Dual-purpose grouting guide pipe for reinforcing sandwiched rock in small-clear-distance tunnel

Abstract

The invention relates to the technical field of tunnel engineering, and discloses a dual-purpose grouting guide pipe for reinforcing middle clamping rock of a small-clear-distance tunnel, which penetrates through the middle clamping rock between a left cavern and a right cavern of the tunnel, and comprises a left side grouting guide pipe and a right side grouting guide pipe which are arranged in a middle clamping rock grouting hole and are connected with each other, the left grouting guide pipe and the right grouting guide pipe are both variable-section cone-like grouting guide pipes, and grout outlet pipe openings of the left grouting guide pipe and the right grouting guide pipe are both located in the grouting holes. Loosening force of the two grouting guide pipes and opposite pulling force of locking of the locking bolts on the two sides are resisted through the connecting bolts, the two grouting guide pipes are connected into an integral structure and penetrate through a middle clamping rock body, a complete supporting and reinforcing component is formed, the loose middle clamping rock body is tighter, and the integrity of the middle clamping rock body is enhanced. The method has the advantages of being good in small-clear-distance tunnel interlaced rock reinforcing effect and good in economical efficiency, and the problems that in the prior art, the interlaced rock mass fixing effect is poor, and the method is not economical are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering, and in particular relates to a dual-purpose grouting conduit for rock reinforcement in a small-clearance tunnel. Background Art

[0002] In order to adapt to complex terrain and meet the use requirements during tunnel construction, small clearance tunnels are often selected as the tunnel form in the project. Small clearance tunnels are a special tunnel layout form in which the thickness of the middle rock wall in the tunnel is less than the minimum clearance of the separated independent double tunnels. Due to its special structure, the overall and local stability of the middle rock has a significant impact on the overall safety of the small clearance tunnel. Therefore, the stability control of the middle rock is the focus of the quality control of the small clearance tunnel construction, and it is very necessary to reinforce the middle rock.

[0003] For small-clearance tunnels, the reinforcement measures for the middle rock mainly include grouting reinforcement and anchor reinforcement. The reinforcement of the middle rock can effectively control the displacement of the surrounding rock mass, improve the stress condition of the tunnel, and prevent the plastic zone from being too large or even through cracks. Grouting can increase the mechanical parameters of the middle rock mass, directly improving the mechanical properties and strength of the middle rock. The tension anchor constrains the middle rock mass through the extrusion force on both sides of the anchor, making the middle rock mass tighter and improving the integrity of the middle rock. The existing grouting conduit can only improve the mechanical properties of the middle rock mass during grouting reinforcement, but because the grouting conduit itself cannot constrain the broken rock mass, the reinforcement effect of the middle rock is not good; at the same time, under some relatively simple working conditions, the use of tension anchors may cause unnecessary waste.

[0004] Therefore, in order to make the grouting conduit have a better reinforcement effect on the rock in the small clearance tunnel and be more economical, the present invention proposes a grouting conduit with good grouting and restraint functions to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0005] 1. Technical problems solved: In view of the deficiencies in the prior art, the present invention provides a dual-purpose grouting duct for reinforcing the middle rock in a small clear distance tunnel. The dual-purpose grouting duct can resist the loosening force of the two grouting ducts and the tensile force generated by the locking bolts on both sides through the connecting bolts, so that the two grouting ducts can be tightly connected; the two grouting ducts are tightly connected to form an integral structure and penetrate the middle rock mass to form a complete supporting and reinforcing component, while being able to achieve grouting reinforcement of the middle rock mass, tensile force is applied to the middle rock mass through the locking bolts, thereby making the loose middle rock mass tighter and enhancing the integrity of the middle rock mass; the dual-purpose grouting duct has the advantages of good effect and good economy in reinforcing the middle rock in a small clear distance tunnel, and solves the problems of poor fixing effect and uneconomicalness of the middle rock mass in the prior art.

[0006] (II) Technical solution: In order to achieve the above-mentioned purpose of good centering rock reinforcement effect and good economy, the present invention provides the following technical solutions: A dual-purpose grouting conduit for reinforcing the rock in a small-clearance tunnel, which runs through the middle rock between the left and right caverns of the tunnel, comprises a left grouting conduit and a right grouting conduit which are arranged in a grouting hole in the middle rock and are connected to each other, the left grouting conduit and the right grouting conduit are both variable-section conical grouting conduits, and the grouting outlets of the left grouting conduit and the right grouting conduit are both located in the grouting hole, a left grouting pipe pad end is arranged at the outer end of the left grouting conduit, and a sealing hole assembly is arranged at the end of the right grouting conduit, and the sealing hole assembly is used in conjunction with the grouting hole; Based on the above technical features: the slurry in the right grouting duct enters the grouting hole and the left grouting duct through the grouting end of the right grouting duct to reinforce the middle rock by grouting, and through the structural setting and connection relationship of the left grouting duct and the right grouting duct, the dual-purpose grouting duct formed by the left grouting duct and the right grouting duct can reinforce the middle rock.

[0007] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: the left grouting conduit and the right grouting conduit both include a variable cross-section grouting pipe body and a tapered grouting outlet, and a locking bolt used in conjunction with a sealing assembly is also provided on the right grouting conduit; Based on the above technical features: through the structural setting of the left grouting duct and the right grouting duct, it can achieve the purpose of grouting and reinforcing the sandwiched rock when in use; through the use of locking bolts and sealing components, the grouting holes can be effectively closed to ensure the grouting effect.

[0008] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention, the variable cross-section grouting conduit body comprises a grouting conduit upper cross-section linear inward convergence portion where the upper cross-section of the circular cross-section grouting conduit continuously converges linearly inward and a grouting conduit lower cross-section unchanged portion where the lower cross-section of the circular cross-section grouting conduit remains unchanged; Based on the above technical features: the left grouting conduit and the right grouting conduit can form a large and small head structure, so that they can be tightly pressed in the grouting hole during grouting, the grouting hole is sealed, and the grouting grouting effect is ensured. At the same time, the structural design of the variable-section grouting pipe body can also form a stable skeleton, which is fixed in the grouting hole to reinforce the center rock.

[0009] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: the conical grouting outlet is formed by the linear inward contraction of the upper half section of the grouting conduit and the linear inward contraction of the lower half section of the grouting conduit; Based on the above technical features: it can play the role of grouting and connection in the grouting hole when in use, ensuring the connection effect and grouting effect of the left grouting conduit and the right grouting conduit.

[0010] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: a curved thickening section and a constant height thickening section are also provided on the outer surface of the linear inward part of the upper half section of the grouting conduit, the constant height thickening section is provided at one end close to the conical grouting outlet, and the constant height thickening section provided on the left grouting conduit is used in conjunction with the constant height thickening section provided on the right grouting conduit, and the curved thickening section is provided at one end away from the conical grouting outlet and is connected to the constant height thickening section; Based on the above technical features: by setting the curved thickening section and the equal height thickening section, the upper thickness of the grouting conduit wall can be increased to prevent the grouting conduit itself from being damaged; at the same time, the stability of the connection between the left grouting conduit and the right grouting conduit is ensured.

[0011] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: bolt holes penetrating the variable cross-section grouting pipe body and the grouting conduit are also opened along the central axis direction, and the bolt holes also penetrate the nut pads and are used in conjunction with the connecting bolts. The nut pads are padded on the inner sides of the left grouting conduit and the right grouting conduit, and the connecting bolts are used in conjunction with the connecting nuts. Based on the above technical features: through the design of the above connection structure, it is possible to connect the left grouting duct with the right grouting duct, and resist the shear force generated by the locking and pulling of the locking bolts, thereby ensuring the connection effect between the left grouting duct and the right grouting duct.

[0012] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: the sealing assembly includes a first pad and a second pad that are adapted to the right grouting conduit and can be used in conjunction with each other, and the first pad is used in conjunction with the grouting port of the grouting hole, and the second pad is used in conjunction with the locking bolt; Based on the above technical features: the arrangement of the first pad and the second pad can increase the contact area between the tensile extrusion pressure and the rock mass, while preventing the locking bolt from contacting the slurry and causing rust on the locking bolt.

[0013] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: a rectangular extrusion groove is further provided on the inner side of the first cushion block, the rectangular extrusion groove is used in conjunction with a rectangular frame provided on the second cushion block, and a return spring is further provided on the rectangular frame; Based on the above technical features: it is convenient to reset the second pad by using the reset spring after grouting, while ensuring the sealing effect of the first pad on the grouting hole and the grouting port.

[0014] As a preferred solution of the dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel described in the present invention: a grouting connection section is also provided at the end of the right grouting conduit, and the grouting connection section is connected to the grouting hose; Based on the above technical features: it is convenient to carry out grouting into the right grouting duct through the grouting hose.

[0015] As a preferred solution of the dual-purpose grouting conduit for reinforcing the interlayer rock in a small clear distance tunnel described in the present invention: the construction process of the dual-purpose grouting conduit for reinforcing the interlayer rock in a small clear distance tunnel includes: after the excavation of two holes in the small clear distance tunnel, drilling a hole in the middle rock by machinery, and after drilling, placing the left grouting conduit and the right grouting conduit into the grouting hole respectively, after the placement is completed, the right grouting conduit is passed through the first through hole and the second through hole of the pad structure in sequence, and is locked with a locking bolt to provide a tensile force, and the grouting hose is connected at the grouting connection section, and grouting treatment is performed after the connection is completed to improve the rock mechanical properties of the middle rock.

[0016] Based on the above technical features: the two grouting pipes are closely connected to form an integral structure and penetrate the middle rock mass to form a complete supporting and reinforcing component. While being able to realize grouting reinforcement of the middle rock mass, the locking bolts are used to apply tension to the middle rock mass, thereby making the loose middle rock mass tighter and enhancing the integrity of the middle rock mass.

[0017] (III) Beneficial effects: Compared with the prior art, the present invention provides a dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel, which has the following beneficial effects: 1. The present invention designs a dual-purpose grouting conduit for reinforcing the rock in the middle of a small clear distance tunnel, which runs through the rock in the middle between the left and right caverns of the tunnel, and includes a left grouting conduit and a right grouting conduit arranged in a grouting hole in the rock in the middle, and the grouting outlets of the left grouting conduit and the right grouting conduit are both located in the grouting hole and are connected to each other; the two grouting conduits are closely connected to form an integral structure and run through the rock mass in the middle to form a complete supporting and reinforcing component, and while being able to realize the grouting reinforcement of the rock mass in the middle, a tensile force is applied to the rock mass in the middle by locking the locking bolts, so that the loose rock mass in the rock in the middle is more compact, and the integrity of the rock mass in the rock in the middle is enhanced; 2. Through the structural setting of the left grouting conduit and the right grouting conduit, the nut pads arranged at the height thickening of the grouting conduits, the bolt holes arranged at the horizontal center axis of the nut pads and the connecting bolts passing through the bolt holes can be used to resist the loosening force of the two grouting conduits and the tension generated by the locking bolts on both sides, so that the two grouting conduits can be tightly connected, and at the same time play the role of anchor rod reinforcement in the middle rock, thereby strengthening the reinforcement effect of the middle rock; 3. Through the pad structure on both sides of the grouting pipe, the drill hole through the center rock is blocked to prevent the outflow of slurry; the pad structure increases the range of action of the locking bolt on the center rock and improves the reinforcement effect; the pad structure avoids direct contact between the nut and the rock mass and protects the nut from rusting; the purpose of good center rock reinforcement effect and good economy is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the dual-purpose grouting conduit of the present invention; Figure 2 It is a schematic diagram of the variable cross-section and thickened section of the dual-purpose grouting conduit of the present invention; Figure 3 It is a schematic diagram of the structure of the pads on both sides of the dual-purpose grouting conduit of the present invention; Figure 4 It is a schematic diagram of a nut spacer in a dual-purpose grouting conduit of the present invention; Figure 5 It is a drilling construction drawing during the construction process of the dual-purpose grouting conduit of the present invention; Figure 6 It is a grouting construction drawing during the construction process of the dual-purpose grouting conduit of the present invention; Figure 7 The monitoring situation of the vault settlement of the tunnel structure after the dual-purpose grouting conduit is used in the present invention; Figure 8 The present invention is to monitor the horizontal convergence of the tunnel structure after using the dual-purpose grouting conduit.

[0019] Description of reference numerals: 1. The unchanged part of the lower half section of the grouting conduit; 2. The linear inward part of the lower half section of the grouting conduit opening; 3. Curved thickening section; 4. Equal height thickening section; 5. Nut pad; 6. Connecting bolt; 7. Connecting nut; 8. First pad; 9. Rectangular frame; 10. Second pad; 11. Locking bolt; 12. Grouting connecting section; 13. Grouting hose; 14. Rectangular extrusion groove; 15. First through hole; 16. Second through hole; 17. Reset spring; 18. Right grouting pipe pad end; 19. Left grouting pipe pad end; 20. Bolt hole; 21. The linear inward part of the upper half section of the grouting conduit. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Embodiment 1: See also Figure 1-Figure 4 , the present invention provides a technical solution: A dual-purpose grouting conduit for reinforcing the rock in a small-clearance tunnel, which runs through the rock in the middle between the left and right caverns of the tunnel and is used to reinforce the rock in the middle to improve its stability; it comprises a left grouting conduit and a right grouting conduit arranged in a grouting hole in the rock in the middle, wherein the grouting outlets of the left grouting conduit and the right grouting conduit are both located in the grouting hole and are connected to each other to form an integral structure with a reinforcing function, a left grouting pipe pad end 19 is also arranged at the outer end of the left grouting conduit to block the end of the left grouting conduit, and the end of the right grouting conduit is also connected to the left grouting conduit. A sealing assembly is provided through the locking bolt 11 to seal the grouting hole, and to facilitate grouting, a grouting hose 13 is also installed at the end of the right grouting conduit. When in use, the grouting hose 13 is used to grout the right grouting conduit, and the slurry in the right grouting conduit enters the grouting hole and the left grouting conduit through the grouting end of the right grouting conduit to grout and reinforce the middle rock. Through the structural setting and connection relationship of the left grouting conduit and the right grouting conduit, the dual-purpose grouting conduit formed by the left grouting conduit and the right grouting conduit can also reinforce the middle rock.

[0022] As a preferred embodiment of the present invention, Figure 1-Figure 2 As shown, the left grouting duct and the right grouting duct are both variable-section conical grouting ducts, including a variable-section grouting pipe body and a conical grouting outlet, wherein the variable-section grouting pipe body is provided with a grouting duct upper half-section linear retraction portion 21 in which the upper half-section of the circular grouting duct continuously converges linearly inwardly and a grouting duct lower half-section unchanged portion 1 in which the lower half-section of the circular grouting duct remains unchanged; the conical grouting outlet is formed by the grouting duct upper half-section linear retraction portion 21 and the grouting duct lower half-section linear retraction portion 2 in which the lower half-section changes from a constant diameter to a linear inward contraction diameter; when in use, the two grouting duct upper half-section linear retraction portions 21 of the left grouting duct and the right grouting duct are used in coordination to make way in the grouting hole during installation, and at the same time, the left grouting duct is connected with the right grouting duct to form a grouting and support structure.

[0023] As a preferred embodiment of the present invention, Figure 1-Figure 2As shown, a curved thickening section 3 and a contour thickening section 4 are also provided on the outer surface of the linear inward part 21 of the upper half section of the grouting conduit, and the contour thickening section 4 is arranged at one end close to the tapered slurry outlet, and the contour thickening sections 4 arranged on the left grouting conduit and the right grouting conduit are used in conjunction with each other; the curved thickening section 3 is arranged at the end away from the tapered slurry outlet, and is connected to the contour thickening section 4; by providing the curved thickening section 3 and the contour thickening section 4, the upper thickness of the grouting conduit wall can be increased to prevent the grouting conduit itself from being damaged; at the same time, the stability of the left grouting conduit when connected to the right grouting conduit is ensured.

[0024] As a preferred embodiment of the present invention, Figure 1 , Figure 2 and Figure 4 As shown, the left grouting duct and the right grouting duct are also provided with bolt holes 20 along the central axis direction, which penetrate the variable-section grouting pipe body and the grouting duct equal height thickened section 4. The bolt holes 20 also penetrate the nut spacer 5 and are used in conjunction with the connecting bolts 6. The nut spacer 5 is cushioned on the inner side of the left grouting duct and the right grouting duct, and the connecting bolts 6 are used in conjunction with the connecting nuts 7. Through the above-mentioned arrangement, the shear force generated by the locking and pulling of the locking bolts 11 can be resisted, thereby ensuring the connection effect between the left grouting duct and the right grouting duct.

[0025] As a preferred embodiment of the present invention, Figure 3 As shown, the sealing assembly includes a first cushion block 8 and a second cushion block 10, on which a first through hole 15 and a second through hole 16 are respectively provided, the first through hole 15 and the second through hole 16 are both used in conjunction with the right grouting conduit, and the second cushion block 10 is used in conjunction with the locking bolt 11; when in use, the right grouting conduit is passed through the first through hole 15 and the second through hole 16 in sequence, and the second cushion block 10 is squeezed by adjusting the position of the locking bolt 11 on the right grouting conduit to provide sufficient squeezing force.

[0026] As a preferred embodiment of the present invention, Figure 3 As shown, a rectangular extrusion groove 14 is also provided on the inner side of the first pad 8, and the rectangular extrusion groove 14 is used in conjunction with a rectangular frame 9 provided on the second pad 10. The four walls of the rectangular frame 9 are inserted into the rectangular extrusion groove 14, and a reset spring 17 is also provided on the rectangular frame 9. The reset spring 17 is used in conjunction with the first pad 8 to tighten the first pad 8 at the grouting port position of the grouting hole to seal the grouting. At the same time, the arrangement of the first pad 8 and the second pad 10 can increase the contact area between the tensile extrusion pressure and the rock mass, and at the same time, avoid the locking bolt 11 from contacting the slurry and causing the locking bolt 11 to rust.

[0027] As a preferred embodiment of the present invention, Figure 1 and Figure 2 As shown, a grouting connection section 12 is also provided at the end of the right grouting conduit, and is connected to a grouting hose 13 via the grouting connection section 12 .

[0028] As a preferred embodiment of the present invention, Figure 1 and Figure 2 As shown, the variable cross-section grouting pipe body should select the grouting pipe diameter and appropriate variable cross-section parameters according to the actual site conditions.

[0029] The construction process of the dual-purpose grouting conduit for reinforcing the middle rock in a small clear distance tunnel described in this embodiment includes: first, after excavating two holes in the small clear distance tunnel, a hole is drilled at a suitable position in the middle rock by a machine, and after drilling, the left grouting conduit and the right grouting conduit are respectively placed in the grouting hole. After the placement is completed, the right grouting conduit is passed through the first through hole 15 and the second through hole 16 of the pad structure in sequence, and is locked with a locking bolt 11 to provide a tensile force and increase the integrity of the middle rock structure. The grouting hose 13 is connected at the grouting connection section 12, and grouting treatment is performed after the connection is completed to improve the rock mechanical properties of the middle rock, thereby achieving a better reinforcement effect.

[0030] Embodiment 2: Example 2 is a case application of the method in Example 1. The specific application tunnel conditions are as follows: the starting and ending mileage of the project tunnel is K2+830~K3+324, with a total length of 494m, of which Class IV surrounding rock is 90m long and Class V surrounding rock is 400m long. The tunnel cross-sectional dimensions are width × height = 12.37m × 8.71m, and the average thickness of the rock pillar between the left and right tunnels is 4.0m. The on-site geological environment is complex, and the excavation process is prone to cause rock deformation, which poses certain construction risks.

[0031] (1) The overburden in the tunnel site is relatively thin, mainly composed of the Quaternary Holocene slope residual layer (Q4 dl+el), containing gravel silty clay with a thickness of about 0.50 to 1.50 m. The underlying bedrock is Variscan-Indosinian (γ43+γ51) granite and Jinningian (υ2) gabbro. The rock mass has well-developed joints and fissures, mainly weathering fissures, which pose a potential hazard to the deformation of the tunnel surrounding rock.

[0032] (2) The thickness of the rock column between the left and right tunnels is small and its stability is poor, so the conventional support method has poor effect.

[0033] In response to the above problems, the project department organized technical personnel to carry out technical research. Through scheme comparison and analysis, it was finally determined to use a small grouting tube and a low prestressed anchor rod to jointly reinforce the middle rock column. When in use, the dual-purpose grouting tube should be passed through the middle rock mass between the left and right holes to carry out grouting and tension locking anchoring, which will improve the properties of the rock mass and achieve the effect of tension reinforcement.

[0034] The specific construction process is as follows: after the excavation of the left and right holes of the small clearance tunnel, the total station is used to lay out the positions in the tunnel according to the construction drawings, and the drilling positions are marked. The drilling is done manually on the work trolley using the YT28 pneumatic rock drill to drill horizontally along the interlayer rock. The on-site construction is as follows: Figure 5 As shown, during the drilling process, the guiding role of the drill bit should be strengthened to drill horizontally, the hole inclination error should be detected in time, and corrective measures should be reasonably adopted according to the drilling needs.

[0035] refer to Figure 6 , the borehole diameter should be slightly larger than the dual-purpose grouting catheter diameter to facilitate the placement of the grouting catheter and provide convenience for grouting. After the placement is completed, the left and right grouting catheters are connected and grouting is carried out simultaneously. A water pressure test must be carried out before grouting the small catheter to check whether the mechanical equipment is normal and whether the pipeline connection is correct. 42.5 grade cement is used, the slurry water-cement ratio is 1: 1, JB500 double-layer mixer is used for mixing, KBY50 / 70 grouting machine is used for grouting, and the grouting pressure is controlled at 0.5-1MPa. During the grouting process, the grouting pressure should be increased slowly step by step, with a certain injection volume. When the design final pressure of 1.0MPa is reached, the slurry injection volume is generally 20-30L / min, and the injection is continued for more than 10min; when the groundwater is large, cement + water glass slurry is injected with pressure, the volume ratio of cement slurry to water glass is 1:0.5, the water glass concentration is 35 degrees Baume, the grouting pressure remains unchanged, and the on-site grouting of the small catheter is shown in 6.

[0036] After the grouting is completed, a woven bag is used to seal the hole, and a manual pneumatic pick is used to chisel out a groove for the pad on the initial support surface to ensure that the pad is easy to install. The schematic diagram of the pad structure is shown in the figure. Figure 3 As shown. After the groove of the pad is chiseled out, the first pad is installed in the left and right holes at the same time. The grouting conduit passes through the through hole of the pad. The pad needs to fit the chiseled groove. The dual-purpose grouting conduit is prestressed and tensioned. Since there are high-strength bolts at the connection and the pipe body is thickened, the prestressed tensioning is single-control tensioning. The tensioning equipment is a torque wrench with a design tonnage of 40KN. It must be calibrated before tensioning. According to the calibration report, the torque wrench scale reading corresponding to the tensioning force of the prestressed anchor rod is converted. After adjusting the torque wrench scale value to the corresponding tension value, the prestressed anchor rod is tensioned. When the torque wrench alarms, it is considered that the prestressed anchor rod is locked to the design tonnage.

[0037] After the tensioning is completed, the second pad is locked and anchored with the first pad by high-strength bolts. After the prestressed anchor is tensioned, the reserved grouting port is used to grout the anchor immediately. The slurry uses M20 early-strength cement mortar, the water-cement ratio is controlled at 0.45-0.5:1, and the grouting pressure is controlled at 0.3-0.8MPa. The slurry should be mixed strictly according to the mix ratio. When the slurry with the same grouting concentration as the grouting pipe is discharged without bubbles, the load is maintained for 2 minutes until the grouting end standard is reached, then the grouting can be stopped and the grouting port can be sealed in time (the anchor hole grouting should not be simply repeated. If the effect cannot meet the design requirements, other remedial measures should be studied). After reinforcement, the tunnel deformation monitoring is as follows Figure 7-Figure 8 As shown in the figure, it is shown that the middle rock is stabilized earlier when excavating a tunnel with a small clearance.

[0038] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel, characterized in that: The grouting conduit runs through the middle rock between the left and right caverns of the tunnel, and comprises a left grouting conduit and a right grouting conduit which are arranged in the grouting hole of the middle rock and are connected to each other. The left grouting conduit and the right grouting conduit are both variable-section conical grouting conduits, and the grouting outlets of the left grouting conduit and the right grouting conduit are both located in the grouting hole. A left grouting pipe pad end (19) is arranged at the outer end of the left grouting conduit, and a sealing hole assembly is arranged at the end of the right grouting conduit, and the sealing hole assembly is used in conjunction with the grouting hole.

2. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 1, characterized in that: The left grouting conduit and the right grouting conduit both comprise a variable-section grouting conduit body and a tapered grouting outlet, and a locking bolt (11) for use in conjunction with the hole sealing assembly is also provided on the right grouting conduit.

3. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 2, characterized in that: The variable cross-section grouting pipe body comprises a grouting pipe upper cross-section linear inward convergence portion (21) where the upper cross-section of the circular cross-section grouting pipe continuously and linearly converges inwardly and a grouting pipe lower cross-section unchanged portion (1) where the lower cross-section of the circular cross-section grouting pipe remains unchanged.

4. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 3, characterized in that: The conical grout outlet is formed by a linear inward contraction (21) of the upper half section of the grouting conduit and a linear inward contraction (2) of the lower half section of the grouting conduit opening having a linear inward contraction of the pipe diameter.

5. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 4, characterized in that: The surface of the linear inward portion (21) of the upper half cross-section of the grouting conduit is also provided with a curved thickening section (3) and a contour thickening section (4); the contour thickening section (4) is provided at one end close to the conical grouting outlet, and the contour thickening section (4) provided on the left grouting conduit is used in conjunction with the contour thickening section (4) provided on the right grouting conduit; the curved thickening section (3) is provided at one end away from the conical grouting outlet and is connected to the contour thickening section (4).

6. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 5, characterized in that: Bolt holes (20) penetrating the variable-section grouting pipe body and the grouting pipe equal height thickening section (4) are also provided on the left grouting pipe and the right grouting pipe along the central axis direction. The bolt holes (20) also penetrate the nut spacer (5) and are used in conjunction with the connecting bolt (6). The nut spacer (5) is cushioned on the inner side of the left grouting pipe and the right grouting pipe. The connecting bolt (6) is used in conjunction with the connecting nut (7).

7. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 2, characterized in that: The sealing assembly comprises a first cushion block (8) and a second cushion block (10) adapted to the right grouting conduit and used in conjunction with each other, wherein the first cushion block (8) is used in conjunction with the grouting port of the grouting hole, and the second cushion block (10) is used in conjunction with the locking bolt (11).

8. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 7, characterized in that: A rectangular extrusion groove (14) is provided inside the first cushion block (8), the rectangular extrusion groove (14) is used in conjunction with a rectangular frame (9) provided on the second cushion block (10), and a return spring (17) is provided on the rectangular frame (9).

9. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 1, characterized in that: A grouting connection section (12) is also provided at the end of the right grouting conduit, and the grouting connection section (12) is connected to a grouting hose (13).

10. A dual-purpose grouting conduit for rock reinforcement in a small clearance tunnel as claimed in claim 1, characterized in that: The construction process of the dual-purpose grouting pipe used for rock reinforcement in small clearance tunnels includes: After the excavation of two small-clearance tunnels, holes are drilled in the middle rock by machinery. After drilling, the left grouting conduit and the right grouting conduit are placed in the grouting holes respectively. After placement, the right grouting conduit is passed through the first through hole and the second through hole of the sealing component in turn, and is locked with locking bolts to provide tension. The grouting hose is connected at the grouting connection section, and grouting is carried out after the connection is completed.

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