scholarly journals Stability and Control of Retracement Channels in Thin Seam Working Faces with Soft Roof

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Binbin Qin ◽  
Fulian He ◽  
Xiaobing Zhang ◽  
Xuhui Xu ◽  
Wei Wang ◽  
...  
Keyword(s):  
Coal Mine ◽  
Main Roof ◽  
Field Application ◽  
Control Effect ◽  
Working Face ◽  
Safety Production ◽  
Thin Seam ◽  
Practice Methods ◽  
Working Resistance ◽  
Hydraulic Supports

To reduce the risk of roof falling and rib spalling during equipment retracement in thin coal seam faces with soft roofs, the 25070 working face of Xuehu Coal Mine was taken as the research object, and theoretical analysis, numerical simulation, and field practice methods were used. Under different space relationships between retracement channels and main roof fracture, the load of hydraulic supports was quantitatively analyzed. The relationship between the working resistance of the hydraulic support and the sinking rotation angle of the immediate roof was analyzed, and a reasonable time for the arrangement of the retracement channel was determined. The sublevel excavation technology and the combined support technology of roof anchor cables and coal rib anchors were proposed. The field application shows that the falling height and rate of movable prop of the hydraulic supports, working resistance of the hydraulic supports, and the roof subsidence all meet the requirements of safety production during the terminal mining period, and the surrounding rock control effect of retracement channel was determined to be good. The safe and efficient mining of the coal mine is ensured, and the research results can provide guidance for similar working faces.

Analyses of Actual Measurement and Numerical Simulation on Gently Inclined Thin Seam

2011 ◽  
Vol 361-363 ◽  
pp. 130-134
Author(s):  
Jian Xin Tang ◽  
Le Le Sun ◽  
Yue Hua Deng ◽  
Hua Hui Jin
Keyword(s):  
Numerical Simulation ◽  
Dynamic Pressure ◽  
Pressure Coefficient ◽  
River Mouth ◽  
Main Roof ◽  
Simulation Method ◽  
Actual Measurement ◽  
Working Face ◽  
Thin Seam ◽  
Working Resistance

Based on the numerical simulation method and actual measurement analyses, characteristics of working face mineral pressure of the River Mouth Mine has been analyzed and this paper has obtained the following results: First weighting step of the main roof is 23.2 m, the average dynamic pressure coefficient is 1.54~1.74, mine strata behaviors is fiercer; hydraulic prop’s average working resistance is 45.72 KN of each, which indicates hydraulic prop’s working resistance has larger surplus coefficient, some measures should be taken to increase utilization ratio; advanced support length of return airway and mechanical roadway should reach to 30 m, the method and results can be used to improve support pattern of working face and guide safety production.

scholarly journals Study on the Instability Characteristics and Bolt Support in Deep Mining Roadways Based on the Surrounding Rock Stability Index: Example of Pansan Coal Mine

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Jucai Chang ◽  
Kai He ◽  
Zhiqiang Yin ◽  
Wanfeng Li ◽  
Shihui Li ◽  
...  
Keyword(s):  
Coal Mine ◽  
Stability Index ◽  
Surrounding Rock ◽  
Full Length ◽  
Control Effect ◽  
Support Design ◽  
Rock Stability ◽  
Working Face ◽  
The Stability ◽  
Bolt Support

In view of the influence of mining stress on the stability of the surrounding rock of inclined roof mining roadways in deep mines, the surrounding rock stability index is defined and solved based on the rock strength criterion and the stress distribution. The mining roadway of the 17102(3) working face of the Pansan Coal Mine is used as the engineering background and example. The surrounding rock’ stabilities under the conditions of no support and bolt support are analyzed according to the surrounding rock’s stability index and the deformation data. The results show that the areas of low wall and high wall instability are 1.68 m2 and 2.12 m2, respectively, and the low wall is more stable than the high wall; the areas of the roof and floor instability are 0.33 m2 and 0.35 m2, respectively, and the roof and floor are more stable than the two sides. During mining, the area of instability greatly increases at first, then decreases to 0, and reaches a maximum value at the peak of the abutment pressure. The stability of the surrounding rock decreases first and then increases. Compared with the end anchoring bolt support, the full-length anchoring bolt support reduces the area of instability to a greater extent, and the full-length anchoring bolt support effect is better. The surrounding rock in the end anchoring zone and the full-length anchoring zone began to deform significantly at 200 m and 150 m from the working face, respectively. This indicates that the control effect of the full-length anchoring bolt support is better and verifies the rationality of the surrounding rock stability index to describe the instability characteristics. This research method can provide a theoretical reference for analysis of the stability characteristics and support design of different cross-section roadways.

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.

Study on the Supporting Method of Crossheading in Shallow-Buried Coal Seams Working Face Using FLAC Simulation

2013 ◽  
Vol 275-277 ◽  
pp. 1564-1568
Author(s):  
Jian Feng Luo
Keyword(s):  
Coal Mine ◽  
Field Tests ◽  
Reference Value ◽  
Working Face ◽  
Site Monitoring ◽  
Deformation Law ◽  
Before And After ◽  
Safety Production ◽  
Northern Shaanxi ◽  
Seam Mining

Taking 1403 coal face of Fengjia coal mine in northern Shaanxi as background, put forward three supporting schemes of crossheading according to different buried depth and coal seam interval. Applying FLAC software, established relevant calculating model, analyzed the stress field and surrounding rock deformation caused by shallow seam mining before and after supporting. Combining the result from site monitoring, obtained the deformation law of crossheading surrounding rocks in the short distance seam: the vertical deformation is the main deformation under the A support scheme. The field tests showed that: the supporting schemes according to the section of crossheading is feasible and it ensured haulage gate roadway’s surrounding rocks stability , met the requirements of safety production in the coal mine, the supporting schemes of crossheading proposed in this paper has reference value to similar project.

Characters Evaluation of Ground Pressure in Fully Mechanized Top Coal Caving Face in Soft Coal Seams

2011 ◽  
Vol 255-260 ◽  
pp. 3735-3739
Author(s):  
Wei Dong Pan ◽  
Xiao Hua Wu ◽  
Yang Li
Keyword(s):  
Coal Seam ◽  
Mining Area ◽  
Base Point ◽  
Coal Seams ◽  
Distribution Law ◽  
Soft Coal ◽  
Ground Pressure ◽  
Working Face ◽  
Working Resistance ◽  
Hydraulic Supports

Based on the big thickness, low stiffiness and other characters of No. 8 coal seam in Huaibei mining area, the moving laws of top coal seam and roof, and distribution law of ground pressure were studied under the fully mechanized top coal caving. The research methods included working resistance observation of hydraulic supports in working face, deformation observation of stope roadways and deeper base point observation in roof and top coal. The results show that, in the thick and soft coal seams, the influence coverage of mining ground pressure in fully mechanized top coal caving face is much wider than that in the working face with general mining technology, but the intensity of pressure is much lower.

Analysis on Instability of Surrounding Rock in Gob-Side Entry Retaining with the Character of Soft Rock Composite Roof

2012 ◽  
Vol 524-527 ◽  
pp. 396-403 ◽  
Author(s):  
De Chuan Yang ◽  
Ming Zhong Gao ◽  
Yun Hai Cheng ◽  
Wu Sheng ◽  
Jia Sheng Chen
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Main Roof ◽  
Wide Distribution ◽  
Economic Security ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Working Face ◽  
Immediate Roof ◽  
Plastic Zones

The filling belt of gob-side entry retaining with the character of soft rock composite roof,deforms violently,affected by the fracture and rotation of the main roof,and is prone to instability.This essay,considering characteristecs of coal mine pressure behavior on -790m 1311 (1) working face ventilation roadway at DingJi coal mine in HuaiNan,puts forward structural mech -anics model of the key block of gob-side entry retaining,which is used to forecast the position of the fracture line of the main roof, and analyze the roof subsidence at the side of the filling belt;It applies FLAC and UDEC to simulate distribution of plastic zones of surrounding rock of gob-side entry retaining,and stress variation law of the immediate roof and the main roof along coal seam inclination.The results show that:stress concentration factor of the immediate roof on the filling belt is about 1.6,first decreasing and then increasing with increasing width of the filling belt,which indicates that reasonable width of the filling belt is 3.0 m in accordance with the requirement of economic security requirment. The filling belt has significantly wide distribution of the plastic zones,with its four corners obviously plasticized,and overlying strata above the filling belt at side of goaf suffering upward plasticization,which is the result of rotation of the main roof; Deform- ation instability of filling belt is mainly caused by fracture rotation of the main roof;Finally, the measures to reduce the instability of gob-side entry retaining with the character of soft rock comp- osite roof are put forward.

Research on the Transition Section Length of the Mixed Workface Using Gangue Backfilling Method and Caving Method

2019 ◽  
Vol 11 (1) ◽  
pp. 649-663
Author(s):  
Yang Tai ◽  
Shuai Guo ◽  
Kun Fang
Keyword(s):  
Physical Simulation ◽  
Main Roof ◽  
Sudden Increase ◽  
Transition Section ◽  
Movement Characteristics ◽  
Geological Conditions ◽  
Definition Of ◽  
Working Resistance ◽  
Hydraulic Supports ◽  
Overburden Strata

Abstract Aiming at the problem of the sudden increase of the working resistance of the support in the transition section of the mixed workface, this paper adopts the physical simulation to study the fracture and movement characteristics of the overburden strata in the backfilling section and the caving section after analysis of the system layout of mixed workface. Then, the definition of the transition section of the mixed workface is given. Next, a numerical model of the transition section length is established based on the geological conditions of the Ji15-31010 mixed workface of Pingdingshan No.12 Coal Mine. In the numerical simulation, it is used to study the influence of the advancing length of the mixed workface and the length of the backfilling section on the transition section length. The results show that with the increase of the advancing length of the mixed workface and the decrease of the backfilling section length, the transition section length increases continuously and eventually stabilizes. The range of variation is 6.2~13.5 m, corresponding to 4~9 hydraulic supports with a width of 1.5 m. Based on the above conclusions and the price of transitional hydraulic supports, the 4 transitional hydraulic supports used in the transition section of the Ji15-31010 mixed workface is determined. Filed measurement shows that as the mixed workface is advanced from 10 m to 40 m, the transition section length increases from 2 supports to 4 supports, and decreases to 2 supports again when advanced to 60 m. This indicates that the main roof of the mixed workface between 40 and 60 m experiences the initial caving. The maximum length of the transition section is 6.0 m, corresponding to 4 hydraulic supports.

ASSESSMENT OF MAIN ROOF CA VING INCREMENTS IN WORKING FACE PROCESSING OF TOLMACHEVSKY COAL LAYER WITHIN THE DIP-WORKING PANEL 18-2

2019 ◽  
Vol 4 (1) ◽  
pp. 157-166
Author(s):  
V.O. Torro ◽  
◽  
A.V. Remezov ◽  
E.V. Kuznetsov ◽  
V.V. Klimov ◽  
...  
Keyword(s):  
Coal Mine ◽  
Face Processing ◽  
Main Parameter ◽  
Abutment Pressure ◽  
Main Roof ◽  
Roof Caving ◽  
Coal Layer ◽  
Working Face ◽  
Mine Tunnels

This work reviews the study aimed to assess the actual increments of the main roof caving which appear in the course of working face processing of ‘Tolmachevsky ' coal layer in ‘Polysayevskaya' coal mine as the main parameter defining the degree of abutment pressure influence on mine tunnels adjacent to working face.

A fiber Bragg grating tilt sensor for posture monitoring of hydraulic supports in coal mine working face

Measurement ◽  
2019 ◽  
Vol 138 ◽  
pp. 305-313 ◽  
Author(s):  
Minfu Liang ◽  
Xinqiu Fang ◽  
Shuang Li ◽  
Gang Wu ◽  
Meng Ma ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Coal Mine ◽  
Mine Working ◽  
Bragg Grating ◽  
Working Face ◽  
Posture Monitoring ◽  
Tilt Sensor ◽  
Hydraulic Supports

scholarly journals The characteristics of mining induced stress fluctuations in broken rock mass over one kilometer deep coal mine

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 843-851
Author(s):  
Cong Li ◽  
Xiangang Yin ◽  
Jing Xie ◽  
Gaoyou Peng
Keyword(s):  
Fractal Dimensions ◽  
In Situ Monitoring ◽  
Mine Pressure ◽  
Deep Coal Mine ◽  
Working Face ◽  
Power Spectral ◽  
The Difference ◽  
Mining Face ◽  
Working Resistance ◽  
Hydraulic Supports

Mine pressure is critical to the safety of working face. Evaluating the working resistance accurately of the stope hydraulic supports is one of the most effective and direct ways to reflect the overall stress characteristics of the roof and the defor?mation, movement and destruction of overlying strata. Due to the complex breaking form of the roof, the working resistance of the hydraulic supports at different positions of the mining face varies in different ways. One can obtain the pressure of hydraulic support system by pressure monitoring and analyze its fractal characteristics. Through spectrum analysis, a new parameter called accumulation power spectral density is defined which is used to describe the difference of working resistance of stope hydraulic supports. The results show that the fractal dimensions of face-end supports are smaller and face-end supports are unco-ordinated. Through in-situ monitoring, it is found that the mining stress has unstable periodic fluctuation characteristics. The conclusion can provide reference for rational selection and optimization of the similar-mining lay-outs.

Sign in / Sign up

Export Citation Format

Share Document