Method for removing H-shaped steel in range of starting portal of rectangular jacking pipe

Abstract

The invention discloses a method for removing H-shaped steel in a range of a rectangular jacking pipe starting portal, which comprises the following steps of: 1) increasing the diameter and the depth of a cement-soil mixing pile during construction of a starting well enclosure structure; (2) before the pipe jacking is started, tunnel portal water exploration is conducted; (3) the distance between the pipe jacking machine and the starting tunnel portal is adjusted, and a working face and a leaking stoppage working space are formed in the tunnel portal; (4) preparing double-liquid slurry and grouting equipment and grouting pipes thereof; 5) pulling out the H-shaped steel; (6) fixing; and (7) the pipe jacking machine starts to enter the hole. The H-shaped steel is removed through a pulling-out method, time can be saved, efficiency can be improved, and it is guaranteed that the pipe jacking machine can be started rapidly. And meanwhile, the whole section steel can be completely recycled without leaving, so that materials can be saved. In addition, the stability of soil on the tunnel face of the tunnel portal is not damaged when the profile steel is pulled out, and construction safety can be guaranteed. In addition, double-liquid slurry is injected into the gap after the profile steel is pulled out, underground water can be rapidly sealed, sudden gushing of the foundation pit is prevented, and construction safety is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of pipe jacking construction, in particular to a method for removing H-shaped steel in the range of a rectangular pipe jacking starting tunnel. Background Art

[0002] Subways are mostly located in densely populated areas, where the surrounding environment is often complex. For example, there are many pipelines and rivers nearby. If the pipelines are located in the tunnel reinforcement area and cannot be cut or modified, the reinforcement effect will be greatly reduced in order to avoid the pipelines. In addition, abundant groundwater will also increase the difficulty of underground project construction, and in severe cases will lead to pipe bursts and instability in the foundation pit.

[0003] The street crossing between the subway station and the entrance and exit is often constructed by the pipe jacking method. The entrance and exit are generally shallow, and the retaining structure usually uses SMW piles. In order to ensure the stability of the soil at the starting and receiving ends of the street crossing when the pipe jacking machine enters and exits the hole, cement soil mixing piles or high-pressure rotary jet piles are often used to reinforce the soil around the hole. If there are pipelines that cannot be cut and modified within the scope of the reinforced soil, it is necessary to avoid the pipeline for reinforcement. At this time, the reinforced soil will not form a whole, and the waterproof effect is poor.

[0004] Before the pipe jacking machine starts at the entrance, the H-shaped steel within the starting tunnel gate must be cut off in advance so that the pipe jacking machine can start smoothly. The common method of removing H-shaped steel is to manually dig out the reinforced soil between the H-shaped steels, and after a certain working surface is available, the steel will be cut and hoisted out. This method has the following disadvantages. First, the construction period is long, and it cannot ensure that the pipe jacking machine can start to enter the tunnel quickly. Second, the internal digging method will destroy the integrity of the reinforced soil. When the reinforcement effect is poor, it will cause water and mud gushing and collapse accidents at the tunnel gate. Third, after the H-shaped steel in the tunnel gate range is cut off, the steel under the tunnel gate will be permanently buried underground, resulting in material waste. At this time, a safe and economical method of removing H-shaped steel in the tunnel gate range is urgently needed. Summary of the invention

[0005] The present invention provides a method for removing H-shaped steel in the range of a rectangular jacking tunnel to solve the technical problems existing in the known technology. The method has high construction efficiency, does not damage the reinforced soil, and does not waste H-shaped steel.

[0006] The technical solution adopted by the present invention to solve the technical problems existing in the known technology is: a method for removing H-shaped steel in the range of the rectangular jacking tunnel, which adopts the following steps: 1) the starting well enclosure structure adopts SMW method piles. When constructing the starting well enclosure structure, the diameter and depth of the cement soil mixing pile are increased to ensure that the H-shaped steel is wrapped by the mixing pile after being inserted into place, and the cement soil mixing pile remains a whole after the H-shaped steel is removed; 2) before the jacking starts, the tunnel gate is probed to determine the reinforcement blind area, and then horizontal injection is used to remove the H-shaped steel. 3) Adjust the distance between the pipe jacking machine and the starting tunnel door to form a working surface and a plugging working space at the tunnel entrance, and enable the pipe jacking machine to quickly push into the starting tunnel door in an emergency and seal the tunnel entrance together with the outermost water-stop curtain; 4) Prepare double-liquid slurry and its filling equipment and grouting pipe; 5) After the grouting slurry in step 2) reaches the designed strength, select an H-shaped steel on one side of the tunnel door for trial pulling. During the trial pulling, observe the working surface to see if there is groundwater gushing out and whether the soil is stable If water gushing or soil collapse occurs, stop pulling out immediately, and continue to reinforce the reinforced soil within the tunnel portal with horizontal grouting, and then conduct trial pulling out again. When there is no water gushing or soil collapse on the working surface during the pulling out process, start pulling out at intervals from the trial pulling out position until all H-shaped steels within the tunnel portal are pulled out. The specific method for pulling out H-shaped steel is as follows: 5.1) Pull out H-shaped steel until the bottom elevation of the steel is 20cm-30cm higher than the bottom of the tunnel portal, and use the grouting pipe to fill the gap left after the H-shaped steel is pulled out with double liquid slurry. , 5.2) Continue to pull out the H-shaped steel until the bottom of the steel is 5-10cm higher than the tunnel gate, 5.3) Use connecting component I to fix the pulled out H-shaped steel on the crown beam of the retaining structure, 5.4) Cut off the H-shaped steel above 50cm above the top of the crown beam of the retaining structure of the starting well; 6) After all the H-shaped steels within the tunnel gate are pulled out, connect all the pulled out H-shaped steels together with connecting component II, and then fix them with the retaining piles outside the tunnel gate; 7) The pipe jacking machine quickly pushes into the tunnel entrance to start.

[0007] In the step 1), the diameter of the cement-soil mixing pile is 250-350 mm greater than the height of the H-shaped steel, and the bottom depth of the cement-soil mixing pile is 800-1000 mm deeper than the H-shaped steel.

[0008] In the step 5), the H-shaped steel to be pulled out is selected from the side with good reinforcement effect, and the H-shaped steel is pulled out in sequence from the end with good reinforcement effect to the end with poor reinforcement effect.

[0009] The advantages and positive effects of the present invention are as follows: the H-shaped steel is removed by pulling out, breaking the traditional tunnel chiseling process, which can save time, improve efficiency, and ensure that the pipe jacking machine can start quickly. At the same time, the entire steel section can be recycled without any residue, which can save materials. In addition, the pulling out of the steel section does not destroy the stability of the soil at the tunnel face, which can ensure construction safety. In addition, injecting double liquid slurry into the gap after the steel section is pulled out can quickly seal the groundwater, prevent sudden surges in the foundation pit, ensure construction safety, and avoid adverse effects on the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A longitudinal section view of the application of the present invention;

[0011] Figure 2 This is a plan view of the application of the present invention.

[0012] In the figure: 1. Reinforcement area, 2. Uncut pipes, 3. Mixing piles, 4. H-shaped steel, 5. Crown beam, 6. Guard piles outside the tunnel portal, 7. Pipe jacking machine, 8. Center cutter head, 9. PVC grouting pipe, 10. Outermost water-stop curtain, 11. Starting tunnel portal, 12. Hydraulic jack. DETAILED DESCRIPTION

[0013] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0014] See also Figure 1 and Figure 2 A method for removing H-shaped steel in the range of a rectangular jacking tunnel portal adopts the following steps:

[0015] 1) The starting well retaining structure adopts SMW method piles. When constructing the starting well retaining structure, the diameter and depth of the mixing pile 3 are increased to ensure that the H-shaped steel 4 is wrapped by the mixing pile 3 after being inserted into place, and the cement soil mixing pile 3 remains a whole after the H-shaped steel 4 is removed.

[0016] For example, the model of the mixing pile 3 in the conventional SMW method pile is 850@600, the H-shaped steel 4 is 700×300×13×24mm, the diameter of the mixing pile 3 is 150mm larger than that of the H-shaped steel 4, and the pile bottom is 500mm deeper than that of the H-shaped steel 4. When the H-shaped steel 4 is inserted into the mixing pile 3 after the construction is completed, due to construction errors, the bottom of the H-shaped steel 4 may be inserted into the outside of the mixing pile 3. After the H-shaped steel 4 is pulled out later, groundwater will gush out along the damaged part of the mixing pile 3 and the gap after the steel 4 is pulled out. Therefore, it is recommended to appropriately increase the diameter and depth of the mixing pile 3 during the SMW method pile construction. In this embodiment, the diameter of the mixing pile 3 is adjusted from 150mm larger than the H-shaped steel 4 to 250-350mm larger, and the depth is adjusted from 500mm deeper than the H-shaped steel 4 at the bottom of the pile to 800-1000mm deep, so as to ensure that after the H-shaped steel 4 is inserted into place, it is still inside the cement soil mixing pile 3 and is wrapped by the mixing pile. After the H-shaped steel 4 is pulled out, the cement soil mixing pile 3 is still a whole, and groundwater will not gush up.

[0017] 2) Before the start of pipe jacking, water detection is carried out at the tunnel entrance to determine the blind area for reinforcement, and then the blind area for reinforcement is reinforced by grouting using the horizontal grouting method.

[0018] In this embodiment, there are uncut pipes 2 within the starting reinforcement area 1, resulting in poor reinforcement effect of the reinforcement area 1. In order to improve the reinforcement effect of the reinforcement area 1 and ensure the safety of the pipe jacking machine 7 at the start, horizontal grouting is used within the starting tunnel gate 11 to reinforce the area with poor reinforcement effect.

[0019] 3) Adjust the distance between the pipe jacking machine 7 and the starting tunnel door 11 to form a working surface and a plugging working space at the tunnel opening, and at the same time enable the pipe jacking machine 7 to quickly push into the starting tunnel door 11 in an emergency and seal the tunnel opening together with the outermost water-stop curtain 10.

[0020] Specifically, the hydraulic jack 12 pushes the pipe jacking machine 7 so that its center cutter head 8 is about 1.2m away from the starting tunnel gate 11, and the center cutter head 8 is about 20cm away from the outermost water-stop curtain 10. This distance can firstly ensure the working space for the plugging personnel, and secondly, in case of an emergency, the pipe jacking machine 7 can be quickly pushed into the starting tunnel gate 11, so that the outermost curtain 10 can stop water and mud, thereby reducing construction risks.

[0021] 4) Prepare double liquid slurry, its filling equipment and grouting pipe.

[0022] Specifically, a double-liquid grouting machine is prepared, the grouting pipeline is connected, and a disposable grouting pipe 9 is connected at the end of the grouting pipeline. The grouting pipe 9 adopts a PVC pipe with certain flexibility and certain rigidity. At the same time, the double-liquid grout is prepared so that after the H-shaped steel 4 is pulled out, vertical grouting can be carried out in time in the pulled-out gap to block the groundwater and prevent the groundwater from rising. A cover is set at the bottom of the grouting pipe 9 to prevent blockage during the insertion process, and it is opened later by the grouting pressure to realize grouting.

[0023] 5) After the grouting slurry in step 2) reaches the design strength, select an H-shaped steel on one side of the tunnel portal for trial pulling. During the trial pulling, observe the working surface to see if there is groundwater gushing out and whether the soil is stable. If water gushing out or soil collapse occurs, stop pulling out immediately, and continue to perform horizontal grouting reinforcement on the reinforced soil within the tunnel portal range, and then conduct trial pulling out again. If there is no water gushing out or soil collapse on the working surface during the pulling out process, start pulling out at intervals from the trial pulling position until all H-shaped steels within the tunnel portal range are pulled out;

[0024] The specific removal method of H-beam is as follows:

[0025] 5.1) Pull out the H-shaped steel until the bottom elevation of the steel is 20cm-30cm higher than the bottom of the tunnel. Use the grouting pipe to fill the gap left after the H-shaped steel is pulled out with double liquid slurry.

[0026] 5.2) Continue to pull out the H-shaped steel until the bottom of the steel is 5-10cm higher than the tunnel door.

[0027] 5.3) Use connecting member I to fix the pulled-up H-shaped steel 4 on the crown beam 5 of the starting shaft enclosure structure.

[0028] 5.4) Cut off the H-shaped steel over 50cm above the top of the crown beam 5 of the starting well enclosure structure;

[0029] 6) After all H-shaped steels 4 within the scope of the tunnel are pulled up, all the pulled-up H-shaped steels are connected together using connecting members II, and then fixedly connected to the retaining piles 6 outside the scope of the tunnel;

[0030] 7) The pipe jacking machine quickly pushes into the hole and starts construction.

[0031] The H-shaped steel to be pulled out is selected from the side with good reinforcement effect. The H-shaped steel is pulled out in sequence from the end with good reinforcement effect to the end with poor reinforcement effect. Figure 2 The H-shaped steels 4 are removed in sequence from the west end with good reinforcement to the east end with poor reinforcement until all the H-shaped steels 4 within the range of the starting tunnel gate 11 are removed, which ensures good safety.

[0032] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many forms without departing from the scope of protection of the present invention and the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for removing H-shaped steel in the range of a rectangular jacking tunnel, characterized in that: Use the following steps: 1) The starting well retaining structure adopts SMW method piles. When constructing the starting well retaining structure, the diameter and depth of the cement soil mixing piles are increased to ensure that the H-shaped steel is wrapped by the mixing piles after being inserted into place, and the cement soil mixing piles remain as a whole after the H-shaped steel is removed; 2) Before the start of pipe jacking, water exploration is carried out at the tunnel entrance to determine the blind area for reinforcement, and then the blind area for reinforcement is reinforced by grouting using the horizontal grouting method; 3) Adjust the distance between the pipe jacking machine and the starting tunnel door to form a working surface and plugging working space at the tunnel entrance, and at the same time enable the pipe jacking machine to quickly push into the starting tunnel door in an emergency and seal the tunnel entrance together with the outermost water-stop curtain; 4) Prepare double-liquid slurry and its grouting equipment and grouting pipe; 5) After the grouting slurry in step 2) reaches the design strength, select an H-shaped steel on one side of the tunnel portal for trial pulling. During the trial pulling, observe the working surface to see if there is groundwater gushing out and whether the soil is stable. If water gushing out or soil collapse occurs, stop pulling out immediately, and continue to perform horizontal grouting reinforcement on the reinforced soil within the tunnel portal range, and then conduct trial pulling out again. If there is no water gushing out or soil collapse on the working surface during the pulling out process, start pulling out at intervals from the trial pulling position until all H-shaped steels within the tunnel portal range are pulled out; The specific removal method of H-beam is as follows: 5.1) Pull out the H-shaped steel until the bottom elevation of the steel is 20cm-30cm higher than the bottom of the tunnel. Use the grouting pipe to fill the gap left after the H-shaped steel is pulled out with double liquid slurry. 5.2) Continue to pull out the H-shaped steel until the bottom of the steel is 5-10cm higher than the tunnel door. 5.3) Use connecting member I to fix the pulled-up H-shaped steel on the crown beam of the enclosure structure. 5.4) Cut off the H-shaped steel more than 50cm above the top of the crown beam of the starting well enclosure structure; 6) After all H-shaped steels within the scope of the portal are pulled out, all the pulled out H-shaped steels are connected together using connecting member II, and then fixedly connected with the retaining piles outside the scope of the portal; 7) The pipe jacking machine quickly pushes into the hole and starts construction.

2. The method for removing H-shaped steel in the range of the rectangular jacking tunnel according to claim 1 is characterized in that: In the step 1), the diameter of the cement-soil mixing pile is 250-350 mm greater than the height of the H-shaped steel, and the bottom depth of the cement-soil mixing pile is 800-1000 mm deeper than the H-shaped steel.

3. The method for removing H-shaped steel in the range of the rectangular jacking tunnel according to claim 1 is characterized in that: In the step 5), the H-shaped steel to be pulled out is selected from the side with good reinforcement effect, and the H-shaped steel is pulled out in sequence from the end with good reinforcement effect to the end with poor reinforcement effect.

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