High and steep slope continuous beam side span cast-in-place section construction method
Patent Information
- Application Number
- CN202510208522.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-05-23
Smart Images
Figure CN120026559A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of cast-in-place construction of side spans, and in particular to a method for constructing cast-in-place side spans of high-steep slope continuous beams. Background Art
[0002] Tudong Xinzhai No. 3 Bridge is 326m long and has 3 spans. The lower structure of the main pier is a thin-walled hollow pier with pier heights of 72.5m and 78m respectively. The span combination of the bridge is 86m+148m+86m. The structure is a continuous rigid frame. The main body of the bridge is arranged as follows: Figure 1 As shown in the figure, the 3# pier is located on a steep slope of the mountain, with a height of about 50 meters and a slope of about 1:05. The maximum length of the cast-in-place section of the side span hanging out of the slope line is about 7 meters. The original design of the cast-in-place section of the side span is 10.84 meters long, and the concrete volume is 124 3 m, and the closed length of the side span is 2m. Due to the high and steep slope terrain, the conventional ground support method is difficult to construct, with high cost and high safety risks, which has a great impact on the stability and safety of the support system, such as the full-floor support method and the steel pipe pile construction method. Among the existing construction methods, there is also a bracket method, that is, by installing brackets on the square pedestals on both sides, the brackets carry the side span formwork to carry out the cast-in-place section of the side span of the beam body, but this bracket method is generally suitable for occasions where the length of the cast-in-place section of the side span is shorter. When the length of the cast-in-place section of the side span designed for Tudong Xinzhai No. 3 Bridge exceeds 10m and is in a high and steep slope terrain and the bearing capacity of the foundation is insufficient, how to better complete the construction of the cast-in-place section of the continuous beam side span at this location becomes one of the problems to be solved urgently. Summary of the invention
[0003] The invention discloses a novel high-steep slope continuous beam side span cast-in-place section construction method to adapt to the actual working conditions of Tudong Xinzhai No. 3 Bridge.
[0004] The present invention is achieved by adopting the following technical solutions: A method for constructing a cast-in-place section of a side span of a continuous beam on a high-steep slope comprises the following steps: 1) reinforcing and replacing the foundation within a safe range of the high-steep slope so that the foundation in the area meets the bearing capacity; 2) installing an extended cap, wherein the cross section of the extended cap is in a concave shape and comprises two square caps distributed on the left and right and a convex cap, wherein the convex cap is composed of two side square caps and a raised middle cap, wherein the bearing ends of the two side square caps are respectively fixed to the two end caps, the middle cap is located between the bearing ends of the two square caps, and the bearing ends of the two square caps and the convex cap constitute an extended cap bearing part; 3) installing a cap beam; 4) installing a bracket system between the extended cap bearing part and the cap beam and pre-pressing it to ensure the safety of the bracket system; 5) constructing a cast-in-place section.
[0005] Furthermore, the length of the cast-in-place section of the side span is 8.84m, and the length of the closed section of the side span is 4m. In order to ensure the safety of the cast-in-place section of the side span of the continuous beam of the Tudong Xinzhai No. 3 Bridge, the length of the cast-in-place section of the side span originally designed was optimized and shortened to 8.84m, and the length of the closed section of the side span was optimized to 4m. By combining with the extended pedestal, the safety of the construction was guaranteed. According to the conventional design cognition of those skilled in the art, the length of the closed section of the side span is generally 2m, and the length of the cast-in-place section of the side span will basically not be modified in the later stage. In order to ensure the construction of the cast-in-place section of the side span under this working condition, the present invention breaks the traditional construction design idea, that is, the length of the cast-in-place section of the side span is optimized, and the construction of the cast-in-place section of the side span of the continuous beam with high steep slope under this working condition is realized by combining with the extended pedestal. The design is ingenious and reasonable, and has great reference value.
[0006] Further, the bracket system in step 3) includes three groups of brackets, a transverse distribution beam, a longitudinal distribution beam, and a template. The three groups of brackets are respectively the first bracket, the second bracket, and the third bracket. The first bracket and the third bracket are respectively installed on the left and right sides of the extended platform bearing part, and the second bracket is installed in the middle of the left and right directions of the extended platform bearing part. The first bracket, the second bracket, and the third bracket all include a transverse support frame, two steel columns, and a diagonal brace. One end of the transverse support frame is fixed to the cap beam and the other end is a free end. The two steel columns are fixedly supported between the top surface of the extended platform bearing part and the transverse support frame. The diagonal brace is fixed between the front side of the extended platform bearing part and the transverse support frame. The transverse distribution beam, the longitudinal distribution beam, and the template are sequentially placed on the three groups of brackets and form a bracket system together with the three groups of brackets. The bracket system structure is specific and rationalized, and its bearing capacity is further improved in conjunction with the extended platform.
[0007] Furthermore, the diagonal braces of the first bracket and the third bracket are made of double-jointed 56 I-beams, and the diagonal brace of the second bracket is made of single-jointed 56 I-beams.
[0008] Furthermore, the first bracket, the second bracket and the third bracket are all installed and fixed at corresponding positions of the extended platform bearing part and the cap beam through embedded parts, and each embedded part is composed of embedded steel plates and precision-rolled threaded steel bars.
[0009] During construction, before the construction of the cap beam, the site first processes the embedded steel plate and prepares the corresponding size of φ32 fine-rolled threaded steel to check whether its material, structural dimensions, eye position, etc. meet the requirements of the plan. During the construction of the pedestal and cap beam, the position of the embedded parts is set out according to the bracket system design plan; the steel columns in the bracket system are embedded during the construction of the pedestal, and their positions are rechecked after the embedding is completed to ensure accurate installation. During the construction process, the structural dimensions, installation positions, vertical support verticality, embedded holes, etc. of the embedded parts are required to be accurate.
[0010] Furthermore, in step 4), before pre-stressing the bracket system, an observation point is set on the cross support frame of the bracket, and the deformation of the bracket system is regularly observed and relevant data is recorded using a total station before pre-stressing, during pre-stressing, before pre-stressing unloading and after pre-stressing unloading.
[0011] Furthermore, in step 4), when the bracket system is pre-stressed, 20 I-beams are directly stacked on the bracket system. The load combination is the sum of the concrete load (2.45t / m³) and the construction load (formwork load 0.1t / ㎡; construction personnel, machinery, and vibration load 0.4t / m³). The loading order is arranged in the middle first and then on both sides. The loading procedure is graded loading according to load 60% → load 100% → load 120%. After the bracket is pre-stressed, it is unloaded symmetrically, evenly, and synchronously from both sides to the middle and the pre-stressing system is dismantled. 6 hours after unloading, read and record the elevation of each monitoring point after unloading to further ensure the safety of the bracket system.
[0012] Furthermore, in step 5), the construction of the cast-in-place section mainly includes the following steps: formwork installation, steel bar binding, box girder concrete pouring, and prestressing.
[0013] Formwork installation: The side formwork of the cast-in-place section of the side span adopts a standard steel formwork. After the bracket elevation is adjusted, the bottom formwork and side formwork can be installed. After the bottom plate and web reinforcement are tied, the inner formwork is installed, and finally the end formwork is installed. The bottom formwork elevation adjustment is controlled by the bracket and the adjusting wedge; Rebar binding: The reinforcement is centrally manufactured in a processing plant and transported to the site by flatbed trucks. When installing and binding reinforcement, the position of the ordinary reinforcement can be appropriately adjusted when it collides with the prestressed pipe; corresponding ring reinforcements must be set at all reserved hole positions; when binding, the number of reinforcement joints of the same cross section shall not exceed 50% of the total number of reinforcements. The reinforcement protection layer of this beam section is 35mm, and pads are used between the reinforcement and the formwork. The wire heads of the binding pads and reinforcement shall not extend into the protection layer. When binding reinforcement, pay attention to the position, size, and specifications of various embedded parts and reserved holes, and do not omit them; Box girder concrete pouring: The concrete pouring of the side span cast-in-place section is poured by a concrete pump truck. The concrete pouring is continuously poured in longitudinal sections and horizontal layers. The material is first poured synchronously and symmetrically from the webs on both sides of the box girder. Each section is poured symmetrically and layered at a uniform speed. The bottom plate is poured first in the transverse direction of the bridge, then the web area is poured, then the top plate area is poured, and the surface is slurryed and plastered. After the concrete pouring is completed, the concrete surface is roughened, and after the concrete is finally set, it is covered to retain water and maintain curing; Prestressing: All prestressing should be carried out after the box girder concrete strength reaches more than 90% of the design strength.
[0014] The beneficial effects of the present invention are as follows: 1) The present invention cleverly combines the length of the cast-in-place section of the side span and the length of the closed section of the side span after the expansion and optimization of the pedestal, thereby ensuring the safety of the cast-in-place section of the side span constructed by the bracket method, and provides a new design idea for the bracket method construction of the cast-in-place section of the side span; 2) The bracket can be processed, assembled and welded in advance outside the construction site, and is not affected by other factors. It can be directly installed and constructed during the cast-in-place beam construction. The bracket is easy to transport and install, simple to operate, has far fewer parts than the construction of steel pipe columns and full-span brackets, and has a short construction period; 3) It can be suitable for the construction of cast-in-place sections of side spans of continuous beams on steep slopes, and has high construction safety. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.
[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.
[0017] Figure 1 This is a schematic diagram of the main structure of the Tudong Xinzhai No. 3 Bridge; Figure 2 This is the side view of the bracket system, cap beam and cap after installation; Figure 3 This is the plan layout after the bracket system, cap beam and pedestal are installed.
[0018] In the figure: 1-extended pedestal, 101-square pedestal, 102-convex pedestal, 2-cap beam, 3-transverse support frame, 4-steel column, 5-diagonal brace, 6-transverse distribution beam, 7-longitudinal distribution beam, 8-formwork, 9-cast-in-place section. DETAILED DESCRIPTION
[0019] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.
[0020] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.
[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.
[0022] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0023] like Figure 2 , 3 As shown, a method for constructing a cast-in-place section of a high-steep slope continuous beam side span includes the following steps: 1) Strengthen and replace the foundation within the safety range of the high and steep slopes to ensure that the foundation in this area meets the bearing capacity; 2) Installation of the extended platform 1. The cross section of the extended platform 1 is in a concave shape and includes two square platforms 101 distributed on the left and right and a convex platform 102. The convex platform 102 is composed of two side square platforms 101 and a raised middle platform. The bearing ends of the two side square platforms 101 are respectively fixed to the two end platforms. The middle platform is located between the bearing ends of the two square platforms 101. The bearing ends of the two square platforms 101 and the convex platform 102 constitute the bearing part of the extended platform 1. 3) Installation of cap beam 2; 4) Install the bracket system between the bearing part of the extended platform 1 and the cap beam 2 and pre-press it to ensure the safety of the bracket system; Among them, the bracket system includes three groups of brackets, a transverse distribution beam 6, a longitudinal distribution beam 7, and a template 8. The three groups of brackets are respectively the first bracket, the second bracket, and the third bracket. The first bracket and the third bracket are respectively installed on the left and right sides of the bearing part of the extended platform 1, and the second bracket is installed in the middle of the left and right directions of the bearing part of the extended platform 1. The first bracket, the second bracket, and the third bracket all include a transverse support frame 3, two steel columns 4, and a diagonal brace 5. One end of the transverse support frame 3 is fixed to the cap beam 2, and the other end is a free end. The two steel columns 4 are fixedly supported between the top surface of the bearing part of the extended platform 1 and the transverse support frame 3. The diagonal brace 5 is fixed between the front side of the bearing part of the extended platform 1 and the transverse support frame 3. The transverse distribution beam 6, the longitudinal distribution beam 7, and the template 8 are sequentially placed on the three groups of brackets and form a bracket system together with the three groups of brackets. The bracket system structure is specific and reasonable, and its bearing capacity is further improved in conjunction with the extended platform 1.
[0024] In the specific implementation, the diagonal braces 5 of the first and third brackets are made of double-joined 56 I-beams, and the diagonal braces 5 of the second bracket are made of single-joined 56 I-beams. The transverse distribution beam is I45, with a length of 13.5m and a longitudinal spacing of 1, 0.5, and 0.9m; the longitudinal distribution beam is made of 8cm×8cm square wood, with a transverse spacing of 0.1m for the web, and a transverse spacing of 0.2m for the bottom plate and flange; the template 8 is made of 2cm thick bamboo plywood.
[0025] During specific implementation, the first bracket, the second bracket and the third bracket are all installed and fixed to the corresponding positions of the bearing part of the extended platform 1 and the cap beam 2 through embedded parts, and each embedded part is composed of embedded steel plates and precision-rolled threaded steel bars.
[0026] During construction, before the construction of the cap beam 2, the site first processes the embedded steel plate and prepares the corresponding size of φ32 fine-rolled threaded steel to check whether its material, structural dimensions, eye position, etc. meet the requirements of the plan. During the construction of the pedestal and cap beam 2, the position of the embedded parts is laid out according to the bracket system design plan; the steel columns 4 in the bracket system are embedded during the construction of the pedestal, and their positions are rechecked after the embedding is completed to ensure accurate installation. During the construction process, the structural dimensions, installation positions, vertical support verticality, embedded holes, etc. of the embedded parts are required to be accurate.
[0027] In addition, before preloading the bracket system, an observation point is set on the cross support frame 3 of the bracket. Before preloading, during preloading, before unloading and after unloading, the deformation of the bracket system is regularly observed and relevant data is recorded using a total station. During preloading, 20 I-beams are directly stacked on the bracket system. The load combination is the sum of the concrete load (2.45t / m³) and the construction load (template 8 load 0.1t / ㎡; construction personnel, machinery, and vibration load 0.4t / m³). The loading sequence is arranged in the middle first and then on both sides. The loading procedure is graded loading according to load 60% → load 100% → load 120%. After the bracket is preloaded, it is unloaded symmetrically, balanced and synchronously from both sides to the middle and the preloading system is dismantled. 6 hours after unloading, the elevation of each monitoring point after unloading is read and recorded again to further ensure the safety of the bracket system.
[0028] 5) Construction of cast-in-place section 9: The length of the cast-in-place section 9 of the side span is 8.84m, and the length of the side span closing section is 4m. In order to ensure the safety of the cast-in-place section 9 of the continuous beam of the Tudong Xinzhai No. 3 Bridge, the length of the cast-in-place section 9 of the side span originally designed was optimized and shortened to 8.84m, and the length of the side span closing section was optimized to 4m. By combining with the extended pedestal 1, the safety of the construction was guaranteed. According to the conventional design cognition of those skilled in the art, the length of the side span closing section is generally 2m, and the length of the cast-in-place section 9 of the side span will basically not be modified in the later stage. In order to ensure the construction of the cast-in-place section 9 of the side span under this working condition, the present invention breaks the traditional construction design idea, that is, the length of the cast-in-place section 9 of the side span is optimized, and the construction of the cast-in-place section 9 of the side span continuous beam with high steep slope under this working condition is realized by combining with the extended pedestal 1. The design is ingenious and reasonable, and has great reference value.
[0029] The construction of cast-in-place section 9 mainly includes the following steps: Installation of formwork 8: The side formwork of the cast-in-place section 9 of the side span adopts a standard steel formwork 8. After the bracket elevation is adjusted, the bottom formwork and side formwork can be installed. After the bottom plate and web reinforcement are tied, the inner formwork is installed, and finally the end formwork 8 is installed. The elevation adjustment of the bottom formwork 8 is controlled by the bracket and the adjusting wedge; Rebar binding: The reinforcement is centrally manufactured in a processing plant and transported to the site by flatbed trucks. When installing and binding reinforcement, the position of the ordinary reinforcement can be appropriately adjusted when it collides with the prestressed pipe; corresponding annular reinforcements must be set at all reserved hole positions; when binding, the number of reinforcement joints of the same cross section shall not exceed 50% of the total number of reinforcements. The reinforcement protection layer of this beam section is 35mm, and pads are used between the reinforcement and the formwork 8. The wire heads of the binding pads and reinforcement shall not extend into the protection layer. When binding reinforcement, pay attention to the position, size, and specifications of various embedded parts and reserved holes, and do not omit them; Box girder concrete pouring: The side span cast-in-place section 9 concrete pouring is poured by concrete pump truck. The concrete pouring is carried out in longitudinal sections and horizontal layers. The material is first poured synchronously and symmetrically from the webs on both sides of the box girder. Each section is poured symmetrically and layered at a uniform speed. The bottom plate is poured first in the transverse direction of the bridge, then the web area is poured, then the top plate area is poured, and the surface is slurryed and smoothed. After the concrete pouring is completed, the concrete surface is roughened and covered with water retention and curing after the concrete is finally set; Prestressing: All prestressing should be carried out after the box girder concrete strength reaches more than 90% of the design strength.
[0030] The actual application of the construction method of the present invention on the No. 3 platform of Tudong Xinzhai Bridge No. 3 has proved the practicability of this construction method under the condition of limited working environment. It has completed the working task safely and quickly, created good technical and economic benefits, and can provide experience and reference for similar projects in the future.
[0031] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.
Claims
1. A method for constructing cast-in-place side span sections of high and steep slope continuous beams, characterized in that: The invention comprises the following steps: 1) reinforcing and replacing the foundation within the safety range of the high and steep slope so that the foundation in the area meets the bearing capacity; 2) installing the extended cap (1), wherein the cross section of the extended cap (1) is in the shape of a concave letter and comprises two square caps (101) distributed on the left and right and a convex letter cap (102), wherein the convex letter cap (102) is composed of two side square caps (101) and a raised middle cap, wherein the bearing ends of the two side square caps (101) are respectively fixed to the two end caps, the middle cap is located between the bearing ends of the two square caps (101), and the bearing ends of the two square caps (101) and the convex letter cap (102) constitute the bearing part of the extended cap (1); 3) installing the cap beam (2); 4) installing a bracket system between the bearing part of the extended cap (1) and the cap beam (2) and pre-pressing the bracket system to ensure the safety of the bracket system; and 5) constructing the cast-in-place section (9).
2. The method for constructing a cast-in-place side span section of a high-steep slope continuous beam according to claim 1, characterized in that: The length of the cast-in-place section (9) of the side span is 8.84 m, and the length of the closed section of the side span is 4 m.
3. The method for constructing a cast-in-place side span section of a high-steep slope continuous beam according to claim 2, characterized in that: The bracket system in step 3) comprises three groups of brackets, a transverse distribution beam (6), a longitudinal distribution beam (7), and a template (8). The three groups of brackets are respectively a first bracket, a second bracket, and a third bracket. The first bracket and the third bracket are respectively installed on the left and right sides of the bearing part of the extended platform (1), and the second bracket is installed in the middle of the left and right directions of the bearing part of the extended platform (1). The first bracket, the second bracket, and the third bracket all comprise a transverse support frame (3), two steel columns (4), and a diagonal brace (5). One end of the transverse support frame (3) is fixed to the cap beam (2) and the other end is a free end. The two steel columns (4) are fixedly supported between the top surface of the bearing part of the extended platform (1) and the transverse support frame (3). The diagonal brace (5) is fixed between the front side surface of the bearing part of the extended platform (1) and the transverse support frame (3). The transverse distribution beam (6), the longitudinal distribution beam (7), and the template (8) are sequentially placed on the three groups of brackets and together with the three groups of brackets form a bracket system.
4. The method for constructing a cast-in-place side span section of a high-steep slope continuous beam according to claim 3, characterized in that: The diagonal braces (5) of the first bracket and the third bracket are made of double-jointed 56 I-beams, and the diagonal braces (5) of the second bracket are made of single-jointed 56 I-beams.
5. The method for constructing a cast-in-place side span section of a high-steep slope continuous beam according to claim 4, characterized in that: The first bracket, the second bracket and the third bracket are all installed and fixed at corresponding positions of the bearing part of the extended platform (1) and the cap beam (2) through embedded parts, and each embedded part is composed of embedded steel plates and precision-rolled threaded steel bars.
6. A method for constructing a cast-in-place side span section of a high-steep slope continuous beam according to claim 5, characterized in that: In step 4), before preloading the bracket system, an observation point is set on the cross support frame (3) of the bracket, and the deformation of the bracket system is regularly observed and relevant data is recorded using a total station before preloading, during preloading, before preloading unloading and after preloading unloading.
7. A method for constructing a cast-in-place side span section of a high-steep slope continuous beam according to claim 6, characterized in that: In step 4), when the bracket system is pre-stressed, 20 I-beams are directly stacked on the bracket system. The load combination is the sum of the concrete load and the construction load. The loading order is first in the middle and then on both sides. The loading procedure is graded loading according to 60% load → 100% load → 120% load. After the bracket is pre-stressed, it is unloaded symmetrically, evenly and synchronously from both sides to the middle and the pre-stressing system is dismantled. 6 hours after unloading, read and record the elevation of each monitoring point after unloading.
8. The method for constructing the cast-in-place side span of a high-steep slope continuous beam according to claim 7, characterized in that: In step 5), the construction of the cast-in-place section (9) mainly includes the following steps: installation of formwork (8), steel bar binding, box girder concrete pouring, and prestressing.