An advanced small conduit pre-reinforcement system and construction method thereof

Abstract

The present invention discloses an advanced small conduit pre-reinforcement system, including an advanced small conduit, wherein the advanced small conduit is provided with a double layer along the entire circumference of the tunnel, wherein the double layer includes an inner layer and a middle layer, wherein the inner layer and the middle layer of the advanced small conduits are uniformly inserted in the water-rich soft rock along the circumference of the tunnel, wherein the inner layer of the advanced small conduits and the middle layer of the advanced small conduits are staggered, wherein an outer layer of the advanced small conduits is added within an angle range of 110°-130° of the top pressure arch of the tunnel, wherein the outer layer of the advanced small conduits are uniformly inserted in the water-rich soft rock along the circumference of the tunnel, wherein the outer layer of the advanced small conduits and the middle layer of the advanced small conduits are staggered, wherein grouting holes are uniformly provided on the advanced small conduits, wherein the advanced small conduits are used for injecting grouting liquid, and wherein the ends of the advanced small conduits are fixed on the arch frame of the tunnel. The present invention enables a large grouting reinforcement area, a good reinforcement effect, effectively reinforces loose rock mass, prevents tunnel collapse, and thus improves surrounding rock grade and construction safety.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, in particular to an advanced small-duct pre-reinforcement system and a construction method thereof. Background Art

[0002] With the advancement of the country's modernization construction, more and more tunnels are about to be built, and the advanced support technology for poor geological tunnels is becoming more and more perfect. However, for water-rich soft rock tunnels, due to the rich groundwater, the rock mass strength is very low, the surrounding rock conditions are poor, and collapse and other accidents are very likely to occur during the construction process, which greatly increases the difficulty of construction. Therefore, the requirements for its advanced pre-support are extremely high, which is directly related to the safety and progress of tunnel construction.

[0003] The main pre-reinforcement measures for water-rich soft rock tunnels are advance small ducts and advance pipe sheds. For the advance small duct, although this method achieves the purpose of water stopping and consolidation, the grouting reinforcement range is limited and cannot effectively ensure safe construction; for the advance pipe shed, due to its high construction process requirements, the external insertion angle is difficult to control, the construction period is long, the cost is high, and because of its large diameter, it causes a large disturbance to the surrounding rock during excavation and layout. This significantly reduces the safety and economy of the initial stage of construction for water-rich soft rock tunnels. Summary of the invention

[0004] The purpose of the present invention is to provide an advanced small-duct pre-reinforcement system and a construction method thereof to solve the problems existing in the above-mentioned prior art, so that the grouting reinforcement area is large, the reinforcement effect is good, the loose rock mass is effectively reinforced, and tunnel collapse is prevented, thereby improving the surrounding rock grade and construction safety.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides an advance small pipe pre-reinforcement system, comprising an advance small pipe, wherein the advance small pipe is provided with a double layer along the entire circumference of the tunnel, the double layer comprises an inner layer and a middle layer, the advance small pipes of the inner layer and the middle layer are uniformly inserted in the water-rich soft rock along the circumference of the tunnel, the advance small pipes of the inner layer and the advance small pipes of the middle layer are staggered, an outer layer of the advance small pipe is added within an angle range of 110°-130° of the top pressure arch of the tunnel, the advance small pipes of the outer layer are uniformly inserted in the water-rich soft rock along the circumference of the tunnel, the advance small pipes of the outer layer and the advance small pipes of the middle layer are staggered, the overlapping length of the horizontal projection of the advance small pipes of adjacent layers is 1.5-1.8m, grouting holes are uniformly provided on the advance small pipes, the advance small pipes are used for injecting grouting, and the ends of the advance small pipes are fixed on the arch frame of the tunnel.

[0007] Preferably, the external insertion angles of the advanced small ducts in the outer layer are all 25°, the external insertion angles of the advanced small ducts in the middle layer are all 15°, and the external insertion angles of the advanced small ducts in the inner layer are all 10°.

[0008] Preferably, the circumferential spacing of the advance small ducts in the outer layer is 0.5 m, the circumferential spacing of the advance small ducts in the middle layer is 0.4 m, and the circumferential spacing of the advance small ducts in the inner layer is 0.35 m.

[0009] Preferably, the small leading conduit is a seamless steel pipe, and the diameter of the small leading conduit is The length of the advance small duct is 5.2m, the tip of the advance small duct is 0.2m long, a pipe clamp is welded at the tail of the advance small duct, and the pipe clamp is welded to the arch frame. The advance small duct within 1.5m from the tail of the advance small duct is the grouting stop section, and the grouting hole is not set on the grouting stop section.

[0010] Preferably, the diameter of the grouting hole is The adjacent grouting holes are arranged in a plum blossom shape, and the spacing between the adjacent grouting holes located on the same straight line along the length direction of the advance small conduit is 15 cm.

[0011] The present invention also provides a construction method of an advanced small-duct pre-reinforcement system, comprising the following steps:

[0012] S1. Measure and locate the installation holes according to the design plan, and drill and clean the installation holes after positioning;

[0013] S2, installing the outer layer's leading small conduit, installing the leading small conduit in the outer layer's mounting hole drilled in step S1;

[0014] S3, check whether the installation quality of the outer layer of the leading small catheter meets the requirements, if not, repeat steps S2-S3;

[0015] S4, sequentially install the advanced small conduit of the middle layer and the advanced small conduit of the inner layer, and check whether the installation quality of the advanced small conduit meets the quality requirements. If it does not meet the quality requirements, repeat this step;

[0016] S5. Design and prepare the slurry mix according to the construction geology;

[0017] S6, respectively perform double-controlled high-pressure grouting on the advanced small conduits of the outer layer, the middle layer and the inner layer, and terminate the grouting after reaching the designed grouting volume or the designed grouting pressure, and at the same time, use a grouting stopper to block the pipe opening of the advanced small conduit;

[0018] S7, checking the grouting effect in step S6, if it does not meet the quality requirements, then grouting is performed, if it meets the quality requirements, then adding a pad to the end of the advance small conduit and welding the tail of the advance small conduit to the arch frame.

[0019] Preferably, in step S1, a pneumatic drill is used to drill a hole using a mud wall protection method, and then high-pressure air is used to clean the hole.

[0020] Preferably, in step S2 and step S4, the drill rod of the pneumatic drill is replaced with a drill tail, and the advance small guide tube is penetrated into the installation hole.

[0021] Preferably, in step S2 and step S4, the overlapping length of the horizontal projections of the advance small ducts of adjacent layers is 1.5-1.8m, the length of the advance small ducts penetrating into the mounting hole is not shorter than 95% of the length of the advance small ducts, and at least 0.2m is reserved at the end of the advance small ducts.

[0022] Preferably, in step S6, the outer layer, the middle layer and the inner layer of the advanced small conduits are subjected to layered group grouting respectively, and the grouting pressure is 0.5-1.0 MPa.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] In the present invention, firstly, middle and inner double-layer advance small ducts are used throughout the whole circumference of the tunnel, and then an outer layer of advance small ducts is added within the angle range of 110°-130° of the top pressure arch of the tunnel to locally strengthen the upper part of the pressure arch, which can avoid waste of materials and achieve better reinforcement effect. The three layers of advance small ducts, namely the outer layer, the middle layer and the inner layer, are staggered and work together, thereby significantly increasing the grouting reinforcement area, achieving good reinforcement effect, effectively reinforcing loose rock mass, preventing tunnel collapse, and improving surrounding rock grade and construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a structural schematic diagram of the advanced small duct pre-reinforcement system of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the advanced small catheter in the present invention;

[0028] Among them: 1-advance small guide tube, 2-seamless steel pipe, 3-grouting hole, 4-tip, 5-pipe clamp, 6-tunnel, 7-pressure arch, 8-invert arch. DETAILED DESCRIPTION

[0029] 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.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1

[0032] like Figure 1-Figure 2 As shown: This embodiment provides a pre-reinforcement system of an advanced small conduit 1, including an advanced small conduit 1, wherein the advanced small conduit 1 is provided with a double layer along the entire circumference of the tunnel 6, wherein the double layer includes an inner layer and a middle layer, wherein the inner layer and the middle layer of the advanced small conduits 1 are uniformly inserted in the water-rich soft rock along the circumference of the tunnel 6, wherein the inner layer of the advanced small conduits 1 and the middle layer of the advanced small conduits 1 are staggered, and an outer layer of the advanced small conduits 1 is added within an angle range of 110°-130° of the top pressure arch 7 of the tunnel 6, as shown in FIG. Figure 1 The angle a marked in the figure, the outer layer of the advance small conduits 1 are uniformly inserted in the water-rich soft rock along the circumferential direction of the tunnel 6, the outer layer of the advance small conduits 1 and the middle layer of the advance small conduits 1 are staggered, the overlapping length of the horizontal projection of the advance small conduits 1 of adjacent layers is 1.5-1.8m, and the advance small conduits 1 are evenly provided with grouting holes 3, which are used for injecting grouting liquid, and the ends of the advance small conduits 1 are fixed on the arch frame (pressure arch 7 or invert arch 8) of the tunnel 6 to form a pre-support system. In this embodiment, the external insertion angles of the outer layer of the advance small conduits 1 are all 25°, the external insertion angles of the middle layer of the advance small conduits 1 are all 15°, and the external insertion angles of the inner layer of the advance small conduits 1 are all 10°. The circumferential spacing of the outer layer of the advance small conduits 1 is 0.5m (such as Figure 1 The circumferential spacing of the leading small ducts 1 in the middle layer is 0.4m (as shown in D1). Figure 1 The circumferential spacing of the inner leading small ducts 1 is 0.35m (as shown in D2). Figure 1D3 marked in the figure), and the spacing between adjacent advanced small conduits 1 in different layers is D4, and D4 can be 0.35m. First, a middle layer and an inner layer double-layer advanced small conduits 1 are used throughout the whole circumference of the tunnel 6, and an outer layer of advanced small conduits 1 is added within the 110°-130° angle range of the top pressure arch 7 of the tunnel 6, and arranged according to the requirements of the external insertion angle and circumferential spacing of each layer in this embodiment, so as to locally strengthen the upper part of the pressure arch 7, and the double-layer arrangement at the invert arch 8 can effectively prevent water inrush accidents at the bottom of the tunnel 6, improve the safety of construction, not only avoid waste of materials, but also have a good reinforcement effect, the outer layer, the middle layer and the inner layer of the three layers of advanced small conduits 1 are staggered and work together, thereby significantly increasing the grouting reinforcement area, which can effectively block water and stop water, and has a good reinforcement effect, effectively reinforces loose rock mass, prevents tunnel 6 from collapsing, and improves surrounding rock grade and construction safety.

[0033] In this embodiment, the leading small conduit 1 is preferably a seamless steel pipe 2, and the diameter of the leading small conduit 1 is The length of the leading small catheter 1 is 5.2m, and the tip 4 of the leading small catheter 1 is 0.2m long (such as Figure 2 L1) is marked in the figure, the tail of the leading small conduit 1 is welded with a pipe hoop 5, and the pipe hoop 5 is made of The pipe clamp 5 is welded to the arch frame. The leading small pipe 1 within 1.5m of the tail of the leading small pipe 1 is not provided with a grouting hole 3 to form a grouting stop section. The diameter of the grouting hole 3 is The adjacent grouting holes 3 are arranged in a plum blossom shape, and the distance between adjacent grouting holes 3 located on the same straight line along the length direction of the leading small pipe 1 is 15 cm (e.g. Figure 2 L2 marked in the figure).

[0034] Embodiment 2

[0035] like Figure 1-Figure 2 As shown: This embodiment provides a construction method for a pre-reinforcement system of an advanced small conduit 1, comprising the following steps:

[0036] S1. Measure and locate the installation holes according to the design plan, and drill and clean the installation holes after positioning; in this step, a pneumatic drill is used to drill holes using a mud wall protection method to effectively prevent hole collapse or hole diameter reduction, and then high-pressure air is used to clean the holes;

[0037] S2, installing the outer layer of the leading small catheter 1, the leading small catheter 1 is installed in the outer layer of the installation hole drilled in step S1; the drill rod of the pneumatic drill in step S1 is replaced with a drill tail, and the leading small catheter 1 is penetrated into the installation hole;

[0038] S3, check whether the installation quality of the outer leading small catheter 1 meets the requirements. If not, repeat steps S2-S3;

[0039] S4, sequentially install the middle layer advance small conduit 1 and the inner layer advance small conduit 1, and use the same method as in step S2 to penetrate the advance small conduit 1 into the installation hole, and check whether the installation quality of the advance small conduit 1 meets the quality requirements. If it does not meet the quality requirements, repeat this step;

[0040] S5. Design and prepare the slurry mix according to the construction geology;

[0041] S6, respectively carry out double-controlled high-pressure grouting on the outer layer, middle layer and inner layer of the advance small conduit 1, and stop grouting after reaching the designed grouting volume or the designed grouting pressure, and at the same time use the grouting stopper to seal the pipe mouth of the advance small conduit 1; in this step, the outer layer, middle layer and inner layer of the advance small conduit 1 can also be respectively subjected to layered group grouting, and the grouting pressure is 0.5-1.0MPa to improve the grouting efficiency, double-controlled high-pressure grouting, that is, when the grouting of each advance small conduit 1 reaches the designed grouting volume, the grouting is stopped, or when each advance small conduit 1 reaches the designed grouting pressure, the grouting is stopped, and the high-pressure grouting ensures that the grouting range can be expanded more effectively to increase the grouting reinforcement area and improve the reinforcement effect;

[0042] S7, check the grouting effect in step S6, if it does not meet the quality requirements, then add grouting, if it meets the quality requirements, add a pad at the end of the leading small conduit 1 and weld the tail of the leading small conduit 1 to the arch frame.

[0043] Furthermore, in step S2 and step S4 of this embodiment, it is required that the overlapping length of the horizontal projection of the advance small ducts 1 of adjacent layers is 1.5-1.8m, the length of the advance small ducts 1 penetrating the installation hole is not shorter than 95% of the length of the advance small ducts 1, and at least 0.2m is reserved at the end of the advance small ducts 1 to facilitate the addition of pads and welding and fixing them to the arch frame, so as to better fix the advance small ducts 1 and form a pre-support system.

[0044] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An advanced small duct pre-reinforcement system, characterized in that: It comprises an advance small conduit, which is provided with a double layer along the whole circumference of the tunnel, and the double layer comprises an inner layer and a middle layer, and the advance small conduits of the inner layer and the middle layer are uniformly inserted in the water-rich soft rock along the circumference of the tunnel, and the advance small conduits of the inner layer and the advance small conduits of the middle layer are staggered, and an outer layer of the advance small conduit is added within the angle range of 110°-130° of the top pressure arch of the tunnel, and the advance small conduits of the outer layer are uniformly inserted in the water-rich soft rock along the circumference of the tunnel, and the advance small conduits of the outer layer and the advance small conduits of the middle layer are staggered, and the overlapping length of the horizontal projection of the advance small conduits of adjacent layers is 1.5-1.8m, and grouting holes are uniformly provided on the advance small conduits, and the advance small conduits in the advance small conduits are used for injecting grouting liquid, and the ends of the advance small conduits are fixed on the arch frame of the tunnel; the outer insertion angle of the advance small conduits of the outer layer is 25°, and the middle layer The external insertion angle of the advance small duct is 15°, and the external insertion angle of the advance small duct in the inner layer is 10°; the circumferential spacing of the advance small duct in the outer layer is 0.5m, the circumferential spacing of the advance small duct in the middle layer is 0.4m, and the circumferential spacing of the advance small duct in the inner layer is 0.35m; the advance small duct is a seamless steel pipe, the diameter of the advance small duct is φ45-55mm, the length of the advance small duct is 5.2m, the tip of the advance small duct is 0.2m long, and a pipe clamp is welded at the tail of the advance small duct, and the pipe clamp is welded to the arch frame. The advance small duct within 1.5m from the tail of the advance small duct is a grouting stop section, and the grouting hole is not arranged on the grouting stop section; the diameter of the grouting hole is φ7mm, and the adjacent grouting holes are arranged in a plum blossom shape. The spacing between adjacent grouting holes along the length direction of the advance small duct and located on the same straight line is 15cm.

2. A construction method for an advanced small-duct pre-reinforcement system, characterized in that: The advanced small catheter pre-reinforcement system described in claim 1 comprises the following steps: S1. Measure and locate the installation holes according to the design plan, and drill and clean the installation holes after positioning; S2, installing the outer layer's advanced small conduit, installing the advanced small conduit in the outer layer's installation hole drilled in step S1; S3, check whether the installation quality of the outer layer of the leading small catheter meets the requirements, if not, repeat steps S2-S3; S4, sequentially install the advanced small conduit of the middle layer and the advanced small conduit of the inner layer, and check whether the installation quality of the advanced small conduit meets the quality requirements. If it does not meet the quality requirements, repeat this step; S5. Design and prepare the slurry mix according to the construction geology; S6, respectively perform double-controlled high-pressure grouting on the advanced small conduits of the outer layer, the middle layer and the inner layer, and terminate the grouting after reaching the designed grouting volume or the designed grouting pressure, and at the same time, use a grouting stopper to block the pipe opening of the advanced small conduit; S7, checking the grouting effect in step S6, if it does not meet the quality requirements, then grouting is performed, if it meets the quality requirements, then adding a pad to the end of the advance small conduit and welding the tail of the advance small conduit to the arch frame.

3. The construction method of the advanced small duct pre-reinforcement system according to claim 2 is characterized in that: In step S1, a pneumatic drill is used to drill a hole using a mud wall protection method, and then a high-pressure air is used to clean the hole.

4. The construction method of the advanced small duct pre-reinforcement system according to claim 3 is characterized in that: In step S2 and step S4, the drill rod of the pneumatic drill is replaced with a drill tail, and the leading small guide tube is inserted into the installation hole.

5. The construction method of the advanced small duct pre-reinforcement system according to claim 2 is characterized in that: In step S2 and step S4, the overlapping length of the horizontal projection of the advance small ducts of adjacent layers is 1.5-1.8m, the length of the advance small ducts penetrating into the installation hole is not less than 95% of the length of the advance small ducts, and at least 0.2m is reserved at the end of the advance small ducts.

6. The construction method of the advanced small duct pre-reinforcement system according to claim 2 is characterized in that: In step S6, the outer layer, the middle layer and the inner layer of the advanced small conduits are subjected to layered group grouting respectively, and the grouting pressure is 0.5-1.0 MPa.

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