(s):  
Fly Ash ◽  
Coal Pillar ◽  
Maximum Level ◽  
Application Research ◽  
Feed System ◽  
Mining Technology ◽  
Hydraulic Mining ◽  
Backfill Mining ◽  
The Face ◽  
Pillar Mining

Gangue and fly ash combined mining technology is the direct filling of the gangue and fly ash to the surface by the feed delivered to the face well, and then filling is in gob areas, while ensuring under the premise of the safe use of surface buildings subjects to the normal maximum level for achieving Coal Mining under the buildings. In the paper, gangue and fly ash on the exploitation of the feed system were designed for filling and compaction equipment, the hydraulic mining was developed on the backfill mining, the conveyor was modified, and the gangue and fly ash mining technology were designed. As the result, the filling rate and surface subsidence was controlled effectively, the service life of the mine was extended, and the good economic and social benefits were achieved.

A New Trip Fault of Transmission Line Caused by Lightning Striking to Ground Wire and Conductor Simultaneously

2014 ◽  
Vol 701-702 ◽  
pp. 1187-1193
Author(s):  
Qing Wu ◽  
Guan Jun Qian ◽  
Bin Hu ◽  
Song Huang ◽  
Xian He Dou ◽  
...  
Keyword(s):  
Transmission Line ◽  
High Speed ◽  
Lightning Protection ◽  
Simulation Test ◽  
Lightning Stroke ◽  
Intelligent Monitoring ◽  
Shielding Failure ◽  
Fault Type ◽  
Protection Method ◽  
Observation Results

Lightning strokes are the main cause for the trip fault of transmission line with a rated voltage of 110 kV and above. The counterattack trip and the shielding failure trip were thought to be the two kinds of fault type caused by lightning strokes. According to the development process of the two fault types, a few effective lightning protection methods are proposed. However, there is no relative report about the case that the ground wire and the conductor are stricken simultaneously. Therefore, no specific protection method is presented. In this paper, the possibility of the both stroke is analyzed, according the the mechanism of lightning stroke and the characteristics of lightning strokes. Then, a series of simulation test were designed and carried out. The observation results recorded by high-speed camera indicate that the downward leader could strike grounded wire and conductor simultaneously. At last, based on the intelligent monitoring system of transmission line, the traveling wave current of a lightning stroke was recorded. And after comparing the current with the simulation results by ATP/EMTP, the stroke was thought to be a both stroke. The photos in the fault point indicate that there are discharge points both on the grounded wire and conductor. And this field data clarified that the trip fault was caused by both stroke. A new lightning stroke fault was presented and verified in this paper, this report will supply important reference for lightning protection of transmission line.

Sign in / Sign up

Export Citation Format

Share Document