Prefabricated assembled bearing platform structure with horizontally and vertically bidirectionally partitioned, staggered and superposed and construction method thereof

Abstract

The invention relates to the technical field of prefabricated assembled bearing platforms, and discloses a prefabricated assembled bearing platform structure with horizontally and vertically bidirectionally partitioned, staggered and superposed and a construction method thereof, the prefabricated assembled bearing platform structure comprises: a horizontal prefabricated assembly for realizing torque transmission in a bending state; the vertical prefabricated assembly is arranged at the top end of the horizontal prefabricated assembly, the vertical prefabricated assembly and the horizontal prefabricated assembly are staggered and stacked to form the prefabricated assembled bearing platform structure, and transverse bending resistance and longitudinal shearing resistance of the prefabricated assembled bearing platform structure are guaranteed; and the splicing assembly is arranged in the horizontal prefabricated assembly and the vertical prefabricated assembly in a penetrating mode and used for achieving connection of the horizontal prefabricated assembly and the vertical prefabricated assembly. By means of the horizontal prefabricated assemblies and the vertical prefabricated assemblies, a plurality of problems of an existing prefabricated bearing platform, namely, the problems that transportation is difficult, the construction period is long, the splicing technology is complex, and the overall stress performance after splicing is poor are solved.

Description

Technical Field

[0001] This invention relates to the field of prefabricated assembly foundation technology, specifically to a prefabricated assembly foundation structure with horizontal and vertical bidirectional blocks stacked alternately and its construction method. Background Technology

[0002] With the rapid development of urban infrastructure construction, bridge and elevated engineering projects, including national railways, subways, suburban railways, and urban rail transit, occupy a crucial position in the transportation network. Traditional cast-in-place pier caps, due to their long construction cycles, significant environmental impact, and susceptibility to human factors in construction quality, are gradually failing to meet the demands of modern bridge construction for high efficiency, high quality, and environmental protection. Therefore, precast assembled pier cap structures have emerged.

[0003] Precast bridge piers, through factory prefabrication, on-site hoisting, and rapid assembly, effectively improve construction quality and efficiency, shorten the construction period, and reduce disruption to the surrounding environment and traffic during construction. In bridge foundation engineering in water or densely populated urban areas, precast bridge piers offer significant advantages, not only avoiding prolonged underwater operations but also significantly reducing the impact on the hydrological environment and construction safety. Therefore, precast bridge pier technology has become an important component of prefabricated bridge structural systems, with broad application prospects and promotional value.

[0004] Currently, existing technologies related to precast foundation technology include: (I) Existing Technical Solution 1: Precast concrete substructure components, including cofferdams, abutments, and piers, were used during bridge construction and then connected into a single integral component using post-tensioned prestressed bonding technology. The shortcomings of this existing technical solution 1 are: these components require prestressed bonding later, which significantly increases construction costs for multi-pier bridges; furthermore, achieving a unified effect through prestressed bonding of multiple components is challenging. For the abutments, the bending resistance decreases after segmentation and connection with prestressed tendons, and leveling is difficult when connecting the pier components.

[0005] (II) Existing Technical Solution Two: The foundation is divided into two parts: prefabricated and cast-in-place. The bottom of the foundation and the columns are prefabricated first, and then the remaining part of the foundation is cast after being transported to the site, thereby achieving the effect of the prefabricated foundation and columns bearing the load as a whole. Disadvantages of Existing Technical Solution Two: Although this method prefabricates the bottom of the foundation and the columns in advance and has a high degree of integrity in load-bearing performance, its transportation process has no significant advantage over the prefabricated column and foundation as a whole component. Moreover, for underwater operations, on-site casting is more difficult and the construction is more complicated.

[0006] (III) Existing Technical Solution 3: Two-part precast foundation and multi-part precast foundation. The two-part precast foundation is precast in two sections along the transverse or longitudinal direction, transported to the site, and then concrete is poured. The multi-part precast foundation is precast in multiple sections, transported to the site, and then poured. Disadvantages of Existing Technical Solution 3: Both the two-part and multi-part methods inevitably involve on-site pouring, and to maintain good performance after connection, strict requirements are placed on the joints, making on-site operation difficult and construction challenging.

[0007] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0008] To address the problems in related technologies, this invention proposes a prefabricated assembly foundation structure with horizontal and vertical bidirectional block staggered stacking and its construction method, in order to overcome the aforementioned technical problems existing in the existing related technologies.

[0009] Therefore, the specific technical solution adopted by the present invention is as follows: According to one aspect of the present invention, a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered arrangement is provided, the structure comprising: Horizontal prefabricated components are used to transmit torque under bending conditions; Vertical prefabricated components are placed on top of horizontal prefabricated components and are stacked alternately with horizontal prefabricated components to form a prefabricated assembly foundation structure, which ensures the lateral bending resistance and longitudinal shear resistance of the prefabricated assembly foundation structure. The splicing component is installed inside both the horizontal and vertical prefabricated components to connect them.

[0010] Furthermore, the horizontal precast component includes lower precast blocks symmetrically arranged at the bottom of the vertical precast component. The top of the lower precast block and the side closest to the vertical precast component have shear grooves that cooperate with the vertical precast component; and the two sets of lower precast blocks are placed side by side.

[0011] Furthermore, the shear groove is a rectangular structure, and the rectangular structure formed by the two sets of shear grooves is staggered with the horizontal prefabricated components, and the torque is transmitted through the connection of the two sets of shear grooves.

[0012] Furthermore, the vertical prefabricated component includes a first upper prefabricated block disposed inside the shear groove; The first upper precast block and the two sets of lower precast blocks form a T-shaped structure.

[0013] Furthermore, the vertical prefabricated component also includes a second upper prefabricated block symmetrically arranged inside the shear groove.

[0014] Furthermore, the two sets of second upper precast blocks are evenly arranged and linearly distributed inside the shear groove, and the two sets of second upper precast blocks and the two sets of lower precast blocks form a T-shaped structure.

[0015] Furthermore, the splicing component includes reserved bolt holes that penetrate the horizontal and vertical precast components. Vertical prestressed threaded steel bars are installed inside the reserved bolt holes, and the two ends of the vertical prestressed threaded steel bars are connected to the horizontal and vertical precast components by several bolts.

[0016] According to another aspect of the present invention, a construction method for a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered arrangement is provided, the method comprising: The dimensions of the horizontal and vertical prefabricated components are determined based on the maximum allowable dimensions for transportation, and prefabrication and curing are carried out based on the dimensions of the horizontal and vertical prefabricated components. The number of vertical prestressed threaded steel bars connecting the horizontal and vertical precast components is calculated using strength verification methods, and the magnitude of the tension control stress is determined. The precast horizontal and vertical precast components are staggered and poured together after prefabrication and curing. The prestressed steel bars are tensioned according to the number of vertical prestressed threaded steel bars and the magnitude of the tension control stress, resulting in a precast assembled pier structure with staggered horizontal and vertical bidirectional blocks.

[0017] Furthermore, the calculation steps for the number of vertical prestressed threaded steel bars include: The total prestress is determined based on the anti-slip verification requirements, and the number of first prestressed steel bars is determined in combination with the prestress of a single steel bar. The prestress required to offset tensile stress is determined by using crack resistance calculation requirements, and the number of second prestressed steel bars is determined by combining the prestress of a single steel bar. The number of third prestressed steel bars is determined based on the preset minimum reinforcement ratio and spacing requirements, and the maximum value among the number of first prestressed steel bars, second prestressed steel bars and third prestressed steel bars is selected as the number of vertical prestressed threaded steel bars.

[0018] Further steps for determining the magnitude of the tension control stress include: Based on the building structure load code, the shear force design value at the connection node is determined by the basic combination, and the standard value of tensile strength and cross-sectional area of ​​a single bar are determined by the selected vertical prestressed threaded steel bars. Based on the anti-slip requirements, the initial tension control stress is determined using the ratio of the shear force design value at the connection node to the preset friction coefficient; The required prestress for a single steel bar is determined by the ratio of the initial tension control stress to the number of vertical prestressed threaded steel bars. The tension control stress is then adjusted by combining it with the cross-sectional area and tensile strength standard value of the single steel bar to obtain the magnitude of the tension control stress.

[0019] The beneficial effects of this invention are as follows: 1. This invention solves several problems of existing precast foundations by using horizontal and vertical precast components, namely, difficult transportation, long construction period, complex splicing technology, and poor overall stress performance after splicing.

[0020] 2. The prefabricated assembly foundation structure of the present invention can realize the segmented assembly structure of the foundation (compression and bending member) according to the stress characteristics of the foundation. The prefabricated foundation structure is composed of prefabricated modules stacked one on top of the other. The upper and lower prefabricated modules, including horizontal prefabricated components and vertical prefabricated components, are all connected by vertical prestressed threaded steel bars. The bottom prefabricated module is connected by prefabricated bolts. The construction is convenient, the force transmission path is clear, and the stress performance is good.

[0021] 3. The foundation of this invention can be prefabricated in the factory simultaneously with the bridge pier construction, pile foundation testing, or site leveling stages, and then transported to the site for assembly before entering the foundation construction process. After the prefabricated components are transported to the site, they are modularly assembled using high-strength bolts and a post-tensioned prestressed system. Compared with the cast-in-place process, which requires waiting for the strength to meet the requirements, this can shorten the on-site operation time by more than 90%, greatly reducing the construction cycle.

[0022] 4. This invention can divide the entire foundation into two layers, with the lower layer divided into two parts, for a total of three components. The size of each component is determined according to the allowable dimensions for transportation, ensuring the feasibility of transporting the prefabricated foundation and making transportation convenient.

[0023] 5. The basis of the precast foundation segmentation method adopted in this invention is that the overall stress characteristics and load resistance of the foundation remain unchanged. From the finite element simulation results of the precast foundation and the integral cast foundation under the compression and bending load using the method of this invention, it can be seen that the tensile damage and failure of the segmented foundation and the cast-in-place foundation are basically the same, and the stress performance of the structure of this invention is good. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is an overall assembly effect diagram of a three-piece and four-piece prefabricated pier structure with horizontal and vertical bidirectional bidirectional block staggered stacking according to an embodiment of the present invention; Figure 2 This is a flowchart of a construction method for a prefabricated assembly foundation structure with horizontal and vertical bidirectional bidirectional block staggered stacking according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the horizontal and vertical segmentation of the main components of a three- or four-piece prefabricated assembly foundation structure, which is horizontally and vertically segmented and interlocked according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the shear groove of the main components of a three-block and four-block prefabricated assembled pier structure with horizontal and vertical bidirectional bidirectional block staggered stacking according to an embodiment of the present invention; Figure 5 This is a diagram showing the prestressed steel reinforcement connection structure of a three-block and four-block prefabricated assembled foundation structure with horizontal and vertical bidirectional bidirectional block staggered stacking according to an embodiment of the present invention. Figure 6 This is a schematic diagram of the prestressed ducts and end anchor bolts of a prefabricated assembled pier structure with horizontal and vertical bidirectional bidirectional block staggered stacking according to an embodiment of the present invention. Figure 7 This is a diagram showing the load and constraint conditions of a three-block and four-block prefabricated assembly foundation structure with horizontal and vertical bidirectional bidirectional block staggered stacking according to an embodiment of the present invention. Figure 8 This is a diagram of the base reaction force of a prefabricated assembled foundation structure with horizontal and vertical bidirectional bidirectional blocks and staggered stacking, as well as a cast-in-place foundation under bending conditions. Figure 9 The tensile damage condition of three-piece and four-piece prefabricated pier structures with horizontal and vertical bidirectional bidirectional block staggered stacking under the bending condition according to the embodiment of the present invention. Figure 10 This is a modeling diagram of a station bridge with a prefabricated assembled pier structure that is horizontally and vertically bidirectionally segmented and interlocked according to an embodiment of the present invention; Figure 11 This is a rendering of the overall assembly of the cast-in-place foundation. Figure 12 This is a diagram showing the load and constraint conditions of the cast-in-place foundation; Figure 13 It describes the tensile damage condition of cast-in-place foundations under compression-bending conditions under the same load. Figure 14 This is a diagram showing the shear stress and compressive stress at the contact surface of the upper and lower piers of a prefabricated pier structure with horizontal and vertical bidirectional bidirectional block staggered stacking, according to an embodiment of the present invention. Figure 15 This is a reinforcement diagram of the cross-section of a station bridge pier with a prefabricated, assembled pier cap structure that is horizontally and vertically bidirectionally segmented and staggered according to an embodiment of the present invention; Figure 16This is a diagram of the foundation assembly of a prefabricated foundation structure with horizontal and vertical bidirectional blocks stacked in an alternating manner according to an embodiment of the present invention. Figure 17 This is a reinforcement diagram of a prefabricated assembled pier structure with horizontal and vertical bidirectional bi-directional block staggered stacking according to an embodiment of the present invention; Figure 18 The stress diagram showing the yield strength of the longitudinal reinforcement of the bridge pier in the prefabricated assembled pier structure with horizontal and vertical bidirectional bi-directional block staggered stacking according to an embodiment of the present invention; Figure 19 This is a diagram showing the ultimate strength stress of the longitudinal reinforcement of a bridge pier in a prefabricated pier cap structure with horizontal and vertical bidirectional bi-directional block staggered stacking, according to an embodiment of the present invention. Figure 20 This is a diagram showing the yield strength of the longitudinal reinforcement of the pier and the tensile damage of the top bearing cap. Figure 21 This is a diagram showing the ultimate strength tensile damage of the longitudinal reinforcement of the pier top of the prefabricated assembled pier structure with horizontal and vertical bidirectional bi-directional block staggered stacking according to an embodiment of the present invention. Figure 22 This is a diagram showing the tensile damage of a cast-in-place foundation under the same load conditions.

[0026] In the picture: 1. Horizontal precast components; 101. Lower precast block; 102. Shear groove; 2. Vertical precast components; 201. First upper precast block; 202. Second upper precast block; 3. Splicing components; 301. Reserved bolt holes; 302. Vertical prestressed threaded steel bars; 303. Bolts; 4. Corrugated pipe; 5. PVC pipe; 6. Steel base plate; 7. Steel sleeve. Detailed Implementation

[0027] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0028] According to an embodiment of the present invention, a prefabricated assembled foundation structure with horizontal and vertical bidirectional bidirectional blocks and staggered stacking, and its construction method are provided.

[0029] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 , Figures 3-7 , Figures 9-10 , Figures 16-17 , Figure 21 As shown, according to one embodiment of the present invention, a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered arrangement is provided, the structure comprising: Horizontal prefabricated component 1 is used to realize the torque transmission under bending conditions; The vertical prefabricated component 2 is set at the top of the horizontal prefabricated component 1 and is stacked with the horizontal prefabricated component 1 to form a prefabricated assembly foundation structure, which ensures the lateral bending resistance and longitudinal shear resistance of the prefabricated assembly foundation structure. The splicing component 3 is installed inside the horizontal prefabricated component 1 and the vertical prefabricated component 2 to connect the horizontal prefabricated component 1 and the vertical prefabricated component 2.

[0030] Specifically, the horizontal precast component 1 includes lower precast blocks 101 symmetrically arranged at the bottom of the vertical precast component 2. The top of the lower precast block 101 and the side near the vertical precast component 2 are provided with shear grooves 102 that cooperate with the vertical precast component 2; and the two sets of lower precast blocks 101 are placed side by side.

[0031] Specifically, the shear groove 102 is a rectangular structure, and the rectangular structure formed by the two sets of shear grooves 102 is staggered with the horizontal prefabricated component 1, and the torque is transmitted through the connection of the two sets of shear grooves 102.

[0032] Specifically, the vertical prefabricated component 2 includes a first upper prefabricated block 201 disposed inside the shear groove 102; The first upper precast block 201 and the two sets of lower precast blocks 101 form a T-shaped structure.

[0033] Specifically, the vertical prefabricated component 2 also includes a second upper prefabricated block 202 symmetrically arranged inside the shear groove 102.

[0034] Specifically, the two sets of second upper precast blocks 202 are evenly arranged and linearly distributed inside the shear groove 102, and the two sets of second upper precast blocks 202 and the two sets of lower precast blocks 101 form a T-shaped structure.

[0035] Specifically, the splicing component 3 includes a reserved bolt hole 301 that runs through the interior of the horizontal precast component 1 and the vertical precast component 2. The interior of the reserved bolt hole 301 is provided with a vertical prestressed threaded steel bar 302. The two ends of the vertical prestressed threaded steel bar 302 are connected to the horizontal precast component 1 and the vertical precast component 2 by a number of bolts 303.

[0036] Specifically, the design of precast foundation blocks and splicing can be divided into three-block precast rigid connection foundation blocks and four-block precast rigid connection foundation blocks, which are staggered according to specific construction requirements. The three-block precast rigid connection foundation block is precast into three blocks (upper, lower, and horizontal): an upper precast block 201 and two lower precast blocks 101. The upper and lower precast blocks are not connected horizontally, but only vertically by prestressed threaded steel bars 302. A shear groove 102 is reserved in the middle of the bottom lower precast block 101. Figure 5 As shown, this is used for installing the first upper precast block 201. After the precast blocks have been cured, they are transported to the construction site for stacking, pouring, and tensioning of prestressed steel bars. The four-block precast rigid connection involves precasting the foundation into four blocks (upper, lower, and horizontal) and transporting them to the site for pouring, namely two second upper precast blocks 202 and two lower precast blocks 101. The connection method is the same as that of the three-block precast rigid connection foundation.

[0037] Modular precast foundation design technology and assembly process: The technical description of foundation module division is that the foundation can be divided into three or four parts, such as... Figure 1 , Figure 3-4 As shown, the structure is specifically divided into three or four parts, with the dimensions of the parts determined by the maximum allowable dimensions for transportation. Two parts are arranged side-by-side on the bottom layer, while the other part is arranged vertically on the top layer. In the four-piece foundation, the two upper parts are placed side-by-side. The two bottom-layer parts are connected by shear grooves 102 to transfer torque, as shown below. Figure 4 As shown, the overall load-bearing performance ensures both lateral bending resistance and longitudinal shear resistance. The modular precast pier dry connection technology is as follows... Figures 5-6 As shown, the bottom and upper foundations are connected by vertical prestressed threaded steel bars 302, that is, the horizontal precast component 1 and the vertical precast component 2 are connected by vertical prestressed threaded steel bars 302. For specimens mainly subjected to compressive bending moments, this connection method is sufficiently safe. Figure 7 , 8 As shown, the three parts are connected to form a single pier cap. When the superstructure of the bridge or viaduct undergoes lateral displacement, the superstructure transmits a pressure and bending moment to the pier cap through the piers. Under this pressure-bending state, the force transmission path of the precast pier cap segmented method designed in this invention is consistent with the force transmission path of the integrally cast pier cap, resulting in good stress performance. Furthermore, because the upper-layer blocks are integral parts, leveling is easier when connecting the piers to the upper-layer blocks, the connection method has lower precision requirements, and is easier to operate on-site.

[0038] like Figure 2 As shown, according to another embodiment of the present invention, a construction method for a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered arrangement is provided, the method comprising: The dimensions of the horizontal prefabricated component 1 and the vertical prefabricated component 2 are determined according to the maximum allowable dimensions for transportation, and prefabrication and curing are carried out based on the dimensions of the horizontal prefabricated component 1 and the vertical prefabricated component 2. The number of vertical prestressed threaded steel bars 302 connecting the horizontal precast component 1 and the vertical precast component 2 is calculated by strength verification, and the magnitude of the tension control stress is determined. The precast horizontal precast component 1 and the vertical precast component 2 are staggered and poured together. The prestressed steel bars are tensioned according to the number of vertical prestressed threaded steel bars 302 and the magnitude of the tension control stress, so as to obtain a precast assembled foundation structure with horizontal and vertical bidirectional blocks staggered and stacked.

[0039] Specifically, the calculation steps for the number of 302 vertical prestressed threaded steel bars include: The total prestress is determined based on the anti-slip verification requirements, and the number of first prestressed steel bars is determined in combination with the prestress of a single steel bar. The prestress required to offset tensile stress is determined by using crack resistance calculation requirements, and the number of second prestressed steel bars is determined by combining the prestress of a single steel bar. The number of third prestressed steel bars is determined based on the preset minimum reinforcement ratio and spacing requirements, and the maximum value among the number of first prestressed steel bars, second prestressed steel bars and third prestressed steel bars is selected as the number of vertical prestressed threaded steel bars 302.

[0040] Specifically, the steps for determining the magnitude of the tension control stress include: Based on the building structure load code, the shear force design value at the connection node is determined by the basic combination, and the standard value of tensile strength and cross-sectional area of ​​a single bar are determined by the selected vertical prestressed threaded steel bar 302. Based on the anti-slip requirements, the initial tension control stress is determined using the ratio of the shear force design value at the connection node to the preset friction coefficient; The required prestress for a single steel bar is determined based on the ratio of the initial tension control stress to the number of vertical prestressed threaded steel bars 302. The tension control stress is then adjusted in conjunction with the cross-sectional area and tensile strength standard value of the single steel bar to obtain the magnitude of the tension control stress.

[0041] Specifically, the modular foundation design involves the following steps: First, the tensile damage failure of the cast-in-place foundation is determined through finite element modeling and simulation. Then, appropriate material parameters, properties, and plastic damage models are selected to establish an integral cast-in-place foundation model. Figure 11 As shown, the cast-in-place foundation is reinforced according to structural requirements, and the same load as the precast foundation is applied to the center of the top foundation, with the bottom supports constrained. Figure 12 As shown, the tensile damage failure of the cast-in-place foundation was determined through finite element analysis. Figure 13 As shown, the process involves first establishing a monolithic cast-in-place foundation model by selecting appropriate material parameters, properties, and plastic damage models through finite element modeling and simulation. Figure 11 As shown, the cast-in-place foundation is reinforced according to structural requirements, and the same load as the precast foundation is applied to the center of the top foundation, with the bottom supports constrained. Figure 12 As shown, the tensile damage failure of the cast-in-place foundation was determined through finite element analysis. Figure 13 As shown.

[0042] Next, the dimensions of the three- or four-piece pier cap components are initially designed, and the number of prestressed threaded steel bars connecting the upper and lower pier caps and the magnitude of the tension control stress are calculated through strength verification. The specific strength verification method is as follows: In determining the design calculation of the number of prestressed threaded steel bars, the total prestress is first determined based on the anti-slip verification requirement, that is, the frictional force generated by the prestress can resist the horizontal thrust design value. N p ,Right now N p ≥ H d / μ ;in H d Design value for horizontal thrust, μ Let be the coefficient of friction between concrete sections, and according to the formula: n 1= N p / N p1 Determine the number of prestressed threaded steel bars based on anti-slip calculations, among which N p1 This refers to the preload of a single reinforcing bar. Based on crack resistance calculations, specifically ensuring no tensile stress occurs at the connection interface under service load, the required preload is determined as follows: N p2 ≥ σ p × A ;actually σ p Preload required to counteract tensile stress σ p ≥∣ σ min |, here is the minimum stress, i.e., tensile stress: σ min = N k / A - M k / W And according to the formula n 2= N p2 / N p1 Then determine the number of prestressed threaded steel bars based on the anti-slip calculation; N k This represents the standard value of the axial force acting on the connection interface (unit: kN). A This represents the total cross-sectional area of ​​the connection interface (unit: mm² or m²). M kThis represents the standard value of the bending moment acting at the centroid of the connection interface (unit: kN.m). W This represents the section modulus acting on the interface about its own centroidal axis (for a rectangular section). W = bh ² / 6, of which b Indicates the width of the rectangular cross-section; h This indicates the height of a rectangular section; for complex sections such as T-shaped and I-shaped sections, the height is calculated based on the actual centroidal axis. Simultaneously, the number of prestressed threaded steel bars is determined according to the structural requirements of GB 50010-2010. n 3. The arrangement of prestressed threaded steel bars should also meet the minimum reinforcement ratio and spacing requirements: the spacing between bars should not exceed 200mm, and for important connections, the minimum number of bars should generally not be less than 20. Final selection. n 1. n 2. n The maximum value among the three is taken as the final number of prestressed threaded steel bars. n .

[0043] Tension control stress N p,total In the selection and calculation of the magnitude, the design value of axial pressure should be determined by using the basic combination according to the "Code for Design of Building Structures" GB50009. N d Horizontal thrust design value H d Shear force design value at connection nodes V d Selecting the appropriate size of prestressed threaded steel bars allows for the determination of the standard value of tensile strength. f pyk Tensile strength design value f py according to f pyk / 1.2 Calculation of cross-sectional area of ​​a single steel bar A s The prestressed design is based on anti-slip requirements. The anti-slip at the connection joints is resisted by friction generated by the prestress, with the friction coefficient taken as... μ =0.6 The required total prestress can be determined between concrete sections: N p,total ≥ V d / μ The required prestress for a single steel bar is: N p ≥ N p,total / n , here n To determine the final selected number of prestressed threaded steel bars, the tension control stress σ is... con =N p / A s It is less than the allowable value of 0.75. f pyk The requirements are met. The total prestressing is finally determined. N p,total .

[0044] After initially determining the basic structure, finite element modeling and analysis are performed using Abaqus. It is important to note that the material property parameters of the segmented foundation model must be consistent with those of the cast-in-place foundation, for example, both being C50 concrete. Appropriate tensile damage and failure properties should be determined based on the mesh division.

[0045] In addition, attention should be paid to the boundary and constraint conditions of the segmented foundation and the simulation of prestressed constraints during the Abaqus design modeling process. This segmented foundation force transmission mode can be identified as similar to a beam-slab raft foundation. Since the connection type between the bottom foundation and the top foundation is a prestressed bolt rigid connection, and a shear groove is reserved at the top of the bottom foundation to place the top foundation.

[0046] Under the premise of sufficient prestressing, it can be assumed that the inter-story constraints are sufficient, with no relative displacement or rotation. At this point, shear force V, bending moment M, and axial force N are all transmitted. The overall working mode follows the behavior of a composite beam. Therefore, during modeling, it can be assumed that when the prestressing constraints are sufficient, there is no slippage between the top and bottom bearing platforms, and their contact interaction can be set as a binding constraint. This can be achieved by analyzing the modeling contour map at this point, as shown below. Figure 14 As shown, the maximum interlayer shear stress is 1.59 MPa. Assuming the interlayer friction coefficient of concrete is 0.6, the maximum interlayer friction stress = friction coefficient × maximum interlayer compressive stress = 1.89 MPa, which is greater than the maximum shear stress. At this point, the concrete is sufficiently constrained and there is no relative slippage.

[0047] In Abaqus, simulating actual construction conditions requires defining prestressed steel reinforcement to have no slippage in the shear direction of the cross-section, while allowing slippage in the axial direction. This is achieved by defining contact or constraints. Specifically, this definition is similar to establishing a "shear connection" behavior between the steel reinforcement and concrete, where the transverse direction (including radial and circumferential) is completely fixed, while relative sliding is allowed in the axial direction. Therefore, we can achieve this by defining contact properties: Normal behavior: hard contact allowing separation; Tangential behavior: setting no slippage in the first circumferential tangential direction (e.g., using a large coefficient of friction or binding), and setting no slippage or friction in the second axial tangential direction. However, if only axial slippage is desired, the circumferential direction should be bound, and the axial direction should have a coefficient of friction of 0 or very small to allow free slippage.

[0048] Under the above operational premise, the design was continuously adjusted, and tensile damage was analyzed using Abaqus finite element method. When the tensile damage of the segmented foundation was consistent with that of the cast-in-place foundation, i.e., significant tensile damage only appeared on the surface of the foundation, such as... Figure 9 , Figures 11-13 As shown, the design can be considered to be initially completed.

[0049] It's important to explain here that the precast pier cap experiences a larger range of tensile damage because the connection between the precast pier cap and the precast pier is a dry connection, requiring a larger steel plate anchor bolt, which is not necessary for cast-in-place piers. Since the contact condition between the top steel plate of the precast and cast-in-place pier caps is designed as a bonded relationship, when the steel plate is subjected to bending moment, it will bend and deform. This will pull up the concrete on the top surface of the pier cap, resulting in significant tensile damage at the connection point between the top surface of the pier cap and the steel plate. Figure 9 , Figures 11-13 As shown. At this point, when calculating and comparing the tensile damage failure of segmented pile caps and cast-in-place pile caps under the same load conditions, attention should be paid to the large-scale tensile damage on the pile cap surface caused by this equivalent situation.

[0050] The specific steps for modular pier construction are as follows: Prefabricated pier blocks, consisting of three components, are transported to the construction site and assembled. The bottom two blocks require pre-reserved shear grooves, shear teeth, and bolt holes. The upper blocks require pre-reserved bolt holes for connecting the bottom blocks to the pier columns. See details... Figure 6 As shown, after completion, it is bolted to the upper block through the reserved bolt holes to form an integral bearing platform; the reserved holes are prestressed duct through holes, which penetrate the top and bottom blocks, and after the prestress is tensioned, the vertical prestressed threaded steel bars 302 are anchored at both ends of the bearing platform by bolts 303.

[0051] The design utilizes a four-piece precast pier cap for the station bridge pier model, with a designed axial load of 1000kN and a horizontal lateral loading point distance of 2050mm from the pier bottom. The pier cross-section dimensions are 400mm × 500mm. The longitudinal reinforcement uses 20mm diameter HRB400 grade III steel, with a total of 24 longitudinal bars arranged in the cross-section. The stirrups use 6mm diameter steel bars, with the stirrup arrangement consistent with the prototype pier. The bottom of the pier (0-525mm height) is a stirrup-reinforced zone with a stirrup spacing of 35mm, while the non-reinforced zone has a stirrup spacing of 60mm. The pier body is constructed with C50 concrete, and the pier uses corrugated pipes with grouting connections. The pier cross-section reinforcement is as follows. Figure 15 As shown, the foundation is spliced ​​as follows Figure 16 As shown in the figure, the components include corrugated pipe 4, PVC pipe 5, steel base plate 6, and steel sleeve 7.

[0052] The precast foundation is constructed by stacking four precast concrete blocks, with the upper and lower blocks connected by vertical prestressed threaded steel bars. The bottom precast block has a cross-sectional dimension of 1500×750×350mm, and a 100mm deep shear groove is pre-reserved in the middle of the bottom precast block for installing the top precast block. The top precast block has a cross-sectional dimension of 1200×600×400mm, and the total height of the precast foundation after assembly is 650mm.

[0053] The design axial pressure is 1000kN, the distance from the horizontal lateral loading point to the pier bottom is 2050mm, the concrete strength of the pier body is C50, and the pier uses corrugated pipe 4-grout connection. The precast pier cap is composed of 4 precast concrete blocks stacked on top of each other, and the upper and lower precast blocks are connected by vertical prestressed threaded steel bars. Abaquas modeling is as follows. Figure 10 , Figure 17 , Figure 18 and Figure 19 As shown.

[0054] Considering the longitudinal reinforcement stress of the pier reaches the yield strength of 500 MPa, the horizontal thrust is 215.4 kN and the bending moment at the pier base is 387.75 kN·m; when the longitudinal reinforcement stress reaches the ultimate strength of 600 MPa, the horizontal thrust is 320.4 kN and the bending moment at the pier base is 576.77 kN·m. The corresponding tensile damage of the segmented pier cap is as follows: Figure 21 As shown.

[0055] When the bending moment at the pier bottom is 387.75 kN·m and 576.77 kN·m, the tensile damage is concentrated on the surface of the top bearing cap. Figures 20-22 As shown, the tensile damage is concentrated on the surface due to the spalling of concrete at the top of the pier caused by the tension of the longitudinal reinforcement of the pier at the top of the pier cap. From the damage characteristics, the tensile damage of the segmented pier cap is basically the same as that of the cast-in-place pier cap. It should be noted that the tensile damage range on the surface of the precast pier cap is larger because the connection between the precast pier cap and the precast pier is a dry connection, requiring a larger steel plate anchor bolt, which is not necessary for cast-in-place pier caps. Therefore, the surface of the precast pier cap experiences a larger range of tensile damage due to the tension of the steel plate. It can be concluded that the four-segment segmented pier cap plays the same role in force transmission and load-bearing performance as the cast-in-place pier, and can be designed and used in the design of bridge pier models.

[0056] At this point, the three prefabricated pier blocks can be transported from the factory to the construction site for stacking. The bottom two blocks need to have pre-reserved shear grooves, shear teeth, and pre-reserved bolt holes. The upper blocks need to have pre-reserved bolt holes to connect the bottom blocks and the pier. After completion, they are bolted together with the upper blocks through the pre-reserved bolt holes to form an integral pier for construction.

[0057] In summary, by utilizing the above-mentioned technical solution of the present invention, several problems of existing precast piers are solved through the use of horizontal precast components 1 and vertical precast components 2, namely, difficulties in transportation, long construction periods, complex splicing techniques, and poor overall load-bearing performance after splicing. The precast assembly pier structure of the present invention can realize the segmented assembly structure of the pier according to the stress characteristics of the pier bending members. The precast pier structure is composed of precast modules stacked one on top of the other. The upper and lower precast modules, including the horizontal precast components 1 and the vertical precast components 2, are all connected by vertical prestressed threaded steel bars 302. The bottom precast module is connected by precast bolts 303, which facilitates construction, has a clear force transmission path, and has good load-bearing performance. The pier of the present invention can be precast in the factory simultaneously during the bridge pier construction, pile foundation testing, or site leveling stages and then transported to the site for splicing into the pier construction process. After the precast components are transported to the site, they are modularly assembled using high-strength bolts and a post-tensioned prestressed system. Compared to the cast-in-place process, which requires waiting for the strength to meet requirements, this method can shorten the on-site operation time by more than 85%, greatly reducing the construction cycle. This invention can divide the entire foundation into two layers, with the lower layer divided into two blocks, for a total of three parts. The size of each block is determined according to the allowable dimensions for transportation, ensuring the feasibility of transporting the precast foundation and making transportation convenient. The precast foundation block division method adopted in this invention is based on the fact that the overall stress characteristics and load resistance of the foundation remain unchanged. From the finite element simulation results of the precast foundation using this invention and the integrally cast foundation under compressive and bending loads, it can be seen that the tensile damage and failure of the block foundation are basically the same as those of the cast-in-place foundation, indicating that the structure of this invention has good stress performance.

[0058] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered arrangement, characterized in that, The structure includes: A horizontal prefabricated component (1) is used to realize the torque transmission under bending conditions; The vertical prefabricated component (2) is set at the top of the horizontal prefabricated component (1) and is stacked with the horizontal prefabricated component (1) to form a prefabricated assembly platform structure, which ensures the lateral bending resistance and longitudinal shear resistance of the prefabricated assembly platform structure. The splicing component (3) is disposed inside the horizontal prefabricated component (1) and the vertical prefabricated component (2) to realize the connection between the horizontal prefabricated component (1) and the vertical prefabricated component (2).

2. The prefabricated assembly platform structure with horizontal and vertical bidirectional segmented and staggered arrangement as described in claim 1, characterized in that, The horizontal prefabricated component (1) includes a lower prefabricated block (101) symmetrically arranged at the bottom of the vertical prefabricated component (2). The top of the lower prefabricated block (101) and the side close to the vertical prefabricated component (2) are provided with a shear groove (102) that cooperates with the vertical prefabricated component (2); and the two sets of lower prefabricated blocks (101) are placed side by side.

3. The prefabricated assembly foundation structure with horizontal and vertical bidirectional segmented and staggered arrangement as described in claim 2, characterized in that, The shear groove (102) is a rectangular structure, and the rectangular structure formed by the two sets of shear grooves (102) is staggered with the horizontal prefabricated component (1), and the torque is transmitted through the connection of the two sets of shear grooves (102).

4. The prefabricated assembly platform structure with horizontal and vertical bidirectional segmented and staggered overlapping as described in claim 2, characterized in that, The vertical prefabricated component (2) includes a first upper prefabricated block (201) disposed inside the shear groove (102); The first upper prefabricated block (201) and the two sets of lower prefabricated blocks (101) form a T-shaped structure.

5. The prefabricated assembly foundation structure with horizontal and vertical bidirectional segmented and staggered arrangement according to claim 2, characterized in that, The vertical prefabricated component (2) also includes a second upper prefabricated block (202) symmetrically arranged inside the shear groove (102).

6. The prefabricated assembly foundation structure with horizontal and vertical bidirectional segmented and staggered arrangement as described in claim 5, characterized in that, The two sets of second upper precast blocks (202) are evenly arranged and linearly distributed inside the shear groove (102), and the two sets of second upper precast blocks (202) and the two sets of lower precast blocks (101) form a T-shaped structure.

7. The prefabricated assembly foundation structure with horizontal and vertical bidirectional segmented and staggered arrangement as described in claim 1, characterized in that, The splicing component (3) includes a reserved bolt hole (301) that runs through the interior of the horizontal prefabricated component (1) and the vertical prefabricated component (2). The interior of the reserved bolt hole (301) is provided with a vertical prestressed threaded steel bar (302). The two ends of the vertical prestressed threaded steel bar (302) are connected to the horizontal prefabricated component (1) and the vertical prefabricated component (2) by a number of bolts (303).

8. A construction method for a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered overlapping sections, used to realize the construction of the prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered overlapping sections as described in any one of claims 1-7, characterized in that, The method includes: The dimensions of the horizontal prefabricated component (1) and the vertical prefabricated component (2) are determined according to the maximum allowable dimensions for transportation, and prefabrication and curing are carried out based on the dimensions of the horizontal prefabricated component (1) and the vertical prefabricated component (2). The number of vertical prestressed threaded steel bars (302) connecting the horizontal prefabricated component (1) and the vertical prefabricated component (2) is calculated by strength verification, and the magnitude of the tension control stress is determined. The precast horizontal precast component (1) and the precast vertical component (2) are staggered and cast together, and the prestressed steel bars are tensioned according to the number of vertical prestressed threaded steel bars (302) and the magnitude of the tension control stress, so as to obtain a precast assembled pier structure with horizontal and vertical bidirectional blocks staggered and stacked.

9. The construction method for a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered layers according to claim 8, characterized in that, The calculation steps for the number of vertical prestressed threaded steel bars (302) include: The total prestress is determined based on the anti-slip verification requirements, and the number of first prestressed steel bars is determined in combination with the prestress of a single steel bar. The prestress required to offset tensile stress is determined by using crack resistance calculation requirements, and the number of second prestressed steel bars is determined by combining the prestress of a single steel bar. The number of third prestressed steel bars is determined based on the preset minimum reinforcement ratio and spacing requirements, and the maximum value among the number of first prestressed steel bars, second prestressed steel bars and third prestressed steel bars is selected as the number of vertical prestressed threaded steel bars (302).

10. The construction method for a prefabricated assembled foundation structure with horizontally and vertically bidirectionally segmented and staggered layers according to claim 9, characterized in that, The steps for determining the magnitude of the tension control stress include: Based on the building structure load code, the shear force design value at the connection node is determined by the basic combination, and the standard value of tensile strength and cross-sectional area of ​​a single steel bar are determined by the selected vertical prestressed threaded steel bar (302). Based on the anti-slip requirements, the initial tension control stress is determined using the ratio of the shear force design value at the connection node to the preset friction coefficient; The required prestress for a single steel bar is determined based on the ratio of the initial tension control stress to the number of vertical prestressed threaded steel bars (302). The tension control stress is then adjusted in combination with the cross-sectional area and tensile strength standard value of the single steel bar to obtain the magnitude of the tension control stress.

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