Construction Method for Positioning Embedded Connecting Devices of Anti-floating Coping Beams of Bored Cast-in-place Piles

Abstract

The present invention discloses a construction method for positioning embedded connectors of anti-floating capping beams of bored cast-in-place piles, comprising the following steps: Step 1, processing of steel reinforcement cages; Step 2, processing of positioning bars for connectors; Step 3, welding and positioning of positioning bars; Step 4, positioning of embedded steel bars and connectors; Step 5, processing, installation and positioning of steel casing; Step 6, forming of bored cast-in-place piles; Step 7, installation of steel reinforcement cages; Step 8, installation of steel bars for anti-floating capping beams. The advantages of the present invention are that it improves the on-site construction accuracy, saves costs and speeds up the construction progress.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction, and particularly relates to a construction method for positioning embedded connectors of anti-floating coping beams of bored cast-in-place piles. Background Art

[0002] At present, many embedded steel bar connectors are adopted in the design of the construction field. Due to the difficult control of construction accuracy in the actual construction process, the position deviation of the embedded connectors is very large, and they cannot be found at all during the later use, so it is necessary to re-adopt the method of implanting steel bars for treatment, which has a large operation difficulty. When drilling the implanting steel bar holes, it is very easy to encounter steel bars and need to re-drill. On the other hand, the quality of the implanted steel bars cannot be guaranteed, and the service life of the implanting glue is relatively short, which cannot meet the durability requirements, resulting in high construction costs and large waste. The cross-section of the bored cast-in-place pile is a circular section. Embedding connectors on the curved section is much more difficult to control the accuracy than the plane control of the diaphragm wall. There are many individual bored cast-in-place piles, and each individual is relatively independent, which is very easy to cause a large elevation deviation of the embedded connectors of adjacent piles. Therefore, it is necessary to study a construction method for coordinated and precise control of the accuracy of embedded connectors and pile positions.

[0003] In the existing publicly disclosed patent application documents, Chinese Patent Application No. CN201810567572.6 discloses a construction method for anti-upward deformation bored cast-in-place piles, which can effectively eliminate the adverse frictional resistance influence of bored cast-in-place piles in the upward deformation area, thereby saving project investment, and includes the following steps: performing construction plane positioning of bored cast-in-place piles on the foundation; constructing the pile holes of bored cast-in-place piles, using slurry for shaft protection until the construction design elevation; manufacturing an outer protection pipe matching the diameter of the bored cast-in-place pile, with the length equal to the depth from the ground to the dividing line of the upward deformation area; covering and fixing a composite geomembrane on the inner wall of the outer protection pipe; pressing the outer protection pipe lined with the composite geomembrane into the pile hole of the bored cast-in-place pile, with the pipe orifice flush with the ground; passing through the outer protection pipe, placing the steel cage of the bored cast-in-place pile in the pile hole; placing a concrete injection pipe at the bottom of the pile hole, injecting concrete from the bottom of the hole, and slowly lifting the concrete injection pipe until the designed pile top elevation.

[0004] Another example is Chinese Patent Application No. CN202210629005.5, which discloses a construction method for bored cast-in-place piles in a tunnel section, characterized by including the following steps:

[0005] Step S1, tunnel reinforcement preparation: arranging monitoring points in the tunnel and performing layout positioning on the area to be reinforced of the foundation soil in the tunnel section;

[0006] Step S2, dividing the reinforced area blocks: dividing the area to be reinforced into multiple reinforced area blocks according to the area of the area to be reinforced and the depth of the foundation soil;

[0007] Step S3: Mark the area of the pile to be drilled: Mark the positions of the bored cast-in-place piles within the area to be reinforced.

[0008] Step S4: MJS reinforcement construction: Carry out MJS reinforcement construction on the areas within multiple reinforcement area blocks where the positions of the bored cast-in-place piles are not marked according to the principle of constructing from deep to shallow and symmetrically and evenly.

[0009] Step S5: Drilling construction with a drilling machine: Use a drilling machine to carry out drilling construction on the marked positions of the bored cast-in-place piles to form cast-in-place pile holes.

[0010] Step S6: Lower the steel reinforcement cage: Vertically hoist the prefabricated steel reinforcement cage into the cast-in-place pile hole and fix it, and a grouting pipe is fixedly arranged on the steel reinforcement cage.

[0011] Step S7: Pour slightly expanded concrete: Pour slightly expanded concrete into the cast-in-place pile hole to form bored cast-in-place piles.

[0012] Step S8: Post-grouting construction: Use the grouting pipe to carry out post-grouting reinforcement construction on the bored cast-in-place piles.

[0013] For another example, Chinese Patent Application No. CN202011230591.3 discloses a construction method for one-time pouring of the static pressure test pile head of a bored cast-in-place pile, which is characterized by including the following steps:

[0014] S1. Install a formed hole steel casing in the already drilled cast-in-place pile hole to prevent the rock and soil around the hole wall of the cast-in-place pile hole from falling into the cast-in-place pile hole and protect the hole wall of the formed hole.

[0015] S2. Design the size of the steel reinforcement cage according to the pile length of the bored cast-in-place pile to ensure that the top surface of the steel reinforcement cage is 50 cm above the ground.

[0016] S3. After the cast-in-place pile hole in step S1 passes the acceptance, install the already designed and fabricated steel reinforcement cage into the cast-in-place pile hole.

[0017] S4. Pour concrete into the cast-in-place pile hole. After the concrete is poured flush with the ground, clean the floating slag.

[0018] S5. Install a pile head steel casing on the ground, and then pull out the formed hole steel casing.

[0019] S6. Continue to pour concrete and vibrate it densely until the top of the pile head steel casing.

[0020] S7. Level the pile head by slurry collection and cure the cast-in-place pile.

[0021] After the curing period ends, use static load test equipment to conduct a static load test on the bored cast-in-place pile to detect the bearing capacity of a single bored cast-in-place pile. A jack is provided at the bottom of the static load test equipment, and the static load test equipment detects the bearing capacity of a single bored cast-in-place pile through the mechanical balance principle of the jack.

[0022] None of the above patent applications have been able to solve the construction process method for the coordinated and precise control of the embedded connector of the anti-floating capping beam of the bored cast-in-place pile and the pile position accuracy in the existing calculation formula. Summary of the Invention

[0023] The purpose of the present invention is to provide a positioning construction method for the embedded connector of the anti-floating capping beam of the bored cast-in-place pile that can overcome the above technical problems.

[0024] The method of the present invention includes the following steps:

[0025] Step 1. Processing of the steel cage: In a digital centralized processing factory, use a rolling cage machine to process the steel cage of the bored cast-in-place pile according to the designed pile length to improve the positioning accuracy of the steel bars in the steel cage;

[0026] Step 2. Processing of the positioning bars for the connector: According to the radius of the bored cast-in-place pile, after deducting the concrete cover thickness + the diameter of the main steel bar, calculate the radius of the semi-circular arc of the positioning bar for the connector, and use a numerical control bending machine to process and bend 2 semi-circular arc positioning bars. The diameter of the positioning bar is φ20 deformed steel bar;

[0027] Step 3. Welding and positioning of the positioning bars: Determine the horizontal position of the connector according to the elevation of the upper and lower layers of steel bars of the anti-floating capping beam, and respectively weld the 2 bent semi-circular arc positioning bars to the inner side of the steel cage. The positioning bars and the main bars are fixed firmly by spot welding. The positioning bars and the embedded connectors are respectively on the same horizontal plane of the two layers of steel bars;

[0028] Step 4. Positioning of the embedded steel bars and the connector:

[0029] Step 4.1. Both layers of embedded steel bars of the capping beam adopt φ32 deformed steel bars, and the embedded length is 35d. One end is threaded externally and connected to an internal thread sleeve with a length of 74 mm, an outer diameter of 47 mm, and an inner diameter of 32 mm;

[0030] Step 4.2. Both ends of the embedded steel bars are bent into 90° right angles with a length of 100 mm. The embedded steel bar with the connector at one end is welded to the semi-circular arc positioning bar. The inner side of the connector is closely attached to the arc positioning bar, and the other end of the embedded steel bar is welded firmly to the main bar;

[0031] Step 4.3: The two layers of embedded steel bars face upward and downward respectively. The first embedded steel bar in each layer is positioned at the middle of the semi-circular arc, that is, in the middle between the two main steel bars. The other four embedded steel bars are evenly distributed on both sides according to the transverse design spacing of the coping beam steel bars and are located in the middle between the other main steel bars, and the direction of the coupler is perpendicular to the central axis of the station;

[0032] Step 4.4: After the coupler is fixed, tighten it with a plastic protective sleeve with external threads, and wrap it with tape for two circles to protect the installed coupler;

[0033] Step 5: Processing, installation and positioning of the steel casing:

[0034] Step 5.1: The steel casing of the bored cast-in-place pile is made of 16 mm thick steel plate and rolled into a shape with a length of 2 - 3 m;

[0035] Step 5.2: The diameter of the steel casing is 100 mm larger than the diameter of the bored cast-in-place pile. The outer sides of both ends of the steel casing are strengthened with the same type of steel plate, and the strengthening range is 200 - 300 mm;

[0036] Step 5.3: Set a steel plate ear plate with a length, width and thickness of 200 mm x 200 mm x 5 mm on the outer side of the upper end of the steel casing. The steel plate ear plate is welded to the reinforcement plate, and a square wood with a size of 150 mm x 200 mm is inserted under the steel plate ear plate to improve the bearing capacity of the steel casing;

[0037] Step 5.4: The steel casing is buried by the total station cross positioning method, and the central positioning deviation is not more than 20 mm. After the buried positioning, backfill the periphery of the casing with medium coarse sand to compact it and control the sinking of the steel casing;

[0038] Step 6: Boring of the bored cast-in-place pile: The bored cast-in-place pile adopts the rotary drilling rig mud retaining wall boring method to ensure the boring quality. After boring, use an ultrasonic detector to detect the boring quality, and the verticality deviation is not more than 1 / 250, and the sediment thickness is not more than 50 mm;

[0039] Step 7: Installation of the steel cage:

[0040] Step 7.1: Use a truck-mounted crane to transport the processed steel cage to the construction site. Weld four lifting bars at the positions of four symmetric main steel bars at the upper end of the steel cage, and the symmetric axis of the lifting bars is the first embedded steel bar coupler;

[0041] Step 7.2: The lifting bar is made of φ16 threaded steel bar welded with a 20 mm thick perforated steel plate. Drill holes for the crossbar on the steel plate. The lifting bar is firmly welded to the main steel bar, and the lap welding length is 5d for double-sided welding and 10d for single-sided welding;

[0042] Step 7.3: During welding, the openings of the two steel plates are relatively parallel to facilitate the passing of the cross arm. Before lowering the reinforcement cage, use a total station to measure and recheck the position and elevation of the steel casing again, and mark the cross axis of the pile shaft with paint on the edge of the steel casing.

[0043] Step 7.4: Lift and lower the reinforcement cage. Install a tooling on the hook that matches the size of the reinforcement cage to lift the reinforcement cage. The tooling is a cross made of welded steel sections. The lifting points of the cross correspond to the four lifting bars to prevent the deformation of the reinforcement cage during hoisting.

[0044] Step 7.5: When lowering the reinforcement cage, align the first embedded steel bar coupler with the point on the side of the cross axis close to the foundation pit and slowly lower the reinforcement cage. When it reaches the designed elevation, use a cross arm to hang the reinforcement cage on the steel casing. Measure and check the elevation of the reinforcement cage again. After rechecking without errors, install the conduit and pour underwater concrete.

[0045] Step 8: Install the anti-floating capping beam steel bars: After the main structure is poured, chisel the protective layer at the position of the embedded coupler of the bored cast-in-place pile, remove the plastic protective sleeve cover with threads, and install the capping beam steel bars.

[0046] The method of the present invention has the following beneficial effects:

[0047] 1. The method of the present invention improves the on-site construction accuracy of the embedded coupler with an arc-shaped cross-section, saves costs, and speeds up the construction progress.

[0048] 2. The method of the present invention ensures the accurate position of the embedded coupler through multi-faceted control of the processing and positioning accuracy of the reinforcement cage, the positioning accuracy of the embedded coupler, and the installation and positioning accuracy of the reinforcement cage. Description of the Drawings

[0049] Figure 1 is a flow schematic diagram of the method of the present invention. Detailed Embodiment

[0050] The following describes the embodiments of the present invention in detail with reference to the drawings. As Figure 1 shown, the method of the present invention

[0051] includes the following steps:

[0052] Step 1: Reinforcement cage processing: In a digital centralized processing plant, use a cage rolling machine to process the bored cast-in-place pile reinforcement cage according to the designed pile length to improve the positioning accuracy of the reinforcement bars in the reinforcement cage.

[0053] Step 2: Processing of the coupler positioning bars: According to the radius of the bored cast-in-place pile, after deducting the concrete protective layer thickness + the diameter of the main reinforcement bars, calculate the radius of the semi-circular arc of the coupler positioning bars, and use a numerical control bending machine to process and bend 2 semi-circular arc positioning bars. The diameter of the positioning bars is φ20 deformed steel bars.

[0054] Step 3. Positioning and welding of positioning bars: Determine the horizontal position of the couplers according to the elevation of the upper and lower layers of steel bars of the anti-floating coping beam. Weld the two bent semi-circular positioning bars to the inner side of the steel cage respectively. The positioning bars and the main bars are fixed firmly by spot welding. The positioning bars and the embedded couplers are on the same horizontal plane of their respective layers of steel bars.

[0055] Step 4. Positioning of embedded steel bars and couplers:

[0056] Step 4.1. The two layers of embedded steel bars of the coping beam are both made of φ32 threaded steel, and the embedded length is 35d. One end is threaded externally and connected to an internal thread sleeve with a length of 74 mm, an outer diameter of 47 mm, and an inner diameter of 32 mm.

[0057] Step 4.2. Bend the two ends of the embedded steel bars into 90° right angles with a length of 100 mm. Weld the embedded steel bar with the coupler at one end to the semi-circular arc-shaped positioning bar. The inner side of the coupler is tightly pressed against the arc-shaped positioning bar. Weld the other end of the embedded steel bar firmly to the main bar.

[0058] Step 4.3. The two layers of embedded steel bars face upward and downward respectively. The first embedded steel bar of each layer is positioned at the middle position of the semi-circular arc, that is, in the middle between the two main bars. The other four embedded steel bars are evenly distributed on both sides according to the transverse design spacing of the coping beam steel bars, in the middle between the other main bars, and the directions of the couplers are all perpendicular to the central axis of the station.

[0059] Step 4.4. After the couplers are fixed, tighten the plastic protective sleeve with an external thread and wrap it with tape for two circles to protect the installed couplers.

[0060] Step 5. Processing, installation and positioning of steel casing:

[0061] Step 5.1. The steel casing of the bored cast-in-place pile is made of 16-mm-thick steel plate and rolled into a length of 2 - 3 m.

[0062] Step 5.2. The diameter of the steel casing is 100 mm larger than the diameter of the bored cast-in-place pile. The outer sides of both ends of the steel casing are strengthened with the same type of steel plate, and the strengthening range is 200 - 300 mm.

[0063] Step 5.3. Set a steel plate ear plate with a length, width and thickness of 200 mm x 200 mm x 5 mm on the outer side of the upper end of the steel casing. The steel plate ear plate is welded to the reinforcement plate, and a square wood with a size of 150 mm x 200 mm is inserted under the steel plate ear plate to improve the bearing capacity of the steel casing.

[0064] Step 5.4. The steel casing is buried by the total station cross positioning method, and the central positioning deviation is not more than 20 mm. After the buried positioning, backfill the sand around the casing with medium coarse sand to compact it and control the sinking of the steel casing.

[0065] Step 6, Bored cast-in-place pile hole formation: The bored cast-in-place pile adopts the rotary drilling rig slurry retaining wall hole formation method to ensure the hole formation quality. After the hole is formed, an ultrasonic detector is used to detect the hole formation quality. The verticality deviation is not more than 1 / 250, and the sediment thickness is not more than 50 mm;

[0066] Step 7, Steel cage installation:

[0067] Step 7.1, Use the truck-mounted crane to transport the processed steel cage to the construction site. Weld four suspension bars at the positions of four symmetric main reinforcements at the upper end of the steel cage. The symmetric axis of the suspension bars is the first embedded steel bar coupler;

[0068] Step 7.2, The suspension bars are welded by φ16 threaded steel bars and 20 mm thick perforated steel plates. Drill holes for the crossbeams on the steel plates. The suspension bars are firmly welded to the main reinforcements. The lap welding length is 5d for double-sided welding and 10d for single-sided welding;

[0069] Step 7.3, During welding, the holes in the two steel plates are relatively parallel to facilitate the passing of the crossbeam. Before the steel cage is lowered, use the total station to measure and recheck the position and elevation of the steel casing again, and mark the pile axis cross line on the edge of the steel casing with paint;

[0070] Step 7.4, Hoist and lower the steel cage. Install a tooling matching the size of the steel cage on the hook to hoist the steel cage. The tooling is a cross made of welded steel sections. The hoisting points of the cross correspond to the four suspension bars to prevent the deformation of the steel cage during hoisting;

[0071] Step 7.5, When the steel cage is lowered, align the first embedded steel bar coupler with the point on the side of the cross axis close to the foundation pit and slowly lower the steel cage. When it reaches the design elevation, use the crossbeam to hang the steel cage on the steel casing. Measure and check the elevation of the steel cage again. After the recheck is correct, install the conduit and pour underwater concrete;

[0072] Step 8, Install the anti-floating capping beam steel bars: After the main structure is poured, chisel off the protective layer at the position of the embedded coupler of the bored cast-in-place pile, remove the plastic protective sleeve cover with screw threads, and install the capping beam steel bars.

[0073] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the scope disclosed by the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. Construction method for positioning embedded connectors of anti - floating coping beams of bored cast - in - place piles, Characterized in that, It includes the following steps: Step 1, Processing of steel reinforcement cages: In a digital centralized processing factory, use a rolling cage machine to process the steel reinforcement cages of bored cast - in - place piles according to the designed pile length to improve the positioning accuracy of the steel bars in the steel reinforcement cages; Step 2, Processing of positioning bars for connectors: According to the radius of the bored cast - in - place pile, after deducting the concrete cover thickness + the diameter of the main steel bars, calculate the radius of the semi - circular arc of the positioning bars for connectors, and use a numerical control bending machine to process and bend 2 semi - circular arc positioning bars. The diameter of the positioning bars is φ20 deformed steel bars; Step 3, Welding and positioning of positioning bars: Determine the horizontal position of the connectors according to the elevation of the upper and lower layers of steel bars of the anti - floating coping beam, and weld the 2 bent semi - circular arc positioning bars to the inner side of the steel reinforcement cage respectively. The positioning bars and the main bars are fixed firmly by spot welding. The positioning bars and the embedded connectors are on the same horizontal plane of their respective two layers of steel bars; Step 4, Positioning of embedded steel bars and connectors; Step 5, Processing, installation and positioning of steel casing; Step 6, Boring of bored cast - in - place piles: The bored cast - in - place piles adopt the rotary drilling rig mud - retaining wall boring method to ensure the boring quality. After boring, use an ultrasonic detector to detect the boring quality. The verticality deviation is not more than 1 / 250, and the sediment thickness is not more than 50mm; Step 7, Installation of steel reinforcement cages; Step 8, Installation of anti - floating coping beam steel bars: After the main structure is poured, chisel off the protective layer at the position of the embedded connector of the bored cast - in - place pile, remove the plastic protective sleeve cover with screw threads, and install the coping beam steel bars.

2. The construction method for positioning embedded connectors of anti - floating coping beams of bored cast - in - place piles according to claim 1, Characterized in that, The said step 4 includes the following steps: Step 4.1, Both layers of embedded steel bars of the coping beam adopt φ32 deformed steel bars, the embedded length is 35d, and one end is threaded externally and connected to an internal thread sleeve with a length of 74mm, an outer diameter of 47mm, and an inner diameter of 32mm; Step 4.2, Bend both ends of the embedded steel bars into 90° right angles with a length of 100mm. Weld the embedded steel bar with the connector at one end to the semi - circular arc positioning bar. The inner side of the connector is closely attached to the arc - shaped positioning bar, and the other end of the embedded steel bar is welded firmly to the main bar; Step 4.3, The two layers of embedded steel bars face upwards and downwards respectively. The first embedded steel bar of each layer is positioned at the middle position of the semi - circular arc, that is, in the middle between two main bars. The other four embedded steel bars are evenly distributed on both sides according to the transverse design spacing of the coping beam steel bars, in the middle between other main bars, and the direction of the connectors is perpendicular to the central axis of the station; Step 4.4, After the connectors are fixed, tighten them with a plastic protective sleeve cover with external screw threads, and wrap them with tape for two circles to protect the installed connectors.

3. The construction method for positioning embedded connectors of anti - floating coping beams of bored cast - in - place piles according to claim 1, Characterized in that, The said step 5 includes the following steps: Step 5.1, The steel casing of the bored cast - in - place pile is made of 16mm thick steel plate and rolled into a length of 2 - 3m; Step 5.2, The diameter of the steel casing is 100mm larger than the diameter of the bored cast - in - place pile. The outer sides of both ends of the steel casing are strengthened with the same type of steel plate, and the strengthening range is 200 - 300mm; Step 5.3: Set steel plate ear plates with a length, width, and thickness of 200 mm x 200 mm x 5 mm on the outer side of the upper end of the steel casing. The steel plate ear plates are welded to the stiffening plate, and a square wood with a size of 150 mm x 200 mm is inserted under the steel plate ear plates to improve the bearing capacity of the steel casing. Step 5.4: The steel casing is buried using the total station cross positioning method, and the central positioning deviation is not more than 20 mm. After the buried positioning, the periphery of the casing is backfilled and compacted with medium-coarse sand to control the sinking of the steel casing.

4. According to the construction method for positioning the pre-embedded connector of the anti-floating capping beam of the bored cast-in-place pile described in claim 1, it is characterized in that the said step 7 includes the following steps: Step 7.1: Use a truck-mounted crane to transport the processed steel cage to the construction site. Weld four suspension bars at the positions of four symmetric main reinforcement bars at the upper end of the steel cage. The symmetric axis of the suspension bars is the first pre-embedded steel bar connector. Step 7.2: The suspension bars are welded by φ16 threaded steel bars and 20 mm thick perforated steel plates. Holes for passing the crossbar are drilled on the steel plates. The suspension bars are firmly welded to the main reinforcement bars. The lap welding length is 5d for double-sided welding and 10d for single-sided welding. Step 7.3: During welding, the holes on the two steel plates are relatively parallel for easy passing of the crossbar. Before lowering the steel cage, use the total station to measure and recheck the position and elevation of the steel casing again, and mark the pile axis cross line with paint on the edge of the steel casing. Step 7.4: Lift and lower the steel cage. Install a tooling matching the size of the steel cage on the hook to lift the steel cage. The tooling is a cross made of welded steel sections. The lifting points of the cross correspond to the four suspension bars to prevent the deformation of the steel cage during the hoisting process. Step 7.5: When lowering the steel cage, align the first pre-embedded steel bar connector with the point on the side of the cross axis close to the foundation pit and slowly lower the steel cage. When it reaches the designed elevation, use a crossbar to hang the steel cage on the steel casing. Measure and check the elevation of the steel cage again. After rechecking and finding no errors, install the conduit and pour underwater concrete.

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