A method for breaking the pile head of a bored cast-in-place pile foundation.

Abstract

A method for breaking the pile head of a bored cast-in-place pile foundation includes the following steps: a) Before the construction of the bored cast-in-place pile, an operable casing door is installed on the pile foundation casing, and a filter screen is fixed inside the casing door; b) The site is leveled, with the site elevation consistent with the elevation of the over-filled portion at the top of the pile foundation, and the casing is embedded in the pile hole; c) After the pile hole is completed, a reinforcing cage is placed in, and the surface of the reinforcing steel bars in the over-filled portion at the top of the pile foundation is coated with anti-rust paint and fitted with a rubber tube; d) A grout channel is excavated at the casing door; e) The casing door is opened, and the over-filled concrete grout above the bottom elevation of the door flows out; f) After the pile body concrete reaches the design strength, the over-filled concrete above the bottom elevation of the door is excavated, and the surface of the pile head is roughened at the same time. This method for breaking the pile head of a bored cast-in-place pile foundation reduces the shaking of the lower pile body during pile head breaking, and the process is simple, time-saving, and labor-saving.

Description

Technical Field

[0001] This invention relates to construction technology for building engineering, and in particular to a method for breaking the pile head of a bored cast-in-place pile foundation. Background Technology

[0002] Drilled pile construction technology is quite common in the construction field. Especially during the construction of drilled piles, due to the presence of a small amount of sediment at the bottom of the pile hole, and the fact that the contact between the mud in the hole and the concrete during pouring can affect the quality of the concrete, in order to ensure the quality of the pile head concrete, the concrete is often poured at least 500mm higher than the designed pile length to fully push out the poor quality concrete. After the concrete hardens later, the part exceeding the designed pile length will be broken up.

[0003] Existing pile head breaking operations are generally carried out after the pile head concrete has reached its design strength. Specialized pile head breaking machines are used for mechanical cutting, supplemented by manual labor. The common problems with these construction processes are that the construction is cumbersome, it is easy to disturb the underlying pile body, and there are certain safety hazards. In addition, the subsequent pile head cleaning requires the assistance of a crane to lift and transfer the cleaned pile head, making the process relatively complicated, labor-intensive, and time-consuming. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a method for breaking the pile head of a bored cast-in-place pile foundation. This method solves the problems mentioned in the background art, such as the cumbersome construction process for breaking the pile head of a bored cast-in-place pile foundation, the easy disturbance to the lower pile body, the potential safety hazards, and the need for a crane to lift and transfer the cleared pile head, which involves numerous, complex, labor-intensive, and time-consuming procedures.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for removing the pile head of a bored cast-in-place pile foundation, comprising the following steps:

[0006] a. Before drilling and grouting pile construction, install an operable casing door on the pile foundation casing, and fix a filter screen inside the casing door;

[0007] b. Level the site, ensuring the site elevation is consistent with the elevation of the over-poured portion at the top of the pile foundation. Embed the casing into the pile hole, ensuring the bottom elevation of the casing is at least 50mm higher than the designed pile top elevation, and the top elevation of the casing is at least 30mm higher than the ground level. After the casing is installed, position the drilling rig and begin drilling the pile hole inside the casing.

[0008] c. After the pile hole is completed, a reinforcing cage is placed in it. The surface of the reinforcing steel in the over-poured part at the top of the pile foundation is coated with anti-rust paint and fitted with a rubber tube. Both ends of the rubber tube are sealed tightly with waterproof sealant to prevent the reinforcing steel in the over-poured part at the top of the pile foundation from rusting.

[0009] d. Begin pile foundation grouting. After the pile foundation concrete is poured, excavate a grout diversion channel at the casing gate.

[0010] e. Open the casing door, and the over-poured concrete cement slurry above the bottom elevation of the door will flow out;

[0011] f. After the concrete of the pile body reaches the design strength, remove the excess concrete above the bottom elevation of the gate, then break the concrete of the reserved protective layer at the bottom of the casing gate, and at the same time roughen the surface of the pile head. Before pouring the upper column and the foundation, remove the rubber tube on the steel bar and scrape off the anti-rust paint.

[0012] Furthermore, in step a, the sides and bottom edge of the filter screen are at least 50mm larger than the corresponding sides and bottom edge of the protective sleeve door.

[0013] Furthermore, in step d, the bottom elevation of the diversion channel is at least 30mm lower than the bottom elevation of the casing door. To ensure that the outflowing mud can be recycled, the bottom slope of the diversion channel is greater than or equal to 5%.

[0014] Furthermore, in step d, the slope of the slurry diversion channel faces the mud collection box, and a layer of plastic sheeting is laid inside the channel as an inner lining to prevent mud from mixing into the soil. The mud collection box is buried at the end of the slurry diversion channel as a mud collection device.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the method for breaking the pile head of a bored cast-in-place pile foundation according to the present invention can reduce the shaking of the lower pile body when breaking the pile head, and the process is simple, time-saving and labor-saving. Attached Figure Description

[0016] Figure 1 A schematic diagram of the casing closing in a method for breaking the pile head of a bored cast-in-place pile foundation according to the present invention;

[0017] Figure 2 A schematic diagram of the casing being opened in a method for breaking the pile head of a bored cast-in-place pile foundation according to the present invention.

[0018] Figure 3 A perspective view of the casing used in a method for breaking the pile head of a bored cast-in-place pile foundation according to the present invention.

[0019] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0020] 1-Casing; 2-Filter screen; 3-Casing door; 4-Insert plate; 5-Design pile top elevation; 6-Door bottom elevation. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] like Figure 1-3 As shown, the present invention provides a method for removing the pile head of a bored cast-in-place pile foundation, the process steps of which include:

[0023] Before the construction of the bored pile, an operable casing gate 3 is installed on the pile casing 1. In this embodiment, the casing gate 3 is 150mm × 150mm in size. A filter screen 2 is installed inside the casing gate 3. The filter screen 2 is welded and fixed to the inner perimeter of the casing gate 3 to filter out the stones inside the concrete, leaving the stones inside the filter screen 2, allowing the grout inside the concrete at the pile head to flow out. In this embodiment, the mesh size is 20mm × 20mm, and the sides and bottom edge of the filter screen 2 are at least 50mm larger than the corresponding sides and bottom edge of the casing gate 3.

[0024] The site is leveled, and the site elevation is consistent with the elevation of the over-grown portion of the pile top. That is, the portion above the designed pile top elevation of 5 is considered the over-grown portion of the pile top. According to the pile position designed in the drawings, the casing 1 is embedded in the pile hole. The bottom elevation of the casing gate 3 is controlled to be at least 50mm higher than the designed pile top elevation of 5; this higher portion serves as a reserved protective layer for the pile foundation. The top elevation of the casing 1 is at least 30mm higher than the ground level to prevent water and soil from flowing into the casing 1 and affecting the pile formation quality. After the casing 1 is embedded, the drilling rig is positioned, and drilling begins inside the casing 1 according to the diameter and depth required by the drawings. In this embodiment, the pile diameter is 1000mm and the depth is 10m.

[0025] After the pile hole is completed, a reinforcing cage is placed in. The surface of the reinforcing steel in the over-poured part at the top of the pile foundation is coated with anti-rust paint and fitted with a rubber tube. The inner diameter of the rubber tube is 10mm larger than the diameter of the reinforcing steel. Both ends of the rubber tube are sealed tightly with waterproof sealant to prevent corrosion of the reinforcing steel in the over-poured part at the top of the pile foundation.

[0026] The pile foundation pouring begins. After the pile foundation concrete is poured, a diversion slurry channel is excavated at the casing gate 3 using a small excavator or manually. In this embodiment, the width of the diversion channel is 400mm, and the bottom elevation of the diversion channel is at least 30mm lower than the bottom elevation 6 of the casing gate 3. To ensure that the outflowing mud can be recycled, the bottom slope of the diversion slurry channel is 5%, and the slope of the diversion slurry channel faces the mud collection box. A layer of plastic sheeting is laid inside the channel as an inner lining to prevent mud from mixing with the soil. A mud collection box is buried at the end of the diversion slurry channel as a mud collection device. The mud collection box has dimensions of 1000mm×1000mm×1000mm and is made of 3mm thick steel plate.

[0027] Pull out the insert plate 4, open the casing 3, and the excess concrete slurry at the bottom elevation 6 will flow out. The flowing slurry enters the slurry collection box through the slurry channel and can be used for material storage areas and for covering and hardening exposed soil where ground hardening is needed. The reserved 50mm excess slurry will not be removed; it will serve as a protective layer to prevent rainwater, dust, and other debris from entering the pile body and affecting the quality of the pile concrete. Due to the outflow of cement slurry, the excess pile head at the bottom elevation 6 will not harden sufficiently, forming gravel particles. Since these gravel particles in the pile hole also serve to protect the lower pile body during hardening and prevent the top of the pile hole from collapsing, they cannot be directly excavated.

[0028] After the pile concrete reaches the design strength, use a hand-held hoe, shovel, or other excavation tools to remove the excess concrete at elevation 6 on the bottom of the gate. At this time, no grout has flowed out from the reserved protective layer at the bottom of the casing gate 3. Use an electric pick to break up this part of the concrete, and at the same time roughen the surface of the pile head, removing the loose stone aggregate and laitance to expose the solid aggregate. Before pouring the upper column and foundation, remove the rubber tubes fitted on the reinforcing bars and scrape off the anti-rust paint.

Claims

1. A method for removing the pile head of a bored cast-in-place pile foundation, characterized in that, Includes the following steps: a. Before the construction of the bored pile, a sluice gate (3) that can be opened and closed is installed on the pile foundation casing (1), and a filter screen (2) is fixedly installed inside the casing gate (3); b. Level the site, and make the site elevation consistent with the elevation of the over-poured part at the top of the pile foundation. Bury the casing (1) into the pile hole, and control the elevation of the bottom of the casing door (3) to be at least 50mm higher than the designed pile top elevation (5), and the elevation of the top of the casing (1) to be at least 30mm higher than the ground. After the casing (1) is buried, the drilling rig is in place and the pile hole is drilled in the casing (1). c. After the pile hole is completed, a reinforcing cage is placed in it. The surface of the reinforcing steel in the over-poured part at the top of the pile foundation is coated with anti-rust paint and fitted with a rubber tube. Both ends of the rubber tube are sealed tightly with waterproof sealant to prevent the reinforcing steel in the over-poured part at the top of the pile foundation from rusting. d. Start the pile foundation pouring. After the pile foundation concrete pouring is completed, excavate the grout diversion channel at the casing gate (3). e. Open the casing door (3), and the excess concrete cement slurry above the bottom elevation (6) of the door flows out; f. After the concrete of the pile body reaches the design strength, the excess concrete above the bottom elevation (6) of the gate is removed. Then, the concrete of the reserved protective layer at the bottom of the casing gate (3) is broken, and the surface of the pile head is roughened at the same time. Before the upper column and the foundation of the pile cap are poured, the rubber tube on the steel bar is removed and the anti-rust paint is scraped off.

2. The method for removing the pile head of a bored cast-in-place pile foundation according to claim 1, characterized in that, The sides and bottom edge of the filter screen (2) in step a are at least 50 mm larger than the sides and bottom edge of the corresponding protective door (3).

3. The method for removing the pile head of a bored cast-in-place pile foundation according to claim 1, characterized in that, In step d, the bottom elevation of the slurry diversion channel is at least 30 mm lower than the bottom elevation (6) of the casing door (3). To ensure that the outflowing slurry can be recycled, the bottom slope of the slurry diversion channel is greater than or equal to 5%.

4. The method for breaking the pile head of a bored cast-in-place pile foundation according to claim 1, characterized in that, In step d, the slope of the slurry diversion channel faces the mud collection box. A layer of plastic sheeting is laid inside the channel as a lining to prevent mud from mixing with the soil. The mud collection box is buried at the end of the slurry diversion channel as a mud collection device.

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