scholarly journals Multiple Influence Factor Sensitivity Analysis and Height Prediction of Water-Conducting Fracture Zone

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xiaobin Li ◽  
Quansheng Li ◽  
Xuhui Xu ◽  
Yongqiang Zhao ◽  
Peng Li
Keyword(s):  
Mathematical Model ◽  
Fracture Zone ◽  
Hard Rock ◽  
Influence Factor ◽  
Processing System ◽  
Sensitivity Coefficient ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Rock Lithology

To explore the influence law and sensitivity of various factors on the height of the water-conducting fracture zone, and further predict the development height of the water-conducting fracture zone, taking the field survey and collected actual measured data as the research foundation, establishing mathematical model, regression analysis, and field measurement were adopted comprehensively. Based on the Data Processing System (DPS), influence factors of the development height of the water-conducting fracture zone were analyzed. By introducing sensitivity coefficient, a sensitivity quantification mathematical model was established, and sensitivity ranking was obtained. The regression relationship between each factor and the height of the water-conducting fracture zone was obtained by single factor analysis. Based on this, the prediction formula was proposed and successfully used in the field practice. Results show that the sensitivity coefficient of mining thickness, ratio coefficient of hard rock lithology, mining depth, and length of working face was 0.75, 0.69, 0.66, and 0.58, respectively. The dispersion degree of working face length and mining depth was greater than that of ratio coefficient of hard rock lithology and mining thickness. To some extent, it also reflects that the sensitivity of working face length and mining depth to the height of the water-conducting fracture zone was the weakest, which was consistent with the previous conclusions. Using the multiple regression mathematical model, a nonlinear statistical relationship between the height of the water-conducting fracture zone and ratio coefficient of hard rock lithology, mining thickness, working face length, and mining depth was obtained. This research provides some scientific basis and guidance for safe and efficient underwater mining.

Numerical Simulation of Strata Behavior in Super-Long and Large Mining Height Working Face

2013 ◽  
Vol 634-638 ◽  
pp. 3428-3432 ◽  
Author(s):  
Zhi Hua Li ◽  
Xin Zhu Hua ◽  
Ruo Jun Zhu ◽  
De Sheng Zhou
Keyword(s):  
Abutment Pressure ◽  
Roof Displacement ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Coal Wall ◽  
Large Mining Height ◽  
Strata Behavior ◽  
Behavior Characteristics ◽  
Mining Height

In order to study the strata behavior characteristics in super-long and large mining height working face, the FLAC-3D software was used to study the roof displacement and the abutment pressure distribution laws of working faces. The results indicate that: ① the influence range is larger of front abutment pressure in Liuzhuang coal mine 171301 super-long large mining height working face, and reaches to 60m. ② the maximum roof displacement increases with the increase of mining depth and working face length, the increase in magnitude decreases gradually, while the maximum roof displacement sharply increases due to the increase of mining height. ③ the peak abutment pressure increases with the increase of mining depth and mining height, the location of peak abutment pressure transfer to ahead of the coal wall. ④ the effect of working face length on abutment pressure is very feeble, so, the strata behavior characteristics remain almost constant with the increase of face length.

scholarly journals Migration Law of the Roof of a Composited Backfilling Longwall Face in a Steeply Dipping Coal Seam

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 188 ◽  
Author(s):  
Wenyu Lv ◽  
Yongping Wu ◽  
Liu Ming ◽  
Jianhui Yin
Keyword(s):  
Coal Seam ◽  
Inclination Angle ◽  
Mechanical Model ◽  
Surrounding Rock ◽  
Longwall Face ◽  
Mining Operations ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Migration Law

The artificial-caved rock composited backfilling approach can effectively restrain the dynamic phenomena in the coal seam and the associated roof and floor during mining operations, and can also improve the stability of the system of support and surrounding rock. In this study, based on the analysis of influencing factors affecting the surrounding rock movement and deformation of the composited backfilling longwall face in a steeply dipping coal seam, the roof mechanical model is developed, and the deflection differential equation is derived, to obtain the roof damage structure and the location of the roof fracture for the area without backfilling. The migration law of the roof under different inclination angles, mining depths, working face lengths, and backfilling ratios are analyzed. Finally, mine pressure is detected in the tested working face. Results show that the roof deflection, bending moment, and rotation drop with the increase of the inclination angle and backfilling ratio, whereas these parameters increase with greater mining depth and working face length. The roof failure location moves toward the upper area of the working face as the inclination angle and working face length increases, while it moves toward the center of the non-backfilling area with greater mining depth and backfilling ratio. Results from the proposed mechanical model agree well with the field test results, demonstrating the validity of the model, which can provide theoretical basis for a safe and efficient mining operation in steeply dipping coal seams.

Numerical Analysis of Influencing Factors of Stability in Thick Coal Seam Mining Roadway

2012 ◽  
Vol 256-259 ◽  
pp. 1453-1457
Author(s):  
Zhi Hua Li ◽  
Xin Zhu Hua ◽  
Ke Yang ◽  
Ruo Jun Zhu ◽  
De Sheng Zhou
Keyword(s):  
Coal Seam ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Rock Body ◽  
Thick Coal Seam ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Seam Mining ◽  
Mining Height

The FLAC-3D software was used to study the surrounding rock displacement and the side abutment pressure distribution laws about roadway in thick coal seam. Based on this model, through change the mining height, working face length and mining depth, the differences of roadway underground pressure characteristics were analyzed between thick coal seam working face and normal working face. The results indicate that: ①the displacement of roadway surrounding rock increases with the increase of mining depth and mining height, the closer to the coal wall the larger of the increase range of roadway displacement. ②the peak of side abutment pressure increases with the increase of mining depth and mining height, the peak district of the stress will move toward the inner department of rock body. ③ the effect of working face length on the roadway displacement and the side abutment pressure is very feeble.

scholarly journals Determination of Long Horizontal Borehole Height in Roofs and its Application to Gas Drainage

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2647
Author(s):  
Gang Wang ◽  
Cheng Fan ◽  
Hao Xu ◽  
Xuelin Liu ◽  
Rui Wang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Fracture Zone ◽  
Coalbed Methane ◽  
High Efficiency ◽  
Gas Drainage ◽  
Methane Drainage ◽  
Working Face ◽  
Variation Characteristics

Accurately determining the height of the gas-guiding fracture zone in the overlying strata of the goaf is the key to find the height of the long horizontal borehole in the roof. In order to determine the height, in this study we chose the 6306 working face of Tangkou Coal Mine in China as a research example and used both the theoretical model and discrete element method (DEM) numerical simulation to find the height of the gas-guiding fracture zone and applied the height to drill a long horizontal borehole in the roof of the 6303 working face. Furthermore, the borehole was utilized to deep into the roof for coalbed methane drainage and the results were compared with conventional gas drainage measures from other aspects. The height of the gas-guiding fracture zone was found to be 48.57 m in theoretical model based on the bulk coefficient and the void ratio and to be 51.19 m in the DEM numerical simulation according to the temporal and spatial variation characteristics of porosity. Taking both the results of theoretical analysis and numerical simulation into consideration, we determined that gas-guiding fracture zone is 49.88 m high and applied it to drill a long horizontal borehole deep into the roof in the 6303 working face field. Compared with conventional gas drainage measures, we found that the long horizontal borehole has the high stability, high efficiency and strong adaptability for methane drainage.

scholarly journals A Mathematical Model and Error Analysis of Shearer Cutting Path Based on Its Attitude

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Shi-bo Wang ◽  
Shijia Wang ◽  
Zhaoliang Ge
Keyword(s):  
Mathematical Model ◽  
Error Analysis ◽  
Inertial Navigation System ◽  
Coordinate Frame ◽  
Medium Thickness ◽  
Position Errors ◽  
Working Face ◽  
Coordinate Position ◽  
Thin Seam ◽  
Cutting Path

The horizon control system is the key technology in the automation of a shearer. The achievement of accurate shearer cutting path plays an important role for horizon control. A mathematical model of cutting path in the local geographic coordinate frame was built. Error analysis based on genetic algorithm (GA) was studied to guarantee the accuracy of the shearer cutting path. Parameters from a MG1000/2660-WD shearer and data from a working face were used to obtain the shearer cutting path with reference to the local geographic coordinate frame. Also, with error analysis based on GA, the desired sensors were chosen, which allowed coordinate position errors of a shearer’s cutting path to be less than 0.01 m. The desired accuracies of the inertial navigation system and encoders mounted on the different shearers used in thin seam, medium-thickness seam, and thick seam were calculated.

scholarly journals Mechanism and Prevention and Control of Mine Earthquake in Thick and Hard Rock Strata considering the Horizontal Stress Evolution of Stope

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ming Zhang ◽  
Xuelong Hu ◽  
Hongtao Huang ◽  
Guangyao Chen ◽  
Shan Gao ◽  
...  
Keyword(s):  
Hard Rock ◽  
Design Method ◽  
Horizontal Stress ◽  
Prevention Measures ◽  
Stress Concentrations ◽  
Estimation Model ◽  
Working Face ◽  
Mining Design ◽  
And Control ◽  
Rock Strata

This study investigated the mechanism, prevention measures, and control methods for earthquake disasters typically occurring in mines with thick and hard rock strata. A mine stope with large faults and thick hard rock strata in Hebei Province was taken as the background study object. Then, theoretical analysis and numerical simulation methods were adopted in conjunction with field monitoring to explore how horizontal stress evolves in the thick and hard hanging roofs of such mines, potentially leading to mining earthquakes. Then, based on the obtained results, a mining design method was proposed to reduce the horizontal stress levels of earthquake mitigation. The results showed that, under the control of large faults, semiopen and semiclosed stopes with thick hard rock strata are formed, which cause influentially pressurized and depressurized zones during the evolution of the overburden movements and horizontal stress. It was determined that the stress concentrations mainly originated from the release and transfer of horizontal stress during the rock fractures and movements in the roof areas, which were calculated using a theoretical estimation model. The horizontal stress concentrations formed “counter torques” at both ends of the thick and hard strata, which prevented the support ending due to tensile failures. As a result, the limit spans were increased. This study proposed a mining strategy of using narrow working faces, strip mining processes, and reasonable mining speeds, which could effectively reduce horizontal stress concentrations and consequently prevent and control mining earthquakes. This study’s research results were successfully applied to the mining practices in working face 16103.

scholarly journals Presplitting Blasting the Roof Strata to Control Large Deformation in the Deep Mine Roadway

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chaowen Hu ◽  
Xiaojie Yang ◽  
Ruifeng Huang ◽  
Xingen Ma
Keyword(s):  
Large Deformation ◽  
Field Tests ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Deep Mine ◽  
Mining Depth ◽  
Working Face ◽  
Support Conditions ◽  
Mine Roadways ◽  
Roof Strata

As the mining depth increases, under the influence of high ground stress, the surrounding rock of deep mine roadways shows soft rock characteristics. Under the influence of mining disturbance at the working face, large deformation of the roadway has occurred. To control the large deformation of the roadway, many mines have adopted the form of combined support, which has continuously increased the support strength and achieved a certain effect. However, since the stress environment of the surrounding rock of the roadway has not been changed, large deformation of the roadway still occurs in many cases. Based on the theoretical basis of academician Manchao He’s “short cantilever beam by roof cutting,” this paper puts forward the plan of “presplitting blasting + combined support” to control the large deformation of the deep mine roadways. Without changing the original support conditions of the roadway, presplitting blasting the roof strata of the roadway, by cutting off the mechanical connection of the roof strata between the roadway and gob, improves the stress distribution of the roadway to control the large deformation. Through field tests, the results show that after presplitting blasting the roadway roof, the roadway roof subsidence is reduced by 47.9%, the ribs displacement is reduced by 45.7%, and the floor heave volume is reduced by 50.8%. The effect is significant.

scholarly journals Size effect of Water-flowing fracture Zone height based on FLAC3D

2020 ◽  
Vol 194 ◽  
pp. 01011
Author(s):  
Chao Zheng ◽  
Lan Yu ◽  
Ning Sun ◽  
Hualong Zhou ◽  
Jiangyi He
Keyword(s):  
Size Effect ◽  
Coal Mine ◽  
Fracture Zone ◽  
Average Distance ◽  
Water Inrush ◽  
Water Diversion ◽  
Effect Of Water ◽  
Face Width ◽  
Working Face ◽  
Simulation Results

The loss of water resources caused by mining fissures is a key factor restricting the green development of coal resources in western mining areas. in order to analyze the influence of mining thickness and face width on the development height of water diversion fracture zone, based on the characteristics of overburden in Xinzhuang Coal Mine, the finite difference software FLAC3D is used to simulate and analyze the size effect of water diversion fracture zone height. The simulation results show that the height of the water diversion fracture zone is positively correlated with the increase of mining thickness and working face width. When the mining thickness is 9m and the width of the working face is 240m, the height of the water diversion fracture zone is 115m, and the average distance between the coal layer 8 of Xinzhuang Coal Mine and the bottom of the Cretaceous aquifer is 106.9m, which may cause water inrush in the mine. Therefore, according to the simulation results and referring to the mining size of part of the mine face in the attached Binchang mining area, it is suggested that the mining thickness of Xinzhuang Coal Mine is about 10m and the width of the working face is not more than 200m.

Determination Method of the Supporting Intensity of Fully-Mechanized Face in Deeply Inclined Medium-Thickness Seam

2014 ◽  
Vol 522-524 ◽  
pp. 1386-1389
Author(s):  
Zhong Ping Guo ◽  
Hui Qiang Duan ◽  
Fan Feng ◽  
Gui Yin Zhang
Keyword(s):  
Coal Seam ◽  
Theoretical Basis ◽  
Surrounding Rock ◽  
Medium Thickness ◽  
Working Face ◽  
Displacement Thickness ◽  
Face Length ◽  
Working Resistance ◽  
Theory Calculation ◽  
The Relationship

According to the occurrence conditions of deeply inclined coal seam of 81206 working face in Yanya coal mine, methods including transmission rock theory calculation and numerical calculation based on the relationship between supports and surrounding rock are used to calculate and analyze. The proper working resistance of support is 5979.2kN and the supporting intensity is 0.8~0.95MPa. The regression equation associated with roof subsidence displacement , thickness of the coal seam, working face length and supporting intensity is accomplished, which provides theoretical basis for the support selection.

Analysis on produce mechanism and influence factor of CO gas on the coal exploitation working face

2008 ◽  
Vol 14 (3) ◽  
pp. 432-435 ◽  
Author(s):  
Jun Deng ◽  
Zhi-gang Jiang ◽  
Lei Xiao
Keyword(s):  
Influence Factor ◽  
Working Face ◽  
Co Gas
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