Tower crane foundation construction method based on basement floor slab

Abstract

The present application relates to the field of basement construction, and in particular to a tower crane foundation construction method based on a basement floor slab. The tower crane foundation construction method comprises the following steps: determining the position of a tower crane foundation on a floor slab; calculating the bearing capacity of foundation soil under the basement floor slab where the tower crane foundation is located, so as to ensure that the bearing capacity of the foundation soil meets requirements; trimming top steel bars of the floor slab, and connecting the top steel bars of the floor slab to steel bars of the tower crane foundation; performing pouring to form the tower crane foundation; providing jacking mechanisms between the cast tower crane foundation and a structure floor slab; and providing on each jacking mechanism a monitoring mechanism for monitoring changes in stress of the jacking mechanism. By means of trimming steel bars of a floor slab and connecting same to steel bars of a tower crane foundation, providing jacking mechanisms and making same counter-support a structure floor slab, etc., the construction method of the present application prevents eccentric load of a tower crane from damaging a floor slab structure, solves related problems of additionally providing a tower crane when the tower crane cannot be piled after a floor slab structure is completed, ensures construction safety and use stability of an additionally-provided tower crane, and provides a reference for subsequent additional provision of tower cranes in the same type of construction scenes.

Description

A tower crane foundation construction method based on basement floor Technical Field

[0001] The present application relates to the field of basement construction, and in particular to a tower crane foundation construction method based on a basement floor. Background Art

[0002] Tower cranes are the most commonly used lifting equipment on construction sites. They are essential for transporting materials such as steel bars, concrete, and steel pipes. The crane foundation is a crucial component of the crane, supporting and securing the crane and essential for its safe operation.

[0003] Conventional tower crane foundations require piling for the crane or using a lattice column steel platform. After the basement floor is completed, additional tower cranes are needed due to construction deployment adjustments, but piling for the crane is not possible.

[0004] Summary of the Invention

[0005] In order to solve the problem in the prior art that it is impossible to pile for a tower crane after the basement floor is completed, the present application provides a tower crane foundation construction method based on the basement floor.

[0006] The tower crane foundation construction method based on the basement floor provided in this application adopts the following technical solution.

[0007] A tower crane foundation construction method based on a basement floor comprises the following steps:

[0008] Position determination: Determine the position of the tower crane foundation on the base plate;

[0009] Calculation of foundation bearing capacity: Calculate the bearing capacity of the foundation soil under the bottom plate of the tower crane foundation to ensure that the foundation bearing capacity meets the requirements;

[0010] Rebar binding: Bind the steel bars of the tower crane foundation, remove the top steel bars of the bottom plate, and connect the top steel bars of the bottom plate with the steel bars of the tower crane foundation;

[0011] Pouring: pouring concrete to form the tower crane foundation;

[0012] Setting up the top support mechanism: setting up the top support mechanism at the four corners of the tower crane foundation after pouring, and the upper end of the top support mechanism is supported against the structural floor;

[0013] Setting up a monitoring mechanism: A monitoring mechanism is set up on each supporting mechanism, and the monitoring mechanism is used to monitor the stress changes of the supporting mechanism.

[0014] In the above technical solution, firstly, the construction of the tower crane foundation can only be carried out when the bearing capacity of the foundation soil under the basement floor is ensured to meet the requirements through the calculation of the foundation bearing capacity, thereby avoiding the problem of poor stability of the tower crane foundation due to insufficient foundation bearing capacity; secondly, by breaking the top steel bars of the bottom plate and connecting them with the steel bars of the tower crane foundation and by setting a supporting mechanism between the tower crane foundation and the structural floor after pouring, the eccentric bending moment of the tower crane is dispersed, and the eccentric load generated by the eccentric bending moment of the tower crane is avoided from having an adverse effect on the bottom plate structure, thereby improving the stability of the tower crane foundation; by obtaining the force magnitude of each supporting mechanism through the monitoring mechanism, the center of gravity offset amplitude and offset direction of the tower crane can be more conveniently analyzed so that corresponding measures can be taken, which improves the safety of tower crane construction. Through the above construction method, the related problem of adding a tower crane when the bottom plate structure is completed but the tower crane cannot be piled is solved, and the construction safety and stable use of the newly added tower crane are ensured, providing a reference for adding tower cranes in subsequent similar construction scenarios.

[0015] Preferably, in the step of calculating the foundation bearing capacity, when the foundation bearing capacity does not meet the requirements, the size of the tower crane foundation is reduced or a smaller model of tower crane is selected to ensure that the foundation bearing capacity meets the requirements.

[0016] By reducing the size of the tower crane foundation or selecting a smaller tower crane, the calculated bearing capacity of the foundation under the base plate is guaranteed to be qualified and meet the requirements, thereby meeting the construction requirements of the tower crane.

[0017] Preferably, during the steel bar binding step, a hook is welded between the top steel bar of the base plate and the bottom steel bar of the tower crane foundation to achieve connection between the two. The hook is formed by bending round steel, and the hook is welded on both sides, with a welding length of not less than 5d, where d is the diameter of the round steel.

[0018] The connection between the top steel bars of the bottom plate and the bottom steel bars of the tower crane foundation is achieved by double-sided welding of round steel. After the tower crane foundation is poured, the stability of the connection between the tower crane foundation and the bottom plate can be improved, thereby improving the safety of subsequent tower crane operations.

[0019] Preferably, when tying the steel bars of the tower crane foundation, the connecting beam steel bars are pre-embedded, and the connecting beam is cast at the same time as the tower crane foundation is cast with concrete. Both ends of the connecting beam extend out of the tower crane foundation, and the extended ends are respectively anchored into the civil defense walls on both sides.

[0020] By adopting the above technical solution, after the tower crane foundation is poured with concrete, the connecting beam provides support on the left and right sides of the tower crane foundation, further dispersing the eccentric bending moment of the tower crane, avoiding the eccentric load generated by the tower crane bending moment from having an adverse effect on the base plate structure, thereby improving the stability of the tower crane foundation.

[0021] Preferably, before pouring the tower crane foundation with concrete, a casing is embedded in advance, and the casing is used for threading the rope saw.

[0022] By adopting the above technical solution, the rope saw is planned in advance for cutting, the rope saw casing is embedded in advance, and the rope saw is used to cut into blocks when dismantling the tower crane. These blocks are transported out by forklift in a safe and fast manner, avoiding noise pollution and structural damage caused by crushing.

[0023] Preferably, the supporting mechanism includes four steel pipe columns, and embedded plates are arranged at corresponding positions on the tower crane foundation and the structural floor. Each end of each steel pipe column is welded to the corresponding embedded plate, and the outer wall of each steel pipe column is provided with multiple stiffening ribs.

[0024] The jacking mechanism composed of four steel pipe columns has a large bearing capacity and high safety. The stiffening ribs strengthen the connection strength between the steel pipe columns and the embedded plates, thereby improving the overall strength and stability of the jacking mechanism.

[0025] Preferably, the monitoring mechanism is a strain sensor, and the strain sensor is installed on the vertical side wall of the supporting mechanism.

[0026] By adopting the above technical solution, the stress changes in each supporting mechanism are detected by strain sensors. The numerical difference of each strain sensor can be compared to indirectly determine the center of gravity offset of the tower crane, and then the verticality change of the tower crane can be deduced, thereby realizing the detection of the verticality of the tower crane. This makes it more convenient to analyze the center of gravity offset amplitude and offset direction of the tower crane so as to make safety response measures.

[0027] In summary, this application includes at least one of the following beneficial technical effects:

[0028] 1. This construction method disperses the eccentric bending moment of the tower crane by breaking the connection between the bottom plate steel bars and the tower crane foundation and setting up a supporting mechanism to push it back to the structural floor, thereby preventing the eccentric load of the tower crane from damaging the bottom plate structure. It solves the problem of adding a tower crane when it is impossible to pile for the tower crane after the bottom plate structure is completed, ensures the construction safety and stable use of the newly added tower crane, and provides a reference for the subsequent addition of tower cranes in similar construction scenarios.

[0029] 2. Further set up connecting beams to connect to the civil defense walls on both sides, break the connection between the bottom plate steel bars and the tower crane foundation, use welded hooks to connect to the tower crane foundation, and set up a top support mechanism and make it push back to the structural floor to avoid the eccentric load of the tower crane from damaging the bottom plate structure.

[0030] 3. Plan the tower crane foundation dismantling plan in advance, pre-embed the wire saw casing for wire saw cutting, and use the wire saw to cut the tower crane foundation into blocks when dismantling the tower crane. Use a forklift to transport these blocks out safely and quickly, avoiding noise pollution and structural damage caused by crushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a flow chart of a tower crane foundation construction method based on a basement floor according to an embodiment of the present application.

[0032] FIG2 is a schematic structural diagram of a tower crane foundation in an embodiment of the present application.

[0033] FIG3 is an enlarged view of point A in FIG2 .

[0034] FIG4 is a schematic structural diagram of the supporting mechanism in an embodiment of the present application.

[0035] FIG5 is a schematic diagram of the connection relationship between the steel pipe column and the embedded plate in an embodiment of the present application.

[0036] FIG6 is a schematic diagram showing the positional relationship among the tower crane foundation, the connecting beam and the top support mechanism in an embodiment of the present application.

[0037] FIG7 is a schematic diagram of the position of the pre-buried sleeve in an embodiment of the present application.

[0038] FIG8 is a schematic diagram of the tower crane foundation dismantling and transportation route in an embodiment of the present application.

[0039] Explanation of the accompanying symbols: 1. Tower crane foundation; 2. Bottom plate; 3. Support mechanism; 31. Steel pipe column; 32. Stiffening rib; 4. Structural floor; 5. Hook; 6. Connecting beam; 7. Civil defense wall; 8. Casing; 9. Buried plate; 10. Tower crane; 11. Hidden beam; 12. Ramp. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to Figures 1-8.

[0041] The present application discloses a tower crane foundation construction method based on a basement floor. Referring to Figure 1 , the tower crane foundation construction method based on a basement floor primarily includes the following steps: determining the tower crane foundation position; calculating the foundation bearing capacity; tying the steel bars of the crane foundation; pouring the tower crane foundation; setting a top support mechanism to form an inverted structural floor; and setting a monitoring mechanism to monitor stress changes in the top support mechanism.

[0042] Among them, before determining the location of the tower crane foundation, the tower crane selection is also included. The detailed steps of the overall construction of the tower crane foundation are as follows:

[0043] (1) Tower crane selection, positioning and foundation model selection

[0044] Taking the surrounding environment into consideration, the location of the tower crane foundation 1 and the installation height of the tower crane 10 are selected, and the model of the tower crane 10 and the size of the tower crane foundation 1 are determined. The layout of the tower crane 10 is related to the logical relationship of the foundation pit construction.

[0045] Take the basement construction project of a certain building in the city as an example. The top elevation of floor 2 in Area D of this basement construction project is -15.2m, and crane foundation 1 is located on this floor. Because the third basement floor is a civil air defense structure, crane foundation 1 must avoid the vertical structure. There are enclosure supports on the outer perimeter of Area D, and the crane must be positioned away from the existing support beams. The crane layout must meet the construction requirements of the basement and main structure above ground on the west side of Area D. The crane layout should avoid ramps and vertically enclosed structures as much as possible. The crane layout must also consider crane 9 on the east side of Area D, the community hospital, and residential buildings to the north, ensuring safe distances for group crane operations. The maximum height of the kindergarten in Area E is 18.1m, the maximum height of the community buildings in Area D is 24.35m, and the highest point of the community hospital and residential buildings to the north is 24m. The top elevation of the basement floor structure is -15.2m. Therefore, to account for these considerations, crane 10 was initially installed at a height of 45.4m; this can be adjusted based on actual conditions, with a maximum stand-alone height of 51m.

[0046] Therefore, the model of tower crane 10 selected is W6017-8B, with a basic size of 7*7*1.35m and a maximum installation height of 51m.

[0047] (2) Position determination: Since the base plate 2 corresponding to the position of the tower crane foundation 1 has been completed, the plane is laid out according to the positioning diagram and the position of the tower crane foundation 1 is determined on the base plate 2.

[0048] (3) Calculation of foundation bearing capacity: Calculate the bearing capacity of the foundation soil under the garage floor 2 where the tower crane foundation 1 is located to ensure that the foundation bearing capacity meets the requirements;

[0049] The main parameters required for foundation bearing capacity calculation are shown in Table 1 below:

[0050] Table 1

[0051] The main calculation process includes eccentricity verification, foundation bottom surface pressure calculation, foundation axial load stress, and foundation bottom surface pressure verification. For example, the parameters in the table above can be used to calculate:

[0052] Corrected foundation bearing capacity characteristic value: fa = 110.00 kPa,

[0053] Foundation bearing capacity under axial action: Pk=46.858kPa≤fa=110kPa

[0054] The verification results meet the requirements!

[0055] Foundation bearing capacity under eccentric action

[0056] Pkmax=119.209kPa≤1.2fa=1.2×110=132kPa

[0057] The verification results meet the requirements!

[0058] The calculation results are used to determine whether the foundation bearing capacity meets the requirements. Only when the foundation bearing capacity requirements are met can the tower crane foundation 1 be set on the base plate 2. If the requirements are not met, the length, width and height dimensions of the tower crane foundation need to be reduced, or a relatively smaller tower crane model should be selected. The construction of the tower crane foundation can only be carried out after the verification results meet the foundation bearing capacity requirements.

[0059] (4) Rebar binding: measure and lay out the lines, lay out the position lines of the steel bars of the tower crane foundation 1, bind the lower steel bars, bind the upper steel bars, bind the single stirrups, and embed the anchor bolts. Before binding the lower steel bars, partially break the top steel bars of the bottom plate 2 and connect the top steel bars of the bottom plate 2 to the lower steel bars of the tower crane foundation 1. As shown in Figures 2 and 3, the connection between the top steel bars of the bottom plate 2 and the bottom steel bars (i.e., the lower steel bars) of the tower crane foundation 1 is achieved by welding a hook 5 between them. The hook 5 is formed by bending 25 round steel, with a longitudinal and transverse spacing of 540mm. The hook 5 is welded on both sides, and the welding length is not less than 5d, where d is the diameter of the round steel. The purpose of breaking the top steel bars of the bottom plate 2 and connecting the top steel bars of the bottom plate 2 to the lower steel bars of the tower crane foundation 1 is to disperse the eccentric bending moment of the tower crane and avoid the eccentric load generated by the eccentric bending moment of the tower crane from causing adverse effects on the bottom plate structure.

[0060] While tying the tower crane foundation's reinforcement, the reinforcement for coupling beam 6 is pre-embedded. See Figures 2 and 6. Two 400*600mm coupling beams are added in the north-south direction of the tower crane foundation. Coupling beam 6 consists of an upper and lower layer of 4C20 steel bars and C8@200 stirrups. The ends of coupling beam 6 extend beyond the tower crane foundation 1 and are anchored to the civil defense walls 7 on either side. The main body of coupling beam 6 is subsequently cast together with the main body of the tower crane foundation 1. This enhances the stability of the base plate 2 and the crane foundation 2 after the crane foundation is poured, dissipating the crane's eccentric bending moment and preventing the eccentric load generated by the crane's eccentric bending moment from adversely affecting the base plate structure.

[0061] After tying the tower crane foundation steel bars and before pouring concrete, a casing 8 is embedded in advance, as shown in Figure 7. The casing 8 is embedded in the tower crane foundation 1 for threading the rope saw. Later, the tower crane foundation is cut into blocks using the rope saw, and these blocks are transported out of the basement through the ramp using a forklift.

[0062] (5) Casting: Cast concrete to form the tower crane foundation 1, and cast the connecting beam 6 at the same time. The tower crane foundation 1 uses ordinary C35 concrete, with a bottom elevation of -15.2 meters, a foundation height of 1.35 meters, a length of 7 meters and a width of 7 meters. The bottom is a single-layer bidirectional HRB400, C25@200, and the top is a single-layer bidirectional HRB400, C25@200. The vertical reinforcement is HPB300, Φ12@500. The main process is:

[0063] A truck pump is used for pouring. Since the tower crane foundation spans the post-casting strip, the corresponding section of the post-casting strip is poured in advance and constructed according to the sealing requirements of the post-casting strip.

[0064] Vibration should make the concrete dense. After vibration, use a scraper to level it for the first time, then use a wooden trowel to level and compact it. Before the concrete reaches initial setting, perform a second leveling and compaction. Use a wooden trowel to pat the concrete until the surface is slurry, and rub it hard to flatten and compact it.

[0065] Two groups of test blocks are retained. One group is 7d test blocks with the same conditions. The tower base installation is determined according to the strength grade of the test blocks. The other group is 28d test blocks with the same conditions.

[0066] A grounding wire is installed at the tower crane foundation, and the grounding resistance is required to be no more than 4Ω, which must be measured by an electrician.

[0067] The maintenance method of tower crane foundation 1 is the same as that of base plate 2.

[0068] The tower crane installation operation can only be carried out after the concrete strength of the tower crane foundation reaches 75%.

[0069] (6) Setting up a jacking mechanism: A jacking mechanism 3 is set up at the four corners of the tower crane foundation 1 after pouring. The upper end of the jacking mechanism 3 is pushed back to the structural floor 4. The jacking mechanism 3 is mainly used to prevent the eccentric load generated by the tower crane bending moment from causing adverse effects on the bottom plate structure.

[0070] 4 and 5 , the supporting mechanism 3 includes four steel pipe columns 31. Embedded plates 9 are set at corresponding positions on the tower crane foundation 1 and the structural floor 4, and each end of each steel pipe column 31 is welded to the corresponding embedded plate 9. The outer wall of each steel pipe column 31 is provided with a plurality of stiffening ribs 32 to improve the stability of the steel pipe column 31. The material of the steel pipe column 31 is Q345. A hidden beam 11 with a width of 500 mm is set around the hole in the structural floor 4 (for the tower crane 10 to pass through), and its height is the same as the plate thickness. The steel bar of the hidden beam 11 is 4C20, and the stirrups are C8@200. The hidden beam 11 is used to connect with the surrounding shear walls to transfer bending moment and prevent the eccentricity of the tower crane from damaging the bottom plate.

[0071] (7) Setting up a monitoring mechanism: A monitoring mechanism is set up on each supporting mechanism 3, and the monitoring mechanism is used to monitor the stress change of the supporting mechanism 3. The monitoring mechanism is a strain sensor.

[0072] After the tower crane 1 is installed, if the tower crane body tilts, the center of gravity of the tower crane will shift. At this time, the forces on different steel pipe columns 31 will be different. Here, strain sensors are used to detect the stress changes in each steel pipe column. By comparing the numerical differences of each strain sensor, the offset amplitude of the tower crane's center of gravity can be indirectly determined, and then the verticality change of the tower crane can be deduced, thereby realizing the detection of the tower crane's verticality. When the verticality deviation of the tower crane is too large or the center of gravity of the tower crane is too large, an alarm should be issued in time to prevent safety hazards. If the tower crane itself swings due to factors such as wind speed changes, tower crane rotation, and hook swing, this will not cause a significant change in the center of gravity of the tower crane and will have little effect on the forces on the steel pipe columns. Strain sensors are installed on the vertical side walls of the steel pipe columns 31. The strain sensors mainly measure the force changes in the vertical direction of the steel pipe columns, thereby further reducing the impact of normal vibration of the tower crane on sensor detection and improving the accuracy of sensor detection data.

[0073] (8) Set up routine settlement observation during tower crane construction:

[0074] Settlement observation points are set up around the top of the tower crane foundation.

[0075] The settlement monitoring of the tower crane foundation is carried out every three days until the construction of the first attached wall is completed, and then the monitoring requirement can be withdrawn.

[0076] The monitoring alarm value is set to 50mm, and the settlement change rate alarm value is 10mm / d.

[0077] When the settlement value of the tower crane reaches the alarm value requirement, the hoisting construction of the tower crane must be stopped, and a comprehensive inspection and reinforcement measures must be carried out on the tower crane foundation and the anti-top steel pipe column. After approval by all parties, the tower crane can be put into operation.

[0078] It should be noted that the above mainly describes the construction process of the tower crane foundation 1. After the construction of the tower crane foundation 1 is completed, the construction of the tower crane 10 is carried out. After the construction of the tower crane 10 is completed, the tower crane operation is carried out. After the tower crane operation is completed, the tower crane needs to be dismantled. At the same time, the tower crane foundation 10 also needs to be dismantled. To this end, the dismantling process of the tower crane foundation 10 is as follows.

[0079] The newly added tower crane foundation 10 is located on the base plate and needs to be demolished after the tower crane 10 is dismantled. A wire saw is used to cut the tower crane foundation into foundation blocks, with each block weighing no more than 5 tons. Referring to Figure 7 , the ends of the connecting beam 6 are cut into blocks using a wire saw. Subsequently, a forklift is used to transport the blocks to a ramp 12 via a dedicated route (see the arrows in Figure 8 ), where they are transported out of the basement to avoid noise pollution and structural damage caused by the crushing. It should be noted that during construction, pre-buried casing 8 (DN28 PVC) is used for wire saw threading. The ends of the casing 8 are well protected to prevent clogging with concrete and mortar. Remaining sections cut by the wire saw are removed using a jackhammer. Care is taken to protect the structure during the cutting and transportation of the foundation blocks, and concrete or steel ramps are used for the thresholds. After cutting, the top steel pipe columns 31 and the connecting steel bars connected to the base plate 2 are painted with anti-rust paint at their edges.

[0080] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A tower crane foundation construction method based on basement floor, characterized in that: The following steps are involved: Position determination: determining the position of the tower crane foundation (1) on the base plate (2); Calculation of foundation bearing capacity: Calculate the bearing capacity of the foundation soil under the base plate (2) where the tower crane foundation (1) is located to ensure that the foundation bearing capacity meets the requirements; Rebar tying: tying the reinforcement of the tower crane foundation (1), breaking the top reinforcement of the bottom plate (2), and connecting the top reinforcement of the bottom plate (2) with the reinforcement of the tower crane foundation (1); Casting: pouring concrete to form the crane foundation (1); Setting a top support mechanism: Setting a top support mechanism (3) at the four corners of the poured tower crane foundation (1), with the upper end of the top support mechanism (3) being supported against the structural floor slab (4); Providing a monitoring mechanism: Providing a monitoring mechanism on each supporting mechanism (3), the monitoring mechanism being used to monitor stress changes of the supporting mechanism (3).

2. The tower crane foundation construction method based on the basement floor according to claim 1 is characterized in that: In the step of calculating the foundation bearing capacity, when the foundation bearing capacity does not meet the requirements, the size of the tower crane foundation (1) is reduced or a smaller tower crane is selected to ensure that the foundation bearing capacity meets the requirements.

3. The tower crane foundation construction method based on the basement floor according to claim 1 is characterized in that: In the step of steel bar binding, a hook (5) is welded between the top steel bars of the bottom plate (2) and the bottom steel bars of the tower crane foundation (1) to achieve connection between the two.

4. The tower crane foundation construction method based on the basement floor according to claim 1 is characterized in that: The draw hook (5) is formed by bending a round steel bar. The draw hook (5) is welded by double-sided welding, and the welding length is not less than 5d, where d is the diameter of the round steel bar.

5. The tower crane foundation construction method based on the basement floor according to claim 1 is characterized in that: When tying the steel bars of the tower crane foundation (1), the steel bars of the connecting beam (6) are pre-buried, and the connecting beam (6) is cast while the tower crane foundation (1) is cast with concrete. Both ends of the connecting beam (6) extend out of the tower crane foundation (1), and the two ends are anchored into the civil defense walls (7) on both sides.

6. The tower crane foundation construction method based on the basement floor according to claim 1 is characterized in that: Before pouring concrete on the tower crane foundation (1), a sleeve (8) is pre-buried, and the sleeve (8) is used for threading a rope saw.

7. The tower crane foundation construction method based on the basement floor according to any one of claims 1 to 6, characterized in that: The supporting mechanism (3) comprises four steel pipe columns (31), and embedded plates (9) are arranged at corresponding positions on the tower crane foundation (1) and the structural floor (4). Each end of each steel pipe column (31) is welded to the corresponding embedded plate (9), and the outer wall of each steel pipe column (31) is provided with a plurality of stiffening ribs (32).

8. The tower crane foundation construction method based on the basement floor according to any one of claims 1 to 6, characterized in that: The monitoring mechanism is a strain sensor, and the strain sensor is installed on the vertical side wall of the supporting mechanism (3).

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