Research on the Simulation of the Roof Fracture about the Gob-Side Entry Retaining

2013 ◽  
Vol 734-737 ◽  
pp. 624-627 ◽  
Author(s):  
Jian Jun Shi ◽  
Run Hua Wu ◽  
Tao Yong ◽  
Jing Zhong Guo
Keyword(s):  
Main Roof ◽  
Rock Stratum ◽  
Effective Measure ◽  
Energy Group ◽  
Key Stratum ◽  
Working Face ◽  
Geological Conditions ◽  
Research Findings ◽  
The Stability ◽  
Basic Features

The geological conditions of haulage roadway of the working face 1528 in GeQuan Coal Mine, which belongs to the JiZhong Energy Group CO., Ltd., and the research findings of Key Stratum Theory was taken into consideration, based on which established a mechanical model could reflect the basic features of rock stratum and made a profound investigation on the form and conditions of the fractures on main roofs. A systematic study on the stress, deformation, and damage characters of fractures on main roofs beyond a retained entry has been made by the laboratory test. The experiment shows that the deeper the fracture is in the rib, the greater the differences between dimension of compression and deformation will likely be, and the greater the influences on the stability of surrounding rock will it has. At the same time, smaller is the overhanging beam in mined-out area, more beneficial to roadway maintenance. On a certain deformation of main roof, it creates subsidence that is great difference in different position of a roadway. The subsidence near those mined-out areas is much more than those near the ribs. The application of a strong and effective measure could help cut the roof out and assure its stability.

scholarly journals Evolution Laws of Mining-induced Stress in Floor Strata and Its Influence on the Stability of a Floor Roadway Affected by Overhead Mining

2020 ◽  
Vol 24 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Pu Wang ◽  
Lishuai Jiang ◽  
Changqing Ma ◽  
Anying Yuan
Keyword(s):  
Numerical Simulation ◽  
Mechanical Model ◽  
Scientific Basis ◽  
Pull Out ◽  
Induced Stress ◽  
Working Face ◽  
Geological Conditions ◽  
Evolution Laws ◽  
The Stability

The study of evolution laws of the mining-induced stress in floor strata affected by overhead mining is extremely important with respect to the stability and support of a floor roadway. Based on the geological conditions of the drainage roadway in the 10th district in a coalmine, a mechanical model of a working face for overhead mining over the roadway is established, and the laws influencing mining stress on the roadway in different layers are obtained. The evolution of mining stress in floor with different horizontal distances between the working face and the floor roadway that is defined as LD are examined by utilizing UDEC numerical simulation, and the stability of roadway is analyzed. The results of the numerical simulation are verified via on-site tests of the deformation of the surrounding rocks and bolts pull-out from the drainage roadway. The results indicate that the mining stress in floor is high, which decreases slowly within a depth of less than 40 m where the floor roadway is significantly affected. The mining stress in the floor increases gradually, and the effect of the mining on the roadway is particularly evident within 0 m ≤ LD ≤ 40 m. Although the floor roadway is in a stress-relaxed state, the worst stability of the surrounding rocks is observed during the range -20 m ≤ LD < 0 m, in which the negative value indicates that the working face has passed the roadway. The roadway is affected by the recovery of the abutment stress in the goaf when -60 m ≤ LD <20 m, and thus it is important to focus on the strengthening support. The results may provide a scientific basis for establishing a reasonable location and support of roadways under similar conditions.

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

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.

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

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
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.

Design of High Speed Railway Tunnel and its Construction Method in Abrupt Slope with Loose Rockmass

2014 ◽  
Vol 580-583 ◽  
pp. 1096-1099 ◽  
Author(s):  
Xiao Jun Zhou ◽  
Bo Jiang ◽  
Rui Yang ◽  
Chao Ning
Keyword(s):  
High Speed ◽  
Rational Design ◽  
Composite Fiber ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Working Face ◽  
Tunneling Method ◽  
Geological Conditions ◽  
The Stability ◽  
Tunnel Portal

This paper mainly deals with the structural design of high speed railway tunnel and its driving method in abrupt slope with loose rockmass, meanwhile summarizes the connection between tunnel portal and bridge abutment in loose rockmass according to complicated landform and geology. The anti-slide piles are adopted to retain the stability of abrupt slope near the tunnel portal. In order to eliminate the risk and cost in tunnel construction, four bench cut method is invented to satisfy the safe excavation of loose rockmass in the tunnel. Composite fiber rockbolt is also employed to keep the stability of working face while driving the tunnel. The innovative tunneling method presented in the paper can be applied to guide the rational design and economical construction of high speed railway tunnels in loose surrounding rock under harsh geological conditions.

Buckling and Post-Buckling Behavior for Roof Strata in Longwall Mining

2012 ◽  
Vol 170-173 ◽  
pp. 751-754
Author(s):  
Qun Song ◽  
Zhi Lin Yang
Keyword(s):  
Longwall Mining ◽  
Main Roof ◽  
Equilibrium Path ◽  
Fracture Characteristics ◽  
Key Stratum ◽  
Buckling Behavior ◽  
Roof Stratum ◽  
Post Buckling ◽  
The Stability ◽  
Roof Strata

In accordance with the occurrence behavior of roof strata and the fracture characteristics of key stratum in shallow seam longwall mining, this paper studied the post-buckling behaviors of key roof stratum in the process of mining by using initial post-buckling theory, which derived a critical load and a breaking span of the main roof during the first weighting, determined the final subsidence for broken key stratum, and presented an application with the example of Daliuta 1203 face. The results indicate that the rock blocks a in are state of non-equilibrium after main roof breaking, the equilibrium path of main roof is unstable from breaking to final subsidence; thick unconsolidated layers above roof have effect on post-buckling behaviors of key stratum; the stability for bifurcation point equilibrium configuration and post-buckling equilibrium path of roof strata could be revealed and an effective method for determining displacement field of imperfection structure could be provided by using initial post -buckling theory.

scholarly journals The Formation Mechanism of Surface Landslide Disasters in the Mining Area under Different Slope Angles

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Chi Mu ◽  
Xueyi Yu ◽  
Bingchao Zhao ◽  
Dongdong Zhang ◽  
Xuwei Mao ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Formation Mechanism ◽  
Slope Angle ◽  
Mining Area ◽  
Rock Stratum ◽  
Effective Prevention ◽  
Surface Movement ◽  
Working Face ◽  
Geological Conditions ◽  
Movement And Deformation

Slope stability analysis is important for the safe mining of mineral resources. The collapse of goafs in loess gullies can lead to natural disasters such as surface landslides. In this context, this study analyzes monitoring data obtained from surface observation in the Shendong mining area of the Hanjiawan coal mine based on the geological conditions therein. The monitoring results show that the working face experiences a starting period, an active period, and a declining period, from the start of mining to the end of the working face. At the initial mining stage, there is no evident surface movement or deformation in the mining area. When the advance distance of the 12106 working face is between 13 m and 109 m, the surface movement and deformation vary significantly, and the maximum subsidence reaches 1963 mm, which is enough to cause landslides. We select the physical and mechanical parameters of the rock and soil in the mine and then simulate the formation mechanism of surface landslides under different slope angles of the mining area using FLAC3D software. Because of the collapse of the mined-out area, the overlying strata structure is destroyed, the subsidence basin is shifted to the center as a whole, and the slope mass is subjected to tensile and compression deformation, resulting in plastic damage, which develops downward along the crack and leads to a collapse because of the discontinuous movement and deformation of the surface; moreover, step-type ground fissures are produced. The results also show that when the slope angle is greater than 60°, the displacement of the slope mass is not uniform, and the rock stratum in a position with large displacement loses its support, leading to landslides; when the slope angle is less than 30°, the bedrock surface forms a sliding surface and develops to the surface, thus decreasing the possibility of landslides. Based on the stability analysis of the collapsed slope in the goaf of the loess gully, a scientific basis is provided for the effective prevention and control of geological disasters in the Shendong mining area.

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

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.

scholarly journals The Stability Analysis of Roadway near Faults under Complex High Stress

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Biao Zhang ◽  
Huaqiang Zhou ◽  
Qingliang Chang ◽  
Xu Zhao ◽  
Yuantian Sun
Keyword(s):  
Abutment Pressure ◽  
High Stress ◽  
Peak Stress ◽  
Surrounding Rock ◽  
Distribution Law ◽  
Fault Structure ◽  
Supporting Pressure ◽  
Working Face ◽  
Geological Conditions ◽  
The Stability

Based on geological conditions of 3318 working face haulage roadway in Xuchang Coal Mine, as well as the space-time relationship with surrounding gob, theoretical analysis and numerical simulation were used to study the influence of fault structure on the original rock stress of 3318 working face transport roadway. Considering the composite action of the leading supporting pressure of 3318 working face and the structure and the lateral supporting pressure of gob, the stress distribution and deformation law of roadway under the complex and high-stress condition are studied. The results show that, under the superposition of lateral abutment pressure of goaf and abutment pressure of adjacent working face and fault structure, the peak stress of roadway roof and floor moves to the surface of roadway surrounding rock, and its distribution law changes from obvious symmetry to asymmetry; surrounding rock on both sides of roadway forms asymmetric circular concentrated stress area; roof and floor and two sides of roadway show asymmetric characteristics. This reveals the stability characteristics of roadway surrounding rock under the action of multiple perturbation stresses.

scholarly journals Characteristics of the Roof Behaviors and Mine Pressure Manifestations During the Mining of Steep Coal Seam

2017 ◽  
Vol 62 (4) ◽  
pp. 871-891 ◽  
Author(s):  
Tu Hong-Sheng ◽  
Tu Shi-Hao ◽  
Zhang Cun ◽  
Zhang Lei ◽  
Zhang Xiao-Gang
Keyword(s):  
Coal Seam ◽  
Field Measurement ◽  
Main Roof ◽  
Mine Pressure ◽  
Steep Seam ◽  
Working Face ◽  
Geological Conditions ◽  
Depth Study ◽  
Dip Angle ◽  
Similar Simulation

Abstract A steep seam similar simulation system was developed based on the geological conditions of a steep coal seam in the Xintie Coal Mine. Basing on similar simulation, together with theoretical analysis and field measurement, an in-depth study was conducted to characterize the fracture and stability of the roof of steep working face and calculate the width of the region backfilled with gangue in the goaf. The results showed that, as mining progressed, the immediate roof of the steep face fell upon the goaf and backfilled its lower part due to gravity. As a result, the roof in the lower part had higher stability than the roof in the upper part of the working face. The deformation and fracture of main roof mainly occurred in the upper part of the working face; the fractured main roof then formed a “voussoir beam” structure in the strata’s dip direction, which was subjected to the slip- and deformation-induced instability. The stability analysis indicated that, when the dip angle increased, the rock masses had greater capacity to withstand slip-induced instability but smaller capacity to withstand deformation-induced instability. Finally, the field measurement of the forces exerted on the hydraulic supports proved the characteristics of the roof’s behaviors during the mining of a steep seam.

scholarly journals Parametric Study on the Ground Control Effects of Rock Bolt Parameters under Dynamic and Static Coupling Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zequan Sun ◽  
Lishuai Jiang ◽  
Jinquan Jiang ◽  
Xingyu Wu ◽  
Naser Golsanami ◽  
...  
Keyword(s):  
Static Load ◽  
Ground Deformation ◽  
Surrounding Rock ◽  
Underground Engineering ◽  
Effective Measure ◽  
Support Mechanism ◽  
Working Face ◽  
Cyclic Operation ◽  
The Stability ◽  
Ground Stability

Dynamic and static coupling loads (DSLs) are one of the most common stress environments in underground engineering. As the depth of a roadway increases over the life of a mine, the static load of the ground stress field increase multiplies, and the cyclic operation at the working face releases a large amount of dynamic energy. Therefore, deep roadways easily induce dynamic disasters during production. In this paper, a deep roadway numerical model was built with FLAC3D to test the deep roadway under DSLs and was simulated with 16 different support designs. The ground stability in each support condition was examined and compared in terms of the ground deformation and scope of failure. The underlying support mechanism was further analyzed with numerical modeling in view of the deformation in the surrounding rock mass induced by variations in the support parameters. The results show that shortening the bolt spacing is an effective measure to control the deformation of surrounding rock whatever DSLs or static load. Under static load, the larger the anchoring length is, the more stable the surrounding rock is. Under DSLs, end grouting length (S = 600 mm) and full grouting length (S = 1800 mm) can effectively control the deformation of surrounding rocks and enhance the stability of surrounding rocks. The results contribute to the design of supports in the field of underground coal mines and provide a basis for determining the reasonable support scheme for roadways.

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