Double-layer small guide pipe advance support structure applied to extremely high crustal stress tunnel

Abstract

The utility model discloses a double-layer small guide pipe advance support structure applied to an extremely high crustal stress tunnel. The double-layer small guide pipe advance support structure comprises a sprayed concrete layer and a support steel frame arranged in the sprayed concrete layer. The supporting steel frame is arranged in the axial direction of a tunnel in an equiaxial mode, a plurality of first grouting small guide pipes are arranged on the supporting steel frame in an equiaxial mode, second grouting small guide pipes are arranged between the adjacent first grouting small guide pipes, and the first grouting small guide pipes and the second grouting small guide pipes are different in elevation angle. The original single-layer support is changed into the existing double-layer support, and the first grouting small guide pipe and the second grouting small guide pipe are alternately supported, so that the support can be better carried out, the excavation working surface is better stabilized, and the deformation of the arch part after excavation is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of tunnel construction, in particular to a double-layer small-duct advance support structure applied to extremely high ground stress tunnels. Background Art

[0002] In my country, the construction of extremely high geostress tunnels is common. Traditional treatment methods mainly focus on improving the strength grade of the designed surrounding rock and strengthening support measures. However, the statistical analysis of surrounding rock deformation under different surrounding rock strength grades and excavation support methods is still insufficient. At present, when facing similar tunnel construction, we often rely on relevant data collected and analyzed in the early stage as a reference, but this needs to be further deepened and systematized. Therefore, it is urgent for us to jointly collect and organize different parameters in the construction of extremely high geostress tunnels to continuously improve and optimize the technical achievements of such tunnel construction.

[0003] Under special geological conditions, such as weak, broken areas with extremely high ground stress, such as fault fracture zones, weathered rocks, gravel soil layers, and sand and gravel layers, the application of single-layer advanced small pipe support may face many challenges. These geological conditions can easily lead to large deformation of the surrounding rock, thereby destroying the surrounding rock support system and seriously affecting the construction progress and safety.

[0004] In order to solve the problem that one layer of advanced small conduits can no longer support areas with extremely high ground stress, the utility model provides a double-layer small conduit advance support structure applied to extremely high ground stress tunnels. Utility Model Content

[0005] To achieve the above objectives, the utility model is implemented through the following technical solutions: a double-layer small duct advance support structure applied to extremely high ground stress tunnels, comprising: a shotcrete layer, and a support steel frame arranged inside the shotcrete layer; the support steel frame is equiaxially arranged along the tunnel axis, and a plurality of first grouting small ducts are equiaxially arranged on the support steel frame, and a second grouting small duct is arranged between adjacent first grouting small ducts, and the first grouting small duct and the second grouting small duct have different elevation angles.

[0006] Preferably, the upward elevation angle of the first grouting small duct is 5-15°, and the upward elevation angle of the second grouting small duct is 15-20°.

[0007] Preferably, the first grouting duct and the second grouting duct are both provided with tightening hoops.

[0008] Preferably, the supporting steel frame is arched, and locking foot guide tubes are provided at both ends of the supporting steel frame.

[0009] Preferably, the supporting steel frame is an I-beam, a plurality of connecting sleeves are provided on both sides of the web of the I-beam, adjacent I-beams are connected by longitudinal connecting ribs, and both ends of the longitudinal connecting ribs are provided with right-angle hooks inserted into the connecting sleeves.

[0010] Preferably, after two grouting operations, a reinforced concrete layer is provided on the inner side of the supporting steel frame.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] The utility model changes from the original single-layer support to the existing double-layer support. The first grouting small duct and the second grouting small duct are alternately supported, which can better support and stabilize the excavation working surface, and reduce the deformation of the arch after excavation. The double-layer advance small duct is constructed in steps, and the second layer is constructed after the first layer is completed. The grouting efficiency of the first layer is low, which plays a sealing role and enhances the density between soil bodies. The grouting efficiency of the second layer is relatively high, and the slurry leakage is relatively rare. When the advance small duct is grouting, the grouting pressure can be increased accordingly, and the grouting effect is significantly improved. The stability of the surrounding rock will be enhanced, and the surrounding rock support can be better performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the cross-sectional structure of a double-layer small-conductor advance support structure used in extremely high ground stress tunnels;

[0014] Figure 2 It is a schematic diagram of the transverse structure of the double-layer small-conductor advance support structure used in extremely high ground stress tunnels;

[0015] Figure 3 It is a schematic diagram of the longitudinal connection structure of the supporting steel frame;

[0016] Figure 4 It is a schematic diagram of the structure of the first grouting duct and the second grouting duct.

[0017] In the figure: shotcrete layer 1, supporting steel frame 2, first grouting small duct 3, second grouting small duct 4, locking foot duct 5, I-beam 6, connecting sleeve 7, longitudinal connecting rib 8, reinforced concrete layer 9, reserved grouting section 10, tightening hoop 11, grouting section 12, grouting hole 13. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0019] See also Figures 1 to 4This embodiment provides a double-layer small pipe advance support structure for extremely high ground stress tunnels, including: a shotcrete layer 1, a support steel frame 2 arranged inside the shotcrete layer 1; the support steel frame 2 is equiaxially arranged along the tunnel axis, a number of first grouting small pipes 3 are equiaxially arranged on the support steel frame 2, and a second grouting small pipe 4 is arranged between adjacent first grouting small pipes 3, and the first grouting small pipes 3 and the second grouting small pipes 4 have different elevation angles. During construction, the first grouting small pipe 3 is grouted first, and after the first layer of grouting is completed, the second grouting small pipe 4 performs the second layer of grouting.

[0020] The first grouting small conduit 3 has an upward elevation angle of 5-15°, and the second grouting small conduit 4 has an upward elevation angle of 15-20°. The two layers of grouting small conduits have different upward elevation angles, and surrounding rock support can be performed in all directions. The first grouting small conduit 3 or the second grouting small conduit 4 can be replaced with a grouting anchor.

[0021] The first grouting small conduit 3 and the second grouting small conduit 4 are both provided with a tightening hoop 11. The tightening hoop 11 is mainly used to strengthen the rigidity of the grouting pipe, increase the pressure bearing capacity and torsion capacity of the grouting pipe, thereby improving the stability and safety of the grouting pipe during use. The tightening hoop 11 is made of a steel pipe or a steel plate.

[0022] The first grouting small duct 3 and the second grouting small duct 4 are both provided with a reserved grouting stop section 10, one end of which is provided with the tightening hoop 11, and the other end of the reserved grouting stop section 10 is a grouting section 12, and the grouting section 12 is provided with a plurality of grouting holes 13.

[0023] The support steel frame 2 is arched, and locking foot conduits 5 are provided at both ends of the support steel frame 2. The locking foot conduits 5 can be used to inject cement slurry, which can prevent the soil around the tunnel from loosening and collapsing, and ensure the stability and safety of the tunnel.

[0024] The support steel frame 2 is an I-beam 6, and a plurality of connecting sleeves 7 are provided on both sides of the web of the I-beam 6. Adjacent I-beams 6 are connected by longitudinal connecting ribs 8, and both ends of the longitudinal connecting ribs 8 are provided with right-angle hooks inserted into the connecting sleeves 7. The longitudinal connecting ribs 8 connect the I-beams 6 into a more stable whole.

[0025] After two groutings, a reinforced concrete layer 9 is provided inside the support steel frame 2. The reinforced concrete layer 9 fills the gap between the support steel frames 2 to add a layer of stable support.

[0026] The first grouting conduit 3 and the second small grouting conduit 4 are installed by drilling method. The diameter of the drill hole is 3 to 5 mm larger than the diameter of the steel pipe. Then the first grouting conduit 3 and the second small grouting conduit 4 are passed through the supporting steel frame 2 and pushed in by hammering or drilling. The pushed-in length is not less than 90% of the length of the steel pipe, and the sand and gravel in the steel pipe are blown out by high-pressure wind.

[0027] After the first grouting conduit 3 and the second small grouting conduit 4 are installed, the hole opening and the surrounding cracks are sealed with plastic mud. If necessary, concrete is sprayed near the first grouting conduit 3 and the second small grouting conduit 4 and the working surface to prevent the working surface from collapsing.

[0028] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A double-layer small-pipe advance support structure applied to extremely high ground stress tunnels, characterized in that: include: A shotcrete layer (1), and a supporting steel frame (2) arranged inside the shotcrete layer (1); the supporting steel frame (2) is equiaxially arranged along the tunnel axis, a plurality of first grouting small ducts (3) are equiaxially arranged on the supporting steel frame (2), a second grouting small duct (4) is arranged between adjacent first grouting small ducts (3), and the first grouting small duct (3) and the second grouting small duct (4) have different upward elevation angles.

2. The double-layer small-pipe advance support structure for extremely high ground stress tunnels according to claim 1 is characterized in that: The upward elevation angle of the first grouting small duct (3) is 5-15°, and the upward elevation angle of the second grouting small duct (4) is 15-20°.

3. The double-layer small-pipe advance support structure for extremely high ground stress tunnels according to claim 2 is characterized in that: The first grouting small conduit (3) and the second grouting small conduit (4) are both provided with tightening hoops.

4. The double-layer small-pipe advance support structure for extremely high ground stress tunnels according to claim 1 is characterized in that: The supporting steel frame (2) is arched, and locking foot guide tubes (5) are provided at both ends of the supporting steel frame (2).

5. The double-layer small-pipe advance support structure for extremely high ground stress tunnels according to claim 4 is characterized in that: The supporting steel frame (2) is an I-beam (6), and a plurality of connecting sleeves (7) are provided on both sides of the web of the I-beam (6). Adjacent I-beams (6) are connected by longitudinal connecting ribs (8), and right-angle hooks inserted into the connecting sleeves (7) are provided at both ends of the longitudinal connecting ribs (8).

6. The double-layer small-pipe advance support structure for extremely high ground stress tunnels according to claim 1 is characterized in that: After two grouting operations, a reinforced concrete layer (9) is provided on the inner side of the supporting steel frame (2).

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