A pre-buried guide pipe assembly and pre-buried method for tunnel curtain grouting suitable for ultra-high water pressure

Abstract

The present invention discloses a pre-embedded guide pipe assembly and pre-embedded method suitable for tunnel curtain grouting with ultra-high water pressure, using a pre-embedded guide pipe and a pipe head; the pre-embedded guide pipe includes a pipe body, a pipe tail, a pipe cap and a filling bag, the pipe body and the pipe tail are threadedly connected, both are steel pipes, and a filling bag is filled in the connecting guide pipe between the pipe body and the pipe tail, and the filling bag is a rubber bag, and its length is the same as the sum of the lengths of the pipe body and the pipe tail; when pouring the grouting wall, the pipe cap is sleeved on the head end of the pipe body to protect the external thread of the head end of the pipe body; when grouting, the pipe cap is removed; the pipe head, when grouting, the tail end of the pipe head is threadedly connected to the head end of the pipe body; the head end is used to connect with the grouting pipe. Using this pre-embedded method, in the construction of tunnel curtain grouting, a pre-embedded guide pipe assembled in sections is designed, pre-embedded in the grouting wall for integral casting, avoiding the cumbersome positioning and opening work in conventional curtain grouting construction, and avoiding damage to the grouting wall.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel grouting reinforcement, and in particular relates to a pre-buried guide pipe assembly and a pre-buried method suitable for tunnel curtain grouting under ultra-high water pressure. Background Art

[0002] The depth and length of tunnels are increasing, and tunnels face the problems of high water pressure and large water output during construction. In conventional tunnel curtain grouting construction, after the grouting wall is constructed, it is first necessary to design and install the guide pipe according to the grouting plan. After drilling the hole in the grouting wall, insert the guide pipe, fill the gap between the guide pipe and the drill hole with hemp, cement, anchoring agent, etc., and after the guide pipe is firmly installed, start drilling and grouting along the guide pipe. There are three problems in the process of constructing the guide pipe: First, the number of holes required for tunnel curtain grouting is large. According to the size of the tunnel section and the surrounding rock conditions, the number of holes in the grouting scheme can reach 60-150, and the position and spatial angle of each hole are different. When the drill rig initially opens holes in the stop wall to install the guide pipe, it is necessary to use a compass and a ruler to repeatedly move the position and adjust the angle, which takes a long time and there are positioning deviations; second, the dense drilling of holes in the stop wall causes great damage to the wall, and the subsequent grouting process is prone to cracking and leakage of the stop wall; third, grouting in high-water-pressure formations, the grouting pressure is higher. In order to ensure the anchoring strength of the guide pipe and prevent it from flying out during the grouting process, the length of the guide pipe needs to be greatly increased, which brings great inconvenience to the construction and also causes waste of materials. For example, the water pressure is 20MPa, the grouting pressure is 30MPa, and the anchoring length of the guide pipe needs to be greater than 8m; while for conventional grouting, the grouting pressure is 0.5-2.5MPa, and the anchoring length of the guide pipe is 0.5-2.0m.

[0003] Therefore, a feasible method for pre-embedding guide tubes for tunnel curtain grouting is needed to avoid the tediousness and errors of subsequent drilling positioning work, ensure the overall strength of the grouting wall, and ensure that the guide tubes have sufficient anchoring strength to withstand extremely high grouting pressures. This also saves guide tube steel and improves recycling rates. Summary of the invention

[0004] The purpose of the present invention is to provide a pre-embedded guide pipe assembly and pre-embedding method suitable for tunnel curtain grouting with ultra-high water pressure. In the tunnel curtain grouting construction, a pre-embedded guide pipe assembled in sections is designed and embedded in a grouting-stopping wall for integral casting, thereby avoiding the tedious positioning and hole-opening work in conventional curtain grouting construction, and avoiding damage to the grouting-stopping wall, thereby ensuring sufficient anchoring strength of the pre-embedded guide pipe.

[0005] The present invention adopts the following technical solutions: A method for pre-embedding a pre-embedded guide pipe assembly suitable for tunnel curtain grouting with extremely high water pressure, characterized in that a pre-embedded guide pipe and a pipe head are used;

[0006] The embedded guide pipe includes a pipe body, a pipe tail, a pipe cap and a filling bag. The pipe body and the pipe tail are threadedly connected. Both are steel pipes. A filling bag is filled in the connecting guide pipe between the pipe body and the pipe tail. The filling bag is a rubber bag that can be injected or discharged with air. The length of the filling bag is the same as the sum of the lengths of the pipe body and the pipe tail. When pouring the grout-stopping wall, the pipe cap is sleeved on the head end of the pipe body to protect the external thread of the head end of the pipe body. When grouting, the pipe cap is removed.

[0007] The pipe head is a seamless steel pipe. During grouting, the tail end of the pipe head is threadedly connected to the head end of the pipe body; the head end is used to connect to the grouting pipe;

[0008] The pre-embedding method is as follows:

[0009] Step 1: In the excavated tunnel, a casting template is erected layer by layer from bottom to top behind the excavation surface, a cavity to be cast is formed between the casting template and the excavation surface, and a steel grid is arranged in the cavity to be cast and close to the excavation surface. The steel grid is parallel to the excavation surface and has the same shape as the excavation surface;

[0010] Step 2: a plurality of horizontal nozzle positioning strips are arranged on the inner side of each layer of casting template, each nozzle positioning strip is perpendicular to the corresponding casting template; each nozzle positioning strip is located on the extension line of the corresponding orifice passing through the grouting hole;

[0011] Step 3: From top to bottom, bury the pre-buried guide pipes in layers; in each layer, place the pipe cap end of the pre-buried guide pipe on the corresponding pipe opening positioning strip, and according to the spatial angle of each grouting hole, place the pipe tail at the far end of the spatial angle for grouting into the tunnel curtain; and the pipe tail is fixed on the steel grid;

[0012] Step 4: Casting the slurry-stopping wall. Pour concrete into the cavity to be cast through the holes on the casting template. The concrete wraps the embedded guide pipe to form the slurry-stopping wall. After the concrete hardens, remove the casting template, and the outer end of the pipe opening positioning strip remains on the surface of the slurry-stopping wall.

[0013] Step 5. The position of the pipe mouth positioning strip is the hole mouth position area of ​​the grouting hole. Chisel away the concrete around the hole mouth to expose the pipe cap and remove it, release the air in the filling bag, take it out of the pipe cavity, and tightly connect the pipe head and the head end of the pipe body with threads.

[0014] Furthermore, two positioning whiskers are provided at the end of the pipe tail. Both positioning whiskers are smooth round steel bars, symmetrically welded to the outer wall of the end of the pipe tail, and both are axially arranged along the direction of the pipe tail and extend toward the far end. In step three, the positioning whiskers are bent and welded to the steel grid to bind and fix the pipe tail to the steel grid.

[0015] Furthermore, at least three clamp rings are provided at intervals in the middle of the pipe body. The clamp rings are made of plain round steel bars bent into a circular ring shape and welded closely to the pipe body to form a whole, so as to increase the bonding between the pipe body and the poured concrete.

[0016] Furthermore, in step one, before erecting the casting formwork, a trench is dug in the excavated tunnel at the location where the slurry stop wall is pre-installed, and then the casting formwork is erected layer by layer from bottom to top on the outside of the trench away from the excavation surface.

[0017] Furthermore, before step 2, the positions of the grouting holes are designed in a rectangular array on the casting template surface, the terminal hole positions are designed along the shape of the tunnel contour, and the spatial angles of the grouting holes are calculated.

[0018] Furthermore, a flange is welded on the head end of the pipe head, and an internal thread is arranged on the tail end, and the flange end is used to be connected to the grouting pipe.

[0019] The present invention also discloses a pre-buried guide pipe assembly suitable for tunnel curtain grouting with ultra-high water pressure, comprising a pre-buried guide pipe and a pipe head;

[0020] The embedded guide pipe includes a pipe body, a pipe tail, a pipe cap and a filling bag. The pipe body and the pipe tail are threadedly connected. Both are steel pipes. A filling bag is filled in the connecting guide pipe between the pipe body and the pipe tail. The filling bag is a rubber bag that can be injected or discharged with air. When pouring the grout-stopping wall, the filling bag is inflated. The pipe cap is sleeved on the head end of the pipe body to seal the pipe body. When grouting, the pipe cap is removed.

[0021] The pipe head is a seamless steel pipe. During grouting, the tail end of the pipe head is threadedly connected to the head end of the pipe body; the head end of the pipe head is used to connect with the grouting pipe;

[0022] At least three clamps are arranged at intervals in the middle of the pipe body. The clamps are made of round steel bars bent into a ring shape and welded to the pipe body to form a whole. They are used to increase the bonding between the pipe body and the poured concrete.

[0023] Two positioning whiskers are arranged at the end of the pipe tail. Both positioning whiskers are plain round steel bars, symmetrically welded to the outer wall of the end of the pipe tail, and are axially arranged along the direction of the pipe tail and extend toward the far end.

[0024] The beneficial effects of the present invention are: 1. After the grouting wall is formed by pre-embedding and pouring, the concrete around the pipe opening positioning strip is chiseled off to expose each pipe head, which is used to connect with the grouting pipe, so that the setting of the position and angle of each drilling hole is faster and more accurate. 2. By using the embedded parts as grouting channels and the pipe heads as grouting holes, dense drilling of holes in the grouting wall is avoided, which greatly reduces the damage to the strength of the grouting wall itself. 3. After pre-embedding and pouring, the embedded parts are tightly combined and wrapped with the grouting wall to form a whole, which can withstand extremely high grouting pressure and water pressure. 4. Under extremely high water pressure and extremely high grouting pressure conditions, the length of the pre-embedded guide pipe is much smaller than that of the conventional guide pipe, and most of it can be recycled, saving a large amount of steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a pre-buried guide pipe assembly and a pipe head for tunnel curtain grouting suitable for ultra-high water pressure;

[0026] Figure 2 It is a schematic diagram of the embedded parts of a pre-buried guide pipe assembly suitable for tunnel curtain grouting with extremely high water pressure;

[0027] Figure 3 This is a schematic diagram of the longitudinal section of the tunnel curtain grouting scheme;

[0028] Figure 4 A schematic diagram of the construction method of burying the pre-buried guide pipe assembly for tunnel curtain grouting suitable for ultra-high water pressure;

[0029] Among them: 1. Pipe head; 11. Flange; 2. Pipe body; 21. Clamp ring; 3. Pipe tail; 31. Positioning whisker; 4. Pipe cap; 5. Filling bag; 6. Steel bar grid; 7. Casting template; 8. Pipe mouth positioning strip. DETAILED DESCRIPTION

[0030] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The present invention discloses a method for pre-embedding a pre-embedded guide pipe assembly for tunnel curtain grouting with ultra-high water pressure, which is suitable for situations where poor geology is encountered during tunnel excavation, high-pressure water gushing occurs, endangering construction safety, and systematic advanced curtain grouting construction is required. The construction of the grout-stopping wall and the installation of the guide pipe are the prerequisites for the success or failure of the curtain grouting. The pre-embedded guide pipe and the pipe head 1 are used to clamp the pre-embedded guide pipe in the grout-stopping wall, such as Figure 1 and 2 As shown:

[0032] The embedded guide tube includes a tube body 2, a tube tail 3, a tube cap 4 and a filling bag 5. The tube body 2 and the tube tail 3 are threadedly connected, and both are seamless steel tubes. The diameter of the tube body 2 is slightly smaller than the tube head 1, and both ends are provided with external threads, which match the internal threads of the tube head 1 and the internal threads of the tube tail.

[0033] A filling bag 5 is filled in the connecting guide pipe between the pipe body 2 and the pipe tail 3. The filling bag 5 is a rubber bag that can be injected or discharged with air. When pouring the stop wall, the pipe cap 4 is sleeved on the head end of the pipe body 2 to protect the external thread of the head end of the pipe body 2. When grouting, the pipe cap 4 is removed. The pipe cap 4 is a cylindrical rubber sleeve with one end open and the other end closed. The pipe head 1 is a seamless steel pipe. When grouting, the tail end of the pipe head 1 is threadedly connected with the head end of the pipe body 2. A steel flange 11 is welded to the head end of the pipe head 1, which is used to connect the grouting pipeline in the subsequent grouting operation.

[0034] The above-mentioned filling bag 5 is a long cylindrical shape, and the length of the filling bag 5 is the same as the sum of the lengths of the pipe body 2 and the pipe tail 3; an air port is provided at one end, and it is inflated when inflation is required. After inflation, it is used to occupy the internal space of the connecting guide pipe and is poured into the slurry stop wall together with the embedded guide pipe. When pouring the slurry stop wall, it prevents concrete from entering the pipe tail 3 and the pipe body 2 from the end of the pipe tail 3, saving some concrete materials and reducing some subsequent grouting and drilling workload.

[0035] At least three clamps 21 are arranged at intervals in the middle of the pipe body 2. The clamps 21 are round steel bars bent into a circular ring shape and welded to the pipe body 2 to form a whole, which is used to increase the combination of the pipe body 2 and the poured concrete. Two positioning whiskers 31 are arranged at the end of the pipe tail 3. The two positioning whiskers 31 are round steel bars, symmetrically welded on the outer wall of the end of the pipe tail 3, and are arranged axially along the direction of the pipe tail 3 and extend toward the far end, which are used to bind and fix the pipe tail 3 to the steel grid 6.

[0036] The invention also discloses a pre-buried guide pipe assembly suitable for tunnel curtain grouting with extra-high water pressure, comprising a pre-buried guide pipe and a pipe head 1.

[0037] The embedded guide pipe includes a pipe body 2, a pipe tail 3, a pipe cap 4 and a filling bag 5. The pipe body 2 and the pipe tail 3 are threadedly connected. Both are steel pipes. A filling bag 5 is filled in the connecting guide pipe between the pipe body 2 and the pipe tail 3. The filling bag 5 is a rubber bag that can be injected or discharged with air. When pouring the slurry stop wall, the pipe cap 4 is sleeved on the head end of the pipe body 2 to seal the pipe body 2. When grouting, the pipe cap 4 is removed.

[0038] The pipe head 1 is a seamless steel pipe. During grouting, the tail end of the pipe head 1 is threadedly connected to the head end of the pipe body 2; the head section of the pipe head 1 is used to connect with the grouting pipe.

[0039] At least three clamp rings 21 are arranged at intervals in the middle of the pipe body 2. The clamp rings 21 are made of round steel bars bent into a ring shape and welded tightly against the pipe body 2 to form a whole. The clamp rings 21 are used to increase the bonding between the pipe body 2 and the poured concrete.

[0040] Two positioning whiskers 31 are arranged at the end of the tube tail 3. Both positioning whiskers 31 are plain round steel bars, symmetrically welded to the outer wall of the end of the tube tail 3, and are axially arranged along the direction of the tube tail 3 and extend toward the distal end.

[0041] The pre-embedding method is as follows:

[0042] Step 1: In the excavated tunnel, a casting template 7 is erected layer by layer from bottom to top behind the excavation surface, and a cavity to be cast is formed between the casting template 7 and the excavation surface. A steel mesh 6 is arranged in the cavity to be cast and close to the excavation surface. The steel mesh 6 is parallel to the excavation surface and consistent with its shape; the end of the steel mesh 6 is embedded in the surrounding rock.

[0043] Before erecting the casting template 7, a groove with a depth of about 1m is dug on the ground where the pre-installed slurry stop wall is located in the excavated tunnel, which is used to embed the slurry stop wall into the surrounding rock after pouring. Afterwards, the casting template 7 is erected layer by layer from bottom to top on the outside of the groove far from the excavation surface, which is used for the subsequent casting of the slurry stop wall.

[0044] Step 2: Set a plurality of horizontal nozzle positioning strips 8 on the inner side of the cavity of each layer of casting template 7, and each nozzle positioning strip 8 is perpendicular to the corresponding casting template 7; each nozzle positioning strip 8 is located on the extension line of the corresponding hole through the grouting hole; the nozzle positioning strip 8 is a wooden square strip, and the end is fixed to the casting template 7 with steel nails.

[0045] Step 3: From top to bottom, bury the pre-buried guide pipe in layers; in each layer, place the pipe cap 4 end of the pre-buried guide pipe on the corresponding pipe opening positioning strip 8, and according to the spatial angle of each grouting hole, place the pipe tail 3 at the far end of the spatial angle for grouting into the tunnel curtain; and the positioning bead 31 on the pipe tail 3 is welded to the steel mesh 6. The positioning bead 31 can be easily bent to ensure its overlap with the steel mesh 6.

[0046] Specifically, the pipe cap 4 end of the pre-buried guide pipe is placed at the end of the pipe opening positioning strip 8, and then the pre-buried guide pipe is placed according to the spatial angle of the grouting hole and along the direction of the grouting hole, so that the far end of the pipe tail 3 of the pre-buried guide pipe is located at the entrance of the grouting channel in the curtain, and the pre-buried guide pipe is used as the grouting hole pipe. Figure 3 and 4 shown.

[0047] Step 4, pouring the slurry-stopping wall, pouring concrete into the cavity to be poured through the holes on the casting template 7, the concrete wraps the embedded guide pipe to form a slurry-stopping wall; after the concrete hardens, the casting template 7 is removed, and the outer end of the pipe mouth positioning strip 8 is left on the surface of the slurry-stopping wall; the pipe body 2, the pipe tail 3, the pipe cap 4 and the filling bag 5 are assembled to form an embedded body, which is cast together with the slurry-stopping wall in the casting template 7, avoiding the need to open holes in the template and no longer using the traditional method of grouting by opening holes in the template, thereby ensuring the overall sealing performance of the template.

[0048] Step 5: The position of the pipe opening positioning strip 8 is the opening position area of ​​the grouting hole. The concrete around the opening is chiseled off to expose the pipe cap 4 and remove it. The air in the filling bag 5 is released and taken out from the pipe cavity. The pipe head 1 is tightly connected with the head end of the pipe body 2 by thread. After connection, a complete embedded guide pipe assembly for curtain grouting is formed.

[0049] The embedded guide tube acts as a guide support, providing the drilling direction for the drilling rig. The tube head 1 is used as the inlet end, and the drill rod with a drill bit passes through the tube head 1, the tube body 2 and the tube tail 3 in sequence to drill holes in the designed spatial direction.

[0050] During UHV grouting, the grouting pressure exceeds 5MPa, which places high demands on the anti-cracking performance of the grouting wall itself, and also tests the bonding strength between the guide pipe and the grouting wall.

[0051] The traditional solution is to cast the grouting wall separately, and then according to the curtain grouting design plan, use the total station to determine the hole position on the wall, use the compass and ruler to determine the spatial angle, move the drill repeatedly, and drill all the grouting holes in the grouting wall in sequence, such as drilling 50 to 100 holes in a 100m2 section, with a hole diameter of 16cm, a center distance of 30cm between holes, and a drilling depth that matches the length of the guide tube. This intensive drilling seriously damages the strength of the grouting wall itself, and is prone to cracking and leakage under high-pressure grouting conditions. Water leakage; then insert the guide tube into the hole, fill the gap between the guide tube and the drill hole with cement slurry and hemp, etc., to fix the guide tube. The bonding strength between the guide tube and the stop wall is low. When grouting under extremely high water pressure conditions, the site is often forced to increase the length of the guide tube (6~8 meters) to increase the contact area between the outer wall of the wire tube and the inner wall of the drill hole to prevent the guide tube from being pushed out of the stop wall by high pressure during the grouting process. The long tube has a large weight and requires multiple people to install at high altitude, which is risky and causes serious waste of steel.

[0052] The present invention adopts the design concept of pre-buried guide pipe, which forms a tight whole with the stop wall through pouring, can resist extremely high grouting pressure and water pressure, and avoids cracking of the stop wall and the guide pipe being pushed out by the grouting pressure. At the same time, the length of the pre-buried guide pipe only needs to be about 1 meter, and the pipe body 2 and pipe tail 3 of the split design are adopted, which is convenient for personnel to install.

[0053] After grouting is completed, the pipe head 1 is removed and recycled. The pipe head 1, pipe cap 4, and filling bag 5 can be 100% recycled. The pipe body 2 and pipe tail 3 are designed as separate parts, and the structure is simple and the length is short. After grouting is completed, the probability of deformation and damage during excavation is low, and they can also be recycled repeatedly.

[0054] Before step 2, the opening positions of the grouting holes should be designed in a rectangular array on the 7th surface of the casting template, the final hole positions should be designed along the shape of the tunnel contour, and the spatial angles of each grouting hole should be calculated. The opening positions should be designed in a rectangular array with regular shapes to facilitate the positioning and arrangement of the guide pipes.

Claims

1. A method for pre-embedding a pre-embedded guide pipe assembly for tunnel curtain grouting with ultra-high water pressure, characterized in that: Use pre-buried guide tube and tube head (1); The embedded guide pipe comprises a pipe body (2), a pipe tail (3), a pipe cap (4) and a filling bag (5); the pipe body (2) and the pipe tail (3) are threadedly connected, both of which are steel pipes; a filling bag (5) is filled in the connecting guide pipe between the pipe body (2) and the pipe tail (3); the filling bag (5) is a rubber bag, and air can be injected or discharged; the length of the filling bag (5) is the same as the sum of the lengths of the pipe body (2) and the pipe tail (3); when pouring the grout-stopping wall, the pipe cap (4) is sleeved on the head end of the pipe body (2) to protect the external thread of the head end of the pipe body (2); when grouting, the pipe cap (4) is removed; The pipe head (1) is a seamless steel pipe. During grouting, the tail end of the pipe head (1) is threadedly connected to the head end of the pipe body (2); the head end of the pipe head (1) is used to connect to the grouting pipe; The pre-embedding method is as follows: Step 1: In an excavated tunnel, a casting template (7) is erected layer by layer from bottom to top behind the excavation surface, a cavity to be cast is formed between the casting template (7) and the excavation surface, a steel grid (6) is arranged in the cavity to be cast and close to the excavation surface, the steel grid (6) is parallel to the excavation surface and has the same shape as the excavation surface; the positions of the grouting holes are designed in a rectangular array on the surface of the casting template (7), the terminal hole positions are designed along the shape of the tunnel contour, and the spatial angles of each grouting hole are calculated; Step 2: a plurality of horizontal nozzle positioning strips (8) are arranged on the inner side of each layer of the casting template (7), each nozzle positioning strip (8) is perpendicular to the corresponding casting template (7); each nozzle positioning strip (8) is located on the extension line of the corresponding orifice passing through the grouting hole; Step 3: bury the pre-buried guide pipes in layers from top to bottom; in each layer, place the pipe cap (4) end of the pre-buried guide pipe on the corresponding pipe opening positioning strip (8), and place the pipe tail (3) at the far end of the spatial angle of each grouting hole according to the spatial angle of the hole, so as to be used for grouting into the tunnel curtain; and the pipe tail (3) is fixed on the steel mesh (6); Step 4: Casting the slurry-stopping wall. Concrete is poured into the cavity to be cast through the holes on the casting template (7). The concrete wraps the embedded guide pipe to form the slurry-stopping wall. After the concrete hardens, the casting template (7) is removed. The outer end of the pipe opening positioning strip (8) remains on the surface of the slurry-stopping wall. Step 5: The position of the pipe opening positioning strip (8) is the opening position area of ​​the grouting hole. The concrete around the opening is chiseled off to expose the pipe cap (4) and remove it. The air in the filling bag (5) is released and taken out from the pipe cavity. The pipe head (1) is tightly connected with the head end of the pipe body (2) by threading. At least three clamp rings (21) are arranged at intervals in the middle of the pipe body (2); the clamp rings (21) are made of round steel bars bent into a circular ring shape and welded to the pipe body (2) to form a whole, so as to enhance the bonding between the pipe body (2) and the poured concrete.

2. A method for pre-embedding a pre-embedded guide pipe assembly for tunnel curtain grouting with ultra-high water pressure as claimed in claim 1, characterized in that: Two positioning whiskers (31) are arranged at the end of the tube tail (3), and the two positioning whiskers (31) are both plain round steel bars, symmetrically welded to the outer wall of the end of the tube tail (3), and are both axially arranged along the direction of the tube tail (3) and extend toward the far end; in step three, the positioning whiskers (31) are bent and welded to the steel mesh (6) to bind and fix the tube tail (3) to the steel mesh (6).

3. A method for pre-embedding a pre-embedded guide pipe assembly for tunnel curtain grouting with ultra-high water pressure as claimed in claim 2, characterized in that: In step 1, before erecting the casting formwork (7), a trench is dug in the ground at the location where the pre-installed slurry stop wall is located in the excavated tunnel, and then the casting formwork (7) is erected layer by layer from bottom to top on the outside of the trench away from the excavation surface.

4. A method for pre-embedding a pre-embedded guide pipe assembly for tunnel curtain grouting with ultra-high water pressure as claimed in claim 3, characterized in that: The head end of the pipe head (1) is welded with a flange (11), and the tail end is provided with an internal thread, and the flange end is used to be connected to a grouting pipe.

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