Raft foundation pile cap sealing pile automatic locking structure and limiting and reinforcing construction method thereof

Abstract

The application discloses a raft foundation pile cap sealing and automatic locking structure and a limiting and reinforcing construction method thereof, and belongs to the field of building deviation rectification and reinforcement. After a hole is formed on the raft foundation, a micro pipe pile is pressed into the raft hole to a design depth by using a jack and a counterforce frame, and an automatic locking and limiting device is automatically opened, and is constrained to the bottom of the raft; limiting steel bars are welded with rotating shafts to form an integrated body; after the locking and limiting device works, the excess micro steel pipes are cut off, and self-compacting concrete is injected into a grouting opening, and after curing to a design strength, a reinforcing structure of uniformly dispersed pile end counterforce is formed. The application has reliable reinforcing effect on the raft foundation, clear reinforcing mechanism, low cost, short construction period and convenience for on-site construction; the application provides a pile cap sealing and automatic locking structure of uniformly dispersed pile end counterforce and preventing local punching damage for the raft foundation, and provides a limiting and reinforcing construction method.

Description

Technical Field

[0001] This invention belongs to the field of building tilt correction and reinforcement technology, specifically relating to an automatic locking structure for raft foundation pile cap sealing and its limiting reinforcement construction method. Background Technology

[0002] High-rise buildings generally use pile-raft foundations, independent column foundations, strip foundations, etc., among which pile-raft foundations have better overall integrity and higher seismic resistance. It is a combination of pile foundation and raft foundation. For buildings with basements, raft foundations are usually used. It is a foundation treatment method used when the foundation soil cannot meet the bearing capacity requirements under large loads.

[0003] However, due to the highly sensitive water properties of collapsible loess, and the fact that some projects are built on embankment foundations, consolidation settlement and collapsing deformation may occur due to improper construction and the influence of water, leading to uneven settlement of the building foundation. During initial settlement, the building's center of mass may not coincide with the reaction center of the raft foundation, causing eccentricity and exacerbating the building's tilt. If the building is not reinforced and its settlement stopped in time, the superstructure may crack, potentially leading to collapse. Therefore, timely reinforcement and replacement of pile-raft foundation structures during initial settlement can save the building.

[0004] Common foundation replacement technologies include anchor-driven static pressure replacement and micro-static pressure pile replacement. Rebound is unavoidable during the replacement process. With anchor-driven static pressure replacement, the physical properties and stress state of the soil around and below the pile tip change during pile driving, resulting in additional settlement. Micro-static pressure pile replacement involves driving micro-steel pipes into the soil to the designed depth, grouting inside the pipes, and welding reinforcing steel to the pile cap beam at the top of the pile. The ends are welded to the anchor rods of the original fixed reaction frame, and the pile is sealed with a higher-grade concrete. However, this method involves sealing the pile at the top of the raft foundation, which cannot resolve the rebound problem during pile driving, and the upper pile sealing may experience localized punching shear under heavy loads. Summary of the Invention

[0005] To avoid the problems existing in current anchor bolt static pressure replacement technology and micro static pressure pile replacement technology, this invention provides an automatic locking structure for raft foundation pile cap sealing and its limiting and reinforcement construction method.

[0006] Therefore, the present invention adopts the following technical solution:

[0007] An automatic locking structure for sealing pile caps on raft foundations includes an opening in the raft foundation. A micro-pipe pile is vertically and statically pressed into the center of the opening. A self-locking support assembly is fixed to the wall of the micro-pipe pile, which supports the raft foundation. Before static pressing, the self-locking support assembly is located above the raft foundation and is in a retracted state. When the micro-pipe pile is statically pressed downwards, the self-locking support assembly moves downwards with the micro-pipe pile. After the micro-pipe pile is statically pressed to the design depth, the self-locking support assembly moves to the bottom of the raft foundation and opens. The upper part of the self-locking support assembly abuts against the bottom surface of the raft foundation to provide support for the raft foundation. Concrete is poured into the opening to solidify the self-locking support assembly and the micro-pipe pile into one piece, and the concrete seals the opening.

[0008] Furthermore, the self-locking support assembly includes a support seat that is fixed in a ring to the wall of the micro-pipe pile. The upper part of the support seat is connected to support legs that are arranged in a ring around the micro-pipe pile. The support legs are used to support the raft. When each support leg is closed, it is close to the micro-pipe pile. When the support legs are opened, each support leg extends outward in a petal shape and moves away from the micro-pipe pile.

[0009] Furthermore, the support base is a channel steel, and multiple channel steels are vertically welded and fixed to the wall of the micro-pipe pile along the circumferential direction, with adjacent channel steels arranged at equal angles.

[0010] Furthermore, stiffening plates are welded between adjacent channel steels to fix each channel steel into a whole.

[0011] Furthermore, the lower end of the support leg is connected to a pin, which is arranged in a "T" shape with the support leg; both ends of the pin are rotatably connected to the left and right sides of the channel steel.

[0012] Furthermore, a notch is provided at the center of the upper edge of the channel steel, and the support leg is inserted into the notch when it is opened. The notch is used to limit the maximum rotation angle of the support leg.

[0013] A construction method for reinforcing and limiting pile caps on raft foundations, comprising the aforementioned automatic locking structure for sealing pile caps on raft foundations, and including the following steps:

[0014] Step 1: Based on the tilt and settlement of the raft foundation structure, determine the location where the original piles need to be replaced, and measure the ultimate bearing capacity of the original piles and the ultimate bearing capacity of the micro-pipe piles to determine the number of original piles to be replaced with micro-pipe piles.

[0015] Step 2: After determining the location and number of replacement piles, drill holes in the raft foundation and use a hole enlarging device to enlarge the holes at the bottom of the raft foundation according to the design and construction requirements.

[0016] Step 3: Fabricate miniature pipe piles of the corresponding specifications and weld and fix the self-locking support components to the miniature pipe piles;

[0017] Step 4: After the reaction frame and jacks are vertically arranged, the pile driving operation is carried out; when the last section of micro-pipe pile is driven into the design depth, the support legs open outwards, and the support legs contact the bottom of the raft slab by relying on the rebound of the pile body.

[0018] Step 5: After the micro-pipe piles are driven to the designed depth, the excess steel pipes are cut off; early-strength concrete is injected into the steel pipes, and self-compacting concrete is injected into the grouting port to integrate the micro-pipe piles, self-locking support components, and raft foundation into one unit to jointly bear the pressure.

[0019] The beneficial effects of this invention are as follows:

[0020] The pin shaft is welded to the support leg as a single unit to form a locking support leg. The support block and the locking support leg are connected at a smooth joint, and then channel steel is welded to the outer wall of the steel pipe to constrain the support block and the locking support leg, forming a self-locking support assembly. Stiffeners are welded to the self-locking support assembly on all four sides for better constraint. After the hole is drilled in the raft slab, when the last steel pipe pile is driven to the design depth, the self-locking support assembly automatically opens and contacts the bottom of the raft slab due to the rebound phenomenon, and injects concrete one level higher than that inside the steel pipe to form a pile cap sealing structure. This disperses the reaction force at the end of the steel pipe pile, prevents local punching shear, and greatly enhances the reinforcement effect of the building. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the reinforcement structure of the present invention;

[0022] Figure 2 This is a three-dimensional schematic diagram of the self-locking support component of the present invention;

[0023] Figure 3 This is a front view of the self-locking support component of the present invention;

[0024] Figure 4 This is a top view of the self-locking support assembly with the support legs retracted.

[0025] Figure 5 This is a top view of the self-locking support assembly with the support legs in the open state.

[0026] Figure 6 This is a schematic diagram of the support leg of the present invention;

[0027] Figure 7 This is a schematic diagram of the support leg pin of the present invention;

[0028] Figure 8 This is a schematic diagram of the support leg of the present invention being fixed on the channel steel;

[0029] In the diagram: 1. Raft foundation, 2. Micro-pipe pile, 3. Grouting port, 4. Channel steel, 5. Support leg, 6. Support block, 7. Stiffening plate, 8. Pin. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0031] like Figure 1-3 As shown, an automatic locking structure for raft foundation pile caps includes drilling holes in the raft foundation 1 and enlarging the holes in the foundation soil. Micro-pipe piles 2, each equipped with a self-locking support assembly on all four sides, are then driven into the designed depth. When the micro-pipe piles 2 reach the designed depth, the self-locking support assemblies automatically open and abut against the bottom of the raft foundation, locking and limiting the micro-pipe piles 2. After the self-locking support assemblies have functioned, excess micro-steel pipes are cut off, and self-compacting concrete is injected through the grouting port 3. After curing to the designed strength, a reinforcement structure that uniformly distributes the load on the raft foundation is formed. This disperses the concentrated force of the steel pipe piles, prevents localized punching shear, and greatly enhances the reinforcement effect of the structure.

[0032] like Figure 6-8 As shown, the self-locking support assembly consists of a support block 6, a pin 8, a support leg 5, a channel steel 4, and a stiffening plate 7. The pin 8 is welded to the support leg 5 in a "T" shape. The support block 6 and the locking support leg 5 are connected at a smooth connection joint and welded to the outer wall of the micro-pipe pile 2 steel pipe. The channel steel 4 is welded to the outer wall of the micro-pipe pile 2 steel pipe to constrain the support block 6 and the locking support leg 5. The locking support leg 5 is a 32mm diameter grade III steel bar, forming the self-locking support assembly. The stiffening plate 7 has a diameter of 8-12mm and is welded to the four sides of the self-locking support assembly. Its length allows for continuous and uninterrupted welding of the four sides of the self-locking support assembly, thus better constraining the self-locking support assembly.

[0033] A method for limiting and reinforcing an automatic locking structure for pile cap sealing in raft foundations, the specific implementation steps of which are as follows:

[0034] Step 1: Based on the tilting and settlement of the raft foundation 1 building, determine the location where the original piles need to be replaced, and measure the ultimate bearing capacity of the original piles and the ultimate bearing capacity of the micro-pipe piles 2, and determine the number of original piles to be replaced by micro-pipe piles 2.

[0035] Step 2: After determining the location and the number of supports, drill holes in the raft foundation 1, and use a hole enlarging device to enlarge the holes at the bottom of the raft foundation according to the design and construction requirements.

[0036] Step 3: Fabricate miniature pipe piles 2 of the corresponding specifications and weld the self-locking support assembly to the miniature pipe piles 2. The last section of steel pipe is made 10-20cm longer than the rest of the steel pipes. The pin 8 is welded to the support leg 5 as a single unit. The support block 6 is connected to the locking support leg 5 at a smooth connection joint and welded to the outer wall of the steel pipe. Channel steel 4 is welded to the outer wall of the steel pipe to constrain the support block 6 and the locking support leg 5, forming the self-locking support assembly. Rib plates 7 are welded to the four sides of the self-locking support assembly for better constraint.

[0037] In this embodiment, the self-locking support assembly is made of materials commonly used on construction sites, which are easy to obtain locally. First, the support block 6 is welded to the outer wall of the steel pipe, and the locking support leg 5 is connected to the support block 6. Channel steel 4 is welded to the outer wall of the steel pipe to constrain the support block 6 and the locking support leg 5. Finally, stiffening plates 7 are welded to the four-sided self-locking support assembly to better constrain the self-locking support assembly. The manufacturing process is simple and easy for construction personnel to understand and operate.

[0038] Step 4: After the reaction frame and jacks are vertically arranged, pile driving is carried out and the pile driving process must be completed in one go. The welding of steel pipes must ensure the welding quality. During the process of replacing the original pile with pile driving, a rebound phenomenon will inevitably occur. When the locking support leg 5 of the last section of micro pipe pile 2 opens the contact hole wall and is pressed into the design depth, the self-locking support component will open and produce a certain amount of play. It will contact the bottom of the raft slab by relying on the rebound amount of the pile body.

[0039] The locking support legs 5 on the four sides of the device disperse the concentrated reaction force at the end of the steel pipe pile, prevent local punching shear, and greatly enhance the reinforcement effect of the building.

[0040] Step 5: After the micro-pipe pile 2 is driven into the designed depth, the excess steel pipe is cut off, and high-early-strength concrete of not less than C30 is injected into the steel pipe. Self-compacting concrete is injected into the grouting port 3 to form the micro-pipe pile 2, the locking and limiting structure and the raft foundation 1 into one unit to work together.

Claims

1. A raft foundation pile cap sealing and spacing reinforcement construction method, characterized by, This includes openings in the raft foundation, with micro-pipe piles vertically and statically pressed at the center of the openings, and self-locking support components fixed to the pipe walls of the micro-pipe piles, which are used to support the raft foundation. The self-locking support assembly includes a support seat that is fixed in a ring to the wall of the micro-pipe pile. The upper part of the support seat is connected to support legs that are arranged in a ring around the micro-pipe pile. The support legs are used to support the raft slab. Before the micro-pipe pile is statically pressed, the self-locking support assembly is located above the raft slab. When each support leg is retracted, it is close to the micro-pipe pile and is in a retracted state. When the micro-pipe pile is statically pressed downward, the self-locking support assembly moves downward with the micro-pipe pile. After the micro-pipe pile is statically pressed to the design depth, the self-locking support assembly moves to the bottom of the raft slab. Each support leg extends outward in a petal shape and moves away from the micro-pipe pile, thus opening the self-locking support assembly. The upper part of the self-locking support assembly abuts against the bottom surface of the raft slab to provide support for the raft slab. The support base is a channel steel. Multiple channel steels are vertically welded and fixed to the wall of the micro-pipe pile along the circumference. Adjacent channel steels are arranged at equal angles. A notch is opened in the center of the upper edge of the channel steel. When the support leg is opened, it is embedded in the notch. The notch is used to limit the maximum rotation angle of the support leg. Concrete was poured into the opening to solidify the self-locking support assembly and the micro-pipe pile into one piece, and the concrete sealed the opening position. Includes the following steps: Step 1: Based on the tilt and settlement of the raft foundation structure, determine the location where the original piles need to be replaced, and measure the ultimate bearing capacity of the original piles and the ultimate bearing capacity of the micro-pipe piles to determine the number of original piles to be replaced with micro-pipe piles. Step 2: After determining the location and number of replacement piles, drill holes in the raft foundation and use a hole enlarging device to enlarge the holes at the bottom of the raft foundation according to the design and construction requirements. Step 3: Fabricate miniature pipe piles of the corresponding specifications and weld and fix the self-locking support components to the miniature pipe piles; Step 4: After the reaction frame and jacks are vertically arranged, the pile driving operation is carried out; when the last section of micro-pipe pile is driven into the design depth, the support legs open outwards, and the support legs contact the bottom of the raft slab by relying on the rebound of the pile body. Step 5: After the micro-pipe piles are driven to the designed depth, the excess steel pipes are cut off; early-strength concrete is injected into the steel pipes, and self-compacting concrete is injected into the grouting port to integrate the micro-pipe piles, self-locking support components, and raft foundation into one unit to jointly bear the pressure.

2. The raft foundation pile cap sealing and spacing reinforcement construction method according to claim 1, characterized by, Stiffening plates are welded between adjacent channel steels to fix the channel steels together as one unit.

3. The construction method for pile cap sealing and reinforcement of raft foundation according to claim 1, characterized in that, The lower end of the support leg is connected to a pin, which is arranged in a "T" shape with the support leg; both ends of the pin are rotatably connected to the left and right sides of the channel steel.

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