Construction method for in-situ jacking and falling of existing building, underpinning protection and underground storey addition

Abstract

The application relates to a construction method for in-situ jacking and falling replacement protection and underground storey increasing of an existing building, which comprises the following steps: S1, constructing column piles around the building and columns on the upper parts of the column piles; S2, reserving the soil body around the foundation of the existing building, excavating the soil outside and inside the building to the first supporting bottom, and ensuring a set safety distance between the slope top and vertical components such as building walls or columns; then, simultaneously constructing counterforce platforms located on both sides of the vertical components, building internal support beams connected to adjacent counterforce platforms in the building, wall clamping beams on both sides of the bottom above the ground of the vertical components, and temporary support frames above the wall clamping beams for supporting the vertical components; S3, installing replacement columns on the counterforce platforms; S4, reserving holes outside the replacement columns to pour replacement beam plates, so that the replacement columns and the replacement beam plates can move up and down relative to each other; and S5, installing a jacking structure, which is divided into group A and group B.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically to a construction method for in-situ jacking and lowering of existing buildings for protection and underground layer addition. Background Technology

[0002] In urban renewal, the protection of architectural heritage and historical districts is central to preserving the city's cultural DNA, while the development of underground space is key to improving the quality of urban life, particularly in effectively alleviating parking difficulties in city centers. With increasingly scarce land in central urban areas, urban renewal often involves developing underground space beneath existing buildings. This requires organically combining underground space development with architectural heritage protection, exploring new construction methods, and solving the problem of adding underground floors beneath existing buildings.

[0003] When constructing underground additions beneath existing buildings or structures, common solutions include building relocation and protection, and in-situ underpinning and protection. The existing protection technologies have the following problems: 1. Building relocation for protection requires vacant areas within the site for temporary relocation of existing buildings. In most central urban areas, surrounding buildings are densely packed or sites are limited, making building relocation impractical. Alternatively, multiple back-and-forth relocations of buildings can be used to develop underground space in designated zones, but this involves complex construction, high risks, long construction periods, and high costs.

[0004] 2. In-situ underpinning protection of buildings requires first constructing underpinning slabs and piles to protect the building, followed by the construction of the foundation pit support structure and earthwork excavation. The foundation pit is often constructed using the reverse construction method. This approach has a long development cycle, is inconvenient for excavation, and exacerbates the adverse effects on existing buildings.

[0005] 3. Using anchored static pressure piles for in-situ underpinning protection of the building presents challenges. Since the anchor piles rely on the building's own weight for driving, their penetration depth is limited, and excavation reduces their bearing capacity. To provide sufficient bearing capacity, a large number of anchor piles are required. This method results in numerous obstacles such as underpinning piles and support columns in the excavation area beneath the existing building, making excavation difficult and inefficient.

[0006] To address the aforementioned problems, this invention provides a construction method for in-situ jacking and lowering of existing buildings for protection and underground addition. This method utilizes supporting columns as support points for the jacking and lowering replacement columns, and uses the foundation pit support as a construction platform for jacking and lowering, eliminating the need for separate replacement piles. By constructing the first layer of support in batches and sections, the temporary replacement structure of the existing building and the support structure outside the building's protection zone can be constructed simultaneously, shortening the construction period. The jacking and lowering method increases the space available for the construction of the first layer of support structure and underground structure within the influence zone of the existing building, resulting in high construction efficiency, low risk of underground space development, and high building protection safety. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a construction method for in-situ jacking and lowering of existing buildings for protection and underground addition. This method employs a sequential construction approach, using zoned construction of support structures and utilizing these structures as construction platforms. This allows for the simultaneous construction of temporary support structures and support structures outside the affected area, resulting in high construction efficiency and minimal impact on existing buildings. The jacking structure enables the lifting and lowering of the building, providing space for foundation pit support and underground structure construction, making construction convenient and ensuring high safety.

[0008] A construction method for in-situ jacking and lowering underpinning protection and underground layer addition of existing buildings includes the following steps: S1, Construction pit retaining structure; Constructing column piles 3 around the existing building 1, and column 4 on the top of column piles 3; S2. Retain the soil around the existing building foundation 2, and excavate the soil outside and inside the building on a slope to the bottom of the first support. Ensure a set safety distance between the top of the slope and the vertical components of the building wall or column. Then, simultaneously construct the reaction platform 5 on both sides of the vertical component, the internal building support 6 connected to the adjacent reaction platform 5, the wall beam 17 on both sides of the bottom of the vertical component, and the temporary support frame 18 above the wall beam 17 for supporting the vertical component. S3. Install the support column 10 on the reaction platform 5, and fix the support column 10 to the reaction platform 5. S4. Fill the holes 9 on the outside of the supporting column 10 with the supporting beam 8 to ensure that the supporting column 10 and the supporting beam 8 are not connected and can move up and down relative to each other; the supporting beam 8 is fixedly connected to the wall beam 17; anchor rods 14 are pre-embedded on the supporting beam 8 or anchor rods 14 are planted later. S5. Install the lifting structure. The lifting structures corresponding to the same reaction platform 5 are divided into group A and group B. S6. Remove the foundation 2 below the support beam 8; S7. The existing building 1 is lifted to the design height through the lifting and lowering control system; the support a19 under the construction of the replacement beam 8 is fixedly connected to the reaction platform 5. S8. Excavate the foundation pit to the bottom and construct the basement floor slab 20mm. S9. Remove the supports outside the affected area of ​​the replacement beam 8 layer by layer, and construct the underground structure 21. S10. After the underground structure 21 is completed, the existing building 1 will be lowered back onto the top slab of the underground structure. S11. Remove the lifting structure, reaction platform 5, remaining supports and columns 4; S12. Remove part of the replacement beam 8 and transform the replacement beam 8 into the permanent foundation of the existing building.

[0009] Preferably, in step S1, the column piles 3 and the columns 4 on the upper part of the column piles 3 are constructed inside the building; and the column piles 3 and columns 4 distributed in the room can be implemented using low-headroom miniaturized equipment.

[0010] Preferably, in step S2, the reaction platform 5 serves as the installation platform for the lifting structure and the operation platform for the lifting construction; the wall clamping beam 17 is located on both sides of the wall of building 1 and is fixedly connected to the wall of building 1 through the wall through structure.

[0011] Furthermore, prestressing tendons can be installed inside the through-wall structure. Once the through-wall structure and the wall-clamping beam 17 have reached the design strength, the prestressing tendons are tensioned and locked with anchors. Furthermore, the reaction platform 5 and the first support within the influence range of the existing building 1 will be designed and constructed together with the top beams and slabs of the underground structure. The basement slab will be constructed first as a construction operation platform to reduce the workload of dismantling the support after completion.

[0012] Preferably, in step S3, an embedded part is first set on the upper part of the reaction platform 5, and the support column 10 is fixed by welding or mechanical connection with the embedded part; or when casting the reaction platform 5, the support column 10 is directly cast into one piece with the reaction platform 5.

[0013] Preferably, in step S4, reinforcing bars are pre-reserved at the overlap position between the wall beam 17 and the supporting beam 8, or the connection is made by rebar installation.

[0014] Preferably, in step S5, group A contains one or more support columns 10, with one jack 11 placed on top of each support column 10; group B contains one or more support columns 10, with jacks 11 selectively placed on the support columns 10 as needed; the number and arrangement of the lifting structures are comprehensively considered based on factors such as the load distribution of the existing building 1, the form of the support beam 8, and the arrangement of the support structure, to ensure that the building can be lifted smoothly; the jacks 11 are located on the support columns 10, the reaction beams 12 are located on the jacks 11, and the tie rods 16 are symmetrically distributed on both sides of the jacks 11. The lower part of the tie rods 16 is connected to the anchor rods 14 on the support beam 8 through the sleeves 15, and the upper part of the tie rods 16 is connected to the anchors 13. The tie rods 16 pass through the reserved holes on the reaction beams 12; the anchors 13 can be nuts, clamps, or through-hole jacks, etc. When Group A is being lifted, the anchor 13 on the reaction beam 12 of Group A is locked. The reaction beam 12 transmits the lifting force of the jack 11 to the anchor 13, and the anchor 13 transmits the lifting force to the tie rod 16. The tie rod 16 lifts the replacement beam 8 and the building 1. When the jack 11 of Group A completes one stroke, the anchor 13 on the reaction beam 12 of Group B is locked, the jack 11 of Group A retracts, and the reaction beam 12 falls back. Since the reaction beam 12 and the tie rod 16 of Group B are locked by the anchor 13, the replacement beam 8 is locked by the tie rod 16 of Group B, thus limiting the fall of the replacement beam 8 and the building 1. The jack 11 of Group A retracts, and the reaction beam 12 falls back into place. The anchor 13 on the reaction beam 12 of Group A is locked, and the next stroke begins. When Group B is also equipped with jacks 11, after Group A completes one stroke, the anchor 13 on the reaction beam 12 of Group B is locked, and the jacks 11 of Group B are lifted. The reaction beam 12 transmits the lifting force of the jacks 11 to the anchor 13, and the anchor 13 transmits the lifting force to the tie rod 16. The tie rod 16 will lift the supporting beam 8 and the building 1. When the jacks 11 of Group A are retracted, the reaction beam 12 falls back simultaneously, and the anchor 13 on the reaction beam 12 of Group A is locked. The alternating locking and lifting of Group A and Group B can realize the relay lifting of the building 1. Through the cooperation of the lifting structures of Group A and Group B, the lifting and lowering of the building 1 can be realized.

[0015] Preferably, in step S7, the lower support a19 of the supporting beam plate 8 is a concrete support or a steel support; when it is a concrete support, steel bars can be reserved or rebars can be installed at the corresponding position of the reaction platform 5; when it is a steel support, embedded parts can be set on the reaction platform 5.

[0016] Preferably, in step S9, during the excavation of the foundation pit and the construction of the underground structure, the existing building 1 is temporarily lowered onto the supporting reaction platform 5, or a limiting pad is set between the replacement beam 8 and the reaction platform 5 as a protective device to prevent unexpected situations from occurring in the jacking structure during construction or from being affected by extreme weather, so that the replacement beam 8 may experience differential deformation or even instability of the jacking structure.

[0017] Preferably, in step S12, a horizontal limiting device can be installed between the basement roof slab and the replacement beam slab 8 that has been converted into a permanent foundation; or a new foundation can be built on the top slab of the underground structure to connect with the existing building.

[0018] The beneficial effects of this invention are as follows: 1) The foundation pit retaining structure, supporting structure, wall beams, and temporary support frame outside the protection zone of the existing building can be constructed simultaneously. After the replacement structure is completed, the earthwork within the foundation protection zone is excavated, the foundation is cleared, and the lower support of the replacement beams and slabs is constructed, which shortens the construction period and reduces the impact on the building.

[0019] 2) By using support column piles and support structures as jacking support points and reaction platforms, there is no need to use anchor static pressure piles or other replacement piles to replace the building foundation, which saves foundation replacement costs and avoids the difficulty of excavation caused by too dense piles during subsequent earthwork excavation. Construction is convenient and resources are saved.

[0020] 3) Using Group A and Group B jacking structures in coordination to lift and lower the building can effectively reduce the risks of unforeseen situations that may occur during the lifting and lowering process. By locking the anchors on the Group A and Group B reaction beams in groups, the jacks on the upper part of the support columns can be replaced in groups, or the support columns of Group A or Group B can be extended in groups. The upper and lower support columns can be connected by welding or mechanical connection.

[0021] 4) By lifting and lowering the existing building, the construction space for foundation pit excavation and underground structure can be increased, ensuring the net height requirement for foundation pit construction, shortening the development cycle of underground space, reducing the protection risk of existing buildings during underground space development, and making construction convenient and safe.

[0022] 5) If conditions permit, the reaction platform and the first support within the influence range of the existing building can be designed and constructed together with the top beams and slabs of the underground structure. If necessary, part of the top slab of the underground structure can be constructed first as a construction operation platform to reduce the workload of dismantling the support after completion, thus saving resources and construction time. Attached Figure Description

[0023] Figure 1 The present invention provides a plan view of the support and support structure for in-situ jacking and lowering of existing buildings.

[0024] Figure 2 The present invention provides an elevation view of the support and support structure for in-situ jacking and lowering of existing buildings.

[0025] Figure 3 Construction drawings of retaining piles, engineering piles, column piles and columns.

[0026] Figure 4Excavation of the first layer of earthwork, construction of the first support (including reaction platform) outside the protection range of the building foundation, temporary protective wall beams, temporary support frames, and column replacement work conditions diagram.

[0027] Figure 5 Construction and replacement of beams and slabs - working condition diagram.

[0028] Figure 6 Installation diagram of the lifting structure (jacks, reaction beams, tie rods, anchors).

[0029] Figure 7 Diagram showing the condition of the existing building foundation under the replacement beam slab.

[0030] Figure 8 Lifting the existing building to the design elevation and constructing the supporting structure for the lower part of the beams and slabs.

[0031] Figure 9 Excavation of the foundation pit to the bottom, construction of the basement floor slab.

[0032] Figure 10 The construction process diagram of the underground structure involves the gradual removal of supports outside the affected area of ​​the beam replacement layer by layer.

[0033] Figure 11 Diagram showing the working conditions of the existing building being lowered to the top of the basement structure.

[0034] Figure 12 Figure 1 shows the working condition of the dismantling of the jacking structure, reaction platform, remaining supports, and columns.

[0035] Figure 13 Remove part of the supporting beams and slabs, and convert the supporting beams and slabs into permanent building foundation construction drawings.

[0036] Figure 14 Side view and plan layout of embodiment 1 of the lifting structure. Among them, (a) is a side view, (b) is a plan layout, and (c) is another plan layout.

[0037] Figure 15 Side view and plan layout of embodiment 2 of the lifting structure. Among them, (a) is a side view, (b) is a plan layout, and (c) is another plan layout.

[0038] Figure 16 Side view and plan layout of embodiment 3 of the lifting structure. Among them, (a) is the side view and (b) is the plan layout.

[0039] Figure 17 Side view and plan layout of embodiment 4 of the lifting structure. Among them, (a) is the side view and (b) is the plan layout.

[0040] Figure 18Example 1: Connection structure between reaction platform and lower support of replacement beam plate.

[0041] Figure 19 Example 2: Connection structure between reaction platform and lower support of replacement beam plate.

[0042] Figure 20 Example 3: Connection structure between reaction platform and lower support of replacement beam plate.

[0043] Figure 21 Schematic diagram of the lifting process in Example 1 of the lifting structure. (a) Locking the lifting structure A in preparation for lifting; (b) Lifting structure A is lifted; (c) Locking the lifting structure B, and the jacks in group A retract and the reaction beam descends; (d) Locking the lifting structure A, preparing for the next lifting stroke.

[0044] Figure 22 Schematic diagram of the lifting process in embodiment 2 of the lifting structure. (a) Locking the lifting structure A in preparation for lifting; (b) Lifting structure A is lifted; (c) Locking the lifting structure B, and the jacks in group A retract and the reaction beam descends; (d) Lifting structure B is lifted; (e) Locking the lifting structure A, and the jacks in group B retract and the reaction beam descends.

[0045] In the diagram, 1. Existing building (structure), 2. Foundation, 3. Column pile, 4. Column, 5. Reaction platform, 6. Internal building support, 7. Support outside the influence range of the replacement beam (support b), 8. Replacement beam, 9. Reserved hole, 10. Replacement column, 11. Jack, 12. Reaction beam, 13. Anchor, 14. Anchor rod, 15. Sleeve, 16. Tie rod, 17. Wall beam, 18. Temporary support frame, 19. Lower support of the replacement beam (support a), 20. Basement floor slab, 21. Underground structure, 22. Reinforcing bar connector, 23. Reinforcing bar, 24. Embedded part, 25. Connecting beam, 26. Horizontal limiting device. Detailed Implementation

[0046] The features of the present invention and other related features will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art.

[0047] There are two construction methods for foundation pit engineering: the forward construction method and the reverse construction method. The forward construction method and the reverse construction method are introduced below.

[0048] The first construction method involves: first, creating a slope or constructing a supporting structure (such as a diaphragm wall or pile foundation); then, excavating the foundation pit to the design bottom elevation in layers and sections; starting from the bottom of the pit, constructing the foundation slab, underground floor slab, side walls, and columns layer by layer from bottom to top, until the top floor; simultaneously, removing temporary supports from bottom to top. Features: intuitive procedures, mature technology, strong adaptability, and fast construction speed; requires the installation of numerous temporary horizontal supports or anchor bolts; the superstructure construction proceeds after the entire underground structure is completed.

[0049] Reverse construction method: First, construct the retaining structure (diaphragm wall or pile wall) and intermediate column piles; immediately after excavating one floor, pour the underground roof slab to serve as the first horizontal support; "excavate and build simultaneously" from top to bottom: after each layer of earthwork is excavated, the completed floor slab is used as the next horizontal support before pouring the next floor slab, until the bottom slab is completed; on the underground roof slab or the completed underground floors, the above-ground structure can be constructed simultaneously upwards, achieving "parallel construction from top to bottom". Features: Uses permanent structural beams and slabs "instead of supports," saving a large amount of temporary supports; allows for simultaneous construction from top to bottom, enabling earlier construction of the above-ground structure and shortening the overall construction period; underground structure construction is more difficult, and earthwork excavation efficiency is low; quality control is difficult, and risks are relatively concentrated.

[0050] As described in the background section, in-situ underpinning protection of a building requires first constructing underpinning slabs and piles to protect the building, followed by the construction of the foundation pit support structure and earthwork excavation. The foundation pit is often constructed using the reverse construction method. This method first forms the basement roof slab, serving as the first horizontal support and platform for supporting the existing building above. However, the excavation space is narrow and enclosed, construction is restricted, the underground structure construction period is long, quality control is difficult, and risks are concentrated, which can exacerbate the adverse effects on the existing building.

[0051] Furthermore, in the reverse construction method for foundation pits, the floor slabs serve as the horizontal support structure for the pit. If the floor slabs within the existing building foundation protection area are constructed before the floor slabs in other areas, the first-constructed beams require a large number of reinforcing bars to connect with the beams constructed later. This makes the construction of the remaining beams inconvenient, and the connection between the beams and slabs constructed sequentially is difficult. In addition, the contact surfaces of the underground structural beams and slabs constructed sequentially will form a large number of construction joints, making quality control difficult. The long construction period increases the risks associated with foundation pit construction and building protection.

[0052] Therefore, this implementation method focuses on how to overcome numerous difficulties and complete the construction of the existing building's in-situ jacking and lowering support and underground addition using the sequential construction method, thereby shortening the construction period of the foundation pit excavation and underground structure construction and reducing interference with the building.

[0053] like Figures 1-22As shown in the figure, 1 to 26 are respectively: 1. Existing building (structure), 2. Foundation, 3. Column pile, 4. Column, 5. Reaction platform, 6. Internal building support, 7. Support outside the influence range of the replacement beam slab (support b), 8. Replacement beam slab, 9. Reserved hole, 10. Replacement column, 11. Jack, 12. Reaction beam, 13. Anchor, 14. Sleeve, 15. Tie rod, 16. Wall clamp beam, 17. Temporary support frame, 18. Lower support of the replacement beam slab (support a), 19. Basement floor slab, 20. Underground structure, 21. Reinforcing bar connector, 22. Reinforcing bar, 23. Embedded part, 24. Connecting beam, 25. Horizontal limiting device, 26. Example

[0054] See Figures 1-2 , Figures 1-2 This illustration shows a schematic diagram of the support and underpinning structure for the in-situ jacking and lowering of an existing building during the construction process. Figure 1 It is a floor plan. Figure 2 It's an elevation view.

[0055] Figures 3-13 It demonstrates the steps of the entire construction process.

[0056] like Figures 3-13 As shown in this embodiment, an existing building's in-situ jacking and lowering support structure with underground floor addition is described. The support structure includes a reaction platform 5, internal building supports 6, support beams 8, wall beams 17, temporary support frames 18, and lower supports a19 for the support beams 19. The jacking structure is divided into groups A and B, including support columns 10, jacks 11, reaction beams 12, anchors 13, and tie rods 16.

[0057] The materials, models, dimensions, quantities, and spacing of the columns 3, columns 4, reaction platforms 5, replacement beams 8, supports, wall clamps 17, temporary support frames 18, replacement columns 10, jacks 11, reaction beams 12, anchors 13, and tie rods 16 used in this embodiment are determined according to the design.

[0058] Implementation method: The specific implementation method of this example is described below with reference to the accompanying drawings: like Figure 3 As shown, existing building 1 is located within the impact area of ​​underground space development. Before construction, the site must be leveled and obstacles such as hard surfaces removed. The foundation pit retaining structure, engineering piles (not shown in the diagram), column piles 3, and columns 4 are constructed according to design requirements. Due to the limited indoor space, the column piles and columns distributed indoors can be installed using low-headroom, miniaturized equipment. The engineering piles and column piles 3 can be bored piles or precast piles, etc. Columns 4 are inserted into the column piles 3 to a certain depth. Columns 4 can generally be steel columns, structural steel, lattice columns, etc. Columns 4 can be constructed in sections by hoisting, and the upper and lower sections can be joined by welding or mechanical connection.

[0059] like Figure 4 As shown, a certain range of soil around the foundation 2 of the existing building 1 is retained. The soil outside and inside the existing building 1 is excavated at a slope to the bottom of the first supports 6 and 7, with a certain safety distance maintained between the top of the slope and the foundation of the existing building 1. The reaction platform 5, the internal support 6 of the existing building 1, the external support (support b) 7 of the supporting beam slab, the wall beam 17, and the temporary support frame 18 are constructed simultaneously. The reaction platform 5 serves as the installation platform for the lifting structure and the operation platform for the lifting construction. The wall beam 17 is located on both sides of the wall of building 1 and can be fixedly connected to the wall of building 1 through a (pull-through) structure (such as a wall beam, not shown in the attached diagram). During the construction of the wall beam, holes can be drilled at certain intervals in the wall using methods such as water drilling or partial demolition. The wall beam can be made of steel, concrete beams, or a combination of both. To ensure a firm connection between the wall beam 17 and the existing building 1, prestressed tendons can be installed inside the wall beam. Once the strength of the wall beam and the wall beam 17 reaches the design requirements, the prestressed tendons are tensioned and locked using anchors.

[0060] The support column 10 is fixedly connected to the reaction platform 5. Pre-embedded parts (not shown in the attached diagram) can be installed on the upper part of the reaction platform 5 beforehand. After the reaction platform 5 reaches its design strength, the support column 10 is fixedly connected to the pre-embedded parts by welding or mechanical connection. Alternatively, the support column 10 can be cast directly as a single unit with the reaction platform 5 during its construction. The support column 10 can be a steel column, structural steel, concrete component, etc. If a steel column is used, concrete can be poured inside the support column 10 to improve its strength and load-bearing capacity.

[0061] If conditions permit, the reaction platform and the first support within the influence range of the existing building can be designed and constructed together with the top beams and slabs of the underground structure. If necessary, part of the basement roof slab can be constructed first as a construction operation platform to reduce the workload of dismantling the support after completion, thus saving resources and construction time.

[0062] like Figure 5 As shown, a replacement beam 8 is cast through a pre-drilled hole 9 on the outside of the replacement column 10, ensuring that the replacement column 10 and the replacement beam 8 are not connected and can move vertically relative to each other. The replacement beam 8 is fixedly connected to the wall beam 17. Anchor rods 14 are pre-embedded on the replacement beam 8, and the anchor rods 14 can be rebar installed later. To ensure a fixed connection between the wall beam 17 and the replacement beam 8, steel bars can be pre-reserved at the overlap position between the wall beam 17 and the replacement beam 8, or the connection can be achieved through rebar installation.

[0063] like Figure 6 As shown, the jacking structure is installed. The jacking structure corresponding to the same reaction platform 5 includes group A and group B. Group A contains one or more support columns, and each support column is equipped with one jack on top. Group B contains one or more support columns, and jacks are installed on the support columns as needed.

[0064] In the first and second embodiments, as Figure 14 and 15 As shown, when Group A consists of one supporting column and Group B contains two or more supporting columns, Group B is evenly distributed on both sides of Group A, or Group B is evenly distributed around Group A. The number and arrangement of the lifting structure and the supporting columns of Groups A and B included in each lifting structure can be comprehensively considered based on factors such as the load distribution characteristics of the existing building 1, the reaction platform 5, the supporting beam 8, and the form and arrangement of supports 6 and 19, to ensure that building 1 can be lifted and lowered evenly and smoothly.

[0065] In the third embodiment, when group A contains one replacement column and group B also contains one replacement column, such as Figure 16 As shown.

[0066] In the fourth embodiment, when group A contains two support columns and group B also contains two support columns, groups A and B are arranged uniformly and symmetrically, such as... Figure 17 As shown.

[0067] Specifically, jack 11 is located on support column 10, reaction beam 12 is located on jack 11, and tie rods 16 are symmetrically distributed on both sides of jack 11. The lower part of tie rod 16 is connected to anchor rod 14 through sleeve 15, and the upper part of tie rod 16 is connected to anchor 13. Tie rod 16 passes through a reserved hole on reaction beam 12. Anchor 13 can be a nut, clamp, or through-hole jack, etc.

[0068] like Figure 7 As shown, the foundation 2 of the existing building 1 under the supporting beam slab 8 is removed. When there is insufficient construction space, the building 1 can be lifted to the preset height first, and then the foundation 2 can be removed.

[0069] like Figure 8 As shown, the existing building 1 is lifted to the design height through the control system, and the lower support a19 of the construction support beam is replaced. If there is a local tilt in building 1 before lifting, the lifting amount of the large settlement area can be increased through differentiated lifting to achieve the purpose of correcting the tilt of building 1.

[0070] In one embodiment, combined with append Figure 18 This demonstrates one of the structures for connecting the reaction platform 5 to the lower support of the supporting beam 8. It uses steel reinforcement connector 22, steel reinforcement 23, and support a19. Steel reinforcement 23 is reliably connected to steel reinforcement connector 22 and support a19. Support a19 can be cast on site or is a precast component.

[0071] In the second embodiment, in conjunction with the appendix Figure 19 The second structure for connecting the reaction platform 5 with the lower support of the supporting beam 8 is shown. It uses steel bars 23, which are pre-reserved or later implanted on the side of the reaction platform 5 and reliably connected with the steel bars (not shown) in the support a19, and the support a19 is poured.

[0072] In the third embodiment, in conjunction with the appendix Figure 20 This demonstrates a third type of structure for the connection between the reaction platform 5 and the lower support of the supporting beam 8. It uses embedded parts 24, which are embedded in the reaction platform 5. The support a19 is a steel support or a prefabricated component, which is connected and fixed to the reaction platform through the embedded parts.

[0073] In one embodiment, combined with append Figure 21 When preparing for jacking, the anchor 13 on the reaction beam 12 of group A is locked. The reaction beam 12 transmits the jacking force of the jack 11 to the anchor 13, and then to the tie rod 16. The tie rod 16 drives the supporting beam 8 and the building 1 to rise. When the jack 11 of group A completes one stroke, the anchor 13 on the reaction beam 12 of group B is locked, the jack 11 of group A retracts, and the reaction beam 12 falls back. Since the reaction beam 12 of group B and the tie rod 16 are locked by the anchor 13, the supporting beam 8 is locked by the tie rod 16 of group B, thus limiting the fall of the supporting beam 8 and the building 1. The jack 11 of group A retracts, and the reaction beam 12 falls back into place. The anchor 13 on the reaction beam 12 of group A is locked, and the next stroke begins. In the second embodiment, in conjunction with the appendix Figure 22 When Group B is also equipped with jacks 11, after Group A completes one stroke, the anchor 13 on the reaction beam 12 of Group B is locked, and the jacks 11 of Group B are lifted. The reaction beam 12 transmits the lifting force of the jacks 11 to the anchor 13, and the anchor 13 transmits the lifting force to the tie rod 16. The tie rod 16 will lift the supporting beam 8 and the building 1. When the jacks 11 of Group A are retracted, the reaction beam 12 falls back simultaneously, and the anchor 13 on the reaction beam 12 of Group A is locked. Group A and Group B lock and lift alternately, which can realize the relay lifting of the building 1.

[0074] By coordinating the lifting structures of Group A and Group B, the existing building 1 can be lifted to its designed height. Conversely, the existing building 1 can be lowered back down.

[0075] The lower support a19 of the supporting beam is fixedly connected to the reaction platform 5 at both ends. The support a19 can be a concrete support or a steel support. When a concrete support is used, steel reinforcement connectors 22, steel reinforcement 23, or post-installed reinforcement can be pre-embedded at the corresponding positions on the reaction platform 5. When a steel support or precast component is used, steel reinforcement connectors 22 or pre-embedded parts 24 can be installed on the reaction platform 5.

[0076] like Figure 9 As shown, the foundation pit is excavated sequentially to the bottom, and the basement floor slab is constructed.

[0077] like Figure 10As shown, the supports b7 outside the influence range of the replacement beam 8 are removed layer by layer, and the underground structure 21 is constructed. During the excavation of the foundation pit and the construction of the underground structure, the existing building 1 can be lowered back onto the reaction platform 5 as needed, or a limiting pad (not shown in the attached diagram) can be installed between the replacement beam 8 and the reaction platform 5 as a limiting protection device to avoid unexpected situations (such as jack failure) or extreme weather (such as typhoons) during the foundation pit construction, which could lead to differential deformation of the replacement beam 8 or even instability of the lifting structure.

[0078] like Figure 11 As shown, after the underground structure 21 is completed, the existing building 1 will be lowered back onto the top slab of the underground structure 21.

[0079] like Figure 12 As shown, remove the lifting device, reaction platform 5, remaining supports, and column 4.

[0080] like Figure 13 As shown, a portion of the replacement beam slab 8 is removed, and the remaining replacement beam slab 8 is converted into the permanent foundation of the existing building 1. Alternatively, a new foundation can be built on the top slab of the underground structure and connected to the existing building. Depending on the needs, connecting beams 25 can be installed between the remaining replacement beam slabs 8 to improve the overall stability of the permanent foundation. A horizontal limiting device 26 can be installed between the top slab of the underground structure 21 and the replacement beam slab 8, and the horizontal limiting device 26 is fixedly connected to the top slab structure 21. The horizontal limiting device 26 can be installed at the position required by the design, or it can be installed by using part of the opening 9, reinforcing bars are installed on the top slab of the underground structure in the opening 9, or part of the replacement column 10 in the opening 9 is retained, and then concrete is poured into the opening 9 to form the horizontal limiting device 26.

[0081] In this embodiment, the foundation pit retaining structure, support structure, wall beams, and temporary support frames outside the existing building's foundation protection area are constructed simultaneously. The wall beams and temporary support frames form a self-contained protection system. The foundation pit columns, columns, supports, and reaction platform constructed simultaneously outside the foundation protection area form a stable structural system, providing a flat and stable support structure and operating platform for the lifting and lowering of the existing building. This overcomes the limitation of traditional techniques that require constructing the underpinning structure before the foundation pit support. Before constructing the support within the building's foundation protection area, the existing building has already undergone underpinning protection before lifting, leaving relatively few remaining support components under the foundation. Precast components can be used when conditions permit, allowing the foundation pit horizontal support system to quickly form a unified structure. In the event of extreme weather such as typhoons during construction, it is not necessary to wait for all support construction to be completed and cured to the design strength; the existing building can be lowered onto the completed reaction platform at any time, ensuring high safety. The reverse construction method for foundation pits typically uses the underground structural floor slab as the support structure for the foundation pit. When construction space is insufficient, the existing building must first be lifted to a certain height. Only after the top floor slab of the underground structure is constructed and cured to its design strength can the building be lowered back onto the top slab. During the construction of the underground structural floor slab, the horizontal constraint of the vertical support columns is weak, and the existing building needs to be suspended on the vertical support columns for a long time, which is risky.

[0082] Furthermore, in the reverse construction method, the vertical support columns of the underground structure also serve as the replacement columns for the existing building. The location and number of these replacement columns are limited by the underground structure. However, this invention allows for the installation of multiple sets of replacement columns and lifting structures on the same reaction platform. The number of replacement columns and lifting structures is not limited by the vertical support columns, resulting in a relatively smaller number of vertical support columns and more flexible arrangement. Simultaneously, the reaction platform meets the needs of both lifting and lowering operations and reduces the limitations imposed on foundation pit construction by the underground beam-slab structure serving as support in the reverse construction method. In the reverse construction method, the underground structural floor slabs serve as the support structure for the foundation pit, limiting the clear height of the underground structure and making it unsuitable for underground structures with high floor heights. The lifting structure of this invention can raise the existing building to a higher height through relay lifting, ensuring sufficient space for the forward construction of the foundation pit and meeting the needs of underground spaces with high floor heights. Overall, this invention can employ the forward construction method, ensuring the safety and stability of the existing building during replacement construction while reducing the protection time and risks of the existing building during underground space development and construction.

[0083] Although the concept and embodiments of the present invention have been described in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can be made to the present invention without departing from the scope of the claims. These modifications may involve variations in the types, materials, quantities, arrangements, spacing, and dimensions of existing buildings, foundations, piles, columns, reaction platforms, supporting beams, supports, supporting columns, tie rods, jacks, reaction beams, anchors, etc., and therefore will not be elaborated upon here. Those skilled in the art can make their own modifications or improvements based on this, and all such modifications or improvements should fall within the scope of protection claimed by the present invention without departing from the overall concept of the invention.

Claims

1. A construction method for in-situ jacking and lowering underpinning protection and underground layer addition of existing buildings, characterized in that, Includes the following steps: S1, Construction pit retaining structure; Constructing column piles (3) around the existing building (1), and column (4) on the top of the column piles (3); S2. Retain the soil around the foundation (2) of the existing building, and excavate the soil outside and inside the building on a slope to the bottom of the first support. Ensure a safe distance between the top of the slope and the vertical components of the building wall or column. Then, simultaneously construct the reaction platform (5) on both sides of the vertical component, the internal support (6) of the building connected to the adjacent reaction platform (5), the wall beam (17) on both sides of the bottom of the vertical component, and the temporary support frame (18) above the wall beam (17) for supporting the vertical component. S3. Install the support column (10) on the reaction platform (5) and fix the support column (10) to the reaction platform (5); S4. Cast the supporting beam plate (8) in the reserved hole (9) on the outside of the supporting column (10) to ensure that the supporting column (10) and the supporting beam plate (8) are not connected and can move up and down relative to each other; the supporting beam plate (8) is fixedly connected to the wall beam (17); anchor rods (14) are pre-embedded on the supporting beam plate (8) or anchor rods (14) are planted later. S5. Install the lifting structure. The lifting structures corresponding to the same reaction platform (5) are divided into group A and group B. In step S5, group A contains one or more support columns (10), and one jack (11) is placed on top of each support column (10); group B contains one or more support columns (10), and jacks (11) are selectively placed on the support columns (10) as needed; the number and arrangement of the lifting structures are comprehensively considered based on the load distribution of the existing building (1), the form of the support beams (8), and the arrangement of the supporting structures to ensure that the building can be lifted smoothly; The jack (11) is located on the support column (10), the reaction beam (12) is located on the jack (11), and the tie rods (16) are symmetrically distributed on both sides of the jack (11). The lower part of the tie rod (16) is connected to the anchor rod (14) on the support beam plate (8) through the sleeve (15), and the upper part of the tie rod (16) is connected to the anchor (13). The tie rod (16) passes through the reserved hole on the reaction beam (12). The anchor (13) is a nut, clamp or through-hole jack. When Group A has jacks but Group B does not, during the lifting of Group A, the anchor (13) on the reaction beam (12) of Group A is locked. The reaction beam (12) transmits the lifting force of the jack (11) to the anchor (13), and the anchor (13) transmits the lifting force to the tie rod (16). The tie rod (16) will lift the replacement beam (8) and the existing building (1). When the jack (11) of Group A completes one stroke, the anchor on the reaction beam (12) of Group B is locked. (13) The A group jack (11) retracts and the reaction beam (12) falls back; since the B group reaction beam (12) and tie rod (16) are locked by the anchor (13), the replacement beam plate (8) is locked by the tie rod (16) of the B group, thus restricting the fall of the replacement beam plate (8) and the building (1); the A group jack (11) retracts and the reaction beam (12) falls back into place, locking the anchor (13) on the A group reaction beam (12), and the next stroke begins; When Group B is also equipped with jacks (11), after Group A completes one stroke, the anchor (13) on the reaction beam (12) of Group B is locked. The jacks (11) of Group B are lifted, and the reaction beam (12) transmits the lifting force of the jacks (11) to the anchor (13). The anchor (13) transmits the lifting force to the tie rod (16). The tie rod (16) will lift the replacement beam (8) and the existing building (1). The jacks (11) of Group A retract, and the reaction beam (12) falls back simultaneously, locking the anchor (13) on the reaction beam (12) of Group A. Group A and Group B lock and lift alternately to achieve relay lifting of the existing building (1). Through the cooperation of the lifting structures of Group A and Group B, the lifting and lowering of the existing building (1) is achieved. S6. Remove the foundation (2) below the supporting beam slab (8); S7. The existing building (1) is lifted to the design height by the lifting and lowering control system; the support a (19) under the construction of the replacement beam (8) is fixedly connected to the reaction platform (5); S8. Excavate the foundation pit to the bottom of the pit and construct the basement floor slab (20). S9. Remove the support b (7) outside the influence range of the replacement beam slab (8) layer by layer, and construct the underground structure (21). S10. After the underground structure (21) is completed, the existing building (1) will be lowered back onto the top slab of the underground structure. S11. Remove the lifting structure, reaction platform (5), remaining supports and columns (4). S12. Remove part of the replacement beam (8) and transform the replacement beam (8) into the permanent foundation of the existing building (1).

2. The construction method for in-situ jacking, lowering, and underpinning protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S1, column piles (3) and columns (4) on top of the column piles (3) are also constructed inside the building; and the column piles (3) and columns (4) distributed in the interior are implemented using low-headroom miniaturized equipment.

3. The construction method for in-situ jacking and lowering replacement protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S2, the reaction platform (5) serves as the installation platform for the jacking structure and the operation platform for the jacking construction; the wall clamping beam (17) is located on both sides of the building wall and is fixedly connected to the building wall through the wall-penetrating structure.

4. The construction method for in-situ jacking, lowering, and underpinning protection and underground layer addition of existing buildings as described in claim 3, characterized in that: Prestressed tendons are installed inside the through-wall structure. Once the strength of the through-wall structure and the wall beam (17) reaches the design requirements, the prestressed tendons are tensioned and locked with anchors.

5. The construction method for in-situ jacking and lowering replacement protection and underground layer addition of existing buildings as described in claim 4, characterized in that: The reaction platform (5), the first support, and the top beams and slabs of the underground structure are designed and constructed together. The basement slab is constructed first as a construction operation platform to reduce the workload of dismantling the support after completion.

6. The construction method for in-situ jacking, lowering, and underpinning protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S3, firstly, embedded parts are set on the upper part of the reaction platform (5), and the support column (10) is fixed by welding or mechanical connection with the embedded parts; or when casting the reaction platform (5), the support column (10) and the reaction platform (5) are directly cast into one piece.

7. The construction method for in-situ jacking and lowering replacement protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S4, steel bars are reserved at the overlap position of the wall beam (17) and the supporting beam (8), or they are connected by rebar installation.

8. The construction method for in-situ jacking, lowering, and underpinning protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S7, the support a (19) at the bottom of the supporting beam plate is a concrete support or a steel support; when it is a concrete support, steel bars are reserved or rebars are installed at the corresponding position on the reaction platform; when it is a steel support, embedded parts are set on the reaction platform.

9. The construction method for in-situ jacking and lowering replacement protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S9, during the excavation of the foundation pit and the construction of the underground structure, the existing building is temporarily lowered onto the supporting reaction platform (5), or a limiting pad is set between the replacement beam (8) and the reaction platform (5) as a protective device to avoid unexpected situations or extreme weather affecting the lifting structure during construction, and to prevent differential deformation of the replacement beam or even instability of the lifting structure.

10. The construction method for in-situ jacking, lowering, and underpinning protection and underground layer addition of existing buildings as described in claim 1, characterized in that: In step S12, a horizontal limiting device is installed between the basement roof slab and the replacement beam slab (8) that has been converted into a permanent foundation; or a new foundation is built on the basement roof slab and connected to the existing building.

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