Cutting Roof Roadway Regional Stress Characteristics Numerical Analysis of Thin Coal Seam Group

2014 ◽  
Vol 522-524 ◽  
pp. 1382-1385
Author(s):  
Zhen Wen Liu ◽  
Tao Qin
Keyword(s):  
Stress State ◽  
Numerical Analysis ◽  
Stress Concentration ◽  
Coal Seam ◽  
Rock Burst ◽  
Horizontal Stress ◽  
Vertical Stress ◽  
State Characteristic ◽  
Regional Stress ◽  
Thin Coal Seam

The stress state characteristic of the cutting roof roadway region was simulated and analyzed by FLAC3D. The results showed that the low side of return airway and gas roadway had higher vertical stress while the horizontal stress concentration was obviously in floor and low side of the return airway, the stress of cutting roof roadway was obviously, thus the level of rock burst hazard increased. range of stress concentration are 5~10m when using cutting roof roadway, thus distance between two cutting roof roadway are no less than 20m, to avoid stress concentration regions by two adjacent cutting roof roadway superposition.

scholarly journals Distribution Law of Mining Stress of the Gob-Side Entry Retaining in Deep Mining Thin Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Tao Qin ◽  
Kai Ren ◽  
Chen Jiang ◽  
Yanwei Duan ◽  
Zhi Liu ◽  
...  
Keyword(s):  
Coal Seam ◽  
High Stress ◽  
Horizontal Stress ◽  
Stability Control ◽  
Vertical Stress ◽  
Boundary Line ◽  
Thin Coal Seam ◽  
Working Face ◽  
Distribution Rule ◽  
Seam Mining

In order to explore the mining pressure development rule of gob-side entry retaining during deep thin coal seam mining, FLAC3D numerical simulation is applied to analyze the stress distribution rule of gob-side entry retaining, observing the left third working face of 49# coal seam in No. 8 mining area of Xinxing Coal Mine as the research object. The results show that the working face stress field is asymmetrical which is caused by the reserved roadway and the over goaf. After roadway tunneling, features of obvious stress redistribution are formed. The vertical and horizontal stress in the coal seam develop a U-shaped distribution. The vertical stress in the roadway is less than that in the lower roadway, and the horizontal stress is half that in the lower roadway. The phenomenon of high stress “nucleation” appears and becomes more obvious in the process of working face advancing, and the nuclear body disappears after working face advanced to the boundary line. With the working surface advancing, the trend of horizontal stress of gob-side entry retaining decreases gradually and the vertical stress of gob-side entry retaining is less than the original rock stress. The research findings provide a basis for the supporting design of gob-side entry retaining in the deep thin coal seam and the stability control of surrounding rock.

scholarly journals Study on the Mechanism and Control of Rock Burst of Coal Pillar under Complex Conditions

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Xingping Lai ◽  
Huicong Xu ◽  
Jingdao Fan ◽  
Zeyang Wang ◽  
Zhenguo Yan ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Rock Burst ◽  
Coal Mine ◽  
High Stress ◽  
Coal Pillar ◽  
Vertical Stress ◽  
Body Area ◽  
High Stress Concentration ◽  
Solid Coal ◽  
Working Face

In order to explore the mechanism of coal pillar rock burst in the overlying coal body area, taking W1123 working face of Kuangou Coal Mine as the engineering background, the full mining stage of W1123 is simulated by FLAC3D. It is found that the high stress concentration area has appeared on both sides of the coal pillar when W1123 does not start mining. With the advance of the working face, the high stress concentration area forms X-shaped overlap. There is an obvious difference in the stress state between the coal pillar under the solid coal and the coal pillar under the gob in W1123. The concrete manifestation is that the vertical stress of the coal pillar below the solid coal is greater than the vertical stress of the coal pillar below the gob. The position of the obvious increase of the stress of the coal pillar in the lower part of the solid coal is ahead of the advancing position of the working face, and the position of the obvious increase of the stress of the lower coal pillar in the gob lags behind the advancing position of the working face. At the same time, in order to accurately reflect the true stress environment of coal pillars, the author conducted a physical similarity simulation experiment in the laboratory to study the local mining process of the W1123 working face, and it is found that under the condition of extremely thick and hard roof, the roof will be formed in the gob, the mechanical model of roof hinged structurer is constructed and analyzed, and the results show that the horizontal thrust of roof structure increases with the increase of rotation angle. With the development of mining activities, the self-stable state of the high stress balance in the coal pillar is easily broken by the impact energy formed by the sudden collapse of the key strata. Therefore, the rock burst of coal pillar in the overlying coal body area is the result of both static load and dynamic load. In view of the actual situation of the Kuangou Coal Mine, the treatment measures of rock burst are put forward from the point of view of the coal body and rock mass.

Numerical Analysis of Widened Embankments with Geogrid Reinforcement

2012 ◽  
Vol 256-259 ◽  
pp. 2004-2008
Author(s):  
Min Yong Chen ◽  
Yu Liu ◽  
Hai Li Shi ◽  
Rui Chen ◽  
Bing Xiang Yuan
Keyword(s):  
Shear Stress ◽  
Numerical Analysis ◽  
Horizontal Stress ◽  
Vertical Stress ◽  
Stress Redistribution ◽  
Small Decrease ◽  
Geogrid Reinforcement ◽  
Layer Number

The mechanism of geogrid reinforcement in an embankment widening project was investigated in this study using numerical analysis. It was found that the geogrid reinforcement mainly affects the new embankment by decreasing settlement slightly and restraining the horizontal outward displacement effectively. This effect of geogrid reinforcement on embankment deformations is due to the stress redistribution in the new embankment and in the subsoil caused by geogrid reinforcement. The inclusion of geogrid reinforcement produces a small decrease in vertical stress in the new embankment and leads to a relatively larger increase in horizontal stress in the subsoil, thereby decreasing the shear stress of the subsoil. The effect of geogrid reinforcement on the new embankment and subsoil increases with the increasing geogrid layer number.

Analysis on Supporting Performance of the High-Water Material Filling Body in the Gob-Side Entry Retaining of Thin Coal Seam

2012 ◽  
Vol 616-618 ◽  
pp. 316-319
Author(s):  
Zhong Ping Guo ◽  
Dao Zhi Chen ◽  
Feng Guo ◽  
Yan Wang
Keyword(s):  
Numerical Analysis ◽  
Coal Seam ◽  
Theoretical Calculation ◽  
High Water ◽  
Industrial Test ◽  
Thin Coal Seam

According to the occurrence condition of one mine’s primary face coal seam and using the methods of theoretical calculation and numerical analysis, this paper determined the reasonable parameters of the high-water material filling body and made an industrial test in the field haulage entry. The results showed that the parameters of the filling body were reasonable and the filling body can maintain the roof of the entry effectively and obtain good supporting results.

scholarly journals Characteristics of top coal fall in front of face support in longwall: A case study

2020 ◽  
Vol 42 (2) ◽  
pp. 152-160
Author(s):  
Tien Dung Le ◽  
Dinh Hieu Vu ◽  
Anh Tuan Nguyen
Keyword(s):  
Numerical Analysis ◽  
Stress Concentration ◽  
Longwall Mining ◽  
Empirical Studies ◽  
Horizontal Stress ◽  
Material Failure ◽  
Roof Fall ◽  
Mode A ◽  
Face Support

Top coal fall in front of face support severely affects the safety and productivity in mechanized longwall mining. This paper presents a discontinuous numerical analysis on the important characteristics of the fall such as abutment stress, material failure, and fall mode. A top coal fall model is validated against site observation and past numerical and empirical studies. The numerical results provide further evidence confirming that horizontal stress relaxation, vertical stress concentration, and strength and structure of coal seam control the failure of top coal ahead of support. Top coal fall in longwall mining with large caving height is found in “stress caving” mode or, in other words, “horizontal stress-driven guttering” mechanism. A pre-existing fault running into a mined-out area can facilitate the occurrence of face spall but may not lead to top coal fall.  The results of this study are particularly helpful to engineers in developing proper remedy or prevention solutions to top coal/roof fall incidents.

scholarly journals Identification for Abutment Stress by Drilling Cuttings

2021 ◽  
Vol 11 (20) ◽  
pp. 9467
Author(s):  
Jian Tan ◽  
Yunliang Tan ◽  
Zihui Wang ◽  
Yubao Zhang
Keyword(s):  
Stress Concentration ◽  
Coal Seam ◽  
Rock Burst ◽  
Abutment Pressure ◽  
High Stress ◽  
Coal Seams ◽  
Cutting Test ◽  
Key Factor ◽  
Distribution Of Stress ◽  
The Relationship

The concentration of abutment pressure acting on coal seams induced by mining is a key factor to trigger rock burst. Understanding of abutment pressure or stress concentration is fundamental in preventing and controlling rock burst. The influence on abutment pressure fluctuation caused by the inhomogeneity of coal seams needs to be considered, but it is difficult to obtain by the present usual ways such as acoustic transmission, electromagnetic wave transmission, etc. In this article, the relationship between the amount of cuttings drilled in a coal seam and stress level was analyzed by considering the effect of drilling cutting expansion, and the drilling cutting test was carried out in Xinglongzhuang Coal Mine, Shandong Energy Ltd. It is found that the amount of cuttings drilled is positively related to the degree of stress concentration in both the plastic fracture zone and elastic zone. The amount of drilling cuttings is closely related to the roof weighting. In addition, the irregular fluctuation of drilling cuttings is an approximate map of distribution of stress concentration because of the non-uniformity of cracks and other defects in the coal seam. In order to meet the need of rock burst prevention by accurate pressure relief in high-stress zones, enough boreholes are needed.

scholarly journals Investigation on the CBM Extraction Techniques in the Broken-Soft and Low-Permeability Coal Seams in Zhaozhuang Coalmine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhaoying Chen ◽  
Xuehai Fu ◽  
Guofu Li ◽  
Jian Shen ◽  
Qingling Tian ◽  
...  
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Coalbed Methane ◽  
Research Result ◽  
Horizontal Stress ◽  
Gas Production ◽  
Vertical Stress ◽  
Low Permeability ◽  
Coal Seams

To enhance the coalbed methane (CBM) extraction in broken-soft coal seams, a method of drilling a horizontal well along the roof to hydraulically fracture the coal seam is studied (i.e., HWR-HFC method). We first tested the physical and mechanical properties of the broken-soft and low-permeability (BSLP) coal resourced from Zhaozhuang coalmine. Afterward, the in situ hydraulic fracturing test was conducted in the No. 3 coal seam of Zhaozhuang coalmine. The results show that (1) the top part of the coal seam is fractured coal, and the bottom is fragmented-mylonitic coal with a firmness coefficient value of less than 1.0. (2) In the hydraulic fracturing test of the layered rock-coal specimens in laboratory, the through-type vertical fractures are usually formed if the applied vertical stress is the maximum principal stress and is greater than 4 MPa compared with the maximum horizontal stress. However, horizontal fractures always developed when horizontal stress is the maximum or it is less than 4 MPa compared with vertical stress. (3) The in situ HWR-HFC hydraulic fracturing tests show that the detected maximum daily gas production is 11,000 m3, and the average gas production is about 7000 m3 per day. This implies that the CBM extraction using this method is increased by 50%~100% compared with traditional hydraulic fracturing in BSLP coal seams. The research result could give an indication of CBM developing in the broken-soft and low-permeability coal seams.

scholarly journals Experimental Study of Prevention and Control of Rock Burst in Steeply Inclined Coal Seams by Mining Sequence and Filling

2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
Zhihui Zhang ◽  
Yangyi Liu ◽  
Wenwen Zhu ◽  
Jian Liu ◽  
Tian Ma ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Coal Seam ◽  
Rock Burst ◽  
Vertical Direction ◽  
Geological Structure ◽  
Coal Seams ◽  
Rock Pillar ◽  
Fundamental Information ◽  
Mining Sequence ◽  
Control And Prevention

The control and prevention of rock burst in a steeply inclined coal seam are essential. In order to figure out the effects of filling and mining sequence on rock burst in the steeply inclined coal seam, B3+6 and B1+2 coal seams in Wudong coal mine are chosen as the research objects, and an in-house experiment system of similarity simulation is established in this study. Combined with numerical simulation, the characteristics of collapse, stress distribution, and displacement variations can be measured, which provide useful information to study the effects of the filling body and mining sequence on rock burst. Experimental results show that the key reason for rock burst in a steeply inclined coal seam is the stress concentration of the rock pillar between B3+6 and B1+2 coal seams instead of the stress-lever-effect of a deeper rock pillar. The filling body can support the middle rock pillar, share the geological structure stress in the horizontal and vertical direction, eliminate the stress concentration zone largely, and prevent the occurrence of rock burst. When multiple working faces are working, the opposite side of the coal seam should be mined first to release the energy in the rock in advance, thus preventing the rock burst effectively. The research results provide fundamental information for better understanding the reason for rock burst and preventing rock burst in the steeply inclined coal seam.

scholarly journals Characteristics of top coal fall in front of face support in longwall: A case study

2020 ◽  
Vol 42 (2) ◽  
pp. 152-160
Author(s):  
Tien Dung Le ◽  
Dinh Hieu Vu ◽  
Anh Tuan Nguyen
Keyword(s):  
Numerical Analysis ◽  
Stress Concentration ◽  
Longwall Mining ◽  
Empirical Studies ◽  
Horizontal Stress ◽  
Material Failure ◽  
Roof Fall ◽  
Mode A ◽  
Face Support

Top coal fall in front of face support severely affects the safety and productivity in mechanized longwall mining. This paper presents a discontinuous numerical analysis on the important characteristics of the fall such as abutment stress, material failure, and fall mode. A top coal fall model is validated against site observation and past numerical and empirical studies. The numerical results provide further evidence confirming that horizontal stress relaxation, vertical stress concentration, and strength and structure of coal seam control the failure of top coal ahead of support. Top coal fall in longwall mining with large caving height is found in “stress caving” mode or, in other words, “horizontal stress-driven guttering” mechanism. A pre-existing fault running into a mined-out area can facilitate the occurrence of face spall but may not lead to top coal fall.  The results of this study are particularly helpful to engineers in developing proper remedy or prevention solutions to top coal/roof fall incidents.

Numerical Analysis of Roof Pre-Splitting Roadway Effect in Incline Coal Seam

2014 ◽  
Vol 644-650 ◽  
pp. 1899-1902
Author(s):  
Hua Jin ◽  
Tao Ning ◽  
Bo Yin
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Coal Seam ◽  
Rock Burst ◽  
Prevention And Control ◽  
New Technology ◽  
Simulation Software ◽  
Concentration Degree ◽  
Roof Strength ◽  
And Control

Roof pre-splitting roadway is a new technology in roof induced rock burst prevention and control of incline coal seam. With the purpose of increasing rock burst prevention and control effective, FLAC3D numerical simulation software was used to analyze stress distribution characteristics and roof pre-splitting effect and the layout of the roof pre-splitting roadway parameters. The results showed that the roof pre-splitting roadway changed roof and floor stress distribution, the stress concentration degree is high in the zone of roof and floor around pre-splitting roadway and the two ribs of pre-splitting roadway, which made the roof strength weakened and easy to break, avoiding a large overhang in the process of mining and rock-burst; The roof pre-splitting roadway led to stress concentration in the range of 5 ~ 10 m, roof effective weakening range 12 m, so the distance of two roof pre-splitting roadway should be more than 20m. The research provided the reference basis for rock burst prevention by roof pre-splitting roadway in the incline coal seam group mining.

Sign in / Sign up

Export Citation Format

Share Document