A device and method for controlling cracks in ultra-long concrete slab structures

Abstract

A device and method for controlling cracks in ultra-long concrete slab structures are disclosed. The device includes an anti-buoyancy anchor rod, a container, a moving block, a smooth rod section, and a limiting block. The method includes the steps of assembling the device, anchoring the anchor rod, welding the device to the reinforcing cage, and pouring foundation slab concrete. Based on relevant data on concrete shrinkage, this invention pre-sets a container, a moving block, and a smooth rod section on the rod that can simultaneously satisfy the longitudinal and horizontal shrinkage ranges of concrete. As horizontal and longitudinal shrinkage occurs, the concrete of the foundation slab causes the container to undergo horizontal and longitudinal displacement. At this time, the moving block slides upward on the smooth rod section, simultaneously releasing the constraint force on the foundation slab in the horizontal and longitudinal directions. Since the rod does not hinder the shrinkage deformation of the concrete, cracks caused by the constraint force of the anchor rod will not occur.

Description

Technical Field

[0001] This invention relates to the field of crack control technology for ultra-long concrete structures, specifically to a crack control device and method for ultra-long concrete slab structures. Background Technology

[0002] Extra-long concrete foundation slab structures are widely used in industrial and civil buildings. In order to ensure the stability of the concrete foundation slab structure, it is usually necessary to anchor the structural slab with anti-buoyancy anchor rods.

[0003] Based on existing data and practical applications, traditional anti-buoyancy anchors have achieved significant results in preventing building buoyancy. However, traditional anti-buoyancy anchors still have the following technical problems: After concrete is poured, evaporation continues. Even with particularly high air humidity (as long as it is less than 100%), when the evaporation rate of the concrete surface exceeds the rate of water bleeding, shrinkage will occur. Because this happens during the plastic stage of concrete, it is called plastic shrinkage. When the stress generated by plastic shrinkage exceeds the tensile strength of the concrete itself, plastic cracking will occur. Before the concrete initially sets, it does not have strength, and even a slight shrinkage tension can cause cracks in the concrete. When traditional anti-buoyancy anchors are connected to the foundation slab, the anchors are often directly embedded into the foundation slab from top to bottom without any treatment at the connection surface (the deformation of the foundation slab is hindered by the anti-buoyancy anchors, this effect is called "external constraint", and external constraint stress usually causes through cracks). Although this method helps the foundation slab resist buoyancy, its longitudinal and horizontal constraints on the foundation slab will inhibit the shrinkage of concrete in the longitudinal or horizontal directions, resulting in increased temperature constraint stress, which in turn causes cracking of ultra-long concrete foundation slabs and affects the safety performance of the structure. Summary of the Invention

[0004] This invention provides a crack control device and method for ultra-long concrete foundation slab structures, aiming to solve the problem of cracking of ultra-long concrete foundation slabs caused by the longitudinal and horizontal constraints on the foundation slab due to concrete shrinkage caused by existing anti-buoyancy anchors.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A crack control device for an ultra-long concrete slab structure includes an anti-buoyancy anchor rod, a container, and a movable block. The lower part of the rod is inserted into a pre-set anchor hole on the foundation surface and fixed to the foundation by pouring concrete. The container is an inverted frustum-shaped structure with an open lower end. The upper part of the rod has a smooth rod section, which is inserted into the frustum-shaped structure along the lower port of the container. A movable block is slidably connected to the smooth rod section. The movable block is an inverted frustum-shaped block coaxial with the container and matching its shape. In the initial state, the lower end of the block is flush with the lower port of the container, and the side wall of the block is in contact with the inner wall of the container. A limiting block is fixed at the top of the smooth rod section. The distance between the top of the movable block and the lower end of the limiting block meets the longitudinal shrinkage range of the foundation slab concrete. At the same time, when the foundation slab concrete shrinks horizontally, the movable block slides upward along the smooth rod section and releases the horizontal constraint on the foundation slab concrete, meeting the horizontal shrinkage range of the foundation slab concrete. The outer wall of the container is welded to the bottom of the reinforcing cage of the foundation slab.

[0007] Preferably, the container includes a first steel plate forming the sidewall of the frustum-shaped structure and a second steel plate fixedly connected to the top of the first steel plate by bolts.

[0008] Preferably, the top end of the limiting block is detached from the bottom end of the second steel plate, and the limiting block is a cylindrical structure coaxial with the rod and made of steel.

[0009] Preferably, the movable block is made of steel, and the outer diameter of the lower end of the movable block is the same as the inner diameter of the lower port of the container.

[0010] Preferably, a PVC sleeve is also fitted around the outer periphery of the bare pole section between the top of the concrete poured on the lower outer periphery of the pole and the lower side wall of the container. The PVC sleeve isolates the bare pole section and the top of the concrete poured on the lower outer periphery of the pole from the concrete of the foundation slab.

[0011] A construction method for a crack control device for ultra-long concrete slab structures includes the following steps:

[0012] (1) The rods of the container, moving block, limiting block, PVC sleeve and anchor rod are prefabricated in the factory and the container, moving block, limiting block and PVC sleeve are assembled onto the bare rod section; wherein, the limiting block is coaxially welded to the top of the bare rod section, the moving block is slidably sleeved on the bare rod section, the container is sleeved on the outside of the moving block and the bare rod section, and the PVC sleeve is sleeved on the lower part of the container and the outer periphery of the bare rod section below the container;

[0013] (2) Anchor holes are opened in the foundation of the construction site, the rods of several anchors are inserted into the anchor holes, and concrete is poured to fix them so that the bare rod section is exposed on the foundation surface. At this time, the lower end of the PVC sleeve abuts against the foundation surface around the upper port of the anchor hole, and the upper end abuts against the lower part of the outer wall of the container. The contact between the PVC sleeve and the outer wall of the container is sealed.

[0014] (3) Lay a felt sliding layer on the foundation surface around the outside of the pole, erect a steel cage, and weld the bottom of the steel cage to the outer wall of the shell.

[0015] (4) Pour the foundation slab concrete.

[0016] The beneficial effects of the present invention, a crack control device and method for ultra-long concrete slab structures, are as follows:

[0017] In this invention, when the foundation slab shrinks due to temperature differences, there are two phenomena: horizontal shrinkage and longitudinal shrinkage. Typically, horizontal shrinkage occurs simultaneously with longitudinal shrinkage. Traditional anti-buoyancy anchors, with their rods anchored within the foundation slab, exert a restraining force on the slab regardless of whether horizontal or longitudinal shrinkage occurs. This restraining force hinders concrete deformation, leading to cracks. This invention, based on concrete shrinkage data, pre-sets a container, a moving block, and a smooth rod section on the rod that simultaneously accommodate both longitudinal and horizontal shrinkage. As horizontal and longitudinal shrinkage proceed, the concrete of the foundation slab causes the container to undergo a combined horizontal and longitudinal displacement. At this time, the moving block slides upwards on the smooth rod section, simultaneously releasing the restraining forces on the foundation slab in both the horizontal and longitudinal directions. Since the rod does not hinder concrete shrinkage deformation, cracks caused by the anchor's restraining force do not occur. Furthermore, the anchor itself still provides anti-buoyancy protection. When the foundation slab floats upwards, the moving block, positioned at the bottom of the container, applies a longitudinal tensile force to the foundation slab, thus preventing excessive floating. Attached Figure Description

[0018] Figure 1 A schematic diagram of the structure of the present invention in use;

[0019] 1. Foundation; 2. Pole; 3. Container; 4. Reinforcing cage (illustrated); 5. Bare pole section; 6. Moving block; 7. Limiting block; 8. Anchor hole; 9. PVC sleeve; 10. Foundation slab concrete. Detailed Implementation

[0020] The following description provides a detailed explanation of the embodiments of the present invention in a step-by-step manner. This description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limiting this invention.

[0022] Example 1:

[0023] A crack control device for ultra-long concrete slab structures, such as Figure 1 As shown, the structure includes an anti-buoyancy anchor rod 2, a container 3, and a movable block 6. The lower part of the rod rod 2 is inserted into a pre-set anchor hole 8 on the foundation surface and fixed to the foundation by pouring concrete. The container 3 is an inverted frustum-shaped structure with an open lower end. The upper part of the rod rod 2 has a smooth rod section 5, which is inserted into the frustum-shaped structure along the lower end of the container 3. A movable block 6 is slidably connected to the smooth rod section 5. The movable block 6 is an inverted frustum-shaped block coaxial with and matching the shape of the container 3. In the initial state... The lower end of the block is flush with the lower port of container 3, and the sidewall of the block is in contact with the inner wall of container 3. A limiting block 7 is fixedly provided at the top of the bare rod section 5. The distance between the top of the movable block 6 and the lower end of the limiting block 7 is sufficient to accommodate the longitudinal shrinkage of the foundation slab concrete. Simultaneously, when the foundation slab concrete shrinks horizontally, the movable block slides upward along the bare rod section 5, releasing the horizontal constraint on the foundation slab concrete and satisfying the horizontal shrinkage range of the foundation slab concrete. The outer wall of the container is welded to the bottom of the reinforcing cage of the foundation slab. During the upward sliding process of the movable block, space is continuously provided for both the longitudinal and horizontal shrinkage of the foundation slab concrete. This space refers to the space provided by the rod to release the constraint on the foundation slab.

[0024] like Figure 1 As shown, the container 3 includes a first steel plate forming the sidewall of a frustum-shaped structure and a second steel plate bolted to the top of the first steel plate. The first and second steel plates are detachable for easy assembly of the device.

[0025] like Figure 1 As shown, the top end of the limiting block 7 is detached from the bottom end of the second steel plate. The limiting block 7 is a cylindrical structure coaxial with the rod body 2 and is made of steel. The function of the limiting block is to limit the maximum upward movement distance of the moving block, ensuring the anti-buoyancy performance of the anti-buoyancy anchor while meeting the horizontal and longitudinal shrinkage range of the foundation plate.

[0026] like Figure 1 As shown, the movable block 6 is made of steel, and the outer diameter of the lower end of the movable block 6 is the same as the inner diameter of the lower port of the container.

[0027] like Figure 1 As shown, a PVC sleeve 9 is also fitted around the outer periphery of the bare rod section 5 between the top of the concrete poured on the lower outer periphery of the rod body 2 and the lower side wall of the container 3. The PVC sleeve 9 isolates the bare rod section 5 and the top of the concrete poured on the lower outer periphery of the rod body from the concrete of the foundation slab, so as to prevent the concrete of the foundation slab from being fixedly connected with the concrete of the anchor rod body or the bare rod section and hindering the shrinkage displacement of the foundation slab.

[0028] In this embodiment, when the foundation slab shrinks due to temperature differences, there are two phenomena: horizontal shrinkage and longitudinal shrinkage. Typically, horizontal shrinkage occurs simultaneously with longitudinal shrinkage. Traditional anti-buoyancy anchors, with their rods anchored within the foundation slab, exert a restraining force on the slab regardless of whether horizontal or longitudinal shrinkage occurs. This restraining force hinders concrete deformation, leading to cracks. However, this invention, based on concrete shrinkage data, pre-sets a container, a moving block, and a smooth rod section on the rod that simultaneously accommodate both longitudinal and horizontal shrinkage. As horizontal and longitudinal shrinkage proceed, the concrete of the foundation slab causes the container to undergo a combined horizontal and longitudinal displacement. At this time, the moving block slides upwards on the smooth rod section, simultaneously releasing the restraining force on the foundation slab in both the horizontal and longitudinal directions. Since the rod does not hinder concrete shrinkage deformation, cracks caused by the anchor's restraining force will not occur. Furthermore, the anchor itself still provides anti-buoyancy protection. When the foundation slab floats upwards, the moving block, positioned at the bottom of the container, applies a longitudinal tensile force to the foundation slab, thus preventing excessive floating.

[0029] Example 2:

[0030] This embodiment further discloses, based on embodiment 1, the following:

[0031] A construction method for a crack control device for ultra-long concrete slab structures, such as... Figure 1 As shown, it includes the following steps:

[0032] (1) The container 3, the moving block 6, the limiting block 7, the PVC sleeve 9 and the rod body 2 of the anchor rod are prefabricated in the factory, and the container, the moving block, the limiting block and the PVC sleeve are assembled onto the bare rod section 5; wherein, the limiting block 7 is coaxially welded to the top of the bare rod section 5, the moving block 6 is slidably sleeved on the bare rod section 5, the container 3 is sleeved on the outside of the moving block 6 and the bare rod section 5, and the PVC sleeve 9 is sleeved on the lower part of the container 3 and the outer periphery of the bare rod section 5 below the container;

[0033] (2) Anchor holes 8 are opened in the foundation of the construction site, and the rods 2 of several anchors are inserted into the anchor holes 8 and concrete is poured to fix them so that the bare rod section 5 is exposed on the foundation surface. At this time, the lower end of the PVC sleeve 9 abuts against the foundation surface around the upper port of the anchor hole 8, and the upper end abuts against the lower part of the outer wall of the container 3. The contact between the PVC sleeve 9 and the outer wall of the container 3 is sealed.

[0034] (3) Lay a felt sliding layer (not shown in the figure) on the foundation surface around the outside of the pole body, erect the steel cage 4, and weld the bottom of the steel cage 4 to the outer wall of the shell 3; the function of the felt sliding layer is to avoid excessive friction between the foundation plate and the foundation, which would prevent the concrete of the foundation plate from shrinking smoothly.

[0035] (4) Pour the foundation slab concrete.

[0036] In this embodiment, the above method can effectively avoid the cracking problem of ultra-long concrete foundation slab caused by the restraining effect of anti-buoyancy anchor rods, which has good engineering practical significance.

Claims

1. A crack control device for ultra-long concrete slab structures, characterized in that: The system includes an anti-buoyancy anchor rod, a container, and a movable block. The lower part of the rod is inserted into a pre-set anchor hole on the foundation surface and fixed to the foundation by pouring concrete. The container is an inverted frustum-shaped structure with an open bottom. The upper part of the rod has a smooth rod section, which is inserted into the frustum-shaped structure along the lower end of the container. A movable block is slidably connected to the smooth rod section. The movable block is an inverted frustum-shaped block coaxial with the container and matching its shape. In the initial state, the lower end of the block is flush with the lower end of the container, and the sidewall of the block is in contact with the inner wall of the container. A limiting block is fixed to the top of the smooth rod section, and the top of the movable block is connected to the limiting block. The distance between the lower ends of the blocks meets the longitudinal shrinkage range of the foundation slab concrete. At the same time, when the foundation slab concrete shrinks horizontally, the moving block slides upward along the bare rod section and releases the horizontal constraint on the foundation slab concrete, while meeting the horizontal shrinkage range of the foundation slab concrete. The outer wall of the container is welded to the bottom of the reinforcing cage of the foundation slab. A PVC sleeve is also fitted around the outer periphery of the bare rod section between the top of the concrete poured on the lower outer periphery of the rod body and the lower side wall of the container. The PVC sleeve is fitted around the lower part of the container and the outer periphery of the bare rod section below the container, isolating the bare rod section and the top of the concrete poured on the lower outer periphery of the rod body from the concrete of the foundation slab.

2. The crack control device for ultra-long concrete slab structures as described in claim 1, characterized in that: The container includes a first steel plate forming the sidewall of a frustum-shaped structure and a second steel plate bolted to the top of the first steel plate.

3. The crack control device for ultra-long concrete slab structures as described in claim 2, characterized in that: The top end of the limiting block is detached from the bottom end of the second steel plate. The limiting block is a cylindrical structure coaxial with the rod and is made of steel.

4. The crack control device for ultra-long concrete slab structures as described in claim 3, characterized in that: The movable block is made of steel, and the outer diameter of the lower end of the movable block is the same as the inner diameter of the lower port of the container.

5. The construction method of the crack control device for ultra-long concrete slab structures as described in claim 4, characterized in that, Includes the following steps: (1) The rod body of the container, moving block, limiting block, PVC sleeve and anchor rod is prefabricated in the factory and the container, moving block, limiting block and PVC sleeve are assembled onto the bare rod section; wherein, the limiting block is coaxially welded to the top of the bare rod section, the moving block is slidably sleeved on the bare rod section, the container is sleeved on the outside of the moving block and the bare rod section, and the PVC sleeve is sleeved on the lower part of the container and the outer periphery of the bare rod section below the container; (2) Anchor holes are opened in the foundation of the construction site, and the rods of several anchors are inserted into the anchor holes and concrete is poured to fix them so that the bare rod section is exposed on the foundation surface. At this time, the lower end of the PVC sleeve abuts against the foundation surface around the upper port of the anchor hole, and the upper end abuts against the lower part of the outer wall of the container. The contact between the PVC sleeve and the outer wall of the container is sealed. (3) Lay a felt sliding layer on the foundation surface around the outside of the pole, erect a steel cage, and weld the bottom of the steel cage to the outer wall of the container. (4) Pour the foundation slab concrete.

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