scholarly journals Study on the Working Resistance of a Support under Shallowly Buried Gobs According to the Roof Structure during Periodic Weighting

2021 ◽  
Vol 13 (19) ◽  
pp. 10652
Author(s):  
Chen Wang ◽  
Cheng Zhu ◽  
Yong Yuan ◽  
Zhongshun Chen ◽  
Wenmiao Wang
Keyword(s):  
Coal Mine ◽  
Dynamic Pressure ◽  
Horizontal Displacement ◽  
Mining Area ◽  
Surrounding Rock ◽  
Structural Morphology ◽  
Key Stratum ◽  
Roof Structure ◽  
Coal Wall ◽  
Working Resistance

The phenomenon of dynamic pressure in the panel under shallowly buried gobs is obvious, resulting in limited and challenging support type selection. In this paper, theoretical analysis, numerical simulation and field measurement were combined to study the reasonable working resistance of the support in panels under shallowly buried gobs. First, the definition of the equivalent main key stratum (EMKS) was proposed. Then, a method of identifying the structure of the EMKS and broken key stratum blocks was given. The roof structure of the panel under a shallowly buried gob (PSBG) during strong periodic weighting could be divided into 12 types. Mechanical models of the roof structure were established, and the method to calculate the working resistance of the support was given. The Bulianta coal mine and Fengjiata coal mine in the Yushenfu Mining Area were taken as research objects. Based on the measured working resistance curve of the support, the structural morphology of key stratum blocks during strong periodic weighting was distinguished. On this basis, the working resistance of the support was calculated. Finally, FLAC2D numerical software was used to test the working resistance of the support. Based on the subsidence of the roof, horizontal displacement of the coal wall and the development range of the plastic zone in the surrounding rock, the working resistance of the support and adaptability of the surrounding rock control were verified and evaluated. The results show that it is reasonable to calculate the working resistance of the support based on the roof structure during strong periodic weighting. The research results can provide a reference for the scientific and rational selection of the support in a PSBG.

scholarly journals Failure Mechanisms and the Control of a Longwall Face with a Large Mining Height within a Shallow-Buried Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Haijun Wang ◽  
Yingjie Liu ◽  
Yuesong Tang ◽  
Hao Gong ◽  
Guoliang Xu
Keyword(s):  
Tensile Stress ◽  
Coal Mine ◽  
Horizontal Displacement ◽  
Longwall Face ◽  
Mining Equipment ◽  
Coal Seams ◽  
Increasing Trend ◽  
Support Force ◽  
Coal Wall ◽  
Mining Height

The capabilities of mining equipment and technology in China have been improving rapidly in recent years. Correspondingly, in the western part of the country, the mining heights of longwall faces in shallow-buried coal seams have shown an increasing trend, resulting in enhanced mining efficiency. However, the problems associated with the possible failure of the coal wall then increase and remain a serious difficulty, restricting safe and efficient mining operations. In the present study, the 12401 longwall face of the Shangwan Coal Mine, Inner Mongolia, China, with a mining height of 8.8 m, is taken as an example to study the mechanisms underlying failure phenomena of coal walls and their control methods. Our results show that the failure region inward of the longwall face is small in shallow-buried coal seams, and the damage degree of the exposed coal wall is low. The medium and higher sections of the coal wall display a dynamic failure mode, while the broken coal blocks, given their initial speed, threaten the safety of coal miners. A mechanical model was developed, from which the conditions for tensile failure and structural instability are deduced. Horizontal displacement in the lower part of the coal wall is small, where no tensile stress emerges. On the other hand, in the intermediate and higher parts of the coal wall, horizontal displacement is relatively large. In addition, tensile stress increases first with increasing distance from the floor and then decreases to zero. Experiments using physical models representing different mining heights have been carried out and showed that the horizontal displacement increases from 6 to 12 mm and load-bearing capacity decreases from 20 to 7.9 kN when the coal wall increases in height from 3 to 9 m. Furthermore, failure depth and failure height show an increasing trend. It is therefore proposed that a large initial support force, large maximum support force, large support stiffness, and large support height of a coal wall-protecting guard are required for the improved stability of high coal walls, which operate well in the Shangwan coal mine.

scholarly journals Study of the Stability Control of Rock Surrounding Longwall Recovery Roadways in Shallow Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Cheng Zhu ◽  
Yong Yuan ◽  
Zhongshun Chen ◽  
Chaogui Meng ◽  
Shengzhi Wang
Keyword(s):  
Rock Pressure ◽  
Coal Mine ◽  
Stability Control ◽  
Control Effect ◽  
Support Design ◽  
Key Strata ◽  
Key Stratum ◽  
Discriminative Approach ◽  
The Stability ◽  
Working Resistance

The rock pressure appearance of longwall faces in shallow seams is generally violent, and roofs and supports are susceptible to damage during equipment extraction. Stability control of the rock surrounding longwall recovery roadways allows safe and rapid equipment extraction. Herein, via theoretical analysis, numerical simulations, and field observations, the stability control of the rock surrounding recovery roadways is studied to ensure the release of the accumulated rock pressure on the roof, the working resistance of the supports and the reasonableness of the recovery roadway support design. Pressure-relief technology is introduced to release the accumulated rock pressure before equipment extraction, and a discriminative approach is proposed to determine the breaking and articulated forms of key strata and broken blocks, respectively. On this basis, mechanical models of roof instability are established based on four key stratum structures in the overburden of shallow seams. Methods for calculating a reasonable working resistance for supports are discussed. Finally, Liangshuijing Coal Mine and Fengjiata Coal Mine are taken as research objects to evaluate the roof stability of recovery roadways based on observations of weighting characteristics. The support working resistances and reasonable recovery roadway widths under three key stratum structures are determined. Considering the time effect of plastic zone development, the support design of recovery roadways is optimized. FLAC2D software simulates the surrounding rock control effect of two support designs, and roof subsidence curves are obtained. The results show that the key to equipment extraction in shallow seams is to ensure that supports have reasonable working resistances and to improve the support of recovery roadways. The results provide a reference for the selection and extraction of supports in shallow seam faces.

Numerical Simulation Analysis of Different Coal Mine Roadway Support Effect

2013 ◽  
Vol 807-809 ◽  
pp. 2356-2360 ◽  
Author(s):  
Guang Yi Sun ◽  
Xiao Luo
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Simulation Analysis ◽  
Support Effect ◽  
Surrounding Rock ◽  
Anchor Cable ◽  
Mine Roadway ◽  
Coal Wall ◽  
Roadway Support

The application of FLAC2D software long ditch coal mine extraction tunnel without support boltgrouting. Anchor when the anchor rope supporting and strengthening supporting state ofroadwaywere simulated and analyzed the change of roadway surrounding rock under differentsupport forms. Demonstrated the possibility that the current anchor cable anchor supporting andanalysis under the condition of the coal wall broken grouting bolt is the necessity of reinforcement.

Grout and Anchor Coupling Support in Dynamic Pressure Impact Roadway with Large Deformation in Deep

2014 ◽  
Vol 962-965 ◽  
pp. 1034-1040
Author(s):  
Wen Zhou Li
Keyword(s):  
Large Deformation ◽  
Dynamic Pressure ◽  
Unit Length ◽  
Mining Area ◽  
Surrounding Rock ◽  
Coal Mining Area ◽  
Maximum Shear Force ◽  
Pressure Impact ◽  
Confining Pressures ◽  
Coupling Support

The broken characters of roadway in deep in China were statistical analyzed. Taking unit length anchor body as studying element, interrelations of the maximum shear force max、cementation strength and confining pressures were analyzed, researched and development grouting cable, put forward grouting-anchor coupling support for surrounding rock control in deep. The relation between different water cement ratios (0.5:1-1:1), different grout pressures (0.5:1-1:1) and diffusion radius were analyzed by means of numerical software UDEC. The surrounding rock controlling problems of dynamic pressure impact and large deformation roadway in deep was solved in CHANGCUN mine of Lu’an coal mining area in China.

scholarly journals Influence of Mine Earthquake Disturbance on the Principal Stress of the Main Roadway near the Goaf and Its Prevention and Control Measures

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jiazhuo Li ◽  
Penghui Guo ◽  
Heng Cui ◽  
Xiqing Hao ◽  
Lihua Tian ◽  
...  
Keyword(s):  
Principal Stress ◽  
Coal Mine ◽  
Prevention And Control ◽  
Mining Area ◽  
Surrounding Rock ◽  
Control Measures ◽  
Pressure Relief ◽  
Mining Depth ◽  
Prevention And Control Measures ◽  
And Control

With the reduction and depletion of shallow energy, the mining depth of coal around the world is increasing year by year, and the mining depth of some coal mines in China has reached kilometers. The main roadway near the goaf with the deep high static stress is very easy to be damaged after being disturbed by the mine earthquake. Taking the main roadway in the no. 1 mining area of Gaojiapu coal mine in Binchang mining area, Shaanxi Province, China, as the engineering background, the high-energy mine earthquake monitored by the on-site microseism is equivalently simulated through the dynamic module of FLAC3D, and the spatial-temporal rotation characteristics of the principal stress of roadway surrounding rock under the disturbance of mine earthquake are studied and analyzed and put forward corresponding prevention and control measures. Research shows early stage of mine earthquake disturbance, roadway roof is first affected, and the principal stress of the roof has the trend of deflection to the side of the goaf. In the middle stage of mine earthquake disturbance, the main body of roof principal stress deflects to the side of goaf, and the deflection range is large. In the later stage of mine earthquake disturbance, the principal stress directions in the surrounding rock reverse rotation, and the reverse rotation angle of the principal stress direction in the roof is the largest. Finally, the asymmetric distribution characteristics of principal stress rotation are verified by using the asymmetric deformation phenomenon on both sides of roadway surrounding rock. Based on the rotation characteristics of principal stress under the dual influence of mine earthquake disturbance and goaf, optimize the layout scheme and blasting parameters of blasting pressure relief holes. The transmission direction of principal stress can be changed by blasting pressure relief method; meanwhile, the transmission of principal stress can be blocked; through the comparison of microseismic activity law before and after pressure relief, pressure relief effect is good. The research results can provide a certain reference basis for coal mine roadway pressure relief and reducing disaster conditions.

scholarly journals Stress Distribution and Optimum Spacing Determination of Double-Withdrawal-Channel Surrounding Rocks: A Case Study of Chinese Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yanjun He ◽  
Jianhua Li
Keyword(s):  
Stress Distribution ◽  
Coal Mine ◽  
Field Measurements ◽  
Mining Area ◽  
Surrounding Rock ◽  
Rock Stability ◽  
Working Face ◽  
Optimum Spacing ◽  
Chinese Coal ◽  
Mining Height

In this study, the 31113 fully mechanised working face in the Lijiahao Coal Mine was selected as the project background. The failure characteristics and optimum spacing of a double-withdrawal-channel surrounding rock were extensively investigated through field measurements, theoretical analysis, and numerical simulations. The following results were obtained. The loading influence range of the working face was fixed. Under the influence of mining, the stress distribution variation in the double-withdrawal channels with spacing and the influence of stress distribution on the surrounding rock stability of the withdrawal channels were determined. The optimum distance between the double-withdrawal channels to achieve the stability of the surrounding rock was at least 25 m, and engineering measures are required to limit the mining height in the final mining stage. The rationality of the main and auxiliary withdrawal channel spacing of 25 m and measures to limit the mining height in the final stage were demonstrated. The findings of this study provide a valuable reference for constructing the layout of withdrawal channels in the adjacent working faces of the same mining area.

Research of Unloading Technology of Defect Method in Dynamic Pressure Roadway

2014 ◽  
Vol 945-949 ◽  
pp. 1175-1179
Author(s):  
Rui Xi Zhang ◽  
Cong Jiang
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Dynamic Pressure ◽  
Simulation Method ◽  
Mining Area ◽  
Surrounding Rock ◽  
Theoretical Solution ◽  
Deep Mine ◽  
Material Inhomogeneity ◽  
Working Face

This paper takes typical stoping of deep-mine dynamic pressure working face of Zhaogezhuang mine of Kailuan mining area for the research background, relieving the dynamic pressure of roadway of burst tendency through building defect method in dynamic pressure roadway. Putting forward the theoretical solution of defect method in dynamic pressure roadway based on elastic-plastic theory;Taking numerical simulation method in view of the material inhomogeneity of actual engineering geological, researching the characteristics of stress distribution of roadway surrounding rock after relieving in defect method; Applying the theory to the stoping of deep-mined impact working face, and the implement effect is good on the spot.

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.

Freezing Pressure and its Influencing Factors of Deep Clay Layer in the Huainan Mining Area

2012 ◽  
Vol 170-173 ◽  
pp. 836-841
Author(s):  
Wei Shao ◽  
Bin Lin
Keyword(s):  
Coal Mine ◽  
Good Description ◽  
Mining Area ◽  
Frost Heave ◽  
Dynamic Monitoring ◽  
Clay Layer ◽  
Formation Pressure ◽  
Closed Systems ◽  
Permanent Formation ◽  
Layer Deformation

Gu Bei coal mine deep shaft freezing pressure of calcareous clay dynamic monitoring showed that the freezing pressure of the calcareous clay fastest grow in the first 2 weeks after the sidewall concrete pouring , freezing pressure has obvious direction . Analysis showed that the layer of freezing pressure is mainly calcareous clay layer deformation pressure, size and the temperature of well has a positive correlation. Maximum freezing pressure of the deep calcareous clay layer approximate the permanent formation pressure values and the maximum frost heave force determined by the frost heave experiments in indoor closed systems ,the average freezing pressure with depth variation of the exponential function can be used to good description.

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