A method for rapidly reinforcing a water-rich and extremely broken rock mass

Abstract

The application discloses a kind of strong water-rich extremely broken rock mass rapid reinforcement methods, comprising the following steps: first, in roadway excavation to 5-10m from strong water-rich extremely broken rock mass region outside stop excavation, retreat a distance to roadway expansion support and establish grouting chamber;Second, respectively along the design roadway contour line outside construction borehole and install steel pipe for grouting and reinforcing surrounding rock;Third, guide chamber small section excavation and roadway expansion brush way for roadway construction, roadway support form is shotcrete, anchor net support.The application adopts double-layer borehole working face pre-grouting rapid water plugging and reinforcing surrounding rock, shotcrete, anchor net support and full-length grouting type long anchor cable composite reinforcement surrounding rock and other combined support methods, which can safely, efficiently and quickly realize the reinforcement of strong water-rich extremely broken rock mass.

Description

Technical Field

[0001] This invention relates to a method for supporting horizontal tunnel excavation in metal mines or tunnels, primarily applicable to tunnel construction in highly water-rich and extremely fractured rock masses. These highly water-rich and extremely fractured rock masses refer to rock masses that have been severely affected by geological processes (such as faults, structures, and fissures), resulting in severely damaged integrity, extremely low strength, and very poor stability. They also contain a large amount of groundwater, making them highly susceptible to large-scale collapses, water inrushes, and sudden water surges after excavation. Background Technology

[0002] When constructing tunnels in highly water-rich, extremely fractured rock masses with unfavorable geological conditions, traditional long pipe roof support or pre-grouting with steel supports are commonly used. Both methods have low construction efficiency and poor treatment effects. Specifically, the long pipe roof support method involves drilling holes at an outward angle of 1°-3° along the tunnel excavation outline, installing steel pipes with small holes in the wall, and grouting into the steel pipes to reinforce the surrounding rock. Steel supports are then installed promptly after each blast. Tunnel excavation is carried out under the protection of the long steel pipes, grouting-reinforced surrounding rock, and steel supports. The pre-grouting with steel supports method involves drilling holes at an outward angle of 10°-15° along the tunnel excavation outline, installing small pipes with small holes in the wall, and grouting into the small pipes to reinforce the surrounding rock. Steel supports are then installed promptly after tunnel excavation. Tunnel excavation is carried out under the protection of small-diameter pipes, grouting reinforcement of the surrounding rock, and steel supports. A common drawback of both support methods is that steel supports must be installed promptly after tunnel blasting. Steel support is labor-intensive, inefficient, and passive, failing to actively improve the stress state of the surrounding rock or enhance its bearing capacity. Furthermore, the advanced small-diameter pipe grouting and steel support method has other significant disadvantages: the short grouting length of the advanced small-diameter pipes necessitates frequent drilling and grouting during tunnel construction, resulting in cumbersome procedures and low excavation efficiency. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for rapid reinforcement of highly water-rich and extremely fractured rock masses, so as to further improve the strength of the surrounding rock and the support strength, and realize safe and efficient reinforcement construction for tunnel excavation under adverse geological conditions.

[0004] The technical solution of the present invention is as follows: A rapid reinforcement method for highly water-rich and extremely fractured rock masses includes the following steps: The first step is to stop excavating 5-10m away from the area of ​​highly water-rich and extremely fractured rock mass, and then retreat a certain distance to widen the roadway and build a grouting chamber. The second step involves drilling holes and installing steel pipes along the outer side of the designed tunnel outline to grout and reinforce the surrounding rock. The third step involves tunnel construction using a combination of small-section excavation of the pilot tunnel and tunnel widening, with the tunnel support being shotcrete and anchor mesh support. Every 8-10m of tunnel excavation, the constructed tunnel is reinforced with full-length grouting and long anchor cable support. Every 15-20 meters of tunnel excavation, excavation is stopped and the grouting chamber is reconstructed.

[0005] The specific steps are as follows: Step 1: When the existing roadway is constructed to a point 5-10m away from the area of ​​highly water-rich and extremely fractured rock mass, roadway construction shall be stopped. The roadway shall be moved back 5-8m from the current working face, and the sides and roof of the existing roadway shall be expanded outward by 1.0-1.5m to form a grouting chamber. The second step is to construct the outer grouting holes in the grouting chamber, 50-70cm away from the outer edge of the designed roadway outline; the construction sequence is from top to bottom, and after each outer grouting hole is constructed, a seamless steel pipe is installed. After the construction of the outer grouting holes is completed and the seamless steel pipe is installed, grouting is performed on the outer grouting holes. The third step is to construct inner grouting holes in the grouting chamber, 10-30cm away from the outer edge of the designed roadway outline; the construction sequence is from top to bottom, and after each inner grouting hole is constructed, a seamless steel pipe is installed. After the construction of the inner grouting holes is completed and the seamless steel pipe is installed, grouting is performed on the inner grouting holes. The designed roadway is excavated, and a small-section pilot tunnel is constructed first, and then the pilot tunnel is widened and topped to the designed roadway cross-section. After each cycle of excavation reaches the designed tunnel cross-section specifications, a temporary shotcrete support of 3-5cm thickness is first applied, followed by full-section support of the constructed tunnel using resin anchors and metal mesh; finally, the tunnel roof and walls are shotcreted to the designed thickness. Every 8-10m of tunnel excavation, the constructed tunnel is reinforced with full-length grouting and long anchor cable support. Every 18-20m of tunnel excavation, excavation is stopped and the grouting chamber is reconstructed. After the tunnel excavation stops, the tunnel is moved back 5m from the working face to widen the sides and roof to create a grouting chamber. The sides and roof of the already constructed tunnel are widened to form grouting chambers.

[0006] Preferably, when grouting the outer and inner grouting holes, the grout type is single-component cement grout, and the water-cement ratio of the single-component cement grout is 1:1; the grouting sequence is symmetrical grouting from bottom to top and from left to right.

[0007] Preferably, during the expansion and roofing process, smooth blasting control technology is implemented for the surrounding holes, with a hole spacing of 0.6m, a smooth layer thickness of 0.7m, and a roadway expansion advance of 1.5m.

[0008] The beneficial effects of this invention are as follows: This invention employs a combined support method, including pre-grouting at a double-layer borehole face for rapid water plugging and reinforcement of surrounding rock, shotcrete and anchor mesh support, and full-length grouting with long anchor cables for composite reinforcement of surrounding rock. This method can safely, efficiently, and quickly reinforce highly water-rich and extremely fractured rock masses. Details are as follows: First, the combination of longitudinal outer curtain grouting and inner reinforcement grouting can form a high-strength grouting reinforcement layer, improving the strength of the surrounding rock. When the working face of the outermost grouting hole is pre-grouted, a grouting curtain can be quickly formed to block water; when the working face of the inner grouting hole is pre-grouted, it can further reinforce the fractured surrounding rock, forming a high-strength grouting reinforcement layer, which significantly improves the strength of the surrounding rock; in addition, the pre-embedded steel pipe and the grouting reinforcement layer work together to further improve the support strength.

[0009] Secondly, the use of full-length grouting anchor cables for roadway support increases the thickness of the grouting reinforcement layer and improves the overall support strength of the roadway. The use of full-length grouting anchor cables for the roadway roof and sidewalls effectively increases the thickness of the grouting reinforcement layer and improves the overall support strength of the roadway.

[0010] Third, the roadway adopts a flexible support technology that combines shotcrete mesh and extended anchor cables. This technology has the advantages of actively improving the stress state of the surrounding rock, the support and the surrounding rock working together, fully utilizing the self-bearing capacity of the surrounding rock, and high support strength, which can meet the roadway support requirements under complex geological conditions. Attached Figure Description

[0011] Figure 1 This is a longitudinal projection view of the tunnel in an embodiment of the present invention, and also Figure 2 Section I-I; Figure 2 for Figure 1 Section II-II in the middle; Figure 3 for Figure 1 Section III-III in the diagram.

[0012] In the diagram: 1—Constructed roadway; 2—Grouting chamber; 3—Designed roadway; 4—Outer grouting hole; 5—Inner grouting hole; 6—Seamless steel pipe; 7—Guide tunnel; 8—Shotcrete support; 9—Resin anchor bolt; 10—Metal mesh; 11—Long anchor cable. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0014] See Figure 1 , Figure 2 and Figure 3 This invention relates to an embodiment of a rapid reinforcement method for highly fractured, water-rich rock masses, which includes the following steps: Step 1: When the construction of the existing roadway 1 reaches 5-10m before the area of ​​highly water-rich and extremely fractured rock mass, roadway construction shall be stopped. Move back 5m from the current working face and extend the sides and roof of the existing roadway 1 outward by 1.2m to form grouting chamber 2.

[0015] The second step is to construct outer grouting holes 4 in grouting chamber 2, 60cm away from the outer edge of the outline of the designed roadway 3. The outer insertion angle is 6°, the hole diameter is φ130mm, the hole length is 25m, and the hole spacing is 50cm. The construction sequence is from top to bottom. After each outer grouting hole 4 is constructed, a seamless steel pipe 6 with a diameter of φ108, a wall thickness of 4mm, and a length of 25m is installed. Small holes with a diameter of φ10mm and a spacing of 20cm are arranged on the wall of the seamless steel pipe 6.

[0016] The third step, after the construction of the outer grouting holes 4 is completed and the seamless steel pipe 6 is installed, is to grout the outer grouting holes 4. The grout type is single-component cement grout, and the water-cement ratio of the single-component cement grout is 1:1. The grouting sequence is symmetrical from bottom to top and from left to right.

[0017] Step 4: In the grouting chamber 2, 20cm from the outer edge of the outline of the designed roadway 3, construct the inner grouting hole 5 with an outer insertion angle of 3°, a hole diameter of φ130mm, a hole length of 25m, and a hole spacing of 50cm. The construction sequence is from top to bottom. After each inner grouting hole 5 is constructed, install a seamless steel pipe 6 with a diameter of φ108, a wall thickness of 4mm, and a length of 25m. Small holes with a diameter of φ10mm and a spacing of 20cm are arranged at intervals on the wall of the seamless steel pipe 6.

[0018] Step 5: After the construction of the inner grouting hole 5 is completed and the seamless steel pipe 6 is installed, grouting is performed on the inner grouting hole 5. The grout type is single-component cement grout with a water-cement ratio of 1:1. The grouting sequence is symmetrical from bottom to top and from left to right.

[0019] Step 6: Excavation of the designed tunnel 3. To minimize disturbance to the surrounding rock during construction, a 3m x 3m pilot tunnel 7 will be constructed first, with a blasting advance of 1.5m. Then, the pilot tunnel 7 will be widened and its roof compacted to the designed tunnel 3 cross-section. During the widening and compaction, smooth blasting control technology will be implemented for the surrounding holes, with a hole spacing of 0.6m, a smooth layer thickness of 0.7m, and a tunnel widening advance of 1.5m.

[0020] After each cycle of excavation reaches the designed cross-sectional specifications of tunnel 3, shotcrete support 8 is first applied, with an initial thickness of 30-50mm. Then, resin anchors 9 and metal mesh 10 are used to provide full-section support for the constructed tunnel 1. The anchors are φ20mm*2.2m threaded steel resin anchors, the support mesh is 1m×1m, the metal mesh is 2m×1m, the steel bar diameter is Φ6.5mm, and the mesh size is 100mm×100mm. Finally, shotcrete support 8 is applied to the tunnel roof and walls, with a final shotcrete thickness of 100mm.

[0021] Furthermore, for every 10m of tunnel excavation, the constructed tunnel 1 is reinforced with full-length grouting long anchor cables 11; the long anchor cables 11 are steel strand long anchor cables with a specification of φ18mm*6m, the grouting liquid is single-component cement grout with a water-cement ratio of 1:1, and the long anchor cable support mesh is 1.5m*1.5m.

[0022] Furthermore, every 20m of tunnel excavation is stopped, and grouting chamber 2 is reconstructed. After the tunnel excavation stops, the tunnel is moved back 5m from the working face to widen the sides and roof to build grouting chamber 2. The sides and roof of the already constructed tunnel 1 are all widened by 1.2m to form grouting chamber 2.

[0023] The operation is carried out in a cyclical manner according to the above sequence until all areas with strong water content and extremely fractured rock mass have been traversed.

Claims

1. A method for rapid reinforcement of highly fractured, water-rich rock masses, characterized in that... Includes the following steps: The first step is to stop excavating 5-10m away from the area of ​​highly water-rich and extremely fractured rock mass, and then retreat a certain distance to widen the roadway and build a grouting chamber. The second step is to drill holes and install steel pipes along the outer side of the outline of the designed tunnel (3) to grout and reinforce the surrounding rock. The third step involves tunnel construction using a combination of small-section excavation of the pilot tunnel and tunnel widening, with the tunnel support being shotcrete and anchor mesh support. Every 8-10m of tunnel excavation, the constructed tunnel is reinforced with full-length grouting and long anchor cable support. Every 15-20 meters of tunnel excavation, excavation is stopped and the grouting chamber is reconstructed.

2. The method for rapid reinforcement of highly fractured rock masses with abundant water as described in claim 1, characterized in that... The specific steps are as follows: Step 1: When the construction of the existing roadway (1) reaches 5-10m in front of the area of ​​strong water-rich and extremely fractured rock mass, stop the roadway construction, retreat 5-8m from the current working face, and expand the sides and roof of the existing roadway (1) by 1.0-1.5m to form a grouting chamber (2). The second step is to construct the outer grouting hole (4) in the grouting chamber (2) at a distance of 50-70cm from the outer edge of the outline of the designed roadway (3); the construction sequence is from top to bottom, and after each outer grouting hole (4) is constructed, a seamless steel pipe (6) is installed. After the construction of the outer grouting hole (4) is completed and the seamless steel pipe (6) is installed, grouting is performed on the outer grouting hole (4); The third step is to construct inner grouting holes (5) in the grouting chamber (2) at a distance of 10-30cm from the outer edge of the outline of the designed roadway (3); the construction sequence is from top to bottom, and after each inner grouting hole (5) is constructed, a seamless steel pipe (6) is installed. After the construction of the inner grouting hole (5) is completed and the seamless steel pipe (6) is installed, grouting is performed on the inner grouting hole (5); Excavate the designed roadway (3), first construct a small cross-section guide tunnel (7), and then expand and top the guide tunnel (7) to the cross-section of the designed roadway (3); After each cycle is excavated to the design tunnel (3) cross-section specification, temporary shotcrete support (8) with a thickness of 3-5cm is first carried out, and then resin anchors (9) and metal mesh (10) are used to support the entire cross-section of the constructed tunnel (1); finally, the tunnel roof and sidewalls are shotcrete supported (8) to the design thickness. Every 8-10m of tunnel excavation, the constructed tunnel (1) is reinforced with full-length grouting long anchor cable (11); Every 18-20m of tunnel excavation, the excavation is stopped and the grouting chamber (2) is reconstructed. After the tunnel excavation is stopped, the tunnel is widened and the roof is pressed back 5m from the working face to build the grouting chamber (2). The two sides and the roof of the already constructed tunnel (1) are widened to form the grouting chamber (2).

3. The method for rapid reinforcement of highly fractured rock masses with abundant water according to claim 2, characterized in that: When grouting the outer layer grouting hole (4) and the inner layer grouting hole (5), the grout type is single-component cement grout, and the water-cement ratio of the single-component cement grout is 1:1; the grouting sequence is symmetrical grouting from bottom to top and from left to right.

4. The method for rapid reinforcement of highly fractured rock masses rich in water according to claim 2, characterized in that: During the expansion and roofing process, smooth blasting control technology is implemented for the surrounding holes, with a hole spacing of 0.6m, a smooth layer thickness of 0.7m, and a roadway expansion advance of 1.5m.

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