A slow-bonding prestressed support system and construction method thereof

Abstract

The present invention relates to a slow-bonding prestressed support system and a construction method thereof. The support system comprises support piles, column piles, crown beams and support beams. Slow-bonding prestressed steel strands are placed in the support beams, and a limiting structure is provided at the intersection of the slow-bonding prestressed steel strands. The construction method comprises arranging the slow-bonding prestressed steel strands, pouring concrete, tensioning the slow-bonding prestressed steel strands, and recovering the slow-bonding prestressed steel strands. The slow-bonding prestressed support system of the present invention has the characteristics of pouring first and then tensioning in the post-tensioning method, and also has the characteristics of partially destroying the prestress loss in the pre-tensioning method without affecting the overall prestressing. By placing the slow-bonding prestressed steel strands before pouring the support beams, the gripping force between the slow-bonding prestressed steel strands and the concrete is increased, the purpose of the pre-tensioning method is achieved, the bending and deformation resistance of the entire support system is improved, the number of column piles is reduced, and the span between the column piles is increased. At the same time, it is convenient for rapid excavation of earthwork on site, saving construction time and cost.

Description

Technical Field

[0001] The invention relates to the field of deep foundation pit support, in particular to a slow-bonding prestressed support system and a construction method thereof. Background Art

[0002] When the excavation depth of the foundation pit exceeds 5m, the surrounding environment is complex, and the support form cannot exceed the red line, a reinforced concrete internal support system is usually used. This system mainly transmits the soil pressure generated during the foundation pit excavation process to the opposite support pile body through the concrete internal support beam. Considering the deadweight and safety reasons, the internal support system usually sets a column pile at intervals of about 10-12m for stabilization, which results in too many columns in the entire foundation pit during construction; during the excavation of the foundation pit, the excavator needs to work between the columns. Due to the consideration of the safety protection of the columns, the earthwork is excavated slowly, resulting in a slow construction period. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in order to overcome the deficiencies in the prior art, a slow-bonding prestressed support system and a construction method thereof are provided.

[0004] The technical solution adopted by the present invention is: a slow-bonding prestressed support system, including supporting piles, column piles, crown beams and supporting beams, wherein slow-bonding prestressed steel strands are placed in the supporting beams, and a limiting structure is provided at the intersection of the slow-bonding prestressed steel strands, and the limiting structure includes a limiting block and a limiting steel bar vertically arranged in the limiting block. The reinforced concrete internal support system is combined with the slow-bonding prestressed steel strands to form a slow-bonding prestressed support system, which has the characteristics of post-tensioning method of pouring first and then tensioning (convenient for on-site construction), and the characteristics of pre-tensioning method (the tensioning end does not cause prestress loss due to collision). The limiting structure is set to limit the slow-bonding prestressed steel strands, so that the slow-bonding prestressed steel strands will not be displaced in the left and right and up and down directions during the concrete pouring and tensioning process, thereby ensuring that the expected design prestress requirements are met.

[0005] The limiting steel bars of the limiting structure are arranged in a circular array with the center of the limiting structure as the center. The number of limiting steel bars = 360° / the minimum angle formed at the intersection of the slow-bonding prestressed steel strands. The limiting steel bars arranged in the central circular array make the structure evenly stressed; the spacing a between adjacent limiting steel bars is the outer diameter of the slow-bonding prestressed steel strand, which further ensures that the slow-bonding prestressed steel strand does not move in the left and right and up and down directions during the concrete pouring and tensioning process, thereby ensuring that the expected design prestressing requirements are met. The slow-bonding prestressed steel strands are placed one by one in the channel formed between the limiting steel bars according to the angle required by the design. When placing, ensure that the two ends of the slow-bonding prestressed steel strands are at the same horizontal height to avoid overlapping friction between the slow-bonding prestressed steel strands and cause prestress loss.

[0006] The angle formed at the intersection of the slow-bonding prestressed steel strands is 30°, 45°, 60° or 90°, and the corresponding number of limiting steel bars is 12, 8, 6 or 4, respectively. The distribution position is even, and uneven force or improper arrangement will not occur.

[0007] The support piles are provided with cap beams, and column piles are arranged at the connection between the support beams to form a complete internal support system.

[0008] The limiting structure is fixedly connected to the upper end of the column pile to ensure the stability of the limiting structure, and further ensure that the slow-bonding prestressed steel strand does not move in the left and right and up and down directions during the concrete pouring and tensioning process, thereby ensuring that the expected design prestressing requirements are met.

[0009] The limit blocks include fixed limit blocks fixedly connected to the column piles and movable limit blocks plugged into the limit steel bars, and the fixed limit blocks and the movable limit blocks are adapted to the limit steel bars. The slow-bonding prestressed steel strands are placed in the channel formed by placing them one by one between the limit steel bars at the angle required by the design. When placed, the intersections of the upper and lower slow-bonding prestressed steel strands are separated by movable limit blocks to avoid overlapping friction between the slow-bonding prestressed steel strands and cause prestress loss.

[0010] The single limiting structure includes 1 fixed limiting block and 1-4 movable limiting blocks. Generally, according to design requirements, the number of slow-bonding prestressed steel strands at the intersection does not exceed 4, and excessive stacking will cause loss of prestress.

[0011] The slow-bonding prestressed steel strand is formed by coating the prestressed steel strand with a slow-bonding agent. According to design requirements, within a certain period of time after the slow-bonding prestressed steel strand is tensioned, the slow-bonding agent gradually solidifies and reaches the pre-tensioning strength, ensuring that the prestress is not lost during the construction process.

[0012] A construction method of a slow-bonding prestressed support system comprises the following steps:

[0013] A. Arrangement of slow-bonding prestressed steel strands: Drive support piles and column piles according to design requirements, then fix the limiting structure on the column piles according to the preset angle, and then arrange the slow-bonding prestressed steel strands one by one in the mold while leaving enough length for tensioning at both ends;

[0014] B. Concrete pouring: pour concrete into the mold to make the cap beam and the support beam and cure until the prestressed steel strands can be tensioned and bonded;

[0015] C. Tensioning the slow-bonding prestressed steel strands: Tension the slow-bonding prestressed steel strands to the expected design prestressing requirements, and then carry out foundation pit excavation construction work; during the foundation pit excavation process, the slow-bonding agent quickly plays a curing role, increasing the bond strength between the slow-bonding prestressed steel strands and the concrete, achieving the purpose of the pre-tensioning method. Even if it is partially damaged, it will not affect the overall support system;

[0016] D. Recycling prestressed steel strands: After the foundation pit support is completed, the hot melt method is used to act on the retarding prestressed steel strands to eliminate the bonding force between the prestressed steel strands and the retarding agent, and finally the prestressed steel strands are recycled.

[0017] Compared with the prior art, the present invention has the following advantages: the slow-bonding prestressed support system of the present invention combines the reinforced concrete internal support system with the slow-bonding prestressed steel strand to form a slow-bonding prestressed support system, which has the characteristics of first pouring and then tensioning in the post-tensioning method, which is convenient for on-site construction, and has the characteristics of partial destruction of prestress loss in the pre-tensioning method without affecting the overall prestressing. By embedding the slow-bonding prestressed steel strand before the support beam is poured, the prestress is constructed after it solidifies to reach the design strength. After the prestress is applied, the curing strength of the slow-bonding agent is improved according to the on-site construction time requirements, and the gripping force between the slow-bonding prestressed steel strand and the concrete is increased, so as to achieve the purpose of the pre-tensioning method, improve the bending and deformation resistance of the entire slow-bonding prestressed support system, and do not need to reserve channels, reduce the number of column piles, and increase the span between column piles, so as to facilitate faster excavation of earthwork, save construction time and cost. After the foundation pit support is completed, the hot melt method is used to act on the slow-bonding prestressed steel strand to eliminate the bonding force between the prestressed steel strand and the slow-bonding agent, so as to achieve the effect of easy removal and reuse of the prestressed steel strand. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 The present invention Figure 1 sectional view of

[0020] Figure 3 The present invention Figure 1 The main structural diagram of the limiting structure at A in the middle;

[0021] Figure 4 The present invention Figure 3 A top view of

[0022] Figure 5 The present invention Figure 1 The main structural diagram of the limiting structure at B in the middle;

[0023] Figure 6 The present invention Figure 5 A top view of

[0024] Figure 7 It is a schematic diagram of the reinforced concrete internal support system structure without retarded bond prestressing;

[0025] Figure 8 yes Figure 7 Cross-sectional view of .

[0026] Numbers in the figure: 1. Support piles, 2. Column piles, 3. Crown beam, 4. Support beam, 5. Slow-bonding prestressed steel strand, 6. Limiting structure, 6-1. Limiting block, 6-2. Limiting steel bar, 6-1-1. Fixed limiting block, 6-1-2. Movable limiting block. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0028] Figure 1-Figure 6 A slow-bonding prestressed support system is shown, comprising a supporting pile 1, a column pile 2, a crown beam 3 and a supporting beam 4, wherein a slow-bonding prestressed steel strand 5 is stretched inside the supporting beam 4, and a limiting structure 6 is provided at the intersection of the slow-bonding prestressed steel strand 5, the limiting structure 6 comprising a limiting block 6-1 and a limiting steel bar 6-2 vertically arranged inside the limiting block 6-1.

[0029] The limiting steel bars 6-2 of the limiting structure 6 are arranged in a circular array with the center of the limiting structure 6 as the center, and the number of limiting steel bars 6-2 = 360° / the minimum angle formed at the intersection of the slow-bonding prestressed steel strands 5, and the spacing a between adjacent limiting steel bars 6-2 is the outer diameter of the slow-bonding prestressed steel strands 5. The angle formed at the intersection of the slow-bonding prestressed steel strands 5 is 45° or 90°.

[0030] A cap beam 3 is provided on the support pile 1, and the column pile 2 is provided at the connection between the support beams 4. The limiting structure 6 is fixedly connected to the upper end of the column pile 2. The limiting block 6-1 includes a fixed limiting block 6-1-1 fixedly connected to the column pile 2 and a movable limiting block 6-1-2 plugged into the limiting steel bar 6-2, and the fixed limiting block 6-1-1 and the movable limiting block 6-1-2 are adapted to the limiting steel bar 6-2. A single limiting structure 6 includes 1 fixed limiting block 6-1-1 and 1-4 movable limiting blocks 6-1-2.

[0031] The slow-bonding prestressed steel strand 5 is composed of a prestressed steel strand coated with a slow-bonding agent.

[0032] A construction method of a slow-bonding prestressed support system comprises the following steps:

[0033] A. Arrangement of slow-bonding prestressed steel strands 5: Drive the support piles 1 and column piles 2 according to the design requirements, then fix the limiting structure 6 on the column piles 2 according to the preset angle, and then arrange the slow-bonding prestressed steel strands 5 one by one in the mold while leaving enough length for tensioning at both ends;

[0034] B. Pouring concrete: pouring concrete into the mold to obtain the cap beam 3 and the support beam 4 and curing them until the prestressed steel strands 5 can be tensioned and bonded;

[0035] C. Tensioning the prestressed steel strand 5: tensioning the prestressed steel strand 5 to the expected design prestress requirement, and then carrying out foundation pit excavation construction work;

[0036] D. Recycling the prestressed steel strands: After the foundation pit support is completed, the hot melt method is used to act on the retarding prestressed steel strands 5 to eliminate the bonding force between the prestressed steel strands and the retarding agent, and finally the prestressed steel strands are recycled.

Claims

1. A slow-bonding prestressed support system, characterized in that: The invention comprises a support pile (1), a column pile (2), a cap beam (3) and a support beam (4); a slow-bonding prestressed steel strand (5) is placed in the support beam (4); a limiting structure (6) is provided at the intersection of the slow-bonding prestressed steel strand (5); the limiting structure (6) comprises a limiting block (6-1) and a limiting steel bar (6-2) vertically arranged in the limiting block (6-1); The limiting steel bars (6-2) of the limiting structure (6) are arranged in a circular array with the center of the limiting structure (6) as the center, the number of the limiting steel bars (6-2) = 360° / the minimum angle formed at the intersection of the slow-bonding prestressed steel strands (5), and the spacing a between adjacent limiting steel bars (6-2) is the outer diameter of the slow-bonding prestressed steel strands (5); The angle formed at the intersection of the slow-bonding prestressed steel strands (5) is 30°, 45°, 60° or 90°; The limiting structure (6) is fixedly connected to the upper end of the column pile (2); The limit block (6-1) comprises a fixed limit block (6-1-1) fixedly connected to the column pile (2) and a movable limit block (6-1-2) plugged into the limit steel bar (6-2); the fixed limit block (6-1-1) and the movable limit block (6-1-2) are mutually adapted to the limit steel bar (6-2).

2. The slow-bonding prestressed support system according to claim 1 is characterized in that: The support pile (1) is provided with a cap beam (3), and the column pile (2) is arranged at the connection between the support beams (4).

3. The slow-bonding prestressed support system according to claim 1 is characterized in that: A single limiting structure (6) comprises one fixed limiting block (6-1-1) and 1 to 4 movable limiting blocks (6-1-2).

4. The slow-bonding prestressed support system according to claim 1 is characterized in that: The slow-bonding prestressed steel strand (5) is composed of a prestressed steel strand coated with a slow-bonding agent.

5. The construction method of a slow-bonding prestressed support system according to claim 1, characterized in that: The following steps are involved: A. Arranging the slow-bonding prestressed steel strands (5): driving the support piles (1) and the column piles (2) according to the design requirements, and then fixing the limiting structure (6) on the column piles (2) according to the preset angle, and then arranging the slow-bonding prestressed steel strands (5) one by one in the mold while leaving enough length for tensioning at both ends; B. pouring concrete: pouring concrete into a mold to obtain a cap beam (3) and a support beam (4) and curing them until the prestressed steel strands (5) can be tensioned and bonded; C. tensioning the slow-bonded prestressed steel strand (5): tensioning the slow-bonded prestressed steel strand (5) to the expected design prestress requirement, and then carrying out foundation pit excavation construction work; D. Recovering the prestressed steel strands: After the foundation pit support is completed, the hot melt method is used to act on the retarding prestressed steel strands (5) to eliminate the bonding force between the prestressed steel strands and the retarding agent, and finally the prestressed steel strands are recovered.

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