Method for reinforcing a foundation with differential settlement

Abstract

This invention discloses a method for reinforcing a foundation with uneven settlement, comprising: step 1, adding a first pile foundation (1); step 2, constructing a connecting pile cap (3) to connect the first pile foundation (1) with the original second pile foundation (2); wherein the connecting pile cap (3) is connected to the pile cap (21) of the second pile foundation (2). This method for reinforcing a foundation with uneven settlement improves the overall bearing capacity and deformation resistance of the foundation.

Description

Technical Field

[0001] This invention relates to the field of building foundation reinforcement, and more specifically, to a method for reinforcing foundations with uneven settlement. Background Technology

[0002] Currently, deep layers of shifting sand and silt are widely distributed along my country's coastal areas, reaching depths of hundreds of meters in some places. Influenced by the tidal forces caused by lunar gravity, the seawater in coastal areas experiences periodic rises and falls. During low tide, a large amount of free water in the soft soil layer is carried away with the receding water level, leading to increased effective stress in the soil and consolidation shrinkage. This also easily creates localized cavities or soil hollowing at and around the foundations of buildings. Under the coupled effect of repeated water level changes and soil deformation, existing building foundations are highly susceptible to uneven settlement, which can lead to serious engineering accidents such as cracking of superstructure walls, breakage of beam-column joints, and even complete collapse, severely threatening the lives and property of residents.

[0003] To address the aforementioned foundation settlement issues, commonly used reinforcement methods in engineering projects include anchored static pressure pile reinforcement, micropile reinforcement, foundation grouting reinforcement, and pile-to-base beam replacement. Among these, anchored static pressure piles utilize the building's own weight as a reaction force, pressing precast pile sections into the soil segment by segment. This method offers advantages such as lightweight construction equipment and the ability to operate in confined indoor or outdoor spaces, making it one of the mainstream methods for reinforcing existing building foundations. Micropiles are formed through small-diameter drilling and are suitable for conditions with limited construction space or complex underground pipelines. Grouting reinforcement involves injecting cement grout and other binding materials into the foundation soil to fill pores and compact the soil, thereby improving the bearing capacity of shallow foundations. Summary of the Invention

[0004] The purpose of this invention is to provide a reinforcement method for foundations with uneven settlement, thereby improving the overall bearing capacity and deformation resistance of the foundation.

[0005] To achieve the above objectives, the present invention provides a method for reinforcing foundations with uneven settlement, comprising: Step 1: Add the first pile foundation; Step 2: Construct a connecting pile cap to connect the first pile foundation with the second pile foundation on the original building site; Among them, the pile cap connecting the pile cap and the pile cap of the second pile foundation are connected.

[0006] Preferably, a preload is provided in the connecting pier along the height direction.

[0007] Preferably, a preload is provided in the first pile foundation along the height direction.

[0008] Preferably, the first pile foundation extends into the silt.

[0009] Preferably, in step 1, the first pile foundation is located outside the original building; Multiple first pile foundations are set up, and the multiple first pile foundations are set up around the outer perimeter of the original building.

[0010] Preferably, the connecting pile caps are connected by pile cap beams.

[0011] Preferably, in step 1, the first pile foundation is located inside the original building; One connecting pile cap is set, and multiple first pile foundations are set in the middle of the connecting pile cap.

[0012] Preferably, the bottom surface of the connecting pile cap is connected to the top surface of the pile foundation pile cap; The connecting pile cap and the pile foundation pile cap have at least some overlapping areas.

[0013] Preferably, a crossbeam and a longitudinal beam are provided on the back of the connecting base, and the crossbeam and the longitudinal beam are arranged along a first direction and a second direction of the connecting base, with the first direction being perpendicular to the second direction.

[0014] According to the above technical solution, this invention adds new pile foundations around the original building foundation or in the indoor space, and then pours a reinforced concrete connecting pile cap on top of the new pile foundations. The connecting pile cap is connected to the original pile foundation pile cap by methods such as roughening, rebar installation, and rebar welding to form a whole. By adding new pile foundations to share the upper load, the load burden of the original pile foundation is effectively reduced, and the foundation settlement is slowed down; by connecting the new and old pile foundations into a whole through the connecting pile cap, the two work together to improve the overall bearing capacity and deformation resistance of the foundation.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a floor plan of the building after reinforcement in Example 1; Figure 2 This is a detailed drawing of a first pile foundation; Figure 3 This is a detailed drawing of a grouting conduit. Figure 4 This is a schematic diagram showing the connection between the pile cap and the pile foundation cap; Figure 5 yes Figure 4 Cross-sectional view; Figure 6 This is a floor plan of the building after reinforcement in Example 2; Figure 7 yes Figure 6Cross-sectional view.

[0017] Explanation of reference numerals in the attached figures 1. First pile foundation; 2. Second pile foundation; 3. Connecting pile cap; 21. Pile foundation pile cap; 41. Pile cap beam; 42. Horizontal beam; 43. Longitudinal beam Detailed Implementation The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0018] In this invention, unless otherwise stated, directional terms included in the terminology represent only the orientation of the term in its normal use or as commonly understood by those skilled in the art, and should not be regarded as a limitation on the term.

[0019] See Figure 1 A method for reinforcing foundations with uneven settlement includes: Step 1: Add the first pile foundation 1; The first pile foundation 1 is a new pile foundation added outside the existing building foundation to share the load of the original foundation. The first pile foundation 1 can be a cast-in-place pile, a steel pipe pile, or other types of pile foundations, depending on the construction conditions.

[0020] Step 2: Construct a connecting pile cap 3 to connect the first pile foundation 1 with the second pile foundation 2 on the original building site; The function of the connecting pile cap 3 is to connect the newly added first pile foundation 1 with the original second pile foundation 2 of the building into a whole, so that the newly added pile foundation can work together with the original foundation to jointly bear the load of the superstructure.

[0021] Among them, the pile cap 3 is connected to the pile cap 21 of the second pile foundation 2.

[0022] The pile cap 3 is connected to the pile cap 21 of the second pile foundation 2 to ensure reliable force transmission between the new structure and the original structure.

[0023] New pile foundations are added around the original building foundation or within the interior space. A reinforced concrete connecting pile cap 3 is then poured on top of the new pile foundations. The connecting pile cap 3 is connected to the original foundation's pile cap 21 through methods such as roughening, rebar installation, and rebar welding to form a unified structure. By sharing the load from the superstructure with the new pile foundations, the load burden on the original pile foundations is effectively reduced, mitigating foundation settlement. Furthermore, the connecting pile cap 3 integrates the old and new pile foundations, enabling them to work together and improving the overall bearing capacity and deformation resistance of the foundation.

[0024] In this embodiment, preferably, a pre-tension force along the height direction is provided in the connecting bearing 3.

[0025] When irregular subsidence occurs in the foundation, the first pile 1 and the second pile 2 are hoisted back to their original positions by the pre-tension within the connecting pile cap 3, thus preventing the first pile 1 or the second pile 2 from sinking as well.

[0026] A prestressing force along the height direction is set within the connecting pile cap 3, that is, prestressed steel bars or prestressed steel strands are installed in the connecting pile cap 3, and prestressing stress along the height direction of the pile cap is generated by tensioning. When the receding tide causes the foundation soil to settle, the prestressing force within the connecting pile cap 3 can exert an upward pulling force on the first pile 1 and the second pile 2, restricting the piles from displacing downward with the soil.

[0027] Prestressed steel bars are arranged along the height direction within the connecting pile cap 3. The prestressed steel bars are tensioned using a tensioning device to generate prestress within the connecting pile cap 3. When the foundation settles, the prestress is converted into an upward pulling force on the pile foundation, maintaining the pile foundation at its original design elevation. The beneficial effects of this scheme are: the prestress can actively resist the downward pull of foundation settlement on the pile foundation, effectively controlling uneven settlement; compared to traditional foundations that passively bear settlement, the prestressed connecting pile cap 3 can actively regulate the vertical displacement of the foundation, improving the foundation's ability to resist uneven settlement caused by water level changes.

[0028] In this embodiment, preferably, a preload is provided in the first pile foundation 1 along the height direction.

[0029] This claim further defines the structural features of the first pile foundation 1. The first pile foundation 1 is provided with prestress along its height direction, that is, prestressed steel bars are installed within the pile body, and prestress is applied to the pile body using post-tensioning or pre-tensioning methods, generating pre-compression stress within the pile body. When the soil around the pile settles due to changes in water level, the prestress within the pile body can enhance the pile foundation's pull-out resistance, and together with the frictional force between the pile foundation and the soil, jointly resist the downward load generated by soil settlement on the pile foundation.

[0030] For cast-in-place piles, prestressed steel bars can be arranged longitudinally on the pile reinforcement cage. After pile formation, tension is applied to the prestressed steel bars using the post-tensioning method. For steel pipe piles, prestressed steel bars can be installed inside the steel pipe and tension is applied. The application of prestress puts the pile body in a pre-compression state. When the soil settles and generates a downward load, the pre-compression stress can offset part of the downward stress.

[0031] The pre-tension of the pile body enhances the pull-out bearing capacity of the pile foundation, enabling the pile foundation to remain stable when the soil settles; the pre-tension and the side friction of the pile work together to form a dual pull-out resistance mechanism, effectively resisting the settlement of the pile foundation caused by changes in water level.

[0032] In this embodiment, preferably, the first pile foundation 1 extends into the silt.

[0033] Preferably, the first pile foundation 1 extends into the silt for a length of not less than 50m, meaning the pile foundation needs to penetrate the shallow soft soil and penetrate deep into the silt. In coastal areas, the deep layers of quicksand and silt can reach depths of hundreds of meters. A pile foundation extending into the silt for a length of not less than 50m ensures that the pile foundation has sufficient surface area to contact the silt, thereby generating sufficient friction. When water level changes cause soil subsidence, the friction between the pile foundation and the silt can generate a pull-out effect on the pile foundation, preventing it from sinking along with the soil.

[0034] Ideally, the depth of the pile foundation should be determined based on geological survey data to ensure that the pile tip enters a reliable bearing layer or has sufficient pile side friction area. Long piles penetrate deep into the silt layer, using the friction between the pile and the soil to provide pull-out resistance, anchoring the pile foundation in the deep soil. When the shallow soil settles due to water level changes, the friction of the soil around the deep pile can effectively restrain the vertical displacement of the pile foundation, achieving the technical effect of resisting settlement.

[0035] In this embodiment, preferably, in step 1, the first pile foundation 1 is located outside the original building; Multiple first pile foundations 1 are set up, and multiple first pile foundations 1 are set up around the outer perimeter of the original building.

[0036] The first pile foundation 1 is located outside the original building, that is, the new pile foundation is arranged along the perimeter of the building. Multiple first pile foundations 1 are arranged around the outer perimeter of the original building to form a pile group surrounding the foundation of the original building. Preferably, the second pile foundation 2 located at the corner corresponds to two first pile foundations 1, that is, at each corner of the building, there is originally one second pile foundation 2, and two new first pile foundations 1 are added accordingly. The two first pile foundations 1 are arranged along a first direction and a second direction, respectively. The first direction is perpendicular to the second direction, that is, along the two mutually perpendicular outer wall directions of the building.

[0037] New cast-in-place piles were added at each independent column foundation location around the building's perimeter, with two additional piles at the corners, arranged in two directions respectively. After the piles were constructed, cement grout was injected into the pile tip and sides through grouting pipes embedded in the piles. The grout penetrated and filled the soil pores, forming an enlarged head at the pile tip and a cement-soil reinforced body on the pile sides. Multiple first pile foundations were installed around the building's perimeter, ensuring the reinforcement covered the entire building foundation, providing comprehensive reinforcement and protection. Two piles at the corners were connected to the original pile cap in two directions, enhancing the settlement resistance of this critical corner location.

[0038] Preferably, the first pile foundation 1 is constructed using a post-grouting method. Post-grouting technology can significantly improve the bearing capacity and pull-out resistance of the cast-in-place pile, enabling the pile foundation to better resist settlement caused by water level changes. When constructing using the post-grouting method, cement grout is injected into the pile end and pile side through a pre-embedded grouting pipe after pile formation, thereby improving the bearing capacity of the pile foundation.

[0039] In this embodiment, preferably, the connecting piers 3 are connected by pier beams 41.

[0040] In one embodiment, the pile cap beam 41 connects the connecting pile caps 3 sequentially to form an integral pile cap platform, thereby enabling all pile caps to share the load and resist foundation settlement. Reinforced concrete pile cap beams 41 are installed between adjacent connecting pile caps 3, connecting them in series. The pile cap beam 41 connects the connecting pile caps 3 sequentially to form an integral pile cap platform, transforming the originally independent pile foundation pile caps into a unified spatial load-bearing system, where all pile caps jointly bear the superstructure load and resist foundation settlement.

[0041] Formwork is erected, reinforcing bars are tied, and concrete is poured between adjacent connecting pile caps 3 to form a reinforced concrete pile cap beam 41. The reinforcing bars of the pile cap beam 41 are reliably connected to the reinforcing bars of the connecting pile caps 3, and the concrete is poured together to form a whole. The pile cap beam 41 connects the connecting pile caps 3 into a whole, improving the overall rigidity of the foundation, enabling the pile foundations to work together, and effectively resisting uneven deformation.

[0042] In another implementation, based on the building structure characteristics and settlement observation data, the foundation is divided into several groups. The connecting foundations 3 within each group are connected by foundation beams 41, and there are no connecting components between groups. The advantages of this scheme are that multiple foundation platforms can independently bear the load, avoiding excessive additional stress inside the structure due to excessive constraints, and enabling each platform to autonomously adjust its stress state according to local foundation conditions, thus improving adaptability.

[0043] Example 1: Let's take a five-story dormitory building in a coastal area as an example.

[0044] The original foundation of the dormitory building used 600mm diameter pipe piles with pile caps, i.e., one pile per pile cap, with the pipe piles penetrating approximately 55m into the silt layer. Later, due to tidal changes causing uneven soil settlement, the foundation needed to be reinforced.

[0045] Step 1: Add the first pile foundation 1.

[0046] In this embodiment, the first pile foundation 1 is located outside the existing building. Specifically, a row of cast-in-place piles is added around the existing building's pile foundation as the first pile foundation 1. The cast-in-place piles are constructed using a bored pile construction process. After the pile driver is in place, a casing is installed, and drilling is performed using mud slurry. The drilling depth needs to penetrate a thick layer of silt and soft soil and reach a reliable bearing layer. The pile length is determined based on geological conditions. After drilling, the hole is cleaned, a reinforcing cage is lowered, and concrete is poured to form the pile. The pile driver is typically tens of meters high. Due to the large outdoor space of the building, the pile driving equipment can be operated in the available space. The first pile foundation 1 extends into the silt, with a length of 54m extending into the silt. This utilizes the friction between the first pile foundation 1 and the silt to achieve a pull-out resistance effect, resisting settlement caused by water level changes.

[0047] The first pile foundation 1 was constructed using the post-grouting method. Post-grouting means that after the pile is formed, cement grout is injected under high pressure into the pile end and the soil on the side of the pile through a grouting pipe pre-embedded in the pile. The specific operation is as follows: a grouting pipe is welded longitudinally on the reinforcing cage, with the bottom of the grouting pipe extending out of the bottom of the reinforcing cage. After the pile is formed and the pile concrete reaches a certain strength, cement grout is injected into the pile end and the soil layer on the side of the pile through the grouting pipe. The cement grout penetrates and fills the soil pores, forming an enlarged head at the pile end and a cement-soil reinforced body on the side of the pile.

[0048] New cast-in-place piles are added at each independent column foundation location along the perimeter of the existing building. The number of new piles is determined based on the original building load and foundation settlement. At the corners of the building, the original independent column foundation is increased from one pile to two piles to share the column load. The two new piles are arranged on the outside of the original foundation in two mutually perpendicular directions along the building, and are connected to the original foundation through a connecting foundation 3 constructed later.

[0049] Step 2: Construct a connecting pile cap 3 to connect the first pile foundation 1 with the second pile foundation 2 of the original building. The connecting pile cap 3 is connected to the pile foundation cap 21 of the second pile foundation 2.

[0050] After the first pile foundation 1 is constructed, a reinforced concrete connecting pile cap 3 is poured on top of the first pile foundation 1. The construction of the connecting pile cap 3 includes: firstly, the original structural pile foundation pile cap 21 is partially broken and roughened to expose the reinforcing steel in the original pile cap; then, the reinforcing steel of the connecting pile cap 3 is tied, and the reinforcing steel of the connecting pile cap 3 is lapped and welded to the exposed reinforcing steel of the original pile cap for reinforcement, so that the old and new reinforcing steel form an integral load-bearing structure; finally, the formwork is erected and concrete is poured to firmly connect the connecting pile cap 3 and the original pile foundation pile cap 21 into a whole.

[0051] The connecting pile cap 3 is equipped with a prestressed force along the height direction. Specifically, prestressed steel bars or prestressed steel strands are installed within the connecting pile cap 3. Tensioning is applied to the prestressed steel bars using tensioning equipment, and then they are anchored, generating prestress along the height direction within the connecting pile cap 3. When irregular settlement occurs in the foundation, the prestressed force within the connecting pile cap 3 keeps the first pile 1 and the second pile 2 in their original positions, preventing them from sinking along with the foundation. In other words, when the receding tide causes the foundation soil to settle, the prestressed force within the connecting pile cap 3 can exert an upward pulling force on the first pile 1 and the second pile 2, limiting the downward displacement of the piles with the soil, thereby effectively controlling uneven settlement.

[0052] The first pile foundation 1 also incorporates prestressed steel bars along its height. Specifically, prestressed steel bars are installed within the pile body of the first pile foundation 1, and prestress is applied to the pile body using either post-tensioning or pre-tensioning methods, generating pre-compression stress within the pile body. When the soil around the pile settles due to changes in water level, the prestressed steel bars within the pile body enhance the pile foundation's pull-out resistance. Combined with the frictional force between the first pile foundation 1 and the silt, this helps to resist the downward load generated by soil settlement on the pile foundation.

[0053] The connecting pile caps 3 are connected by pile cap beams 41. Reinforced concrete pile cap beams 41 are installed between adjacent connecting pile caps 3, sequentially connecting them to form a unified pile cap platform. This allows all pile caps to share the load and resist foundation settlement. The cross-sectional dimensions and reinforcement of the pile cap beams 41 are determined by calculation, and the reinforcing bars are reliably connected to the reinforcing bars of the connecting pile caps 3. The concrete is poured together to form a unified whole. Through the connection of the pile cap beams 41, the originally independent pile caps are transformed into a spatially integrated load-bearing system, distributing the load of the superstructure more evenly to the newly added and existing pile caps, effectively resisting uneven deformation caused by tidal changes.

[0054] After the reinforcement treatment is completed, the ground settlement around the connecting pier 3 and around the building is backfilled and compacted with mud and stone, and then a concrete floor and a drainage ditch are poured. At the same time, the settlement and displacement of the building are regularly monitored to monitor the reinforcement effect.

[0055] In this embodiment, preferably, in step 1, the first pile foundation 1 is located inside the original building; One connecting pile cap 3 is set, and multiple first pile foundations 1 are set in the middle of the connecting pile cap 3.

[0056] The first pile foundation 1 is located inside the original building, meaning the new pile foundation is set in the indoor space. A single connecting pile cap 3 is used, employing a single, integral cast-in-place reinforced concrete beam-slab as the connecting pile cap 3. Multiple first pile foundations 1 are located in the middle of the connecting pile cap 3; all new steel pipe piles are arranged in the central area of ​​this integral connecting pile cap 3, connecting all steel pipe piles into a single unit.

[0057] First, the original indoor floor structure needs to be demolished. Multiple steel pipe piles are then constructed at the designed locations as the first pile foundation 1. The length of the steel pipe piles is limited to approximately 2.5m to 3.0m by the indoor floor height. Next, a monolithic reinforced concrete beam-slab is poured at the indoor floor level as a connecting pile cap 3. The tops of all the steel pipe piles are anchored within this beam-slab.

[0058] When outdoor operating space is insufficient, this method can be used to carry out reinforcement construction within indoor space without damaging the outdoor environment; a single connecting pile cap 3 connects all steel pipe piles into a unified load-bearing system, improving the integrity and reliability of the indoor reinforcement; placing the steel pipe piles in the middle of the connecting pile cap 3 ensures even stress distribution and effectively shares the load from the upper structure. In this embodiment, preferably, the bottom surface of the connecting pile cap 3 is connected to the top surface of the pile foundation pile cap 21; The connecting pile cap 3 and the pile foundation pile cap 21 overlap in at least a partial area.

[0059] The bottom surface of the connecting pile cap 3 is connected to the top surface of the pile foundation cap 21, meaning the newly added reinforced concrete beam slab sits on top of the original pile foundation cap 21, and the two transfer loads through the contact surface. The connecting pile cap 3 and the pile foundation cap 21 overlap in at least a portion, meaning the projected area of ​​the newly added beam slab needs to cover at least a portion of the original pile foundation cap 21 to ensure sufficient contact area for load transfer.

[0060] Before constructing the connecting pile cap 3, the laitance and loose layer on the top surface of the original pile cap 21 are thoroughly cleaned to expose fresh concrete. Holes are drilled and rebars are installed on the top surface of the pile cap 21, and the installed rebars are tied to the rebars of the connecting pile cap 3. Then, concrete for the connecting pile cap 3 is poured above the top surface of the pile cap 21, ensuring a tight fit between the bottom surface of the connecting pile cap 3 and the top surface of the pile cap 21. The planar dimensions of the connecting pile cap 3 should ensure that it overlaps with the pile cap 21 in at least a partial area; the area of ​​the overlap is calculated and determined based on load transfer requirements.

[0061] The connecting pile cap 3 sits directly on the original pile foundation pile cap 21, ensuring a clear and reliable load transfer path; the overlapping area between the two ensures sufficient contact area for pressure transfer, avoiding local stress concentration; the rebar connection makes the new and old structures form a whole and work together.

[0062] Meanwhile, the connecting pile cap 3 is anchored to the original indoor structural floor using chemical anchoring.

[0063] In this embodiment, preferably, a crossbeam 42 and a longitudinal beam 43 are provided on the back side of the connecting base 3. The crossbeam 42 and the longitudinal beam 43 are arranged along a first direction and a second direction of the connecting base 3, with the first direction being perpendicular to the second direction.

[0064] A crossbeam 42 and a longitudinal beam 43 are provided on the back of the connecting base 3, that is, a cross beam system is provided above or below the connecting base 3, and the two are perpendicular to each other to form a grid structure.

[0065] During the reinforcement binding process of the connecting pile cap 3, the reinforcement of the horizontal beam 42 and the longitudinal beam 43 are bound simultaneously, and the reinforcement of the horizontal beam 42 and the longitudinal beam 43 are connected to the reinforcement of the connecting pile cap 3. After the formwork of the beam is erected, concrete is poured together with the connecting pile cap 3, so that the horizontal beam 42, the longitudinal beam 43 and the connecting pile cap 3 form an integral whole.

[0066] The crossbeams 42 and longitudinal beams 43 enhance the overall rigidity and bending resistance of the connecting pile cap 3, enabling the connecting pile cap 3 to better transfer the upper load to each steel pipe pile; the grid beam system effectively constrains the uneven deformation between each steel pipe pile, improving the integrity and reliability of the indoor reinforcement system.

[0067] Example 2 This example uses a three-story office building in a coastal area. The original foundation of the building's lobby used 600mm diameter pipe piles with a pile cap, one pile per pile cap, with the pipe piles penetrating approximately 55m into the silt layer. Later, due to tidal changes causing uneven soil settlement, foundation reinforcement was necessary. Because of insufficient outdoor operating space around the building, large-scale piling equipment could not be used for outdoor reinforcement; therefore, an indoor reinforcement solution was adopted. The reinforcement method includes the following steps.

[0068] Step 1: Add the first pile foundation 1.

[0069] In this embodiment, the first pile foundation 1 is located inside the original building. Specifically, after the original indoor structural floor is demolished, steel pipe piles are constructed within the indoor space as the first pile foundation 1. Due to indoor floor height limitations, the length of the steel pipe piles is approximately 2.5m. The steel pipe piles are constructed using small piling equipment or manual driving, with the steel pipes driven into the soil in sections and connected by welding. The pile tip of the steel pipe pile enters the bearing layer, utilizing the friction between the steel pipe pile and the soil to provide bearing capacity and pull-out resistance.

[0070] The first pile foundation 1 is preloaded along its height. Multiple first pile foundations 1 are located in the middle of the connecting pile cap 3. That is, in the indoor area to be reinforced, multiple steel pipe piles are arranged in the middle area of ​​the connecting pile cap 3 according to the design position, and the tops of the steel pipe piles are connected into a whole by the connecting pile cap 3. The number and spacing of the steel pipe piles are calculated and determined based on the superstructure load and foundation reinforcement requirements.

[0071] Step 2: Construct a connecting pile cap 3 to connect the first pile foundation 1 with the second pile foundation 2 of the original building. The connecting pile cap 3 is connected to the pile foundation cap 21 of the second pile foundation 2.

[0072] In this embodiment, the connecting pile cap 3 is a cast-in-place reinforced concrete beam-slab structure. Specifically, after the original indoor structural floor is demolished, a layer of cast-in-place reinforced concrete beam-slab is added at the indoor floor level as the connecting pile cap 3. The bottom surface of the connecting pile cap 3 is connected to the top surface of the pile foundation cap 21, and the connecting pile cap 3 and the pile foundation cap 21 overlap in at least a partial area to ensure reliable load transfer between them. The bottom surface of the connecting pile cap 3 rests on the top surface of the original pile foundation cap 21 and is connected to the original pile foundation cap 21 by structural adhesive or rebar installation.

[0073] A horizontal beam 42 and a longitudinal beam 43 are provided on the back of the connecting pile cap 3. The horizontal beam 42 and the longitudinal beam 43 are arranged along a first direction and a second direction of the connecting pile cap 3, with the first direction perpendicular to the second direction. That is, intersecting horizontal beams 42 and longitudinal beams 43 are provided below or above the cast-in-place reinforced concrete beam-slab. The horizontal beams 42 are arranged transversely along the building, and the longitudinal beams 43 are arranged longitudinally along the building, forming a grid-like beam system through their perpendicular intersections. The reinforcing bars of the horizontal beams 42 and longitudinal beams 43 are tied together with the reinforcing bars of the connecting pile cap 3, and the concrete is poured together, making the beam-slab a monolithic load-bearing structure. The arrangement of the horizontal beams 42 and longitudinal beams 43 enhances the overall rigidity and bending resistance of the connecting pile cap 3, enabling the connecting pile cap 3 to better transfer the upper load to each steel pipe pile, while also restraining uneven deformation between the steel pipe piles.

[0074] The connecting pile cap 3 is integrated with the original structural beam using chemical anchoring. Chemical anchoring ensures a reliable connection between the new and old concrete structures, allowing the new reinforcement system to work in tandem with the original structure to resist foundation settlement.

[0075] The lower part of the central beam slab adopts a steel pipe pile foundation, with steel pipe piles approximately 2.5m to 3.0m in length. The newly added beam slab piles are connected to the original pile foundation to form an integral whole, reducing uneven settlement.

[0076] Within the newly added beam and slab area, the lower part is replaced with 800mm thick 4:6 graded sand and gravel, with the underlying subsoil compacted to ensure the soil around the pile foundation is in a dense state, forming a rigid foundation. Specifically, in the space below the indoor floor level and above the bottom of the beam and slab, graded sand and gravel are mixed in a 4:6 ratio, backfilled in layers, and compacted, with a backfill thickness of 800mm. Below the backfill layer is a compacted subsoil layer. The graded sand and gravel replacement layer has good density and bearing capacity, providing stable lateral restraint for the steel pipe piles, while preventing excessive deformation of the soil around the piles due to water level changes.

[0077] In the reinforcement method provided by this invention, regardless of whether it is an outdoor reinforcement scheme or an indoor reinforcement scheme, the first pile foundation 1 can adopt different pile types to adapt to different construction conditions. In the outdoor reinforcement scheme, the first pile foundation 1 adopts cast-in-place piles, and in the indoor reinforcement scheme, the first pile foundation 1 adopts steel pipe piles. Both pile types can achieve the technical effect of resisting settlement.

[0078] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0079] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0080] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for reinforcing a foundation with uneven settlement, characterized in that, include: Step 1: Add the first pile foundation (1); Step 2: Construct a connecting pile cap (3) to connect the first pile foundation (1) with the original second pile foundation (2) on the building site; The connecting pile cap (3) is connected to the pile cap (21) of the second pile foundation (2).

2. The reinforcement method for uneven settlement foundations according to claim 1, characterized in that, The connecting support (3) is provided with a pre-tension force along the height direction.

3. The reinforcement method for uneven settlement foundations according to claim 2, characterized in that, The first pile foundation (1) is provided with a pre-tension force along the height direction.

4. The reinforcement method for uneven settlement foundations according to claim 3, characterized in that, The first pile (1) extends into the silt.

5. The reinforcement method for uneven settlement foundations according to claim 4, characterized in that, In step 1, the first pile foundation (1) is located outside the original building; Multiple first pile foundations (1) are provided, and multiple first pile foundations (1) are arranged around the outer perimeter of the original building.

6. The reinforcement method for uneven settlement foundations according to claim 5, characterized in that, The connecting pedestals (3) are connected by pedestal beams (41).

7. The reinforcement method for uneven settlement foundations according to claim 4, characterized in that, In step 1, the first pile foundation (1) is located inside the original building; One connecting pile cap (3) is provided, and the plurality of first pile foundations (1) are provided in the middle of the connecting pile cap (3).

8. The reinforcement method for uneven settlement foundations according to claim 7, characterized in that, The bottom surface of the connecting pile cap (3) is connected to the top surface of the pile foundation pile cap (21); The connecting pile cap (3) and the pile foundation pile cap (21) overlap in at least a partial area.

9. The reinforcement method for uneven settlement foundations according to claim 7, characterized in that, The back of the connecting platform (3) is provided with a crossbeam (42) and a longitudinal beam (43). The crossbeam (42) and the longitudinal beam (43) are arranged along a first direction and a second direction of the connecting platform (3), and the first direction is perpendicular to the second direction.

Images