Construction method for pipe blocking treatment of underwater concrete guide pipe

Abstract

The invention discloses a construction method for underwater concrete guide pipe blocking treatment, which comprises the following steps: S1, after an underwater concrete guide pipe is blocked, the blocked concrete guide pipe is pulled out; s2, after the blocked concrete guide pipe is pulled out, all-casing-pipe rotation equipment is adopted for drilling into the steel sleeve; the guide pipe is lowered for the second time under the protection of the steel sleeve, the elevation is measured after the guide pipe is lowered to the bottom of the steel sleeve, and concrete pouring is conducted after the set requirement is met; s4, the steel sleeve is dismantled, specifically, the steel sleeve is dismantled when it is measured that the concrete surface on the periphery of the steel sleeve ascends after the concrete poured through secondary lowering of the guide pipe is smoothly poured; and S5, normally pouring concrete. The construction method for pipe blocking treatment of the underwater concrete guide pipe is convenient to operate, has no influence on the lowered reinforcement cage, can prevent slurry and sediment on the surface of the concrete from being added into the concrete during secondary concrete pouring, improves the pouring quality of a drilled pile or an underground diaphragm wall, and can guarantee the safety in the excavation process of foundation pit engineering.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit engineering, and in particular to a construction method for treating underwater concrete conduit pipe blockage. Background Art

[0002] Foundation pit support is a temporary measure of support, reinforcement, protection and groundwater control for the foundation pit to protect the safety of the underground main structure construction and the surrounding environment of the foundation pit. Whether to use a support structure for foundation pit excavation and what kind of support structure to use should be determined through a comprehensive analysis of economy, technology and environment based on the surrounding environment of the foundation pit, the excavation depth of the foundation pit, engineering geology and hydrogeology conditions, construction conditions, construction season, regional engineering experience, etc. In foundation pit projects with high groundwater levels, poor stratum conditions and large excavation depths, support structures such as bored cast-in-place piles, underground continuous walls and interlocking cast-in-place piles are often used.

[0003] As bored piles or ground-anchored walls commonly used in foundation pit projects, as a retaining structure, they need to bear the water and soil pressure outside the foundation pit. The flexural stiffness of their structure is crucial to controlling the deformation of the foundation pit. Therefore, their structure is required to ensure the uniformity and continuity of the concrete.

[0004] During the pouring of bored piles or ground-connected wall concrete, due to the water and soil pressure around the hole wall or slot wall, it is often necessary to use mud wall protection to ensure the stability of the hole wall or slot wall during the hole forming process. The underwater pouring method is used when pouring bored piles or ground-connected wall concrete. During the mud wall protection process, due to changes in the surrounding ground construction load, the collision of the steel cage hoisting with the hole wall or slot wall, and the collapse of the soil around the hole wall or slot wall, the soil around the hole wall or slot wall often collapses and enters the top surface of the concrete pouring.

[0005] During the concrete pouring process, the one-time pouring of retaining piles or ground-anchored walls requires a large amount of work and a high degree of continuity. It is necessary to ensure that the surrounding concrete tankers are ready for pouring at any time. The concrete inside the concrete tanker will segregate and slump too little due to the long waiting time, resulting in blockage of the concrete conduit during the concrete pouring process.

[0006] When the concrete conduit is blocked due to substandard concrete quality, methods such as vibrating the concrete conduit can be used on site to accelerate the separation of the concrete from the conduit. If the conduit blockage is not improved, the conduit must be pulled out of the concrete pouring surface and cleaned, and the conduit must be lowered a second time and inserted below the concrete pouring surface for concrete pouring. In addition, when the height of the secondary lowered conduit is high, the secondary lowered conduit cannot be accurately inserted into the concrete that has been poured below, and the site can only place the conduit close to the concrete pouring surface and pour it again. In the above method, when the conduit is lowered for the second time, the surface mud of the underwater concrete pouring surface enters the interior of the concrete that has been poured below, which will affect the continuity of the concrete quality.

[0007] In foundation pit engineering, it is necessary to combine the specific location of bored piles or ground-connected walls where pipe blockage occurs, and the stress characteristics of bored piles or ground-connected walls. For areas with large lateral stress, drilling and grouting or adding bored piles and ground-connected walls are often used to reinforce other methods. This method will affect the progress of the site and increase certain safety risks and project investment.

[0008] In the prior art, in order to solve the problem of concrete pouring quality after the conduit is blocked, a Chinese invention patent with publication number CN114875923A discloses a method for secondary insertion of the conduit of a bored pile, in which a solid ball is added to the bottom of the second lowering conduit, and after the second lowering conduit with the solid ball is inserted into the concrete pouring surface, the sealing effect of the solid ball can prevent mud from squeezing into the conduit. When the height of the second lowering conduit is high, the rigidity of the conduit is insufficient, and it is difficult to insert it into the concrete pouring surface again. Moreover, after the lower hemisphere of the solid ball contacts the concrete pouring surface, the mud and sediment on the upper part of the concrete pouring surface will be squeezed into the poured concrete by the solid ball. This method can solve the problem of how to penetrate the poured concrete surface into the second lowering conduit, but the concrete itself still has the problem of partial mud and slag after pouring.

[0009] In addition, the premise of this method is to pour concrete first and then insert the steel cage. When the height of the bored pile is high, the steel cage cannot be inserted smoothly. If the commonly used method of inserting the steel cage first and pouring concrete later is adopted, when the bored pile steel cage is small in size, the solid ball cannot be pulled out of the conduit. Therefore, this method has certain limitations. In order to ensure that the quality of the concrete itself meets the standard after the conduit is blocked, it is necessary to study a construction method for underwater concrete conduit blocking treatment to ensure that the bored pile or ground-connected wall concrete after pouring is uniform and free of mud and slag. Summary of the invention

[0010] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a construction method for underwater concrete conduit blockage treatment. The method is easy to operate and can prevent mud and sediment on the surface of concrete from being added into concrete during secondary pouring of concrete, thereby improving the pouring quality of bored piles or ground-anchored walls and ensuring safety during foundation pit excavation.

[0011] To achieve the above object, the present invention provides a construction method for treating underwater concrete pipe blockage, comprising the following steps:

[0012] S1: Remove the blocked conduit: When the underwater concrete conduit is blocked, remove the blocked concrete conduit;

[0013] S2: Drilling into steel sleeve: After removing the blocked concrete conduit, use the full casing rotation equipment to drill into the steel sleeve;

[0014] S3: Secondary lowering of the conduit: The conduit is lowered for the second time under the protection of the steel sleeve. After it is lowered to the bottom of the steel sleeve, the elevation is measured. After it reaches the set requirements, concrete pouring is carried out;

[0015] S4: Removal of steel sleeve: After the concrete poured by the secondary lowering guide tube is poured smoothly, the steel sleeve is removed when the concrete surface around the steel sleeve rises;

[0016] S5: Concrete pouring: After removing the steel sleeve, pour concrete normally.

[0017] As a preferred embodiment, in step S2, before the full casing rotation equipment drills into the steel sleeve, the steel cage is accurately laid out, and after the full casing rotation equipment is installed, the verticality of the steel sleeve is measured to meet the set requirements, and then the steel sleeve is gradually lowered.

[0018] As a preferred embodiment, in step S2, the verticality of the steel sleeve is not less than 1 / 400.

[0019] As a preferred embodiment, in step S2, after the steel sleeve is lowered to the surface of the poured underwater concrete, the underwater concrete at a height of not less than 2m is drilled out, and during the process of drilling out the concrete, the mud in the steel sleeve is replaced with clean water.

[0020] As a preferred implementation, in step S2, the height of the clean water in the steel sleeve should be higher than the surrounding mud.

[0021] As a preferred embodiment, in step S2, the liquid level of the clean water in the steel sleeve is not less than 2m higher than the liquid level of the mud outside the steel sleeve.

[0022] As a preferred embodiment, in step S2, the top height of the steel sleeve is 0.5-1.0 m above the ground.

[0023] As a preferred embodiment, in step S3, when pouring concrete begins, the distance from the bottom of the conduit to the completed bored pile or ground-anchored wall pouring surface is 50 to 100 mm.

[0024] As a preferred embodiment, in step S3, the conduit is buried at least 0.8 m below the concrete pouring surface.

[0025] As a preferred implementation, in step S3, the depth of the conduit buried in the concrete is 2 to 6 m.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] Firstly, the method of the present invention is suitable for the construction treatment of secondary lowering of bored piles or ground-anchored walls for concrete pouring. The method is easy to operate and has no effect on the steel cage after the lowering. It can prevent mud and sediment on the surface of concrete from being added to the concrete during the secondary pouring of concrete, thereby improving the pouring quality of bored piles or ground-anchored walls and ensuring safety during the excavation of foundation pit projects.

[0028] Secondly, after the concrete conduit is blocked, the method of the present invention pulls out and cleans the conduit, lowers the steel casing to no less than 2m below the poured concrete surface, removes the floating slurry and sediment on the upper part of the underwater concrete, and excavates the 2m underwater concrete, then lowers the concrete conduit in the steel casing for the second time, thereby achieving the purpose of secondary concrete pouring and ensuring uniform concrete pouring quality of bored piles or ground-anchored wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Sectional layout of underwater concrete conduit plugging for bored pile treatment;

[0030] Figure 2 Plan layout for underwater concrete conduit plugging treatment for bored piles;

[0031] Figure 3 Plan layout of underwater concrete conduit plugging for ground-connected wall treatment;

[0032] In the figure, 1-steel sleeve, 2-secondary lowered conduit, 3-steel cage, 31 main stress-bearing reinforcement, 32 truss reinforcement, 41 poured underwater concrete, 42 secondarily poured underwater concrete, 5-mud sediment on the surface of underwater concrete. DETAILED DESCRIPTION

[0033] The following is a detailed description of the implementation of the present invention in conjunction with the implementation cases, but they do not constitute a limitation of the present invention and are only given as examples. At the same time, the advantages of the present invention will become clearer and easier to understand through the description.

[0034] A construction method for treating underwater concrete conduit blockage of the present invention comprises the following steps:

[0035] S1: When bored piles or ground-anchored walls are blocked, remove the blocked concrete conduit;

[0036] S2: Use full casing rotating equipment to drill into the steel casing 1; use full casing rotating equipment to excavate and accurately avoid the lowered steel cage 3, wherein the steel cage 3 includes main force bars 31 and truss bars 32, to ensure that the verticality of the steel casing is not less than 1 / 400, and the diameter of the steel casing can be determined according to the size of the steel cage and the size of the conduit. After considering the verticality deviation, it is ensured that the steel cage is not touched during the lowering process to facilitate the subsequent lowering of the conduit. Generally, the diameter can be 400-600mm.

[0037] Before the full casing rotary equipment drills into the steel sleeve, the already cast bored piles or ground-anchored wall steel cages need to be accurately laid out. After the equipment is installed, the vertical accuracy of the steel sleeve is measured, and the steel sleeve is gradually lowered. When the steel sleeve is lowered to the surface of the already cast underwater concrete 41, the underwater concrete with a height of not less than 2m is drilled out, and the floating slurry on the upper part of the underwater concrete, the mud sediment on the surface of the underwater concrete 5, and the underwater concrete below 2m are excavated. In the process of drilling and taking concrete, the mud in the steel sleeve is replaced with clean water to avoid mud on the surface of the catheter in the later stage. The height of the clean water in the steel sleeve should be higher than the surrounding mud to ensure that the surrounding mud will not flow into the steel sleeve along the bottom of the steel sleeve. The height of the top of the steel sleeve can be 0.5-1.0m above the ground to ensure the convenience of the secondary lowering of the catheter.

[0038] S3: Secondary lowering of the conduit: The conduit is lowered for the second time under the protection of the steel sleeve. After it is lowered to the bottom of the steel sleeve, the elevation is measured. After reaching the set requirements, concrete pouring is carried out. The underwater concrete poured for the second time is 42 Figure 1 The requirements for bored pile or ground-anchored wall concrete pouring are as follows:

[0039] a. When pouring concrete, the distance from the bottom of the conduit to the completed bored pile or ground-anchored wall pouring surface is 50 to 100 mm.

[0040] b. Use sufficient concrete reserves and bury the conduit at least 0.8m below the concrete pouring surface at one time.

[0041] c. The depth of the conduit buried in concrete is about 2 to 6 meters. It is strictly forbidden to lift the conduit out of the concrete pouring surface.

[0042] d. Continuous construction must be ensured when pouring underwater concrete. The concrete must be workable enough for underwater pouring and can only be poured after passing on-site testing.

[0043] S4: Removal of steel sleeve: After the concrete poured by the secondary lowering guide tube is poured smoothly, when the concrete surface around the steel sleeve rises, the steel sleeve can be removed to avoid burying the steel sleeve in the poured concrete and causing secondary mud inclusion problem;

[0044] Technical parameter requirements for bored piles or ground-anchored wall casting:

[0045] (1) Mud leakage in bored piles or ground-anchored walls should be replenished in time to maintain the required liquid level. The mud quality should be checked regularly and the mud indicators should be adjusted in time.

[0046] (2) When lowering the steel sleeve, avoid collision with the steel cage. After lowering, check the plane, elevation and verticality of the steel sleeve. After the steel sleeve reaches the surface of the poured concrete, it needs to be drilled as soon as possible. After drilling, the steel sleeve should be buried below the concrete surface by no less than 2m.

[0047] (3) After the steel sleeve is measured and qualified, the hole in the steel sleeve is cleaned and the water is replaced. The liquid level in the steel sleeve should always be higher than the liquid level outside the steel sleeve by at least 2m to ensure that the mud outside the steel sleeve does not flow around into the steel sleeve.

[0048] (4) After the inside of the steel sleeve is cleaned, lower the concrete guide tube and pour concrete. Pull out the steel sleeve after measuring that the concrete surface outside the steel sleeve rises.

[0049] S5: After removing the steel sleeve, the subsequent work can be carried out according to the conventional concrete pouring technical requirements.

[0050] The present invention is applicable to the construction treatment of secondary lowering of bored piles or ground-connected walls for concrete pouring. The method is easy to operate, has no effect on the steel cage after lowering, and can prevent mud and sediment on the surface of concrete from being added to the concrete during secondary concrete pouring, thereby improving the pouring quality of bored piles or ground-connected walls and ensuring safety during foundation pit excavation. The present invention can also be applicable to various other working conditions where pipe blockage occurs during underwater concrete pouring, such as the pouring of underwater bottom sealing concrete for caissons.

[0051] The above are only specific embodiments of the present invention. It should be pointed out that any changes or substitutions that can be easily thought of by any technician familiar with the field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention, and the rest not described in detail belong to the prior art.

Claims

1. A construction method for treating underwater concrete conduit blockage, characterized in that: The steps include: S1: Remove the blocked conduit: When the underwater concrete conduit is blocked, remove the blocked concrete conduit; S2: Drilling into steel sleeve: After removing the blocked concrete conduit, use the full casing rotation equipment to drill into the steel sleeve; S3: Secondary lowering of the conduit: The conduit is lowered for the second time under the protection of the steel sleeve. After it is lowered to the bottom of the steel sleeve, the elevation is measured. After it reaches the set requirements, concrete pouring is carried out; S4: Removal of steel sleeve: After the concrete poured by the secondary lowering guide tube is poured smoothly, the steel sleeve is removed when the concrete surface around the steel sleeve rises; S5: Concrete pouring: After removing the steel sleeve, pour concrete normally.

2. The construction method for treating underwater concrete conduit blockage according to claim 1 is characterized in that: In step S2, before the full casing rotating device drills into the steel sleeve, the steel cage is accurately laid out, and after the full casing rotating device is installed and the verticality of the steel sleeve is measured to meet the set requirements, the steel sleeve is gradually lowered.

3. The construction method for treating underwater concrete conduit blockage according to claim 2 is characterized in that: In step S2, the verticality of the steel sleeve is not less than 1 / 400.

4. The construction method for treating underwater concrete conduit blockage according to claim 3 is characterized in that: In step S2, after the steel sleeve is lowered to the surface of the poured underwater concrete, the underwater concrete at a height of not less than 2m is drilled out, and during the process of drilling out the concrete, the mud in the steel sleeve is replaced with clean water.

5. The construction method for treating underwater concrete conduit blockage according to claim 4 is characterized in that: In step S2, the height of the clean water in the steel sleeve should be higher than the surrounding mud.

6. The construction method for treating underwater concrete conduit blockage according to claim 5 is characterized in that: In step S2, the liquid level of the clean water in the steel sleeve is not less than 2m higher than the liquid level of the mud outside the steel sleeve.

7. The construction method for treating underwater concrete conduit blockage according to claim 6 is characterized by: In step S2, the top height of the steel sleeve is 0.5-1.0 m above the ground.

8. The construction method for treating underwater concrete conduit blockage according to any one of claims 1 to 7, characterized in that: In step S3, when pouring concrete begins, the distance from the bottom of the conduit to the completed bored pile or ground-anchored wall pouring surface is 50-100 mm.

9. The construction method for treating underwater concrete conduit blockage according to claim 8, characterized in that: In step S3, the conduit is buried at least 0.8 m below the concrete pouring surface.

10. The construction method for treating underwater concrete conduit blockage according to claim 9, characterized in that: In step S3, the catheter is buried in the concrete to a depth of 2 to 6 m.

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