A counter-force wall prestress construction method

Abstract

The application discloses a counter-force wall prestress construction method, 1) prestress reinforcement blanking; 2) installing fixed anchor at lower end; 3) vertical fixing; 4) prefabricating ladder reinforcement; 5) fixing prestress reinforcement on base bottom plate reinforcement by ladder reinforcement; 6) fixing prestress reinforcement on basement top plate reinforcement by ladder reinforcement; 7) repeatedly implementing step 6) to fix prestress reinforcement on structure top plate reinforcement by ladder reinforcement, and setting anchor pad plate above ladder reinforcement of structure top plate reinforcement; 8) after structure top counter-force wall concrete strength reaches 100%, prestress tension is implemented by working anchor; 9) after tension is completed, working anchor is single-point anchor sealing; 10) after monitoring that prestress is less than a set value, anchor sealing structure of corresponding prestress reinforcement is broken, and re-tension is implemented. The application is easy to construct, can implement re-tension, is convenient for guaranteeing quality, can prolong use frequency, and is suitable for popularization and use in vertical prestress engineering.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional reaction structure laboratory construction technology, and in particular to a prestressed construction method for reaction walls. Background Technology

[0002] With the continuous emergence of new structural theories and calculation methods, many complex structures require structural testing for verification, highlighting the increasing importance of structural testing. Structural laboratories are indispensable hardware platforms for scientific experiments in the field of civil engineering. Among them, the three-dimensional reaction structure laboratory is an essential equipment platform for conducting quasi-static and quasi-dynamic tests on large, full-scale structures and components. It includes reaction walls and pedestals, and is a large three-dimensional structure with numerous internal reinforcements, prestressed tendons, and embedded parts. It belongs to a large, uncommon prestressed concrete special structure with complex stress conditions.

[0003] The safety and durability of reaction walls are closely related to the quality of prestressed construction. Current methods for installing prestressed tendons in reaction walls have the following problems:

[0004] (i) When using prestressed tendons with bundles, ducts, and bonding, the repeated turning of the steel strands during construction can cause breakage, deformation, and other damage to the ducts. This can lead to grout leakage within the ducts, affecting the grouting and tensioning effects. Excessively long vertical ducts are prone to cement slurry segregation and bleeding during grouting, making it difficult to fill the ducts completely. This can cause corrosion of the prestressed tendons, leading to breakage and compromising the quality of the prestressed concrete.

[0005] (ii) The vertical installation accuracy of prestressing tendons is difficult to guarantee. The prestressing tendons of reaction walls are relatively long, usually more than 10 meters, and have large deflections, making it difficult to ensure vertical installation accuracy. If the verticality cannot be guaranteed, it will inevitably cause friction loss during prestressing tension, affecting the construction quality of the reaction wall.

[0006] (iii) Each prestressed tendon uses one anchor plate. Due to the small area of ​​the anchor plate, the tensioning process puts a lot of pressure on the reaction wall. Therefore, the local bearing pressure of the concrete structure of the reaction wall is large, which can easily lead to local damage to the reaction wall.

[0007] (iv) During prestressing tensioning, precise monitoring is not possible, and the tension force is not accurately controlled.

[0008] (v) The relaxation of prestressing tendons caused during use cannot be restored. After frequent use, the prestressing tendons of the reaction wall will relax. Once the prestressing tendons relax, they cannot be restored, which will cause the reaction wall to be scrapped.

[0009] Therefore, traditional prestressed construction techniques cannot guarantee the quality of reaction walls and are not suitable for widespread use in vertical prestressed engineering. Summary of the Invention

[0010] This invention provides a prestressed reaction wall construction method to solve the technical problems existing in the prior art. It is easy to construct, allows for re-tensioning, facilitates quality assurance, extends the frequency of use, and is suitable for widespread use in vertical prestressed engineering.

[0011] The technical solution adopted by this invention to solve the technical problems existing in the prior art is: a prestressed construction method for a reaction wall, wherein the prestressing tendons are vertically installed, and the construction method adopts the following steps:

[0012] 1) Cutting prestressing tendons: Cut unbonded steel strands to the design length plus the length of the anchorage and re-tensioning extension section to make prestressing tendons;

[0013] 2) Install fixing anchors at the lower end of the prestressing tendons;

[0014] 3) Fix the anchor perpendicularly to the reinforcement bars of the foundation slab;

[0015] 4) Precast ladder reinforcement: Make a grid-like ladder reinforcement according to the spacing of the prestressing tendons, so that the intersection of the ladder reinforcement corresponds one-to-one with the binding position of the prestressing tendons.

[0016] 5) Use ladder-like reinforcement bars to fix the prestressing tendons to the reinforcement bars of the foundation slab;

[0017] 6) Use ladder-like reinforcement bars to fix the prestressed tendons to the reinforcement bars of the basement roof slab;

[0018] 7) Repeat step 6) multiple times, using ladder bars to fix the prestressed tendons along with the top slab reinforcement of each layer of the structure, and set anchor plates on the ladder bars of the top slab reinforcement.

[0019] 8) After the concrete strength of the reaction wall at the top of the structure reaches 100%, prestressing tensioning is implemented using working anchors;

[0020] 9) After tensioning is completed, the working anchor is sealed at a single point;

[0021] 10) When the prestress is detected to be less than the set value, the sealing and anchoring structure of the corresponding prestressing tendon is broken and re-tensioning is carried out.

[0022] In step 4), two positioning axes, one horizontal and one vertical, are laid out on the ladder ribs.

[0023] Steps 5) and 6) are the same. First, two positioning axes, one horizontal and one vertical, are laid out on the structural steel bars and in the area where the prestressing tendons are arranged. Then, the prestressing tendons are passed through the ladder bars one by one, so that the positioning axes marked on the ladder bars coincide with the positioning axes laid out on the structural steel bars. Then, the ladder bars are welded to the structural steel bars. Finally, the prestressing tendons are tied at the intersection of the ladder bars.

[0024] In step 3), a tensile stress sensor is installed on the fixed anchor to monitor the prestress.

[0025] In step 7), the anchor plates adopt a continuous structure, and the anchor plates on each wall are connected as one unit.

[0026] In step 7), 3-5 layers of steel mesh are provided in the structural top slab reinforcement below the anchor plate.

[0027] In step 3), a spiral steel bar I fitted onto the prestressing tendon is installed above the fixed anchor; in step 7), a spiral steel bar II fitted onto the prestressing tendon is installed below the anchor plate.

[0028] In step 4), the ladder reinforcement is made using threaded steel bars.

[0029] The advantages and positive effects of this invention are:

[0030] (i) Considering the need for multiple flipping during prestressing tendon construction, the prestressing tendons were changed from bonded to unbonded to facilitate construction, adopting an equal-quantity replacement principle. Unbonded prestressing tendons, without ducts, avoid the problems associated with bonded prestressing tendons where ducts cause breakage, deformation, and other damage to the ducts due to multiple (four to five) flipping of the steel strands, leading to grout leakage within the ducts, affecting grouting and tensioning effects, and ultimately compromising the quality of the prestressed concrete. Simultaneously, the unbonded prestressing tendons use a single, dispersed arrangement structure, resulting in a more uniform distribution of prestress in the reaction wall.

[0031] (ii) Horizontal positioning ladder bars are set on the top slab of each layer of structure. Positioning marks corresponding to the design positions of the prestressing tendons are made on each layer of ladder bars. The prestressing tendons are tied to the positioning marks of the ladder bars. The vertical accuracy of the entire prestressing tendon is controlled by multi-point continuous vertical positioning, which can meet the construction requirements, avoid friction loss, eliminate the need for over-tensioning, and achieve the effect of prestressed concrete.

[0032] (iii) A 300mm long extension section is set at the upper end of the prestressing tendon, which can be used to re-tension the reaction wall after the prestressing tendon has loosened due to frequent use, so as to increase the number of times the reaction wall can be used.

[0033] (iv) Tensile stress sensors are installed on the fixed anchors to monitor the prestress, which can avoid inaccurate control of the tension force during the tensioning process and achieve the tensioning effect of dual control of tension force and steel strand elongation.

[0034] (v) If the prestressing tendons adopt a single anchorage structure, and the anchor plates are also single and independent, the local bearing area of ​​the concrete will be small. Therefore, a multi-point evenly distributed four-way continuous anchor plate is used to ensure that the tension force is evenly transmitted to the anchor plate, thereby increasing the bearing area and reducing the pressure. In addition, multiple layers of horizontal steel mesh are set in the concrete under the anchor plate to enhance the integrity and bearing capacity of the concrete structure.

[0035] (vi) The working anchor adopts a single-point sealing anchor structure, which facilitates re-tensioning, allows for the separate removal of the sealing anchor structure, and enables the individual tensioning of any prestressing tendon as needed, with minimal disturbance to adjacent prestressing tendons.

[0036] In summary, this invention is easy to construct, allows for re-tensioning, facilitates quality assurance, extends the frequency of use, and is suitable for widespread application in vertical prestressed engineering. Attached Figure Description

[0037] Figure 1 This is a plan view of the prestressed tendons for the reaction wall;

[0038] Figure 2 Elevation view of the prestressed tendons of the reaction wall;

[0039] Figure 3 This is a cross-sectional view of the fixed anchor of the present invention;

[0040] Figure 4 This is a plan view of the ladder reinforcement arrangement of the present invention;

[0041] Figure 5 This is an elevation view of the ladder reinforcement arrangement of the present invention;

[0042] Figure 6 This is a plan view of the reinforcing mesh of the present invention;

[0043] Figure 7 for Figure 6 AA cross-section diagram;

[0044] Figure 8 This is a plan view of the anchor plate arrangement of the present invention;

[0045] Figure 9 This is an elevation view of the anchor plate of the present invention;

[0046] Figure 10 This is a side elevation view of the anchor plate of the present invention;

[0047] Figure 11 This is a cross-sectional view of the working anchor of the present invention.

[0048] In the diagram: 1. Prestressed tendon; 1-1. Extension section; 2. Fixed anchor; 3. Working anchor; 4. Anchor plate; 5. Tensile stress sensor; 6. Steel mesh; 7. Spiral steel bar I; 8. Spiral steel bar II; 9. Ladder reinforcement; 10. Sleeve mold. Detailed Implementation

[0049] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0050] Please see Figures 1 to 11A prestressed construction method for a reaction wall, wherein the prestressing tendons are vertically installed, and the installation method comprises the following steps:

[0051] 1) Cutting prestressing tendons: Cut unbonded steel strands to the design length plus the length of the anchorage and secondary tensioning extension section to make prestressing tendon 1;

[0052] 2) Install a fixed anchor 2 at the lower end of the prestressing tendon 1. Specifically, the prestressing tendon adopts a one-end fixed structure. The anchor consists of an extrusion sleeve, an anchor spring, an anchor plate, and a spiral reinforcement. Insert the spiral reinforcement and anchor plate into one end of the steel strand, peel off 50mm of the outer sheath of the steel strand, insert the anchor spring, insert the steel strand into the extrusion sleeve, and put it into the fixed anchor extrusion machine; thus, a fixed anchor is made.

[0053] 3) Fix the anchor 2 perpendicularly to the reinforcement bars of the foundation slab;

[0054] 4) Precast ladder reinforcement 9: Make grid-like ladder reinforcement 1 according to the spacing of prestressed tendons 1, so that the intersection of the ladder reinforcement corresponds one-to-one with the binding position of the prestressed tendons 1.

[0055] 5) Use ladder bars 9 to fix the prestressing tendons 1 to the foundation slab reinforcement;

[0056] 6) Use ladder bars 9 to fix the prestressed tendons 1 to the reinforcement of the basement roof slab;

[0057] 7) Repeat step 6) multiple times, using the ladder reinforcement 9 to fix the prestressed tendons 1 along with the top slab reinforcement of each layer of the structure, and set the anchor plate 4 on the ladder reinforcement 9 of the top slab reinforcement of the structure.

[0058] 8) After the concrete strength of the reaction wall at the top of the structure reaches 100%, prestressing tensioning is carried out using working anchor 3;

[0059] 9) After tensioning is completed, the working anchor 3 is sealed at a single point to facilitate re-tensioning. Specifically, after tensioning is completed, grease is applied to the exposed steel strands and a waterproof protective sleeve is put on; PVC pipe is used as the sleeve mold 10, and the inside of the sleeve is coated with release agent to facilitate demolding; high-foam concrete is poured at a single point to seal the anchor to facilitate subsequent re-tensioning.

[0060] 10) When the prestress is detected to be less than the set value, the sealing and anchoring structure of the corresponding prestressing tendon is broken and re-tensioning is carried out.

[0061] In this embodiment, the length of the anchorage and re-tensioning extension section 1-1 is 300mm. To ensure accurate positioning of the ladder reinforcement, in step 4), two positioning axes are marked on the ladder reinforcement 9, one horizontal and one vertical. Steps 5) and 6) are performed in the same way: first, two positioning axes are marked on the structural steel reinforcement and in the area where the prestressing tendons are arranged; then, the prestressing tendons 1 are passed through the ladder reinforcement one by one, so that the positioning axes marked on the ladder reinforcement 9 coincide with the positioning axes marked on the structural steel reinforcement; then, the ladder reinforcement 9 is welded to the structural steel reinforcement; and then, the prestressing tendons 1 are tied at the intersection of the ladder reinforcement 9. To improve the accuracy of tension control, in step 3), a tensile stress sensor 5 is installed on the fixed anchor 2 to monitor the prestress of the prestressing tendons. To improve the safety of the reaction wall, in step 7), the anchor plate 4 adopts a continuous structure, with the anchor plates on each wall connected as one unit. The prestressing tendons pass through the anchor plate 4, and the anchor plate 4 is fixed to the top layer of the reaction wall reinforcement. The prestressing tendons are temporarily fixed to the anchor plate 4 using fixed anchors to prevent them from falling off. Protective sleeves are installed on the exposed steel strands. In step 7), 3-5 layers of steel mesh are provided in the structural top slab reinforcement below the anchor plate, with a vertical spacing of 80mm between the meshes. The main function of the mesh is to enhance the overall strength of the concrete below the anchor plate and prevent local damage during prestressing tensioning. To enhance the pull-out resistance of the fixed anchor and the working anchor and prevent pull-out damage, in step 3), a spiral steel bar I7 fitted onto the prestressing tendon 1 is set above the fixed anchor 2; in step 7), a spiral steel bar II8 fitted onto the prestressing tendon 1 is set below the anchor plate 4. In this embodiment, in step 4), a ladder reinforcement 9 is made using threaded steel bars.

[0062] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A method for prestressed construction of a reaction wall, wherein the prestressing tendons are vertically arranged, characterized in that, The construction method involves the following steps: 1) Cutting prestressing tendons: Cut unbonded steel strands to the design length plus the length of the anchorage and re-tensioning extension section to make prestressing tendons; 2) Install fixing anchors at the lower end of the prestressing tendons; 3) Fix the anchor perpendicularly to the reinforcement bars of the foundation slab; 4) Precast ladder reinforcement: Make a grid-like ladder reinforcement according to the spacing of the prestressing tendons, so that the intersection of the ladder reinforcement corresponds one-to-one with the binding position of the prestressing tendons. Specifically, make two positioning axes, one horizontal and one vertical, on the ladder reinforcement. 5) Use ladder bars to fix the prestressing tendons to the foundation slab reinforcement. Specifically, first, mark two positioning axes, one horizontal and one vertical, on the structural reinforcement and in the area where the prestressing tendons are arranged. Then, pass the prestressing tendons through the ladder bars one by one, so that the positioning axes marked on the ladder bars coincide with the positioning axes marked on the structural reinforcement. Then, weld the ladder bars to the structural reinforcement and then tie the prestressing tendons at the intersection of the ladder bars. 6) Use ladder-like reinforcement bars to fix the prestressed tendons to the reinforcement bars of the basement roof slab. The specific fixing method is the same as in step 5). 7) Repeat step 6) multiple times, using ladder bars to fix the prestressed tendons along with the top slab reinforcement of each layer of the structure, and set anchor plates on the ladder bars of the top slab reinforcement of the structure. 8) After the concrete strength of the reaction wall at the top of the structure reaches 100%, prestressing tensioning is implemented using working anchors; 9) After tensioning is completed, the working anchor is sealed at a single point; 10) When the prestress is detected to be less than the set value, the sealing and anchoring structure of the corresponding prestressing tendon is broken and re-tensioning is carried out.

2. The prestressed construction method for reaction walls according to claim 1, characterized in that, In step 3), a tensile stress sensor is installed on the fixed anchor to monitor the prestress.

3. The prestressed construction method for reaction walls according to claim 1, characterized in that, In step 7), the anchor plates adopt a continuous structure, with the anchor plates on each wall connected as one unit.

4. The prestressed construction method for reaction walls according to claim 1, characterized in that, In step 7), 3-5 layers of steel mesh are provided in the structural top slab reinforcement below the anchor plate.

5. The prestressed construction method for reaction walls according to claim 1, characterized in that, In step 3), a spiral steel bar I, fitted onto the prestressing tendon, is installed above the fixed anchor; in step 7), a spiral steel bar II, fitted onto the prestressing tendon, is installed below the anchor plate.

6. The prestressed construction method for reaction walls according to claim 1, characterized in that, In step 4), the ladder reinforcement is made using threaded steel bars.

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