Segmented and graded arch foot sealing design and construction method for eliminating arch foot concrete cracking

Abstract

The application discloses a segmented and graded foot sealing design and construction method for eliminating arch foot concrete cracking, comprising the following steps: the pre-buried steel pipe in the arch foot foundation is divided into n segments in advance, the consolidation method of the pre-buried steel pipe is that the pre-buried steel pipe is consolidated for n times from bottom to top in segments, and n is greater than or equal to 2; according to the construction steps of the arch bridge, part of the arch bridge structure is installed after each consolidation of the pre-buried steel pipe, and the whole arch bridge construction is completed until the whole arch bridge construction is completed. The application adjusts the traditional pre-buried arch rib one-time foot sealing to segmented and graded foot sealing according to the characteristics that the stress of the arch bridge is completed in multiple times, so that the frictional side resistance between the arch rib and the surface of the arch foot is reduced, the mechanical reason for the arch foot concrete cracking is eliminated, the phenomenon of the "arch bridge rotten root" concrete falling off affecting the structural safety is avoided, meanwhile, the size of the arch foot is more reasonable, the stress is more uniform, and the strength, stiffness and durability of the arch bridge in the whole life cycle are ensured.

Description

Technical Field

[0001] This invention belongs to the field of arch bridge engineering technology, specifically relating to a segmented and graded sealing design and construction method for eliminating cracking in the concrete at the arch foot. Background Technology

[0002] Steel-concrete composite and steel box girder arch bridges have the advantages of being lightweight, high-strength, having a high factory assembly rate, high load-bearing capacity, quick and convenient erection, and having a variety of arch rib designs. They are widely used not only in mountainous canyons but also in plains areas.

[0003] To ensure an effective and reliable connection between the arch foot foundation concrete and the arch rib, an extra section of the arch rib is typically pre-embedded into the arch foot foundation concrete. Then, the pre-embedded portion in the arch foot foundation is used to connect with the exposed arch rib chord. For example... Figure 3 As shown.

[0004] The general construction process of an arch bridge is as follows: construction of the arch abutments and arch feet → erection of exposed arch ribs → construction of columns and hangers on the arch → installation of the main bridge beams → construction of bridge deck ancillary structures (bridge deck pavement, railings) → bridge completion and opening to traffic. The stress on the arch ribs and arch feet is accumulated multiple times, ultimately reaching the stress state of the completed bridge. The main load increases are concentrated during the construction of the arch ribs, the installation of the main bridge beams, and the construction of the bridge deck ancillary structures.

[0005] The arch rib of an arch bridge is the main structure bearing axial force. The transmission of axial force within the arch foot is mainly due to the frictional resistance between the embedded arch rib section and the arch foot concrete, and the end pressure at the ends of the arch rib. Because the surface frictional resistance between the outer surface of the embedded arch rib section and the arch foot concrete has a peeling effect on the concrete outside the arch rib, when the peeling effect exceeds the bonding force between the concrete and the arch rib steel, cracks will appear at the interface between the embedded arch rib and the arch foot. If the cracks become too large, water and water vapor from nature will penetrate deep into the concrete along the cracks, causing corrosion of the steel reinforcement and steel within the arch foot. The corrosion of steel is also a process of volume expansion, which will further worsen the cracks in the arch foot, reducing the arch foot's load-bearing capacity, durability, and service life. Penetrating cracks will destroy the integrity of the arch foot, alter the stress mechanism of the arch foot concrete, and cause concrete spalling damage, commonly known as "arch bridge root rot," ultimately affecting structural safety.

[0006] To avoid excessive surface frictional resistance between the pre-embedded arch ribs in the arch foot and the arch foot concrete, a new arch foot pre-embedded section structure and construction method are urgently needed to solve the above problems. Summary of the Invention

[0007] To address the structural safety issue caused by concrete cracking at the arch foot, as mentioned in the background section, this invention provides a segmented and graded sealing design and construction method for eliminating arch foot concrete cracking. Since the arch foot experiences multiple cumulative stresses, this method segments and grades the pre-embedded steel pipes within the arch foot according to each stress. The pre-embedded arch ribs, after being graded and consolidated, ultimately form an integral whole with the arch foot concrete, reducing the frictional resistance between the arch ribs and the arch foot surface, thereby eliminating the possibility of cracking in the arch foot concrete.

[0008] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0009] A segmented and graded sealing method for eliminating cracking in arch foot concrete includes the following steps:

[0010] The pre-embedded steel pipes in the arch foot foundation are divided into n segments in advance. The consolidation method of the pre-embedded steel pipes is: to consolidate the segments in sequence from bottom to top n times, where n≥2;

[0011] Following the construction steps of the arch bridge, after each consolidation of the pre-embedded steel pipes, a corresponding section of the arch bridge structure is installed until the overall construction of the arch bridge is completed.

[0012] Preferably, the lengths of each segment in the n pre-embedded steel pipes are the same.

[0013] Preferably, when n=3, the specific construction steps for installing parts of the arch bridge structure in stages after each consolidation of the pre-embedded steel pipes, according to the construction steps of the arch bridge, until the overall construction of the arch bridge is completed, are as follows:

[0014] Step 1: Construct the arch foot foundation for the non-hinge section and perform the first consolidation of the first section of the pre-embedded steel pipe.

[0015] Step 2: Pour concrete inside the steel pipes pre-embedded in the arch foot foundation;

[0016] Step 3: Erect the exposed arch rib section until closure. After closure, pour concrete inside the exposed arch rib section.

[0017] Step 4: Inside the arch foot foundation, pour concrete around the pre-embedded steel pipe in section 2 for the second consolidation.

[0018] Step 5: Install the arch support columns and hangers;

[0019] Step six: Construct the main bridge deck beams;

[0020] Step 7: Inside the arch foot foundation, pour concrete around the pre-embedded steel pipe in section 3 for the third consolidation.

[0021] Step 8: Construct the bridge deck and ancillary structures until completion.

[0022] Preferably, the exposed arch rib section is installed by welding or bolting.

[0023] Preferably, the concrete around the pre-embedded steel pipe is tightly connected after being consolidated three times.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] This invention adjusts the traditional method of pre-embedding and consolidating the arch ribs into the arch foot concrete in a single step to a segmented and graded consolidation method. The number of graded consolidation steps is determined based on the main construction procedures of the arch bridge. Simultaneously, the length of the pre-embedded arch ribs embedded in the arch foot is divided into the same number of segments, and the number of consolidation steps is the same as the number of segments of the pre-embedded arch ribs. Stress analysis calculations have confirmed that: 1) the frictional resistance at the arch rib interface is significantly smaller with multiple graded consolidation steps compared to single-step consolidation. Where n is the number of staged consolidation times, the smaller the frictional resistance at the interface, the less likely the concrete surface will crack; 2) After multiple staged consolidation, the frictional resistance around the pre-embedded arch rib section is more uniform, which can give full play to the stress performance of the arch foot concrete. Attached Figure Description

[0026] Figure 1 Overall elevation layout of the arch bridge;

[0027] Figure 2 Arch foot A detailed drawing;

[0028] Figure 3 A diagram showing the force distribution of the pre-embedded arch ribs and the pre-embedded arch ribs in the arch foot pre-embedded ribs that are sealed and consolidated in one step during traditional construction.

[0029] Figure 4 Construction steps for multiple-stage sealing and consolidation of the arch foot of an arch bridge;

[0030] Figure 5 Construction drawing of the first consolidation stage in the three-stage sealing of the arch foot of the arch bridge;

[0031] Figure 6 Construction drawings for pouring concrete into the pre-embedded steel pipes inside the arch foot;

[0032] Figure 7 Construction drawings of concrete inside the steel pipe of the arch rib section of a cast-in-place arch bridge;

[0033] Figure 8 Stress distribution diagram of the first stage of consolidation and pre-embedded arch ribs in the three-stage sealing of the arch foot of the arch bridge;

[0034] Figure 9 Stress distribution diagram of the second consolidation and pre-embedded arch rib in the three-stage sealing of the arch foot of the arch bridge;

[0035] Figure 10The third consolidation and stress distribution diagram of the pre-embedded arch ribs in the three-stage sealing of the arch foot of the arch bridge.

[0036] In the diagram: 1-arch foot foundation, 2-embedded steel pipe, 3-toe sealing section concrete, 4-exposed arch rib section, 5-column, 6-suspender rod, 7-bridge deck main beam. Detailed Implementation

[0037] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to enable those skilled in the art to understand the invention. Obviously, the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, any modifications within the spirit and scope of the invention as defined and determined by the appended claims are considered non-creative and all inventions utilizing the inventive concept of this method are protected.

[0038] like Figure 1-10 As shown, this invention provides a segmented and graded sealing design and construction method for eliminating cracks in arch foot concrete. The pre-embedded steel pipe within the arch foot foundation is divided into three segments of equal length. The specific construction steps are as follows:

[0039] Step 1, according to Figure 5 The arch foot foundation of the non-hinge section was constructed, and the first section of the pre-embedded steel pipe was consolidated for the first time. The stress distribution diagram of the arch rib of the pre-embedded section is shown in the figure. Figure 8 ;

[0040] Step two, according to Figure 6 Concrete is poured into the steel pipes pre-embedded in the arch foot foundation.

[0041] Step 3: Erect the exposed arch rib sections using conventional welding or bolting methods until closure is achieved. Figure 7 After the closure, concrete is poured inside the exposed arch rib section in the conventional manner;

[0042] Step four, according to Figure 4 Within the arch foot foundation, concrete is poured around the pre-embedded steel pipe in the second section for a second consolidation. The stress distribution diagram of the arch rib in the pre-embedded section is shown below. Figure 9 ;

[0043] Step 5: Install the arch support columns and hangers;

[0044] Step six: Construct the main bridge deck beams;

[0045] Step seven, according to Figure 4 Within the arch foot foundation, concrete is poured around the pre-embedded steel pipe in the third section for a third consolidation. The stress distribution diagram of the arch rib in the pre-embedded section is shown below. Figure 10 ;

[0046] Step 8: Construct the bridge deck and ancillary structures until completion and opening to traffic.

[0047] The concrete around the pre-embedded steel pipe is tightly connected after being consolidated three times.

[0048] The stress analysis process for multiple staged consolidation is as follows:

[0049] The arch rib of the arch bridge is mainly subjected to axial force G. The axial force is shared by the frictional resistance q between the arch rib and the arch foot concrete and the end pressure N at the end of the arch rib. The frictional resistance q is f(h) along the axis of the arch rib. The stress is the largest at section II of the arch rib interface, i.e., q1. The stress q2 is at the farthest section IV-IV of the embedded arch rib in the arch foot concrete. According to the equilibrium of forces: If the stress at section II exceeds the tensile strength of the concrete, cracking will occur; therefore, the stress at this section must be strictly controlled.

[0050] This invention divides the consolidation of the embedded arch rib into n stages, and the embedded segment into n segments. The load applied in the first loading stage is G1, and the stress q1 at the interface due to the frictional resistance generated by the loading is... 1-ⅡI The stress q2 at the farthest point of the embedded arch rib within the arch foot concrete. 1-IV The end pressure N1 at the end of the arch rib, according to the force balance, The load applied in the second application is G2, and the stress q1 at the interface caused by the frictional resistance generated by the applied force is... 2-II The stress q2 at the farthest point of the embedded arch rib within the arch foot concrete. 2-IV The end pressure N2 at the end of the arch rib, according to the force balance, The frictional resistance generated by the nth loading force at the interface is q1. n-I The stress q2 at the farthest point of the embedded arch rib within the arch foot concrete. n-IV The end pressure Nn at the end of the arch rib, according to the force balance,

[0051] Based on the final stress distribution of the overall structure, we can conclude that:

[0052]

[0053] The purpose of this invention is to reduce the stress at the arch rib interface II by dividing the primary consolidation of the pre-embedded arch ribs in the arch foot into segments and grades, thereby eliminating the root cause of concrete cracking in the arch ribs and arch foot.

[0054] When the arch foot embedded section is consolidated for the first time, according to conventional mechanics of materials, the stress in sections II, II-II, III-III, and IV-IV decreases linearly according to a curve. Assume that q2 = 0.4 × q1. Its distribution is as follows... Figure 3 As shown.

[0055] Section II is subjected to frictional resistance, q I =q1;

[0056] Section II-II is subjected to frictional resistance, q II =0.8×q1;

[0057] Section III-III is subjected to frictional resistance, q III =0.6×q1;

[0058] Section IV-IV is subjected to frictional resistance, q IV =0.4×q1=q2.

[0059] Assuming the arch foot embedded section is consolidated in three stages, with each consolidation stage having a length of [length missing], [details missing]. The load increment for each arch rib action is The stress distribution at sections II, II-II, III-III, and IV-IV is as follows:

[0060] Section II only bears frictional resistance during the third consolidation, q I =q1 3-I .in

[0061] Section II-II experiences frictional resistance during the second and third consolidation processes. II =q1 3-II +q1 2-II .in Right now:

[0062] Section III-III experiences frictional resistance during the first, second, and third consolidation processes. III =q1 3-III +q1 2-iII +q1 1-III .in Right now:

[0063] Section IV-IV experiences frictional resistance during the first, second, and third consolidation processes, q IV =q1 3-IV +q1 2-IV +q1 1-IV .in Right now:

[0064] Therefore, based on the calculations in the above case, it can be concluded that: (1) the frictional resistance at the arch rib interface is smaller than that in the case of single-stage consolidation after multiple-stage consolidation. Where n is the number of staged consolidation, the smaller the frictional resistance at the interface, the less likely the concrete surface will crack; (2) After multiple staged consolidation, the frictional resistance around the pre-embedded arch rib section is more uniform, which can give full play to the stress performance of the arch foot concrete.

[0065] In summary, this invention provides a consolidation design and construction method suitable for the interface between the arch foot and arch rib of an arch bridge, thereby solving the problem of concrete cracking at the arch foot. This invention leverages the characteristic that the stress on an arch bridge is accumulated over multiple cycles, adjusting the traditional one-time sealing of the pre-embedded arch rib to a segmented and graded sealing method. This reduces the frictional resistance between the arch rib and the arch foot surface, eliminates the mechanical causes of concrete cracking at the arch foot, and avoids the "rotten root" concrete detachment phenomenon that affects structural safety. Simultaneously, it makes the arch foot dimensions more reasonable and the stress distribution more uniform, ensuring the strength, stiffness, and durability of the arch bridge throughout its entire life cycle.

[0066] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0067] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A segmented and graded sealing design and construction method for eliminating cracking in arch foot concrete, characterized in that, Includes the following steps: The pre-embedded steel pipes in the arch foot foundation are divided into n segments. The consolidation method of the pre-embedded steel pipes is: to consolidate the segments from bottom to top in sequence n times, n≥2, and the lengths between each segment in the n pre-embedded steel pipes are the same. According to the construction steps of the arch bridge, after each consolidation of the pre-embedded steel pipe, a corresponding part of the arch bridge structure is installed until the overall construction of the arch bridge is completed. When n=3, the specific construction steps, following the construction procedures for arch bridges, involve installing portions of the arch bridge structure in stages after each consolidation of the pre-embedded steel pipes until the overall construction of the arch bridge is completed, are as follows: Step 1: Construct the arch foot foundation of the non-hinge section and perform the first consolidation of the first section of the pre-embedded steel pipe. Step 2: Pour concrete inside the steel pipes pre-embedded in the arch foot foundation; Step 3: Erect the exposed arch rib section until closure. After closure, pour concrete inside the exposed arch rib section. Step 4: Inside the arch foot foundation, pour concrete around the pre-embedded steel pipe in section 2 for the second consolidation. Step 5: Install the arch support columns and hangers; Step six: Construct the main bridge deck beams; Step 7: Inside the arch foot foundation, pour concrete around the pre-embedded steel pipe in section 3 for the third consolidation. Step 8: Construct the bridge deck and ancillary structures until completion.

2. The segmented and graded sealing design and construction method for eliminating cracking in arch foot concrete according to claim 1, characterized in that, The exposed arch rib sections are installed by welding or bolting.

3. The segmented and graded sealing design and construction method for eliminating cracking in arch foot concrete according to claim 1, characterized in that, The concrete around the pre-embedded steel pipe is tightly connected after being consolidated three times.

Images