Rapid backfilling method for top remaining space of steel arch support

Abstract

The invention discloses a rapid backfilling method for a top remaining space of a steel arch support, which comprises the following steps: firstly, erecting a steel arch in a broken roadway, laying a support steel mesh on the back of the steel arch, laying geotechnical cloth on the support steel mesh, and tightly and fixedly connecting two sides of the geotechnical cloth with the side wall of the roadway; the two ends of the geotechnical cloth and the tunnel vault are sealed through sealing plates to form a filling cavity, finally, curable hard polyurethane is injected into the filling cavity through a filling pipe, and after the hard polyurethane is completely cured, rapid backfilling of the space left at the top of the steel arch support can be achieved. According to the method, by means of the characteristics of high strength, water resistance, acid resistance, good action timeliness and the like of hard polyurethane, a reserved space at the top of a roadway supported by the steel arch is backfilled in time, so that it is guaranteed that the operation safety of the roadway is not disturbed by surrounding rock gravel, and meanwhile it is guaranteed that the steel arch is not disturbed by the acid-base environment.

Description

Technical Field

[0001] This invention relates to the field of mining engineering technology, specifically a method for rapid backfilling of the space left at the top of a steel arch support. Background Technology

[0002] As mineral resource extraction expands to deeper areas, the surrounding rock environment becomes increasingly complex. Fractured surrounding rock, high water pressure, and highly acidic geological conditions are common challenges, seriously threatening the durability of traditional metal arch supports and the safety of the working face. Existing technologies, such as pre-support using small-diameter pipe grouting combined with anchor bolt support, while effective to some extent, suffer from problems such as cumbersome processes, high technical requirements, slow onset of action, and high costs. Backfilling with rigid materials such as sleepers is ill-suited to complex environments, especially under highly acidic conditions, where it fails to effectively protect the arch structure. None of these methods fully consider the comprehensive requirements of the support system for rapid response, corrosion resistance, impermeability, and early strength, making it difficult to meet the requirements for efficient and reliable support in complex deep-earth environments. Summary of the Invention

[0003] The main objective of this invention is to provide a method for rapid backfilling of the space left on top of steel arch support. This method utilizes the high strength, waterproof, acid-resistant, and timely properties of rigid polyurethane to promptly backfill the reserved space on top of the roadway supported by steel arch support, thereby ensuring that the roadway's operational safety is not disturbed by the surrounding rock and gravel, and at the same time ensuring that the steel arch is not disturbed by acid and alkaline environments.

[0004] To address this, the present invention provides a method for rapid backfilling of the space remaining at the top of steel arch support, comprising the following steps: First, a steel arch is erected in the broken tunnel, and a supporting steel mesh is laid on the back of the arch top of the steel arch. Geotextile is then laid on the supporting steel mesh. Next, the two sides of the geotextile are tightly fixed to the sidewalls of the tunnel, and the two ends of the geotextile are sealed to the tunnel arch top with sealing plates to form a filling chamber. Finally, curable rigid polyurethane is injected into the filling chamber through a filling pipe. After the rigid polyurethane has completely cured, rapid backfilling of the space remaining at the top of the steel arch support can be achieved.

[0005] Specifically, an arched airbag is provided between the support net and the geotextile. After the injected rigid polyurethane reaches a predetermined pressure, the filling pipe is closed, and the airbag is inflated to expand it, applying a uniform radial extrusion force to the rigid polyurethane in the filling chamber. This forces the rigid polyurethane to densely fill the entire filling chamber and penetrate into the micro-cracks in the surrounding rock. The extrusion force is then maintained until the rigid polyurethane is basically cured. After the polyurethane is completely cured, the gas in the airbag is released, and concrete is simultaneously filled into the airbag to form a composite support structure.

[0006] Specifically, fire-resistant cotton is also provided between the support net and the airbag.

[0007] Specifically, multiple steel arch frames are arranged longitudinally along the roadway, and adjacent steel arch frames are connected by longitudinal tie rods. Each longitudinal tie rod includes a threaded sleeve and two screws screwed onto both ends of the threaded sleeve. The other end of the two screws is provided with an installation end plate, which is fixedly installed on the corresponding steel arch frame by bolts.

[0008] Specifically, the airbag is divided into multiple independent arched air chambers along the longitudinal direction of the roadway.

[0009] Specifically, the steel arch frame is erected in sections along the tunnel excavation direction. The length of each section is consistent with the width of the arch-shaped air chamber. After the installation of a single steel arch frame section is completed, a sealing plate is installed at the end of the geotextile away from the previous section, while the end closer to the previous section is sealed with fully cured polyurethane. Subsequently, rigid polyurethane is injected into the remaining space at the top of the steel arch frame support section through the filling pipe pre-installed on the sealing plate. After the injection pressure reaches the set value, the filling pipe is closed, and air is injected into the corresponding arch-shaped air chamber of this section to make it expand. After the air chamber expands, it applies a uniform radial extrusion force to the rigid polyurethane in the filling chamber, forcing the polyurethane to densely fill the entire chamber and penetrate into the tiny cracks in the surrounding rock. This extrusion force is maintained until the polyurethane is basically cured. After it is completely cured, the gas in the arch-shaped air chamber is released, and concrete is filled into the air chamber at the same time, finally forming a composite support body of steel arch frame-supporting steel mesh-concrete-polyurethane. The above steps are repeated, advancing section by section, until the support construction of the entire tunnel is completed.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting a supporting steel mesh on the back of the top of the steel arch frame, laying geotextile on the supporting steel mesh, and using the geotextile to seal the remaining space at the top of the steel arch frame support to form a filling cavity, and then filling the filling cavity with rigid polyurethane liquid, the remaining space at the top can be quickly backfilled after the liquid has completely solidified. The whole method has a simple construction process, low cost, and its waterproof and acid-proof properties effectively guarantee the service life of the steel arch frame structure and ensure safety during operation. Attached Figure Description

[0011] Figure 1 This is a schematic diagram illustrating the rapid backfilling of the space remaining at the top of the steel arch support according to the present invention; Figure 2 This is a schematic diagram of injecting rigid polyurethane into the remaining space at the top of the steel arch support of the present invention; Figure 3 This is a schematic diagram of the cavity for filling the space remaining at the top of the steel arch support of the present invention; Figure 4 This is a schematic diagram of the filling chamber of the present invention filled with uncured rigid polyurethane; Figure 5This is a schematic diagram of the secondary pressurization of the airbag in this invention, in which rigid polyurethane fills the entire inflation chamber; Figure 6 This is a schematic diagram of concrete substitution within the gas in the airbag of the present invention; Figure 7 This is a schematic diagram of the connection between the steel arch frames of the present invention; The components are: 1. Tunnel; 2. Steel arch frame; 3. Supporting steel mesh; 4. Geotextile; 5. Sealing plate; 6. Filling chamber; 7. Filling pipe; 8. Cured rigid polyurethane; 9. Airbag; 10. Fire-resistant cotton layer; 11. Longitudinal tie rod; 12. Threaded sleeve; 13. Screw; 14. Mounting end plate; 15. Concrete; 16. Local voids; 17. Uncured rigid polyurethane. Detailed Implementation

[0012] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0013] See Figures 1-6 A method for rapid backfilling of the space left over from the top of a steel arch support 2 includes the following steps: First, a steel arch 2 is erected in a broken tunnel 1, and a supporting steel mesh 3 is laid on the back of the arch top of the steel arch 2. Geotextile 4 is then laid on the supporting steel mesh 3. The two sides of the geotextile 4 are then tightly fixed to the side walls of the tunnel 1, and the ends of the geotextile 4 are sealed with sealing plates 5 to form a filling chamber 6. Finally, curable rigid polyurethane is injected into the filling chamber 6 through a filling pipe 7. After the rigid polyurethane has completely cured, the cured rigid polyurethane 8 is used to support the broken surrounding rock, thereby achieving rapid backfilling of the space left over from the top of the steel arch support 2 (over-excavated irregular space).

[0014] In this embodiment, rigid polyurethane slurry is injected into the remaining space at the top of the steel arch support 2 through the filling pipe 7. Under injection pressure, the low-viscosity polyurethane slurry can penetrate into the tiny cracks in the surrounding rock. After curing, it acts like a rock adhesive, reconsolidating the loose and broken rock mass into a whole, significantly improving the self-supporting capacity and integrity of the surrounding rock at the arch crown. The resulting composite structure, tightly bonded to the steel arch 2, rigid polyurethane, and reinforced surrounding rock, exhibits far superior synergistic load-bearing performance compared to simple filling. Moreover, the excellent waterproof and acid-resistant properties of polyurethane effectively prevent rainwater and acid / alkali corrosion of the steel arch 2. Rigid polyurethane typically sets within minutes to tens of minutes and reaches sufficient strength within hours, greatly shortening the support cycle time and accelerating the tunneling speed.

[0015] See Figures 3-6In some embodiments, an arched airbag 9 is provided between the support net and the geotextile 4. Before the injected rigid polyurethane reaches a predetermined pressure and is cured, the filling pipe 7 is closed, and the airbag 9 is inflated to expand it. This applies a uniform radial extrusion force to the uncured rigid polyurethane 17 in the filling chamber 6, forcing the rigid polyurethane to densely fill the entire filling chamber 6 and penetrate into the micro-cracks in the surrounding rock. The extrusion force is then maintained until the rigid polyurethane is basically cured. After the polyurethane is completely cured, the gas in the airbag 9 is released, and concrete 15 is filled into the airbag 9 to form a composite support. The airbag 9 has a filling port (not shown in the figure), located on one side of the filling pipe, with a valve. Gas or concrete is injected into the airbag through the filling port. A pressure relief valve (not shown in the figure) is also provided at the highest point of the airbag 9 on the side of the filling pipe. Concrete is injected into the airbag through the filling port, and the pressure relief valve releases the gas, thereby achieving the replacement of gas and concrete within the airbag.

[0016] The inventors discovered that even with pressure injection, one-time molding of polyurethane suffers from pressure attenuation and uneven distribution. The injection pressure decreases in areas far from the nozzle, making it difficult to ensure uniform and sufficient pressure throughout the cavity. Furthermore, the polyurethane chemical reaction may cause micro-shrinkage or trap tiny air bubbles, forming internal micro-defects. Faced with uneven rock surfaces, polyurethane cannot be completely forced into every pit, resulting in localized voids.16 The isostatic secondary extrusion of the airbag 9 in this application is an innovative solution proposed to systematically address these problems.

[0017] After the airbag 9 is inflated, it applies a uniform radial pressure to the uncured polyurethane. This pressure is transmitted to every corner and every gap in the filling cavity, ensuring that the filling density is completely consistent from the arch to both sides. This is something that no fixed-point injection can achieve. The uniform and continuous pressure can effectively squeeze out the air and volatiles trapped in the polyurethane, greatly reducing bubbles and voids. The seepage capacity of a single injection is limited, but the uniform high pressure applied by the airbag 9 can force the low-viscosity polyurethane slurry into deeper and finer cracks in the surrounding rock, changing the relationship between the filler and the surrounding rock from a bonded relationship to a symbiotic relationship of mechanical interlocking and chemical bonding. This greatly enhances the load-bearing capacity and shear resistance of the critical area. Under high pressure, the polyurethane is firmly pressed into the steel arch frame 2 and the support net behind it, forming a perfect mechanical transmission interface.

[0018] In addition, after the polyurethane has fully cured, the gas in the airbag 9 is released, and concrete 15 is filled into the airbag 9. After the concrete 15 solidifies, an integrated composite load-bearing arch with internal rigidity and external flexibility, coexisting with the surrounding rock, is finally formed. By filling the airbag 9 with concrete 15, the concrete 15, as the final filling material, provides the excellent long-term durability, compressive strength, fire resistance (Class A non-combustible) and creep resistance of inorganic materials, solving the problems of long-term creep and insufficient fire resistance that may exist in pure polyurethane support. At the same time, the concrete 15 is wrapped by the airbag and is not bonded to the steel arch frame 2 and the supporting steel mesh. After the tunnel 1 is used, the steel arch frame 2 and the supporting steel mesh can be recycled.

[0019] See Figure 2 and Figure 3 In addition, it should be explained that, in order to effectively prevent the supporting steel mesh 3 from puncturing the airbag 9, a layer of fire-resistant cotton 10 can also be set between the supporting mesh and the airbag 9. The fire-resistant cotton 10 can not only prevent the sharp supporting steel mesh from puncturing the airbag, but its own Class A non-combustible properties can also improve the local fire safety level, playing a dual role of physical protection and fire isolation.

[0020] See Figure 7 In some embodiments, multiple steel arch frames 2 are arranged longitudinally along the tunnel 1. Adjacent steel arch frames 2 are connected by longitudinal tie rods 11. Multiple longitudinal tie rods 11 are arranged circumferentially along the steel arch frames 2. Each longitudinal tie rod 11 includes a threaded sleeve 12 and two screws 13 threadedly tightened at both ends of the threaded sleeve 12. The other end of the two screws 13 is provided with an installation end plate 14, which is fixedly installed on the corresponding steel arch frame 2 by bolts. After the tunnel 1 is excavated, the actual installation spacing of the steel arch frames 2 may not be completely consistent with the theoretical value, and there will be errors. Traditional fixed-length connecting bars need to be cut or welded on site, which is time-consuming and labor-intensive. However, this design can infinitely adjust the total length of the entire tie rod set by rotating the threaded sleeve 12, perfectly adapting to the actual spacing between the arch frames, achieving fast and accurate installation, and greatly improving construction efficiency and adaptability to site conditions.

[0021] See Figure 1 and Figure 3 , Figure 4In some embodiments, the airbag 9 is divided into multiple independent arched air chambers along the longitudinal direction of the tunnel 1. Each arched air chamber is equipped with a filling port and a pressure relief valve. The steel arch frame 2 is erected in sections along the tunnel 1 excavation direction, with the length of each section consistent with the width of the arched air chamber. After the installation of a single section of the steel arch frame 2 is completed, a sealing plate 5 is installed at the end of the geotextile 4 away from the previous section, while the end closer to the previous section is sealed using fully cured polyurethane. Subsequently, rigid polyurethane is injected into the remaining space at the top of the support of that section of the steel arch frame 2 through the filling pipe 7 pre-installed on the sealing plate 5. Once the pressure reaches the set value, the filling pipe 7 is closed, and air is injected into the corresponding arched air chamber of this section to expand it. After the air chamber expands, it applies a uniform radial extrusion force to the rigid polyurethane in the filling chamber 6, forcing the polyurethane to densely fill the entire chamber and penetrate into the tiny fissures in the surrounding rock. This extrusion force is maintained until the polyurethane is basically cured. After it is completely cured, the gas in the arched air chamber is released, and concrete 15 is filled into the air chamber at the same time, finally forming a steel arch frame-supporting steel mesh-concrete-polyurethane composite support. The above steps are repeated, advancing section by section, until the support construction of the entire tunnel 1 is completed. In addition, the arched air chamber can be divided into multiple independent circumferential air chambers along the circumference of tunnel 1. By simultaneously injecting air into each circumferential air chamber, the inflation speed can be accelerated. Moreover, by adjusting the air pressure in each circumferential air chamber, the local extrusion force of the polyurethane can be adjusted in a targeted manner, making the polyurethane filling more compact and uniform.

[0022] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for rapid backfilling of the space remaining at the top of a steel arch support, characterized in that, Includes the following steps: First, a steel arch frame is erected in the broken tunnel, and a supporting steel mesh is laid on the back of the arch top. Geotextile is then laid on the supporting steel mesh. The two sides of the geotextile are then tightly fixed to the sidewalls of the tunnel, and the two ends of the geotextile are sealed to the tunnel arch top with sealing plates to form a filling chamber. Finally, curable rigid polyurethane is injected into the filling chamber through a filling pipe. After the rigid polyurethane has completely cured, the remaining space at the top of the steel arch frame support can be quickly backfilled.

2. The method for rapid backfilling of the space remaining at the top of the steel arch support according to claim 1, characterized in that, An arched airbag is also provided between the support net and the geotextile. After the injected rigid polyurethane reaches a predetermined pressure, the filling pipe is closed, and the airbag is inflated to expand it, applying a uniform radial extrusion force to the rigid polyurethane in the filling chamber. This forces the rigid polyurethane to densely fill the entire filling chamber and penetrate into the micro-cracks in the surrounding rock. The extrusion force is then maintained until the rigid polyurethane is basically cured. After the polyurethane is completely cured, the gas in the airbag is released, and concrete is simultaneously filled into the airbag to form a composite support structure.

3. The method for rapid backfilling of the space remaining at the top of the steel arch support according to claim 2, characterized in that, Fire-resistant cotton is also provided between the support net and the airbag.

4. Multiple steel arch frames are arranged longitudinally along the roadway. Adjacent steel arch frames are connected by longitudinal tie rods. Each longitudinal tie rod includes a threaded sleeve and two screws screwed onto both ends of the threaded sleeve. The other end of the two screws is provided with an installation end plate. The installation end plate is fixedly installed on the corresponding steel arch frame by bolts.

5. The method for rapid backfilling of the space remaining at the top of the steel arch support according to any one of claims 2-4, characterized in that, The airbag is divided into multiple independent arched air chambers along the longitudinal direction of the roadway.

6. The method for rapid backfilling of the space remaining at the top of the steel arch support according to claim 5, characterized in that, The arched air chamber is divided into multiple independent circumferential air chambers along the circumference of the roadway.

7. The method for rapid backfilling of the space remaining at the top of the steel arch support according to claim 5, characterized in that, The steel arch frame is erected in sections along the tunnel excavation direction. The length of each section is consistent with the width of the arch-shaped air chamber. After the installation of a single steel arch frame section is completed, a sealing plate is installed at the end of the geotextile away from the previous section, while the end closer to the previous section is sealed with fully cured polyurethane. Then, through the filling pipe pre-installed on the sealing plate, rigid polyurethane is injected into the remaining space at the top of the steel arch frame support section. After the injection pressure reaches the set value, the filling pipe is closed, and air is injected into the corresponding arch-shaped air chamber of this section to make it expand. After the air chamber expands, it applies a uniform radial extrusion force to the rigid polyurethane in the filling cavity, forcing the polyurethane to densely fill the entire cavity and penetrate into the tiny cracks in the surrounding rock. This extrusion force is maintained until the polyurethane is basically cured. After it is completely cured, the gas in the arch-shaped air chamber is released, and concrete is filled into the air chamber at the same time, finally forming a steel arch frame-supporting steel mesh-concrete-polyurethane composite support body. The above steps are repeated, advancing section by section, until the support construction of the entire tunnel is completed.

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