Pile foundation reverse construction method

Abstract

The invention discloses a reverse construction method for a pile foundation. The reverse construction method comprises the following steps that firstly, a three-shaft stirring pile and an underground diaphragm wall are constructed; secondly, integrated construction of the engineering piles and the reverse construction supporting columns is carried out; thirdly, structural beams and structural plates of the first layer of the tower projection area are constructed, and unearthing is conducted on a non-tower projection area; fourthly, upper-layer structures continue to be constructed layer by layer upwards in the tower projection area, structural beams and structural slabs of the negative first layer are completed at the same time, and first-layer beam slabs of a non-tower area are constructed; fifthly, the area between the continuous walls continues to be unearthed downwards, and a bottom plate bearing platform, an anchor rod and a bottom plate of the underground bottommost layer are constructed to complete bottom sealing; and sixthly, construction continues to be conducted upwards in the tower projection area till the top of the tower is sealed, and structural construction from the negative second floor to the bottommost floor continues to be completed layer by layer according to the construction mode of the negative first floor. By means of the method, the engineering piles and the reverse supporting columns are integrally constructed, then protruding bottom sealing is achieved, the working procedure can be simplified, and the construction efficiency can be improved.

Description

Technical Field

[0001] This invention belongs to the technical field of building construction methods, specifically relating to a reverse construction method for pile foundations. Background Technology

[0002] In urban construction, high-rise and super high-rise buildings with large-area, multi-story basements have become the mainstream trend in order to make full use of underground space. Traditional deep foundation pit construction methods, such as the sequential construction method, require the completion of all foundation pit excavation and underground structure construction before the underground main structure construction can proceed. This method has a long construction period, requires a large and uneconomical temporary support system, and poses significant risks, especially in soft soil areas.

[0003] To overcome the aforementioned shortcomings, the reverse construction method for pile foundations has emerged. The core of this method lies in using diaphragm walls or similar structures as retaining structures, pre-constructing vertical support piles, and then using underground structural beams and slabs as horizontal internal supports. The earthwork is excavated layer by layer from top to bottom while the above-ground structure is constructed simultaneously from bottom to top, achieving synchronous construction from top to bottom. This effectively shortens the overall construction period and enhances the stability of the foundation pit.

[0004] However, the existing reverse construction method for pile foundations still has some limitations in engineering practice:

[0005] 1. In the construction of vertical support piles, the engineering piles that bear the final load and the temporary support columns that bear the construction load during the reverse construction stage are often designed and constructed separately. Therefore, it is necessary to set construction transition nodes for the engineering piles and support columns. In addition, the support columns need to undergo secondary treatment such as external concrete encapsulation in the later stage, which leads to complicated procedures.

[0006] 2. Conventional reverse construction method usually involves excavating downwards layer by layer and constructing the structure layer by layer simultaneously. Therefore, in the excavation and structural construction of the second basement level and below, it is often limited by the floor slab structure of the upper level, which may reduce construction efficiency. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the present invention aims to provide a reverse construction method for pile foundations, which can integrate and simultaneously construct engineering piles and support columns to simplify procedures and accelerate construction efficiency. At the same time, for excavation and structural construction below the first basement level, the soil can be excavated to the bottom of the basement and sealed before constructing the structure below the first basement level, thereby reducing the difficulty of excavation and structural construction and improving construction efficiency.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for constructing pile foundations using the reverse construction method includes the following steps:

[0010] Step 1: Constructing triple-axis mixing piles and diaphragm walls;

[0011] Step 2: Construct several holes between the continuous walls according to the drawings. Integrate the construction of engineering piles and reverse support columns at the holes to form pile foundations. Divide the multiple pile foundations into the tower projection area and non-tower area according to the construction drawings. The tower projection area and non-tower area are expected to have interconnected basements, which will be multi-story basements. The pile foundation elevation in the tower projection area is up to the height of the first floor, and the pile foundation elevation in the non-tower area is up to the bottom of the first basement level.

[0012] Step 3: Construct the structural beams and slabs of the first floor in the projection area of ​​the construction tower, and excavate the soil in the non-projection area of ​​the construction tower, with the excavation elevation reaching the bottom of the first basement level.

[0013] Step 4: Continue to construct the upper structure layer by layer from the tower projection area, while completing the construction and maintenance of the structural beams and slabs of the basement level. Further build scaffolding and formwork to construct the wall columns and inner lining walls of the basement level, and complete the construction of the first-floor beams and slabs in the non-tower area.

[0014] Step 5: Continue excavating downwards in the area between the continuous walls, to the depth of the lowest underground level, and then construct the foundation, anchor bolts and foundation plate of the lowest underground level to complete the bottom sealing;

[0015] Step 6: Continue construction upwards in the tower's projection area until the tower is topped out. At the same time, continue the structural construction from the second basement level to the bottom level in the same manner as the first basement level.

[0016] Furthermore, in the second step, the engineering piles and reverse-construction support columns are constructed in an integrated manner at the borehole location to form the pile foundation, using the following method:

[0017] The reinforcing cage is lowered to the borehole position, and then a guide pipe is placed inside the reinforcing cage to clean the borehole. The installation position of the reverse support column is then located, and the reverse support column is lowered to the corresponding height position inside the reinforcing cage and temporarily fixed to form a hollow pile section between the reverse support column and the inner wall of the reinforcing cage. A guide pipe is placed inside the hollow pile section, and self-compacting concrete is poured inside the reinforcing cage and the hollow pile section to the elevation using the guide pipe. This achieves integrated construction of the engineering pile and the reverse support column.

[0018] Further, the reinforcing cage is lowered to the borehole location, and then a guide pipe is placed inside the reinforcing cage. The borehole is then cleaned using the guide pipe, employing the following method:

[0019] The guide pipe is made of multi-section, splicable seamless steel pipe with a diameter of 300mm and a wall thickness of 10mm. After the multi-section seamless steel pipe is spliced, it undergoes further water tightness, pressure bearing and joint tensile tests. After passing the tests, it is lowered into the reinforcing cage. The guide pipe is used to clean the hole by mud replacement method to minimize the thickness of sediment. Then the sediment thickness is re-measured to meet the requirements.

[0020] Furthermore, the installation position of the reverse support column is determined, and then the reverse support column is lowered to the corresponding height position inside the reinforcing cage and temporarily fixed to form a hollow pile section between the reverse support column and the inner wall of the reinforcing cage. The following method is used:

[0021] The center point of the engineering pile hole is obtained by cross intersection method. Then, the center of the positioning platform is aligned with the center point of the rebar cage hole. After the positioning platform is in place, it is leveled and the center is re-aligned. Then, the outriggers of the installation platform are embedded into the outrigger positioning ring of the positioning platform by crane. Then, the horizontality and verticality of the installation platform are adjusted. The installation platform is used to position the elevation of the installation position of the reverse support column by full rotation machine.

[0022] Next, the tool section is connected to the reverse support column with flange bolts, and the connection is sealed. Then, guide ribs are welded to the studs of the reverse support column. The guide ribs cover a whole row of studs along the length direction. At the same time, an electronic inclinometer is installed in the reverse support column to measure the verticality of the reverse support column in real time.

[0023] Next, the reverse support column is hoisted and inserted into the center of the installation platform and passes through the positioning platform. It is then lowered into the hole of the reinforcing cage by its own weight. At the same time, the horizontality and verticality of the reverse support column are calibrated by the level of the four legs of the installation platform and the two theodolite frames. When the reverse support column is lowered to the point where its own elevation position coincides with the elevation positioning position of the full-rotation machine, the hoisting of the reverse support column is completed. Then, several fixing steel bars are welded and fixed between the positioning plate and the tool section of the reverse support column. The fixing steel bars are distributed at equal intervals along the ring to temporarily fix the reverse support column and form a hollow pile section between the reverse support column and the inner wall of the reinforcing cage.

[0024] Furthermore, the horizontal and verticality of the reverse support column are calibrated using the level instruments on the four outriggers of the installation platform and the two theodolite frames. The installation of the reverse support column is complete when its elevation coincides with the elevation positioning position of the slewing machine. The following method is used:

[0025] After the reverse support column is lowered into the hole of the reinforcing cage by its own weight, the clamping mechanism of the installation platform is used to hold the reverse support column. Using the level on the four legs of the installation platform and the two theodolite frames, the verticality and center positioning of the reverse support column are re-measured. If any positional deviation is found, the tilt angle and / or height of the four legs of the installation platform are finely adjusted to ensure the verticality and center positioning of the reverse support column. Then, a positioning device is installed on the positioning platform to abut against the surface of the reverse support column, thus securing the reverse support column. The lowering process is guided and positioned. At this time, an electronic inclinometer is used to collect the verticality information of the reverse support column in real time. Then, the reverse support column is lowered. The real-time verticality information collected by the electronic inclinometer is calibrated with the verticality information collected by the four horizontal and two theodolite frames of the installation platform. When the calibration deviation angle is greater than 0.04 degrees, real-time calibration is performed by fine-tuning the tilt angle and / or height of the four outriggers of the installation platform. When the reverse support column is lowered to its own elevation position and coincides with the elevation positioning position of the slewing machine, the hoisting of the reverse support column is completed.

[0026] Furthermore, a positioning device is installed on the positioning platform to abut against the surface of the reverse support column, guiding and positioning the column during its lowering process. The following method is used:

[0027] The positioning device includes an inverted conical ring and several connecting plates fixedly disposed on the outer circumferential surface of the inverted conical ring. The connecting plates are evenly distributed along the circumferential direction. Several arc-shaped support plates are fixedly connected to the inner circumferential surface of the inverted conical ring. The arc-shaped support plates are evenly distributed along the circumferential direction. Several support wheels are installed on the inner bottom of the inverted conical ring. The support wheels are evenly distributed along the circumferential direction.

[0028] When installing the positioning device, a trapezoidal metal strip is wrapped around the outer circumference of the reverse support column, and the two ends of the trapezoidal metal strip are welded and fixed to form an inverted conical ring. At this time, the arc-shaped parts of several arc-shaped support plates and the wheel surfaces of the support wheels abut against the surface of the reverse support column. Then, several connecting blocks are bolted and connected to the positions of several connecting plates on the positioning platform. Then, several connecting plates are welded and fixed to several connecting blocks to fix the inverted conical ring. At the same time, several arc-shaped support plates and support wheels inside the inverted conical ring are used to guide and position the reverse support column during the lowering process.

[0029] Furthermore, in the third step, the structural beams and slabs of the first floor in the tower projection area are constructed, and the excavation of the non-tower projection area is carried out to the required elevation using the following methods:

[0030] Scaffolding and formwork were erected on the original ground in the tower projection area. Then, the first-floor structural beams and slabs were constructed on the pile foundation in the tower projection area using the scaffolding and formwork. After testing the pile foundation in the non-tower area, the soil was excavated and removed to the bottom of the first basement level, which was two meters above the ground.

[0031] Furthermore, in the fourth step, the construction and curing of the structural beams and slabs on the basement level are completed. Support structures and formwork are then erected to construct the basement walls, columns, and inner lining walls. Additionally, the first-floor beams and slabs in the non-tower areas are constructed using the following methods:

[0032] First, the structural beams and slabs of the basement are completed. Then, the structural beams and slabs are cured to a strength of 75% or higher. At this point, scaffolding and formwork are erected on the structural beams and slabs of the basement to facilitate the construction of the basement walls, columns, and inner lining walls. After that, the structural beams and slabs of the first floor in the non-tower area are constructed.

[0033] The present invention has the following beneficial effects:

[0034] The pile foundation reverse construction method of this invention is mainly completed through six steps. In the second step, the pile foundation is formed by the integrated construction of engineering piles and reverse construction support columns. This process can be carried out simultaneously. Compared with the existing technology that uses separate design and construction of engineering piles and reverse construction support columns, the integrated construction method of engineering piles and reverse construction support columns can better simplify the construction process and improve construction efficiency. At the same time, according to the drawings, multiple pile foundations are divided into tower projection area and non-tower area to facilitate the distinction between the pile foundations of the tower and non-tower areas. The pile foundations in the non-tower area and the tower projection area have different elevations to facilitate effective differentiation and subsequent construction. In the third step, the structural beams and structural slabs of the first floor of the tower projection area are constructed first, which facilitates the normal and continuous upward construction of each floor in the tower projection area. In the fourth step, the structural beams and slabs of the first basement floor are constructed first. The structural slabs are then cured to the required strength to ensure that the structural beams and slabs of the basement level are strong enough to support the formwork and formwork. This facilitates the subsequent construction of the basement walls, columns, and inner lining walls, as well as the construction of the first-floor structural beams and slabs in the non-tower area. In steps five and six, excavation continues in the non-tower area and the tower projection area down to the bottom of the basement to facilitate the construction of the basement foundation, anchor bolts, and slab, thus sealing the bottom and forming the overall main frame of the basement. This facilitates the construction of the main structure from the second basement level to the bottom level within this overall main frame. Compared to the existing technology that uses a layer-by-layer downward construction method, excavating from the second basement level to the bottom level and sealing the bottom in advance greatly improves the excavation efficiency and reduces the difficulty of subsequent excavation and construction of the next floor structure, thereby improving construction efficiency. Attached Figure Description

[0035] Figure 1 This is a construction drawing for the first step of the present invention: the construction of triaxial mixing piles and diaphragm walls.

[0036] Figure 2 This is a construction drawing for the second step of the present invention, which involves the integrated construction of engineering piles and reverse support columns.

[0037] Figure 3 This is a construction drawing for the third step of the present invention, which involves the construction of the first-floor beams and slabs and the excavation of the basement.

[0038] Figure 4 This is a construction drawing for the fourth step of the present invention, which involves the construction of the beams and slabs on the first basement level and the upward construction of the tower.

[0039] Figure 5 This is the construction drawing for the fourth step of the present invention, which involves the construction of the first-floor beams and slabs in the non-tower area and the structural construction of the basement.

[0040] Figure 6 This is a construction drawing for the fifth step of the present invention, which involves continuously excavating soil downwards and completing the bottom sealing construction.

[0041] Figure 7 This is a schematic diagram of the inverted conical ring of the present invention.

[0042] In the diagram: 1. Pile foundation; 2. Engineering pile; 3. Reverse support column; 4. Empty pile section; 5. Triaxial mixing pile; 6. Continuous wall; 7. Structural beam; 8. Structural slab; 9. Inverted cone ring; 91. Connecting plate; 92. Arc-shaped support plate; 93. Support wheel; A. Tower projection area; B. Non-tower area. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Terms such as “upper,” “inner,” “middle,” “left,” “right,” and “one” used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0044] A reverse construction method for pile foundations, such as Figures 1 to 6 As shown, it includes the following steps:

[0045] Step 1: Construct three-axis mixing piles 5 and underground continuous wall 6 on the periphery of the construction area according to the construction drawings.

[0046] Step 2: Construct several holes between the continuous walls 6 according to the drawings, and carry out integrated construction of engineering piles 2 and reverse support columns 3 at the holes to form pile foundation 1. According to the construction drawings, the multiple pile foundations 1 are divided into tower projection area A and non-tower area B. It is expected that the tower projection area A and non-tower area B will be connected to the basement, which will be a multi-story basement. The elevation of pile foundation 1 in tower projection area A is up to the height of the first floor, and the elevation of pile foundation 1 in non-tower area B is up to the bottom of the first basement level.

[0047] Step 3: Build a support frame and template on the original ground in the tower projection area A. Then, construct the first-floor structural beam 7 and structural slab 8 on the pile foundation 1 of the tower projection area A using the support frame and template. After inspecting the pile foundation 1 in the non-tower area B, excavate the soil in the non-tower area B. The soil level is two meters below the bottom of the first basement level.

[0048] Step 4: Continue constructing the upper structure layer by layer from the tower projection area A upwards; then simultaneously carry out the construction of the basement level of the tower projection area A: first complete the structural beams 7 and structural slabs 8 of the basement level, and then cure the structural beams 7 and structural slabs 8 to a strength greater than or equal to 75%. At this time, it is estimated that the construction of the fifth floor structure of the tower projection area A can be completed; next, build scaffolds and formwork on the structural beams 7 and structural slabs 8 of the basement level to construct the wall columns and inner lining walls of the basement level with the help of the scaffolds and formwork, and then construct the first floor structural beams 7 and structural slabs 8 of the non-tower area B. At this time, it is estimated that the construction of the eleventh floor structure of the tower projection area A can be completed.

[0049] Step 5: Continue excavating the soil in the area between the continuous walls 6, and excavate to the bottom of the lowest underground level. Then, construct the foundation, anchor bolts and foundation of the lowest underground level to complete the bottom sealing. At this time, the construction of the 21st floor structure in the tower projection area A can be completed.

[0050] Step 6: Continue construction upwards in the tower projection area A until the tower is topped out. At the same time, continue the structural construction from the second basement level to the bottom level in the same way as the first basement level.

[0051] Based on the above description of the reverse construction method for pile foundation 1, it can be seen that the reverse construction method for pile foundation 1 of the present invention is mainly completed through six steps. In the second step, pile foundation 1 is mainly formed by the integrated construction of engineering piles 2 and reverse support columns 3. This process can be carried out simultaneously. Compared with the existing technology that uses separate design and construction of engineering piles 2 and reverse support columns 3, the integrated construction of engineering piles 2 and reverse support columns 3 can better simplify the construction process and improve construction efficiency. At the same time, according to the drawings, multiple pile foundations 1 are divided into tower projection area A and non-tower area B to distinguish between the pile foundations 1 of the tower and non-tower areas. At the same time, the pile foundation 1 of non-tower area B and tower projection area A have different elevations to facilitate effective differentiation and subsequent construction. In the third step, by first constructing the structural beams 7 and structural slabs 8 of the first floor of tower projection area A, it is easier to carry out normal and continuous upward construction layer by layer in tower projection area A. In the fourth step... First, the structural beams 7 and slabs 8 of the basement are constructed and cured to the required strength. This ensures that the structural beams 7 and slabs 8 are strong enough to support scaffolding and formwork, facilitating subsequent construction of the basement walls, columns, and inner lining walls. It also facilitates the construction of the first-floor structural beams 7 and slabs 8 in the non-tower area B. In steps five and six, excavation continues in the non-tower area B and the tower projection area A until the bottom of the basement is reached. This allows for the construction of the basement's foundation slab, anchor bolts, and slab, ultimately sealing the bottom and forming the overall main frame of the basement. This facilitates the construction of the main structure from the second basement level to the bottom level within this overall main frame. Compared to existing technologies that use a layer-by-layer construction method, excavating from the second basement level to the bottom level and sealing the bottom in advance greatly improves excavation efficiency and reduces the difficulty of subsequent excavation and construction of the next floor, thus improving construction efficiency.

[0052] In this embodiment, regarding the second step of the present invention, the engineering pile 2 and the reverse support column 3 are constructed in an integrated manner at the borehole location to form the pile foundation 1, and the following method is adopted:

[0053] First, the catheter and reverse support column 3 are pre-treated:

[0054] The conduit is made of multi-section, splicable seamless steel pipes with a diameter of 300mm and a wall thickness of 10mm. After splicing, the top section is equipped with 0.5m and 1m seamless steel pipes, the middle section is composed of multiple 2m long seamless steel pipes, and the bottom section is a 4m long seamless steel pipe. Before use, the conduit must pass watertightness, pressure resistance and joint tensile tests.

[0055] The top of the reverse support column 3 is connected to the tool section using flange bolts. The junction between the tool section and the reverse support column 3 is sealed with sealant for waterproofing, thus achieving a sealed connection. Several rows of equally spaced, circularly distributed studs are arranged on the bottom circumference of the reverse support column 3. Multiple studs in each row are evenly spaced along the length of the reverse support column 3. This arrangement of studs increases the contact area between the reverse support column 3 and the concrete, facilitating the subsequent connection between the reverse support column 3 and the concrete, thereby improving the stability of the reverse support column 3 after installation. Guide ribs are then welded to the stud locations of the reverse support column 3, covering an entire row of studs along its length. This arrangement reduces interference between the studs and the reinforcing cage during the lowering of the reverse support column 3. Simultaneously, an electronic inclinometer is installed inside the reverse support column 3 to measure its verticality in real time.

[0056] Next, the integrated construction of engineering pile 2 and reverse support column 3 will be carried out:

[0057] The reinforcing cage is lowered to the borehole location. After the spliced ​​guide pipe passes the watertightness, pressure resistance, and joint tensile tests, it is lowered into the reinforcing cage. The borehole is cleaned using the guide pipe through a mud replacement method. For piles with a borehole diameter of 1800 mm or less, the mud replacement method is used for positive circulation with the guide pipe. For piles with a borehole diameter greater than 1800 mm, the mud replacement method is used for reverse circulation with the guide pipe to minimize the thickness of the sediment. After the sediment thickness is re-measured and meets the requirements, the subsequent construction can proceed.

[0058] Next, the installation position of the reverse support column 3 is located, and then the reverse support column 3 is lowered to the corresponding height position inside the steel cage and temporarily fixed so that a hollow pile section 4 is formed between the reverse support column 3 and the inner wall of the steel cage. A guide pipe is placed in the hollow pile section 4, and self-compacting concrete is poured inside the steel cage and the hollow pile section 4 to the elevation using the guide pipe, thereby realizing the integrated construction of the engineering pile 2 and the reverse support column 3.

[0059] It should be noted that when the concrete is poured through the guide pipe inside the reinforcing cage, the engineering pile 2 is formed. In this invention, after the reinforcing cage is lowered and the hole is cleaned, the custom-made reverse support column 3 is lowered to the elevation depth inside the reinforcing cage, so that a hollow pile section 4 is formed between the reinforcing cage and the reverse support column 3. When the hollow pile section 4 is further poured with concrete, the reinforcing cage can be poured simultaneously, thereby realizing the integrated construction of the engineering pile 2 and the reverse support column 3. Compared with the existing technology of first constructing the engineering pile 2 and then constructing and installing the reverse support column 3, this invention can achieve simultaneous construction, which can effectively improve construction efficiency.

[0060] During this process, the following method is used to locate the installation position of the reverse support column 3: the center point of the rebar cage hole is obtained by cross-intersection method, and then the center of the positioning platform is aligned with the center point of the engineering pile 2 hole. After the positioning platform is in place, the positioning platform is leveled and the center is re-aligned; then the outriggers of the installation platform are embedded into the outrigger positioning ring of the positioning platform by a crane, and then the horizontality and verticality of the installation platform are adjusted. The installation platform is used to locate the elevation of the installation position of the reverse support column 3 by a full rotation machine.

[0061] Next, the reverse support column 3 is hoisted, inserted into the center of the installation platform, and passed through the positioning platform. It is then lowered into the hole of the engineering pile 2 under its own weight. Simultaneously, the horizontal and vertical alignment of the reverse support column 3 is calibrated using the level indicators on the four legs of the installation platform and the two theodolite frames. During this process, after the reverse support column 3 is lowered into the hole of the reinforcing cage under its own weight, the clamping mechanism of the installation platform is used to hold the reverse support column 3 securely. The verticality and center positioning of the reverse support column 3 are then re-measured using the level indicators on the four legs of the installation platform and the two theodolite frames. If any positional deviation is found in the reverse support column 3, the tilt angle and / or height of the four legs of the installation platform are finely adjusted to ensure the verticality and center positioning of the reverse support column 3. Then, a positioning device is installed on the positioning platform to abut against the surface of the reverse support column 3, guiding and positioning the reverse support column 3 during its lowering process. At this point, an electronic inclinometer is used to collect the verticality information of the reverse support column 3 in real time. Then, the reverse support column 3 is lowered. The real-time verticality information collected by the electronic inclinometer is calibrated with the verticality information collected by the four horizontal and two theodolite frames of the installation platform. When the calibration deviation angle is greater than 0.04 degrees (1 / 1000, representing 90°±0.04°), the tilt angle and / or height of the four outriggers of the installation platform are adjusted in real time for calibration. When the reverse support column 3 is lowered to its own elevation position and coincides with the elevation positioning position of the full slewing machine, the hoisting of the reverse support column 3 is completed. Then, several fixing steel bars are welded and fixed between the positioning plate and the tool section of the reverse support column 3. The fixing steel bars are distributed at equal intervals along the ring to temporarily fix the reverse support column 3 and form a hollow pile section 4 between the reverse support column 3 and the inner wall of the steel cage.

[0062] It should be noted that when a positioning device is installed on the positioning platform to abut against the surface of the reverse support column 3, it guides and positions the reverse support column 3 during its lowering process; for example... Figure 7As shown, the positioning device includes an inverted conical ring 9 and several connecting plates 91 fixedly disposed on the outer circumferential surface of the inverted conical ring 9. The connecting plates 91 are evenly distributed along the circumferential direction. Several arc-shaped support plates 92 are fixedly connected to the inner circumferential surface of the inverted conical ring 9. The arc-shaped support plates 92 are evenly distributed along the circumferential direction. Several support wheels 93 are installed on the inner bottom of the inverted conical ring 9. The support wheels 93 are evenly distributed along the circumferential direction.

[0063] When installing the positioning device, a trapezoidal metal strip is wrapped around the outer periphery of the reverse support column 3, and the two ends of the trapezoidal metal strip are welded and fixed to form an inverted conical ring 9. At this time, the arc-shaped parts of several arc-shaped support plates 92 and the wheel surfaces of support wheels 93 are abutted against the surface of the reverse support column 3. Then, several connecting blocks are bolted and connected to the positions of several connecting plates 91 on the positioning platform. Then, several connecting plates 91 are welded and fixed to several connecting blocks to fix the inverted conical ring 9. At the same time, several arc-shaped support plates 92 and support wheels 93 inside the inverted conical ring 9 are used to guide and position the reverse support column 3 during the lowering process.

[0064] The embodiments of the present invention are not limited thereto. Based on the above description of the present invention, and using common technical knowledge and conventional means in the field, the present invention can be modified, replaced or combined in various other forms without departing from the basic technical idea of ​​the present invention, and all such modifications, replacements or combinations fall within the scope of protection of the present invention.

Claims

1. A method for constructing pile foundations using the reverse construction method, characterized in that, Includes the following steps: Step 1: Constructing triple-axis mixing piles and diaphragm walls; Step 2: Construct several holes between the continuous walls according to the drawings. Integrate the construction of engineering piles and reverse support columns at the holes to form pile foundations. Divide the multiple pile foundations into the tower projection area and non-tower area according to the construction drawings. The tower projection area and non-tower area are expected to have interconnected basements, which will be multi-story basements. The pile foundation elevation in the tower projection area is up to the height of the first floor, and the pile foundation elevation in the non-tower area is up to the bottom of the first basement level. Step 3: Construct the structural beams and slabs of the first floor in the projection area of ​​the construction tower, and excavate the soil in the non-projection area of ​​the construction tower, with the excavation elevation reaching the bottom of the first basement level. Step 4: Continue to construct the upper structure layer by layer from the tower projection area, while completing the construction and maintenance of the structural beams and slabs of the basement level. Further build scaffolding and formwork to construct the wall columns and inner lining walls of the basement level, and complete the construction of the first-floor beams and slabs in the non-tower area. Step 5: Continue excavating downwards in the area between the continuous walls, to the depth of the lowest underground level, and then construct the foundation, anchor bolts and foundation plate of the lowest underground level to complete the bottom sealing; Step 6: Continue construction upwards in the tower's projection area until the tower is topped out. At the same time, continue the structural construction from the second basement level to the bottom level in the same manner as the first basement level.

2. The pile foundation reverse construction method as described in claim 1, characterized in that, In the second step, the engineering piles and reverse-construction support columns are constructed in an integrated manner at the borehole location to form the pile foundation, using the following method: The reinforcing cage is lowered to the borehole position, and then a guide pipe is placed inside the reinforcing cage to clean the borehole. The installation position of the reverse support column is then located, and the reverse support column is lowered to the corresponding height position inside the reinforcing cage and temporarily fixed to form a hollow pile section between the reverse support column and the inner wall of the reinforcing cage. A guide pipe is placed inside the hollow pile section, and self-compacting concrete is poured inside the reinforcing cage and the hollow pile section to the elevation using the guide pipe. This achieves integrated construction of the engineering pile and the reverse support column.

3. The pile foundation reverse construction method as described in claim 2, characterized in that, Lower the reinforcing cage to the borehole location, then place a guide pipe inside the cage and use the guide pipe to clean the borehole using the following method: The guide pipe is made of multi-section, splicable seamless steel pipe with a diameter of 300mm and a wall thickness of 10mm. After the multi-section seamless steel pipe is spliced, it undergoes further water tightness, pressure bearing and joint tensile tests. After passing the tests, it is lowered into the reinforcing cage. The guide pipe is used to clean the hole by mud replacement method to minimize the thickness of sediment. Then the sediment thickness is re-measured to meet the requirements.

4. The pile foundation reverse construction method as described in claim 2, characterized in that, The installation position of the reverse support column is determined, and then the reverse support column is lowered to the corresponding height position inside the reinforcing cage and temporarily fixed to form a hollow pile section between the reverse support column and the inner wall of the reinforcing cage. The following method is used: The center point of the engineering pile hole is obtained by cross intersection method. Then, the center of the positioning platform is aligned with the center point of the rebar cage hole. After the positioning platform is in place, it is leveled and the center is re-aligned. Then, the outriggers of the installation platform are embedded into the outrigger positioning ring of the positioning platform by crane. Then, the horizontality and verticality of the installation platform are adjusted. The installation platform is used to position the elevation of the installation position of the reverse support column by full rotation machine. Next, the tool section is connected to the reverse support column with flange bolts, and the connection is sealed. Then, guide ribs are welded to the studs of the reverse support column. The guide ribs cover a whole row of studs along the length direction. At the same time, an electronic inclinometer is installed in the reverse support column to measure the verticality of the reverse support column in real time. Next, the reverse support column is hoisted and inserted into the center of the installation platform and passes through the positioning platform. It is then lowered into the hole of the reinforcing cage by its own weight. At the same time, the horizontality and verticality of the reverse support column are calibrated by the level of the four legs of the installation platform and the two theodolite frames. When the reverse support column is lowered to the point where its own elevation position coincides with the elevation positioning position of the full-rotation machine, the hoisting of the reverse support column is completed. Then, several fixing steel bars are welded and fixed between the positioning plate and the tool section of the reverse support column. The fixing steel bars are distributed at equal intervals along the ring to temporarily fix the reverse support column and form a hollow pile section between the reverse support column and the inner wall of the reinforcing cage.

5. The pile foundation reverse construction method as described in claim 4, characterized in that, The horizontal and verticality of the reverse support column are calibrated using the level and two theodolite frames on the four outriggers of the installation platform. The installation of the reverse support column is completed when its elevation position coincides with the elevation positioning position of the slewing machine. The following method is used: After the reverse support column is lowered into the hole of the reinforcing cage by its own weight, the clamping mechanism of the installation platform is used to hold the reverse support column. Using the level on the four legs of the installation platform and the two theodolite frames, the verticality and center positioning of the reverse support column are re-measured. If any positional deviation is found, the tilt angle and / or height of the four legs of the installation platform are finely adjusted to ensure the verticality and center positioning of the reverse support column. Then, a positioning device is installed on the positioning platform to abut against the surface of the reverse support column, thus securing the reverse support column. The lowering process is guided and positioned. At this time, an electronic inclinometer is used to collect the verticality information of the reverse support column in real time. Then, the reverse support column is lowered. The real-time verticality information collected by the electronic inclinometer is calibrated with the verticality information collected by the four horizontal and two theodolite frames of the installation platform. When the calibration deviation angle is greater than 0.04 degrees, real-time calibration is performed by fine-tuning the tilt angle and / or height of the four outriggers of the installation platform. When the reverse support column is lowered to its own elevation position and coincides with the elevation positioning position of the slewing machine, the hoisting of the reverse support column is completed.

6. The pile foundation reverse construction method as described in claim 5, characterized in that, A positioning device is installed on the positioning platform to abut against the surface of the reverse support column, guiding and positioning the column during its lowering process. The following method is used: The positioning device includes an inverted conical ring and several connecting plates fixedly disposed on the outer circumferential surface of the inverted conical ring. The connecting plates are evenly distributed along the circumferential direction. Several arc-shaped support plates are fixedly connected to the inner circumferential surface of the inverted conical ring. The arc-shaped support plates are evenly distributed along the circumferential direction. Several support wheels are installed on the inner bottom of the inverted conical ring. The support wheels are evenly distributed along the circumferential direction. When installing the positioning device, a trapezoidal metal strip is wrapped around the outer circumference of the reverse support column, and the two ends of the trapezoidal metal strip are welded and fixed to form an inverted conical ring. At this time, the arc-shaped parts of several arc-shaped support plates and the wheel surfaces of the support wheels abut against the surface of the reverse support column. Then, several connecting blocks are bolted and connected to the positions of several connecting plates on the positioning platform. Then, several connecting plates are welded and fixed to several connecting blocks to fix the inverted conical ring. At the same time, several arc-shaped support plates and support wheels inside the inverted conical ring are used to guide and position the reverse support column during the lowering process.

7. The pile foundation reverse construction method as described in claim 1, characterized in that, In the third step, the structural beams and slabs of the first floor in the tower projection area are constructed, and the excavation of the non-tower projection area is carried out to the required elevation using the following methods: Scaffolding and formwork were erected on the original ground in the tower projection area. Then, the first-floor structural beams and slabs were constructed on the pile foundation in the tower projection area using the scaffolding and formwork. After testing the pile foundation in the non-tower area, the soil was excavated and removed to the bottom of the first basement level, which was two meters above the ground.

8. The pile foundation reverse construction method as described in claim 1, characterized in that, In the fourth step, the construction and curing of the structural beams and slabs on the basement level are completed. Further scaffolding and formwork are then erected to construct the basement walls, columns, and inner lining walls. Additionally, the first-floor beams and slabs in the non-tower areas are constructed using the following methods: First, the structural beams and slabs of the basement are completed. Then, the structural beams and slabs are cured to a strength of 75% or higher. At this point, scaffolding and formwork are erected on the structural beams and slabs of the basement to facilitate the construction of the basement walls, columns, and inner lining walls. After that, the structural beams and slabs of the first floor in the non-tower area are constructed.

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