A construction method for an advanced small-duct grouting device

Abstract

The present invention discloses an advanced small-duct grouting device and a construction method thereof, which are particularly suitable for fine-sand geology or fine-sand water-rich geology. Under such geological conditions, a blowing component is used to connect the small duct, and a process of first blowing to form a hole and then grouting support is adopted for construction. Under fine-sand geology, using strong wind pressure is easier to form a hole and less likely to collapse than using a drill rod. It is faster and more efficient than using a drilling machine to form a hole, thereby improving the overall construction progress and not being restricted by the on-site environment and the depth of underground excavation. The different stratum structures during each support can be specially processed, so that the small-duct advance grouting can play a maximum reinforcing and supporting role, achieve a sufficient stabilizing effect, and greatly reduce the risks of soil collapse and sudden water and mud.

Description

Technical Field

[0001] The invention relates to the technical field of grouting in underground tunneling projects, and in particular to an advanced small-pipe grouting device and a construction method thereof. Background Art

[0002] With the rapid development of infrastructure construction in my country, especially the increasing development of highways, railways and urban underground space, tunnel engineering, as a key infrastructure construction project, has increasingly higher requirements for construction technology and safety. In tunnel construction, especially when passing through soft and broken strata, shallow buried sections, sandy sections, portal biased sections, fault fracture zones and gravel sections and other unfavorable geological conditions, how to ensure the stability of the surrounding rock during tunnel excavation has become a technical problem that needs to be solved urgently.

[0003] When faced with the above complex geological conditions, traditional tunnel support methods often have problems such as poor support effect, great construction difficulty, and high cost; especially in weak and broken surrounding rocks with short self-stabilization time or even in fine sand geological conditions, it is not easy to achieve hole formation by drilling with drilling equipment and drill rods, because the fine sand itself is loose, has low cohesion, and is prone to hole collapse. Therefore, it is particularly important to develop an advanced grouting support technology suitable for fine sand geological conditions. Summary of the invention

[0004] The present invention provides an advanced small-duct grouting device and a construction method thereof, which are used to solve the technical problems that it is difficult to drill holes with a drill rod in fine sand geological conditions, and the holes are prone to collapse after being drilled, resulting in inconvenience for grouting, etc. during the process of advanced support for tunnel excavation.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides an advanced small-duct grouting device, comprising a small duct, a blowing assembly, a grouting assembly and a supporting assembly; the front end of the small duct is conical and open, the pipe body of the small duct is provided with grouting holes, the grouting holes are distributed in the front two-thirds of the pipe body of the small duct, and are arranged in a plum blossom shape on the pipe body; the rear end of the small duct is open and filled with a sealing plug, and the sealing plug has an opening in the center; the blowing assembly comprises a first blowing pipe, a second blowing pipe, an air compressor, a positioning ring and a blowing pressure gauge; the first blowing pipe is plugged with the sealing plug and the front end of the first blowing pipe extends into the small duct, and the length of the first blowing pipe is not more than one-third of the length of the small duct; A positioning ring is sleeved on the outer side surface of a blowing pipe, and the positioning ring is tightly arranged against the inner wall of the small duct; the rear end of the first blowing pipe is outside the small duct and extends out of the sealing plug, the rear end of the first blowing pipe is connected to the second blowing pipe, the other end of the second blowing pipe is connected to the air compressor, and the second blowing pipe is provided with a blowing pressure gauge; the grouting assembly comprises a grouting nozzle, a grouting pipe, a grouting pump, a grouting suction pipe, a slurry bucket and a grouting pressure gauge; the grouting nozzle is used to plug the sealing plug, the other end of the grouting nozzle is connected to the grouting pipe, the other end of the grouting pipe is connected to the grouting pump, the grouting pump is connected to a grouting suction pipe for sucking slurry, and the grouting suction pipe extends into the slurry bucket; the grouting pipe is provided with a grouting pressure gauge.

[0007] Preferably, a reinforcement ring is provided at the front end opening of the small catheter, and the reinforcement ring is fixedly arranged at the periphery of the opening to enhance the structural stability of the front end opening of the small catheter.

[0008] Preferably, the positioning ring includes a ring portion, connecting ribs and a hoop; the ring portion is sleeved on the outer side surface of the first blowing pipe, and the inner circle of the ring portion is provided with connecting ribs; there are two connecting ribs, which are distributed at both ends of the inner circle diameter of the ring portion and are perpendicular to the ring portion, and the inner side of the connecting rib is arranged in contact with the outer side surface of the first blowing pipe; the hoop is arranged on the outer side of the connecting rib to clamp the connecting rib to the first blowing pipe.

[0009] Preferably, a handle is provided on the outer side of the bottom of the small conduit for workers to hold and grasp.

[0010] Preferably, the support assembly includes a top support, a main rod and supporting legs; the top support is semicircular and is arranged on the lower side of the bottom of the small catheter to support the small catheter, the main rod is arranged on the lower end surface of the top support, and at least three supporting legs are arranged at the bottom end of the main rod.

[0011] Preferably, it also includes a leakage protector and an overload protector.

[0012] Preferably, the grouting nozzle includes a conical head, a reducing neck, a valve and a connecting pipe; the conical head is arranged through the sealing plug, the reducing neck is clamped at the central opening of the sealing plug, the valve is arranged at the rear end of the reducing neck, and the connecting pipe is arranged at the rear end of the valve, and the connecting pipe is used to connect the grouting pipe.

[0013] The present invention also provides a construction method of the above-mentioned advanced small-duct grouting device, comprising the following steps:

[0014] Step 1: Formation detection: first sample the formation to detect the formation particle composition and the distribution of fine sand formation, and adjust the relevant construction parameters according to the detection results;

[0015] Step 2: Processing and manufacturing the small catheter: using a three-axis tube punching machine to punch holes in the small catheter in the upper, left and right directions at the same time; then using a split small catheter tipping machine to process the small catheter, putting the small catheter into the heating ring, and after heating, the feeding rack automatically feeds the material into the tipping mold for compression molding;

[0016] Step 3: Positioning: Use the contact triangulation method and use the surveying instrument total station to lead the ground control points to the underground tunnel. Arrange the control points in a solid position with good sight. Use the total station to lay out the tunnel centerline. As the tunnel is excavated, continue to introduce the control points forward, locate and stake out the hole positions, and arrange them 10 cm in a circumferential direction outside the arch excavation contour line. Use red paint to mark the layout points of the advance small guide tubes.

[0017] Step 4: Setting up the small conduit: The worker holds the small conduit with the tip of the small conduit facing the tunnel arch, places the small conduit on the top support and securely fixes it, and determines the angle between the small conduit and the tunnel arch surface, that is, the insertion angle of the small conduit;

[0018] Step 5, blowing holes: Assemble the blowing assembly, start the power supply, conduct a trial run first, check the operation of the air compressor, and observe whether the blowing pressure gauge can reach 0.3MPa; after the trial run is normal, extend the first blowing pipe through the sealing plug and into the small duct, and clamp the first blowing pipe to the middle of the small duct with a positioning ring, fix the sealing plug at the tail end of the small duct and fill it tightly, then connect the second blowing pipe to the first blowing pipe and start the power supply, run the air compressor, maintain the wind pressure at 0.3MPa, and the worker pulls back and forth to insert the small duct to form a hole at the mark on the tunnel vault, repeat the above operation until the hole that meets the design requirements is completed, then stop the air supply, and pull the first blowing pipe out of the small duct; repeat the above operation to make holes for the remaining marked points in turn;

[0019] Step 6, grouting: Assemble the grouting components, test the water before grouting to make sure the pipeline is unobstructed and check the sealing; install the sealing plug on the grouting nozzle first, then insert the grouting nozzle into the small tube and start grouting, control the grouting pressure at 0.2~0.5MPa, when the small tube is full of slurry, stabilize the pressure and keep the grouting pressure at 0.5MPa for a period of time to ensure the penetration range of the slurry and stop grouting in this hole; repeat the above operation and grout the remaining holes in turn;

[0020] Step seven, strength test: when the slurry solidifies, core sampling is carried out on the consolidated body, and a compressive strength test is performed. If the strength is not less than 0.6MPa, it is qualified; if the strength is less than 0.6MPa, more drilling and grouting are carried out on the tunnel vault until the strength of the sample meets the design requirements.

[0021] Preferably, in step one, after sampling the formation, BIM modeling is performed based on the collected data to simulate the formation structure, the grouting strengthening process is simulated by changing the formation parameters, and the effects of drilling depth, drilling angle, drilling density and grouting amount on the formation strength are tested to obtain the optimal drilling depth, drilling angle, drilling density and grouting amount.

[0022] Preferably, in step one, the relevant construction parameters are the length of the small conduit, the angle between the small conduit and the tunnel vault, the distribution spacing of the holes, the number of holes arranged, and the pressure stabilization time of grouting.

[0023] The beneficial effects of the present invention are embodied in:

[0024] 1) The present invention provides an advanced small-duct grouting device and a construction method thereof, which are particularly suitable for fine sand geology or fine sand and water-rich geology. Under such geological conditions, a blowing assembly is used to connect a small duct, and the construction is carried out by blowing first and then grouting. The use of strong wind pressure is easier to form a hole and less likely to collapse than a drill rod, and is faster and more efficient than using a drilling machine to form a hole, thereby improving the overall construction progress and being unconstrained by the on-site environment and the depth of dark excavation. The blowing and grouting are both carried out using a small duct, and the construction can be completed by simply replacing the blowing assembly and the grouting assembly, and the operation is relatively convenient.

[0025] 2) The present invention provides an advanced small conduit grouting device and a construction method thereof, which are processed by a three-axial tube punching machine and a split small conduit tipping machine. The small conduit manufacturing machine completely replaces manual labor, and all loading and unloading are automatic. The three-axial small conduit punching machine can punch holes in the small conduit in the three directions of up, left and right at the same time. The holes punched have no depressions, and the appearance is smooth and accurately positioned. In terms of efficiency, 150 small conduits can be punched in one hour; the workpiece made by the split small conduit tipping machine has good forming effect, is sturdy and durable, and the tip shrinking mold is four pieces, which is compressed in four directions, greatly improving the service life of the mold;

[0026] 3) The present invention provides an advance small-duct grouting device and a construction method thereof. After sampling the stratum, BIM modeling is performed based on the collected data to simulate the stratum structure. The grouting reinforcement process is simulated by changing the stratum parameters, and the influence of the drilling depth, angle and grouting amount on the stratum strength is tested to obtain the optimal drilling depth, drilling angle and grouting amount, so that different stratum structures can be specially treated during each support, so that the small-duct advance grouting can play the greatest role in reinforcement and support, achieve sufficient stabilization effect, and greatly reduce the risk of soil collapse and sudden water and mud.

[0027] Other features and advantages of the present invention will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present invention; the main purpose and other advantages of the present invention may be realized and obtained through the solutions particularly pointed out in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the connection between the blowing assembly and the small duct of the present invention.

[0029] Figure 2 It is a schematic diagram of the connection between the grouting component and the small conduit of the present invention.

[0030] Figure 3 It is a plan view of the positioning ring of the present invention.

[0031] Figure 4 It is a schematic diagram of the connecting ribs of the positioning ring of the present invention.

[0032] Figure 5 It is a partial enlarged view of the grouting nozzle of the present invention.

[0033] Figure 6 It is a schematic diagram of the arrangement of holes in the tunnel cross section of the present invention.

[0034] Figure markings: 1-small duct, 11-grouting hole, 12-sealing plug, 13-reinforcement ring, 14-handle, 2-blowing assembly, 21-first blowing pipe, 22-second blowing pipe, 23-air compressor, 24-positioning ring, 241-ring part, 242-connecting rib, 243-hoop, 25-blowing pressure gauge, 3-grouting assembly, 31-grouting nozzle, 311-conical head, 312-reducing neck, 313-valve, 314-connecting pipe, 32-grouting pipe, 33-grouting pump, 34-slurry suction pipe, 35-slurry bucket, 36-grouting pressure gauge, 4-support assembly, 41-top support, 42-main rod, 43-leg. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described in detail below through examples. The following examples are merely exemplary and can only be used to explain and illustrate the technical solution of the present invention, but cannot be interpreted as limiting the technical solution of the present invention.

[0036] Embodiment: This embodiment takes a tunnel construction project as an example, improves the structure of the small duct, and uses air blowing to make holes instead of the traditional drilling rod drilling and then grouting method to carry out advanced support for tunnel excavation. It is flexible to use and easy to operate. It is easier to make holes in fine sand and water-rich geology. It is faster and more efficient than using a drilling machine to make holes, improves the overall construction progress, is not restricted by the site environment and the depth of the underground excavation, and overcomes the shortcomings of underground underground excavation grouting operations. It has been applied in actual construction operations and has received a good response. It can greatly improve construction efficiency and obtain good economic benefits, and has a good application prospect.

[0037] Reference Figure 1-2 The present invention provides an advanced small-duct grouting device, comprising a small duct 1, a blowing assembly 2, a grouting assembly 3 and a supporting assembly 4; the front end of the small duct 1 is tapered and has an opening, the pipe body of the small duct 1 is provided with grouting holes 11, the grouting holes 11 are distributed in the front two-thirds of the pipe body of the small duct 1, and are arranged in a plum blossom shape on the pipe body; the rear end of the small duct 1 is open and filled with a sealing plug 12, and the sealing plug 12 has a central opening; a reinforcement ring 13 is provided at the front end opening of the small duct 1, and the reinforcement ring 13 is fixedly arranged at the periphery of the opening to enhance the structural stability of the front end opening of the small duct 1; a handle 14 is provided on the outer side of the bottom of the small duct 1 for workers to hold and grasp;

[0038] The blowing assembly 2 includes a first blowing pipe 21, a second blowing pipe 22, an air compressor 23, a positioning ring 24 and a blowing pressure gauge 25; the first blowing pipe 21 adopts a steel pipe, the first blowing pipe 21 is plugged with the sealing plug 12 and the front end of the first blowing pipe 21 extends into the small duct 1, and the length of the first blowing pipe 21 is not more than one third of the length of the small duct 1; the outer side of the first blowing pipe 21 is sleeved with a positioning ring 24, and the positioning ring 24 is tightly arranged against the inner wall of the small duct 1; the rear end of the first blowing pipe 21 is outside the small duct 1 and extends out of the sealing plug 12, the rear end of the first blowing pipe 21 is connected to the second blowing pipe 22, the second blowing pipe 22 adopts a high-pressure rubber hose, the other end of the second blowing pipe 22 is connected to the air compressor 23, and the second blowing pipe 22 is provided with a blowing pressure gauge 25;

[0039] The grouting assembly 3 includes a grouting nozzle 31, a grouting pipe 32, a grouting pump 33, a grouting suction pipe 34, a slurry bucket 35 and a grouting pressure gauge 36; the grouting nozzle 31 is used to plug the sealing plug 12, the other end of the grouting nozzle 31 is connected to the grouting pipe 32, the grouting pipe 32 adopts a high-pressure hose, the other end of the grouting pipe 32 is connected to the grouting pump 33, the grouting pump 33 is connected to a grouting suction pipe 34, the grouting suction pipe 34 adopts a hose, the grouting suction pipe 34 is used to absorb slurry, and the grouting suction pipe 34 extends into the slurry bucket 35; the grouting pipe 32 is provided with a grouting pressure gauge 36;

[0040] The support assembly 4 includes a top support 41, a main rod 42 and support legs 43; the top support 41 is semicircular and is arranged on the lower side of the bottom of the small catheter 1 to support the small catheter 1. The main rod 42 is arranged on the lower end surface of the top support 41, and at least three support legs 43 are arranged at the bottom of the main rod 42; wherein, the main rod 42 can adopt a telescopic structure and can adjust the length to provide more stable support for the small catheter 1; the small catheter 1 is placed on the top support 41 to avoid the worker only holding the small catheter 1 with his hands to operate, resulting in the small catheter 1 being unstable and the insertion direction being offset, so the top support 41 plays a supporting and guiding role, so that the small catheter 1 can be quickly and accurately placed in a reasonable position.

[0041] Reference Figure 3-4 The positioning ring 24 includes a ring portion 241, a connecting rib 242 and a hoop 243; the ring portion 241 is sleeved on the outer side of the first blowing pipe 21, and the inner circle of the ring portion 241 is provided with a connecting rib 242; there are two connecting ribs 242, which are distributed at both ends of the inner diameter of the ring portion 241 and are perpendicular to the ring portion 241, and the inner side of the connecting rib 242 is arranged in contact with the outer side of the first blowing pipe 21; the hoop 243 is arranged on the outer side of the connecting rib 242 to clamp the connecting rib 242 and the first blowing pipe 21.

[0042] Reference Figure 5 The grouting nozzle 31 includes a conical head 311, a reducing neck 312, a valve 313 and a connecting pipe 314; the conical head 311 is arranged through the sealing plug 12, the reducing neck 312 is clamped at the central opening of the sealing plug 12, the valve 313 is arranged at the rear end of the reducing neck 312, and the connecting pipe 314 is arranged at the rear end of the valve 313, and the connecting pipe 314 is used to connect the grouting pipe 32.

[0043] Furthermore, the grouting device also includes a leakage protector and an overload protector, which greatly improves safety. If a leakage occurs, the leakage protector will cut off the power in time to avoid accidents; the function of the overload protector is to trip immediately when the line current is too large and exceeds a certain value, thereby ensuring safety during use.

[0044] The present invention also provides a construction method of the above-mentioned advanced small-duct grouting device, comprising the following steps:

[0045] Step 1: Formation detection: First, sample the formation to detect the formation particle composition and the distribution of fine sand formations. The fine sand particles of 0.25~0.075mm in the formation account for ≥47%, which belongs to the fine sand formation; BIM modeling is carried out based on the collected data to simulate the formation structure, and the grouting strengthening process is simulated by changing the formation parameters. The effects of the drilling depth, angle and grouting amount on the formation strength are tested, and the optimal drilling depth is 2m, the drilling angle is 20°, and the drilling density is 30cm. One hole and the grouting amount are calculated by the formula: Q1=πR 2 Lnαβ is calculated, where R is the slurry diffusion radius, which is calculated as 0.3m, L is the grouting length of 2m, n is the porosity, in this embodiment, most of the soil layer is fine sand layer, the porosity is considered to be 45%, α is the formation filling coefficient, which is 0.8; β is the slurry consumption coefficient, which is 1.3; the grouting volume obtained by this formula is 0.26m 3 ;

[0046] Adjust relevant construction parameters according to the above test results, including the length of the small conduit 1, the arrangement spacing of the small conduit 1, the angle between the small conduit 1 and the tunnel vault, and the grouting stabilization time, etc.; in this embodiment, the small conduit 1 is 2.25m long and is a Ф32×3.25 steel pipe; the small conduit 1 is inserted into the hole to a depth of 2m, exposed 25cm, the arrangement spacing of the holes is 30cm, the number is 10, the angle between the small conduit 1 and the tunnel vault is 20°, and the grouting stabilization time is 5 minutes;

[0047] Step 2, processing and manufacturing the small catheter 1: using a three-axial tube punching machine to punch holes in the small catheter 1 in the upper, left and right directions at the same time; then using a split small catheter 1 tipping machine to process the small catheter 1, putting the small catheter 1 into the heating ring, and after heating, the feeding rack automatically feeds the material into the tipping mold for compression molding;

[0048] Step 3, positioning: Use the contact triangulation method and use the surveying instrument total station to lead the ground control points to the underground tunnel. Arrange the control points in a solid position with good sight. Use the total station to lay out the tunnel centerline. As the tunnel is excavated, continue to introduce the control points forward, locate and stake out the holes, and arrange them 10 cm outside the arch excavation contour line in a circular direction. Use red paint to mark the layout points of the advance small guide tube 1. Refer to Figure 6 ;

[0049] Step 4, erecting the small conduit 1: the worker holds the small conduit 1, with the tip of the small conduit 1 facing the tunnel arch, places the small conduit 1 on the top support 41 and securely fixes it, and determines the angle between the small conduit 1 and the tunnel arch surface, that is, the insertion angle of the small conduit 1;

[0050] Step 5, blowing holes: Assemble the blowing assembly 2, start the power supply, conduct a trial run first, check the operation of the air compressor 23, and observe whether the blowing pressure gauge 25 can reach 0.3MPa; after the trial run is normal, pass the first blowing pipe 21 through the sealing plug 12 and extend it into the small duct 1. The first blowing pipe 21 is clamped in the middle of the small duct 1 by the positioning ring 24, and the sealing plug 12 is fixed at the tail end of the small duct 1 and filled tightly, and then the second blowing pipe 22 is connected to the first blowing pipe 21 and started. The power supply is turned on, and the air compressor 23 is running, maintaining the wind pressure at 0.3 MPa. The high-pressure wind enters the small duct 1 from the first blowing pipe 21, and is blown out from the front end opening of the small duct 1 and the grouting hole 11. The worker pulls the inserted small duct 1 back and forth, and the wind pressure makes the small duct 1 blow out a hole at the mark of the tunnel vault. The above operation is repeated until the hole that meets the design requirements is completed, and then the air supply is stopped, and the first blowing pipe 21 is pulled out of the small duct 1; the above operation is repeated to form holes for the remaining marked points in turn;

[0051] Step 6, grouting: assemble the grouting assembly 3, conduct a water test before grouting to ensure that the pipeline is unobstructed and check the sealing; first install the sealing plug 12 on the grouting nozzle 31, and then insert the grouting nozzle 31 into the small conduit 1 to start grouting, and control the grouting pressure at 0.2~0.5MPa. When the small conduit 1 is full of slurry, perform a pressure stabilization operation, and keep the grouting pressure at 0.5MPa. Stabilize the pressure for a period of time to ensure the penetration range of the slurry and then stop grouting in this hole; repeat the above operation and grout the remaining holes in turn;

[0052] Step seven, strength test: after the slurry solidifies, core sampling is carried out on the consolidated body, and a compressive strength test is performed. If the strength is not less than 0.6 MPa, it is qualified; if the strength is less than 0.6 MPa, denser hole grouting is carried out on the tunnel vault until the strength of the sample meets the design requirements; in this embodiment, the sample strength is measured to reach 0.8 MPa, which meets the design requirements.

[0053] 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 changes or substitutions that a technician familiar with the technical field can think of within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. A construction method of an advanced small-duct grouting device, characterized in that: The advanced small-duct grouting device comprises a small duct (1), an air blowing assembly (2), a grouting assembly (3) and a supporting assembly (4); The front end of the small conduit (1) is tapered and open, the body of the small conduit (1) is provided with grouting holes (11), the grouting holes (11) are distributed in the front two-thirds of the body of the small conduit (1), and are arranged in a plum blossom shape on the body; the rear end of the small conduit (1) is open and filled with a sealing plug (12), the sealing plug (12) having a central opening; The blowing assembly (2) comprises a first blowing pipe (21), a second blowing pipe (22), an air compressor (23), a positioning ring (24) and a blowing pressure gauge (25); the first blowing pipe (21) is plugged into the sealing plug (12) and the front end of the first blowing pipe (21) extends into the interior of the small duct (1), and the length of the first blowing pipe (21) is not greater than one third of the length of the small duct (1); the outer side surface of the first blowing pipe (21) is sleeved with a positioning ring (24), and the positioning ring (24) is tightly arranged against the inner wall of the small duct (1); the rear end of the first blowing pipe (21) is outside the small duct (1) and extends out of the sealing plug (12), the rear end of the first blowing pipe (21) is connected to the second blowing pipe (22), the other end of the second blowing pipe (22) is connected to the air compressor (23), and the second blowing pipe (22) is provided with a blowing pressure gauge (25); The grouting assembly (3) comprises a grouting nozzle (31), a grouting pipe (32), a grouting pump (33), a grouting suction pipe (34), a slurry bucket (35) and a grouting pressure gauge (36); the grouting nozzle (31) is used to be plugged into a sealing plug (12); the other end of the grouting nozzle (31) is connected to the grouting pipe (32); the other end of the grouting pipe (32) is connected to the grouting pump (33); the grouting pump (33) is connected to a grouting suction pipe (34) for sucking slurry; the grouting suction pipe (34) extends into the slurry bucket (35); the grouting pipe (32) is provided with a grouting pressure gauge (36); The support assembly (4) comprises a top support (41), a main rod (42) and supporting legs (43); the top support (41) is semicircular and is arranged on the lower side of the bottom of the small catheter (1) for supporting the small catheter (1); the main rod (42) is arranged on the lower end surface of the top support (41); and at least three supporting legs (43) are arranged at the bottom end of the main rod (42); The construction includes the following steps: Step 1: Formation detection: first sample the formation to detect the formation particle composition and the distribution of fine sand formation, and adjust the relevant construction parameters according to the detection results; Step 2, processing and manufacturing the small catheter (1): using a three-axis tube punching machine to punch holes in the small catheter (1) in the upper, left and right directions at the same time; then using a split small catheter (1) tipping machine to process the small catheter (1), placing the small catheter (1) into a heating ring, and after heating, the feeding rack automatically feeds the material into the tipping mold for compression molding; Step 3, positioning: using the connection triangulation method, use the surveying instrument total station to lead the ground control points to the underground tunnel, arrange the control points in a solid position with good sight, use the total station to lay out the tunnel centerline, and as the tunnel is excavated, continue to introduce the control points forward, locate and lay out the hole positions, arrange them circumferentially 10 cm outside the arch excavation contour line, and use red paint to mark the arrangement points of the advance small guide tube (1); Step 4, erecting the small conduit (1): the worker holds the small conduit (1) with the tip of the small conduit (1) facing the tunnel arch, places the small conduit (1) on the top support (41) and securely fixes it, and determines the angle between the small conduit (1) and the tunnel arch top surface, that is, the insertion angle of the small conduit (1) is 15° to 30°; Step 5, blowing holes: assemble the blowing assembly (2), start the power supply, conduct a trial run first, check the operation of the air compressor (23), and observe whether the blowing pressure gauge (25) can reach 0.3 MPa; after the trial run is normal, the first blowing pipe (21) is passed through the sealing plug (12) and then extended into the small duct (1). The first blowing pipe (21) is clamped into the middle of the small duct (1) by the positioning ring (24), and the sealing plug (12) is fixed to the tail end of the small duct (1) and filled tightly. Then, the second blowing pipe (22) is connected to the first blowing pipe (21) and the power supply is started. The air compressor (23) is operated, and the air pressure is maintained at 0.3 MPa. The worker pulls the small duct (1) back and forth to form a hole at the marked position of the tunnel vault. Repeat the above operation until the hole that meets the design requirements is completed, then stop the air supply, and pull the first blowing pipe (21) out of the small duct (1); repeat the above operation to form holes for the remaining marked points in turn; Step 6, grouting: assemble the grouting assembly (3), conduct a water test before grouting to ensure that the pipeline is unobstructed and check the sealing performance; first install the sealing plug (12) on the grouting nozzle (31), then insert the grouting nozzle (31) into the small conduit (1) and start grouting, control the grouting pressure at 0.2-0.5 MPa, and when the small conduit (1) is filled with slurry, perform a pressure stabilization operation to maintain the grouting pressure at 0.5 MPa, stabilize the pressure for a period of time, and stop grouting in the hole after ensuring the penetration range of the slurry; repeat the above operation and grout the remaining holes in turn; Step seven, strength test: when the slurry solidifies, core sampling is carried out on the consolidated body, and a compressive strength test is performed. If the strength is not less than 0.6MPa, it is qualified; if the strength is less than 0.6MPa, more drilling and grouting are carried out on the tunnel vault until the strength of the sample meets the design requirements.

2. The construction method of the advanced small-pipe grouting device according to claim 1, characterized in that: A reinforcement ring (13) is provided at the front end opening of the small catheter (1), and the reinforcement ring (13) is fixedly arranged at the periphery of the opening, and is used to enhance the structural stability of the front end opening of the small catheter (1).

3. The construction method of the advanced small-pipe grouting device according to claim 1, characterized in that: The positioning ring (24) comprises a ring portion (241), a connecting rib (242) and a hoop (243); the ring portion (241) is sleeved on the outer side surface of the first blowing pipe (21), and the inner circle of the ring portion (241) is provided with a connecting rib (242); there are two connecting ribs (242), which are distributed at both ends of the inner circle diameter of the ring portion (241) and are perpendicular to the ring portion (241), and the inner side of the connecting rib (242) is arranged in contact with the outer side surface of the first blowing pipe (21); the hoop (243) is arranged on the outer side of the connecting rib (242) to clamp the connecting rib (242) and the first blowing pipe (21).

4. The construction method of the advanced small-pipe grouting device according to claim 1, characterized in that: A handle (14) is provided on the outer side of the bottom of the small conduit (1) for workers to hold and grasp.

5. The construction method of the advanced small-pipe grouting device according to claim 1, characterized in that: It also includes leakage protector and overload protector.

6. The construction method of the advanced small-pipe grouting device according to claim 1, characterized in that: The grouting nozzle (31) comprises a conical head (311), a reducing neck (312), a valve (313) and a connecting pipe (314); the conical head (311) is arranged through the sealing plug (12), the reducing neck (312) is clamped at the central opening of the sealing plug (12), the valve (313) is arranged at the rear end of the reducing neck (312), and the connecting pipe (314) is arranged at the rear end of the valve (313), and the connecting pipe (314) is used to connect the grouting pipe (32).

7. The construction method of the advanced small-pipe grouting device according to claim 1, characterized in that: In step one, after sampling the stratum, BIM modeling is performed based on the collected data to simulate the stratum structure. The grouting strengthening process is simulated by changing the stratum parameters, and the effects of drilling depth, drilling angle, drilling density and grouting amount on the stratum strength are tested to obtain the optimal drilling depth, drilling angle, drilling density and grouting amount.

8. The construction method of the advanced small-pipe grouting device according to claim 7, characterized in that: In step 1, the relevant construction parameters are the length of the small conduit (1), the angle between the small conduit (1) and the tunnel vault, the distribution spacing of the holes, the number of holes arranged, and the grouting pressure stabilization time.

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