Mechanism and Application of Layered Grouting Reinforcement for Fractured Coal and Rock Roadway
2. Engineering Overview
2.1. General Situation of the Coal Roadway
2.2. Deformation and Failure Characteristics of Roadway
3. Fracture State of Roadway Roof and Its Rock Mechanics Characteristics
3.1. Core Drilling
3.2. Rock Mechanics Experiment
4. Mechanism of Layered Grouting Reinforcement for Surrounding Rock of Roadway
4.1. Roof Failure Analysis Considering Stress Gradient
4.2. Mechanism of Roof Layered Grouting Reinforcement
5. Scheme and Application of Grouting Reinforcement Support
5.1. Implementation of Grouting Reinforcement Support Scheme
- Bolt support parameters: As shown in Figure 10, the roadway roof adopts a φ 20 mm × 2200 mm equal strength threaded steel resin bolt and the row spacing of 0.9 m × 1 m. The arch-type high-strength pallet is adopted, and the specification is 150 mm × 150 mm × 10 mm. The extended anchoring method is adopted, and the anchoring length of the bolt is 1050 mm. A W-shaped steel belt support is combined, and a diamond-shaped metal mesh is hung on the whole section with a mesh size of 50 mm × 50 mm. The two sides are arranged with a φ 20 mm × 2200 mm bolt with a row spacing of 1.3 m × 1 m.
- Cable support parameters: As shown in Figure 10, the roadway roof adopts a φ 22 mm × 6300 mm hollow grouting cable arranged in a “well type” form with anchor support. The row spacing of the cable is 1.5 m, and the cable is perpendicular to the roof. The distance between the upper side cable of the roof and the upper side is 0.3 m, the distance between the middle cable and the upper side is 1.55 m, and the distance between the lower side cable and the lower side is 0.65 m. The anchoring length of the cable is 1300 mm. The cable is supported by a three-hole steel belt, and the stubble is arranged between steel belts.
- Layered grouting reinforcement support: A layered grouting reinforcement support design is implemented for the roadway roof. The “shallow bolt grouting” is based on the original bolt support. The hole depth is 2 m, the grouting holes are located between every two rows of anchor bolts, and the row spacing between grouting holes is 1.8 m × 2 m. When grouting, the borehole shall be used with the grout stop sleeve to make the borehole pass through the fracture zone vertically as far as possible and maximize the diffusion of grouting fluid. The “deep cable grouting” adopts continuous downward grouting carried out in sequence along the roadway. When the design grouting pressure is 10 MPa, the pressure is stabilized for more than 10 min so the grout can spread to the maximum range and the roof rock cracks can be filled as much as possible. The “deep anchor cable grouting” material is superfine cement, and the “shallow anchor bolt grouting” material is GRPC-1 early setting and early strength new material. The “shallow” grouting shall be carried out first and then the “deep” grouting. In the process of “shallow” grouting when there are abnormal phenomena, such as slurry channeling on the surrounding coal wall, the grouting pump shall be stopped in time.
5.2. Analysis of Roadway Surface Displacement Monitoring Results and Support Evaluation
- Layout of monitoring points
- Analysis of displacement monitoring results
- Field investigation and drilling exploration were carried out for the mining roadway of ZF3806’s working face, and rock mechanics experiments were carried out. The analysis results show the coal and rock masses have significant fragmentation, the roof subsidence is severe, and the support failures are more frequent. During mining, accidents, such as the roof falling and anchor bolt failure, occur, and there are significant potential safety hazards.
- The layered grouting reinforcement method of “shallow bolt grouting + deep cable grouting” is proposed, and the bending moment equation of roof rock beam is established. Through layered grouting, the strength of the surrounding rock is increased, and the bending moment of roof rock is reduced so the roadway roof forms a composite beam support structure, and its ability to resist bending deformation is strengthened.
- The layered grouting of “shallow bolt grouting + deep cable grouting” is adopted to reinforce the support, and the field application effect is significant. According to the field-monitoring results, the stability of the roadway is improved, the roof displacement is reduced, and the integrity is better. The displacement of both sides of the roadway is within the controllable range, which ensures safe mining and reduces the later maintenance cost of the roadway.
- The research of this paper is mainly field oriented. This paper mainly studies the rock mechanics failure characteristics of the roadway roof and the mechanism of grouting reinforcement support and carries out field application. Due to the influence of objective factors, such as experimental conditions, further research will be carried out on the performance of grouting materials and the comparison before and after grouting in broken rock mass.
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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Liao, Z.; Feng, T. Mechanism and Application of Layered Grouting Reinforcement for Fractured Coal and Rock Roadway. Appl. Sci. 2023, 13, 724. https://doi.org/10.3390/app13020724
Liao Z, Feng T. Mechanism and Application of Layered Grouting Reinforcement for Fractured Coal and Rock Roadway. Applied Sciences. 2023; 13(2):724. https://doi.org/10.3390/app13020724Chicago/Turabian Style
Liao, Ze, and Tao Feng. 2023. "Mechanism and Application of Layered Grouting Reinforcement for Fractured Coal and Rock Roadway" Applied Sciences 13, no. 2: 724. https://doi.org/10.3390/app13020724