Method for isolating the inner profile steel and concrete of a SMW method pile crown beam

Abstract

The application discloses a kind of SMW method pile crown beam inner section steel and the isolation method of concrete, it is related to pile foundation engineering technical field, the method includes: S1 base surface cleaning, remove the soil and cement paste on the surface of H-shaped steel;S2 isolation sheet prefabrication, select 5mm thick pearl wool, cut the sheet of adaptive section steel and mark the four mark points corresponding to the section steel external corner;S3 wrapping and fixing construction, start from flange plate to fit pearl wool, after mark point is aligned with section steel external corner, it is wrapped with adhesive tape and is dense;S4 pours and forms, utilize the lateral pressure of concrete pouring to make pearl wool fit section steel internal corner, complete isolation.The application can accurately control the size and wrapping positioning of isolation material, solve the problem that section steel internal corner is not dense in traditional process, wrapping difficulty is great, isolation effect is excellent, construction operation is simple, single person can complete operation, greatly improve construction efficiency, while guarantee the structural integrity of crown beam concrete.

Description

Technical Field

[0001] This invention relates to the field of pile foundation construction technology, and more specifically, to a method for isolating the steel structure inside the pile cap beam and the concrete in the SMW method. Background Technology

[0002] SMW (Steel-Modulated Cement-Soil Mixing) piles, also known as steel-cement-soil mixing piles, are widely used in the construction of building foundation pit retaining structures. They have the advantages of fast construction speed and good water-stopping effect. At the same time, the steel inside the pile can be reused, which meets the requirements of green and environmentally friendly construction.

[0003] To ensure the smooth extraction and recovery of the steel sections of SMW method piles after the foundation pit support work is completed, existing technologies typically involve applying a friction-reducing agent to the surface of the steel sections before insertion. For the steel sections within the capping beam area, plastic film or glass wool is used to isolate the steel sections from the concrete. However, existing isolation methods have significant drawbacks: First, the plastic film is too thin and easily damaged during construction, resulting in poor friction-reducing isolation and a high risk of adhesion between the steel sections and concrete, affecting steel recovery. Second, the conventional use of 5mm thick glass wool for wrapping is too thick, making it difficult to bend and wrap, and affecting the integrity of the capping beam concrete structure. Third, the H-section of the steel section has multiple internal and external corners. For ease of operation during on-site construction, the isolation material is often directly wrapped around the steel section with tape, making it impossible to accurately control the size of the isolation material. This easily leads to problems such as the concrete at the internal corners of the H-section not being poured to the edge or being not densely poured, requiring additional grouting work later, making the construction process cumbersome and inefficient. Summary of the Invention

[0004] The purpose of this invention is to solve the problems mentioned in the background art. This invention provides a method for isolating the steel section inside the pile cap beam of the SMW method from the concrete, so as to achieve precise control of the isolation material, improve construction efficiency, and ensure the compactness of the concrete pouring and the isolation effect of the steel section.

[0005] The present invention adopts the following technical solution:

[0006] A method for isolating the internal steel structure and concrete of a pile cap beam using the SMW method includes the following steps:

[0007] S1. Base surface cleaning: After the earthwork excavation of the cap beam is completed, the surface of the H-beam of the SMW method pile is cleaned to remove the mud and cement slurry attached to the surface of the steel.

[0008] S2. Prefabrication of isolation sheet: Select 5mm thick pearl cotton and cut it into pearl cotton sheets with a length that matches the target H-beam cross section and a height that is greater than the design height of the cap beam; mark 4 points along the length of the pearl cotton sheet that correspond one-to-one with the 4 external corner positions of the H-beam cross section;

[0009] S3. Wrapping and fixing construction: Start by attaching the pearl cotton sheet to one side flange of the H-beam. First, fix the overlapping part of the pearl cotton sheet to the flange with tape. Then, align the four marking points with the four external corners of the H-beam section to make the pearl cotton sheet adhere to the outer surface of the H-beam. Wrap the pearl cotton sheet tightly with tape.

[0010] S4. Casting and Shaping: The concrete for the cap beam is poured. The lateral pressure generated during the concrete pouring process is used to make the pearl cotton sheet reserved at the inside corner of the H-beam fit into the inside corner, thus completing the isolation between the steel section and the cap beam concrete.

[0011] Furthermore, in step S2, the target H-beam is an H700×300×13×24 steel, and the length of the cut pearl cotton sheet is 2880mm.

[0012] Furthermore, in step S2, marking points are set sequentially at four positions along the length of the pearl cotton sheet: 300mm, 987mm, 300mm, and 987mm, and a mark is made above and below each point.

[0013] Furthermore, in step S2, the height of the pearl cotton sheet is 50-100mm greater than the designed height of the crown beam.

[0014] Furthermore, based on the changes in the cross-sectional dimensions of the target H-beam, the cutting length of the pearl cotton sheet and the setting position of the marking points are adjusted accordingly; if the density of the inside corner of the H-beam is not good, the reserved length of the pearl cotton sheet in the inside corner groove is increased by 5 to 10 mm.

[0015] Beneficial effects

[0016] This invention uses 5mm thick pearl cotton as the insulating material, which has both good insulating and friction-reducing effects and bendability. Compared with traditional plastic film, it is not easily damaged and has strong insulating stability. Compared with traditional glass wool, it is easier to wrap and will not have an adverse effect on the structural integrity of the cap beam concrete.

[0017] This invention achieves precise positioning during the wrapping process by pre-cutting pearl cotton sheets and accurately setting marking points. At the same time, it pre-reserves the length of pearl cotton for the inside corner groove of the H-beam steel. Combined with the lateral pressure of the concrete pouring, the pearl cotton can be tightly attached to the inside corner. This fundamentally solves the problems of inadequate wrapping at the inside corner and insufficient concrete pouring in traditional processes. It eliminates the need for subsequent grouting operations and simplifies the construction process.

[0018] The construction method of this invention is simple to operate, requires low skill level from construction personnel, and can be completed by a single person, which greatly improves construction efficiency, shortens the construction period of the cap beam, and has low material cost, thus possessing good economic benefits and promotion value. Attached Figure Description

[0019] Figure 1 This is a top view of a cross-section of an H-beam wrapped with pearl cotton, according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the marking points on a pearl cotton sheet according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] This invention discloses a method for isolating the internal steel structure and concrete of the pile cap beam in the SMW method, comprising the following steps:

[0023] S1. Base surface cleaning: After the earthwork excavation of the cap beam is completed, the surface of the H-beam 1 of the SMW method pile is cleaned to remove the mud and cement slurry attached to the surface of the steel.

[0024] Specifically, after the earthwork excavation at the cap beam is completed, a wire brush and clean water are used to thoroughly remove and clean the soil and cement slurry adhering to the surface of the H-beam within the cap beam area, ensuring that the surface of the steel is flat and free of protruding impurities, and avoiding impurities puncturing the pearl cotton and affecting the isolation effect.

[0025] S2. Prefabrication of isolation sheet: Select 5mm thick pearl cotton 2 and cut it to obtain a pearl cotton sheet with a length that matches the target H-beam cross section and a height that is greater than the design height of the cap beam; mark 4 marking points 3 along the length of the pearl cotton sheet, corresponding one-to-one with the 4 external corner positions of the H-beam cross section;

[0026] Specifically, prepare 5mm thick pearl cotton rolls and cut them into pearl cotton sheets 2 with a length of 2880mm. The height of the pearl cotton sheet 2 is 80mm greater than the designed crown beam height to ensure that the entire height range of the crown beam is covered by the isolation material. Along the length of the pearl cotton sheet 2, measure 300mm, 987mm, 300mm, and 987mm in sequence, and mark the upper and lower positions of the four points with a marker pen to form four marking points 3. These four marking points correspond one-to-one with the four external corners of the H700×300×13×24 steel section.

[0027] S3. Wrapping and fixing construction: Start by attaching the pearl cotton sheet 2 to one side flange of the H-beam 1. First, temporarily fix the overlapping part of the pearl cotton sheet 2 and the flange with tape 4. Then, align the four marking points 3 with the four outermost external corners of the flange of the H-beam 1. After alignment, bend the pearl cotton sheet 2 along the outer contour of the steel section and attach it. Finally, use tape 4 to wrap the pearl cotton sheet 2 tightly to prevent the pearl cotton from shifting or curling during the pouring process.

[0028] S4. Casting and Shaping: After the reinforcement of the cap beam is tied and the formwork is supported, the concrete pouring operation of the cap beam is carried out. During the concrete pouring and vibration process, the lateral pressure generated by the concrete will press the pearl cotton sheet 2 reserved in the groove of the H-beam 1 into the inner wall of the corner, so that the pearl cotton and the corner of the steel are tightly attached. This not only achieves full surface isolation between the steel and the concrete, but also ensures that the concrete in the corner can be poured to the edge and formed densely.

[0029] In other alternative embodiments, if other specifications of H-beams are used, the total cutting length of the pearl cotton sheet and the spacing of the marking points are adjusted according to the cross-sectional dimensions of the steel. At the same time, the reserved length of the pearl cotton in the inside corner groove is also adjusted accordingly. If the density of the inside corner is found to be poor after on-site pouring, the reserved length of the pearl cotton at the inside corner can be increased by 5-10mm in subsequent similar constructions to further improve the bonding effect and pouring density.

[0030] Example

[0031] This embodiment is a field engineering application of the above-mentioned isolation method, applied to the foundation pit support construction of the new construction project of plot 25-04, unit JDC11201, in the main urban area of ​​Jiading New City. The foundation pit retaining structure of this project extensively uses SMW method piles, and the steel specifications are H700×300×13×24. The isolation method of this invention is fully adopted in the construction of the capping beam.

[0032] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A method for isolating the internal steel structure and concrete of a pile cap beam in the SMW method, characterized in that: Includes the following steps: S1. Base surface cleaning: After the earthwork excavation of the cap beam is completed, the surface of the H-beam of the SMW method pile is cleaned to remove the mud and cement slurry attached to the surface of the steel. S2. Prefabrication of isolation sheet: Select 5mm thick pearl cotton and cut it into pearl cotton sheets with a length that matches the target H-beam cross section and a height that is greater than the design height of the cap beam; mark 4 points along the length of the pearl cotton sheet that correspond one-to-one with the 4 external corner positions of the H-beam cross section; S3. Wrapping and fixing construction: Start by attaching the pearl cotton sheet to one side flange of the H-beam. First, fix the overlapping part of the pearl cotton sheet to the flange with tape. Then, align the four marking points with the four external corners of the H-beam section to make the pearl cotton sheet adhere to the outer surface of the H-beam. Wrap the pearl cotton sheet tightly with tape. S4. Casting and Shaping: The concrete for the cap beam is poured. The lateral pressure generated during the concrete pouring process is used to make the pearl cotton sheet reserved at the inside corner of the H-beam fit into the inside corner, thus completing the isolation between the steel section and the cap beam concrete.

2. The method for isolating the internal steel structure and concrete of the pile cap beam in the SMW method according to claim 1, characterized in that: In step S2, the target H-beam is H700×300×13×24 steel, and the length of the cut pearl cotton sheet is 2880mm.

3. The method for isolating the internal steel structure and concrete of the pile cap beam in the SMW method according to claim 1, characterized in that: In step S2, marking points are set at four positions along the length of the pearl cotton sheet: 300mm, 987mm, 300mm, and 987mm. Marks are also made above and below each point.

4. The method for isolating the internal steel structure and concrete of the pile cap beam in the SMW method according to claim 1, characterized in that: In step S2, the height of the pearl cotton sheet is 50-100mm greater than the designed height of the crown beam.

5. The method for isolating the internal steel structure and concrete of the pile cap beam in the SMW method according to claim 1, characterized in that: Adjust the cutting length of the pearl cotton sheet and the setting position of the marking point according to the cross-sectional dimensions of the target H-beam; if the density of the inside corner of the H-beam is not good, increase the reserved length of the pearl cotton sheet in the inside corner groove by 5 to 10 mm.

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