Stability Control of a Goaf-Side Roadway under the Mining Disturbance of an Adjacent Coal Working Face in an Underground Mine

Goaf-side roadway driving could not only notably reduce the loss of coal resources and improve the coal recovery rates, but also greatly mitigate the imbalance between excavation speed and production needs, which are able to prolong the service life of the mine and are pivotal to sustainable and efficient development of underground coal mines. However, it is difficult to control the stability of the goaf-side roadway, especially under mining disturbance of another adjacent coal working face. In order to control the stability of the goaf-side roadway, Haulageway 1513 in the Xinyi Coal Mine of China, under mining disturbance, theoretical analysis, numerical simulation, and engineering practice were carried out to reveal the mechanism of overburden key strata fracture, stress distribution, and deformation characteristics of the surrounding rock of the goaf-side roadway due to mining disturbance. Results showed that some key strata above Goaf 1512 did not fracture due to the influence of the strata caving angles. However, these key strata would fracture and break into rock blocks when suffering from mining disturbance of the adjacent coal working face, which changed the stress distribution and increased the deformations of the surrounding rock of the goaf-side roadway. The combined techniques of pressure relief and bolt support were proposed and carried out to control the stability of the goaf-side roadway. Engineering practice indicated that the maximum deformations of the roof and sidewall-to-sidewall were 220 mm and 470 mm, respectively. The deformations of the goaf-side roadway under mining disturbance were efficiently controlled.

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Stability Analysis of Roadway Groups under Multi-Mining Disturbances

Applied Sciences ◽

10.3390/app11177953 ◽

2021 ◽

Vol 11 (17) ◽

pp. 7953

Author(s):

Yuantian Sun ◽

Ruiyang Bi ◽

Qingliang Chang ◽

Reza Taherdangkoo ◽

Junfei Zhang ◽

...

Keyword(s):

Coal Mining ◽

Coal Pillar ◽

Stability Control ◽

Surrounding Rock ◽

Key Strata ◽

Working Face ◽

Roadway Stability ◽

Mining Disturbance ◽

Mining Face ◽

The Stability

The roadway stability has been regarded as the main challenging issue for safety and productivity of deep underground coal mines, particularly where roadways are affected by coal mining activities. This study investigates the −740 m main roadway in the Jining No. 2 Coal Mine to provide a theoretical basis for the stability control of the main deep roadway affected by disturbances of adjacent working activities. Field surveys, theoretical analyses, and numerical simulations are used to reveal mechanisms of the coal mining disturbance. The field survey shows that the deformation of roadway increases when the work face advances near the roadway group. Long working face mining causes the key strata to collapse based on the key strata theory and then disturbs the adjacent roadway group. When the working face is 100 m away from the stop-mining line, the roadway group is affected by the mining face, and the width roadway protection coal pillar is determined to be about 100 m. Flac3D simulations prove the accuracy of the theoretical result. Through reinforcement and support measures for the main roadway, the overall strength of the surrounding rock is enhanced, the stability of the surrounding rock of the roadway is guaranteed, and the safe production of the mine is maintained.

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The Stability of Gob-Side Entry Retaining in a High-Gas-Risk Mine

Advances in Civil Engineering ◽

10.1155/2019/7540749 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Junwen Zhang ◽

Yulin Li

Keyword(s):

Coal Mines ◽

Surrounding Rock ◽

Shanxi Province ◽

Engineering Practice ◽

Efficient Production ◽

Coal Recovery ◽

Working Face ◽

Geological Conditions ◽

The Stability ◽

Strengthening Technique

There are series of problems faced by most of the coal mines in China, ranging from low-coal recovery rate and strained replacement of working faces to gas accumulation in the upper corner of coalfaces. Based on the gob-side entry retaining at the No. 18205 working face in a coal mine in Shanxi Province, theoretical analysis, numerical simulation, and engineering practice were comprehensively used to study the mechanical characteristics of the influence of the width of the filling body beside the roadway and the stability of surrounding rock in a high-gas-risk mine. The rational width of the filling body beside the roadway was determined, and a concrete roadway-side support with a headed reinforcement-integrated strengthening technique was proposed, which have been applied in engineering practice. The stability of the filling body beside the roadway is mainly influenced by the movement of the overlying rock strata, and the stability of the surrounding rock can be improved effectively by rationally determining the width of the filling body beside the roadway. When the width of the roadway-side filling body is 2.5 m, the surrounding rock convergence of the gob-side entry retaining is relatively small at only 5% of the convergence ratio. It has been shown that the figure for roof separation is relatively low, and strata behaviors are relatively alleviated and gas density do not exceed the limit, which are the best results of gob-side entry retaining. The results of this research can provide theoretical guidance for excavation of coal mines with similar geological conditions and have some referential significance to safety and efficient production in coal mines.

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Study of the Stability Control of the Rock Surrounding Double-Key Strata Recovery Roadways in Shallow Seams

Advances in Civil Engineering ◽

10.1155/2019/9801637 ◽

2019 ◽

Vol 2019 ◽

pp. 1-21 ◽

Cited By ~ 2

Author(s):

Cheng Zhu ◽

Yong Yuan ◽

Zhongshun Chen ◽

Zhiheng Liu ◽

Chaofeng Yuan

Keyword(s):

Engineering Application ◽

Stability Control ◽

Surrounding Rock ◽

Control Effect ◽

Pressure Relief ◽

Support Design ◽

Key Strata ◽

Fracture Development ◽

Surrounding Rock Control ◽

The Stability

The stability control of the rock surrounding recovery roadways guarantees the safety of the extraction of equipment. Roof falling and support crushing are prone to occur in double-key strata (DKS) faces in shallow seams during the extraction of equipment. Therefore, this paper focuses on the stability control of the rock surrounding DKS recovery roadways by combining field observations, theoretical analysis, and numerical simulations. First, pressure relief technology, which can effectively release the accumulated rock pressure in the roof, is introduced according to the periodic weighting characteristics of DKS roofs. A reasonable application scope and the applicable conditions for pressure relief technology are given. Considering the influence of the eroded area on the roof structure, two roof mechanics models of DKS are established. The calculation results show that the yield load of the support in the eroded area is low. A scheme for strengthening the support with individual hydraulic props is proposed, and then, the support design of the recovery roadway is improved based on the time effects of fracture development. The width of the recovery roadway and supporting parameters is redesigned according to engineering experience. Finally, constitutive models of the support and compacted rock mass in the gob are developed with FLAC3D software to simulate the failure characteristics of the surrounding rock during pressure relief and equipment extraction. The surrounding rock control effects of two support designs and three extraction schemes are comprehensively evaluated. The results show that the surrounding rock control effect of Scheme 1, which combines improved support design and the bidirectional extraction of equipment, is the best. Engineering application results show that Scheme 1 realizes the safe extraction of equipment. The research results can provide a reference and experience for use in the stability control of rock surrounding recovery roadways in shallow seams.

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Deformation Rules for Surrounding Rock in Directional Weakening of End Roofs of Thin Bedrocks and Ultrathick Seams

Advances in Civil Engineering ◽

10.1155/2020/8882374 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Fei Liu ◽

Zhanguo Ma ◽

Yongsheng Han ◽

Zhimin Huang

Keyword(s):

Abutment Pressure ◽

Main Roof ◽

Stability Control ◽

Surrounding Rock ◽

Western China ◽

Resource Exploitation ◽

Failure Characteristics ◽

Key Strata ◽

Working Face ◽

Geological Conditions

With the deployment of China’s energy strategy in the western regions, complex geological mining conditions such as thin bedrock and ultrathick seams in western China have caused a series of problems such as serious deformation of the surrounding rock at the ends of the working face and the increase in the lead abutment pressure of the roadways; the research on end roof deformation in the resource exploitation in western China has become one of the great demands of the industry. Based on the failure characteristics of rock mass, relying on the actual mining geological conditions of a coal mine in Inner Mongolia, the failure characteristics of the overlying rock strata under the influence of mining were simulated and analyzed using similar material simulation experiment, which intuitively reproduced the failure and deformation processes of the immediate roof, main roof, and key strata and revealed the mechanical mechanism of the directional weakening of the end roof. It is of great significance for the stability control of the surrounding rock at the end of the fully mechanized caving face in the thin bedrocks and ultrathick seams, reducing the abutment pressure of gate roadway and controlling the spontaneous combustion of residual coal in the goaf.

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Research and Application of Directional Roof Cutting and Pressure Releasing Technology for Retracement Channel of 3314 Working Face in Hexi Coal Mine

10.21203/rs.3.rs-449704/v1 ◽

2021 ◽

Author(s):

Jindong Cao ◽

Xiaojie Yang ◽

Ruifeng Huang ◽

Qiang Fu ◽

Yubing Gao

Keyword(s):

Coal Mine ◽

High Stress ◽

Surrounding Rock ◽

Engineering Practice ◽

Mine Pressure ◽

Working Face ◽

Geological Conditions ◽

Cutting Effect ◽

The Stability ◽

Two Sides

Abstract The high stress of the surrounding rock of Hexi Coal Mine easily leads to severe deformation of the retracement channel and the appearance of the mine pressure during the retreat severely affects the stability of the roadway. In order to solve the above problems, a roadway surrounding rock control technology is proposed and tested. The bidirectional energy-concentrated tensile blasting technology is used to perform directional cutting to cut off the stress propagation path. Firstly, the deformation mechanism of the roof is analyzed by establishing the deformation mechanical model of the roof of the retracement channel. Then, according to the geological conditions of working face 3314 and theoretical calculation, the key parameters of roof cutting and pressure releasing of retracement channel are determined, and through the numerical analysis of its cutting effect, the length of cutting seam is 11.5m, and the cutting angle is 10°. Finally, a field test is carried out on the retracement channel of 3314 working face to verify the effect of roof cutting. The results show that the deformation of the retracement channel and the main roadway is very small. In the process of connecting the working face and the retracement channel, the maximum roof to floor convergence is 141mm, and the two sides convergence is 79mm. After the hydraulic support was retracted, the maximum roof to floor convergence of the surrounding rock is 37 mm, and the two sides convergence is 33mm. The roof cutting and pressure releasing of the retracement channel ensures the safe evacuation of the equipment and the stability of the main roadway. The cutting effect is obvious for the release of pressure, which is of great significance to engineering practice.

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Stability of "Support-Surrounding Rock" System for Fully Mechanized Longwall Mining in Steeply Dipping Coal Seams

10.21203/rs.3.rs-403141/v1 ◽

2021 ◽

Author(s):

Luo Shenghu ◽

tong wang ◽

Wu Yongping ◽

Huangfu Jingyu ◽

Zhao Huatao

Keyword(s):

Coal Seam ◽

Longwall Mining ◽

Stability Control ◽

Surrounding Rock ◽

Coal Seams ◽

Physical Test ◽

Rock System ◽

Working Face ◽

The Stability ◽

Mining Height

Abstract The key to the safe and efficient longwall mining of steeply dipping seams lies in the stability control of the "support-surrounding rock" system. This paper analyzes the difficulty of controlling the stability of the support during the longwall mining process of steeply dipping coal seams in terms of the characteristics of the non-uniform filled-in gob using a combination of physical test, theoretical analysis and field measurements. Considering the floor as an elastic foundation, we built a "support-surrounding rock" mechanical model based on data obtained on "support-surrounding rock" systems in different regions and the laws of support motion under different load conditions. Our findings are summarized as follows. First, depending on the angle of the coal seam, the caving gangue will roll (slide) downward along the incline, resulting in the formation of a non-uniform filling zone in the deep gob in which the lower, middle, and upper sections are filled, half-filled, and empty, respectively. In addition, an inverted triangular hollow surface is formed on the floor of the gob in the middle and upper sections behind the support. Furthermore, as the angle of the coal seam, length of the working face, and mining height increase, the characteristics of the non-uniform filled-in gob are enhanced. Second, we found that, as a result of support by the gangue, the "support-surrounding rock" system is relatively stable in the lower part of the working face while, in the middle and upper sections of the working face, the contact method and loading characteristics of the support are more complicated, making stability control difficult. Third, the magnitude and direction of the load, action point, and mining height all affect the stability of the support to varying degrees, with the tangential load and action position of the roof load having the most significant impacts on the stability of the support. Under loading by the roof, rotation and subsidence of the support inevitably occur, with gradually increasing amplitude and effects on the inter-support and sliding forces. Finally, we found that it is advisable in the process of moving the support to adopt "sliding advance of support" measures and to apply a "down-up" removal order to ensure overall stability. These research results provide reference and guidance of significance to field practice production.

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The Stability of Roadway Groups under Rheology Coupling Mining Disturbance

Sustainability ◽

10.3390/su132112300 ◽

2021 ◽

Vol 13 (21) ◽

pp. 12300

Author(s):

Sen Yang ◽

Guichen Li ◽

Ruiyang Bi ◽

Bicheng Yao ◽

Ruiguang Feng ◽

...

Keyword(s):

Coupling Effect ◽

Coal Pillar ◽

Mine Safety ◽

Key Strata ◽

Deep Well ◽

Working Face ◽

Safety Production ◽

Mining Disturbance ◽

The Stability ◽

And Control

The deep roadway groups play an important role in transportation and ventilation in coal mine production. Therefore, it is very important to comprehensively analyze the coupling effect of rheological deformation and coal mining on the stability of the roadway groups. In this paper, the disturbance effects of different stop-mining lines on roadway groups under long-term rheology were investigated by numerical simulation, and the failure mechanism of roadway groups with large sections and multiple disturbances in a deep well was revealed. The results show that the long working face will lead to the collapse of key strata, and the influence range will spread to the adjacent roadway groups. When the distance between the working face and the stop-mining line is 100 m, the roadway groups cannot be affected by the working face mining, and the reserved width of the coal pillar can be determined to be 100 m, which increases the stability of the roadway’s surrounding rock and maintains the mine safety production. This paper aims to provide a reference for groups design and control under similar conditions.

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Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.90-93.2307 ◽

2011 ◽

Vol 90-93 ◽

pp. 2307-2312 ◽

Cited By ~ 2

Author(s):

Wen Jiang Li ◽

Su Min Zhang ◽

Xian Min Han

Keyword(s):

Plastic Strain ◽

Catastrophe Theory ◽

Soft Rock ◽

Surrounding Rock ◽

In Situ Monitoring ◽

Engineering Practice ◽

Stability Of Surrounding Rock ◽

The Stability ◽

Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

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Surrounding Rock Movement of Steeply Dipping Coal Seam Using Backfill Mining

Shock and Vibration ◽

10.1155/2021/5574563 ◽

2021 ◽

Vol 2021 ◽

pp. 1-17

Author(s):

Wenyu Lv ◽

Kai Guo ◽

Jianhao Yu ◽

Xufeng Du ◽

Kun Feng

Keyword(s):

Numerical Simulation ◽

Coal Seam ◽

Surrounding Rock ◽

Maximum Deflection ◽

Coal Seams ◽

Physical Similarity ◽

Working Face ◽

Rock Structure ◽

Backfill Mining ◽

The Stability

The movement of the overlying strata in steeply dipping coal seams is complex, and the deformation of roof rock beam is obvious. In general, the backfill mining method can improve the stability of the surrounding rock effectively. In this study, the 645 working face of the tested mine is used as a prototype to establish the mechanical model of the inclined roof beam using the sloping flexible shield support backfilling method in a steeply dipping coal seam, and the deflection equation is derived to obtain the roof damage structure and the maximum deflection position of the roof beam. Finally, numerical simulation and physical similarity simulation experiments are carried out to study the stability of the surrounding rock structure under backfilling mining in steeply dipping coal seams. The results show the following: (1) With the support of the gangue filling body, the inclined roof beam has smaller roof subsidence, and the maximum deflection position moves to the upper part of working face. (2) With the increase of the stope height, the stress and displacement field of the surrounding rock using the backfilling method show an asymmetrical distribution, the movement, deformation, and failure increase slowly, and the increase of the strain is relatively stable. Compared with the caving method, the range and degree of the surrounding rock disturbed by the mining stress are lower. The results of numerical simulation and physical similarity simulation experiment are generally consistent with the theoretically derived results. Overall, this study can provide theoretical basis for the safe and efficient production of steeply dipping coal seams.

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Study on the Fracture Law of Inclined Hard Roof and Surrounding Rock Control of Mining Roadway in Longwall Mining Face

Energies ◽

10.3390/en13205344 ◽

2020 ◽

Vol 13 (20) ◽

pp. 5344

Author(s):

Feng Cui ◽

Shuai Dong ◽

Xingping Lai ◽

Jianqiang Chen ◽

Chong Jia ◽

...

Keyword(s):

Energy Release ◽

Longwall Mining ◽

Coal Pillar ◽

High Energy ◽

Mechanical Analysis ◽

Engineering Practice ◽

Analysis Model ◽

Hard Roof ◽

Working Face ◽

The Stability

In the inclination direction, the fracture law of a longwall face roof is very important for roadway control. Based on the W1123 working face mining of Kuangou coal mine, the roof structure, stress and energy characteristics of W1123 were studied by using mechanical analysis, model testing and engineering practice. The results show that when the width of W1123 is less than 162 m, the roof forms a rock beam structure in the inclined direction, the floor pressure is lower, the energy and frequency of microseismic (MS) events are at a low level, and the stability of the section coal pillar is better. When the width of W1123 increases to 172 m, the roof breaks along the inclined direction, forming a double-hinged structure, the floor pressure is increased, and the frequency and energy of MS events also increases. The roof gathers elastic energy release, and combined with the MS energy release speed it can be considered that the stability of the section coal pillar is better. As the width of W1123 increases to 184 m, the roof in the inclined direction breaks again, forming a multi-hinged stress arch structure, and the floor pressure increases again. MS high-energy events occur frequently, and are not conducive to the stability of the section coal pillar. Finally, through engineering practice we verified the stability of the section coal pillar when the width of W1123 was 172 m, which provides a basis for determining the width of the working face and section coal pillar under similar conditions.

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