Construction method of combined bridge pier suitable for alpine region

Abstract

This invention discloses a composite bridge pier suitable for high-altitude and cold regions, comprising an inner core and an outer ring. The outer ring encloses the inner core and is made of ultra-high-strength concrete. The inner core is cast on-site from ordinary concrete, while the outer ring is prefabricated in a factory. This composite bridge pier uses only the more expensive ultra-high-strength concrete in the outer ring, which meets the requirements for freeze-thaw resistance while reducing the amount of ultra-high-strength concrete used, thus balancing project costs. Furthermore, the prefabricated outer ring can be directly used as a formwork for the bridge pier on-site, eliminating the material costs and installation / disassembly costs associated with traditional formwork construction.

Description

Technical Field

[0001] This invention relates to the field of construction, and more particularly to a combined bridge pier and construction method suitable for high-altitude and cold regions. Background Technology

[0002] The damage to concrete caused by freeze-thaw cycles in a saturated state is called freeze-thaw damage. It is generally believed that freeze-thaw damage is mainly caused by the expansion of water volume when it freezes at a certain freezing temperature. The supercooled water migrates and causes various pressures. When the pressure exceeds the stress that the concrete can withstand, the pores and microcracks inside the concrete gradually increase, expand and connect with each other, and the strength gradually decreases, resulting in concrete failure.

[0003] Freeze-thaw damage to concrete structures is a common problem in bridge structures in cold, high-latitude regions of northern China. When bridge piers are affected by freeze-thaw cycles, severe necking occurs, endangering bridge safety.

[0004] Currently, ultra-high performance concrete (UHPC) is a cement-based structural material designed based on the principles of dense particle packing and fiber reinforcement, possessing high compressive and tensile strength. Simultaneously, UHPC's extremely low porosity and dense internal structure give it excellent impermeability, frost resistance, and resistance to chemical attack, making it ideal for resisting freeze-thaw damage in cold regions. However, UHPC is relatively expensive, and using it exclusively for bridge piers would significantly increase project costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that in the prior art, bridge piers cast with ordinary concrete in cold regions are easily damaged by freeze-thaw cycles, while using ultra-high performance concrete to cast bridge piers increases costs.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a composite bridge pier suitable for high-altitude and cold regions, comprising a bridge pier inner core and a bridge pier outer ring, the bridge pier outer ring wrapping the bridge pier inner core, the bridge pier outer ring being made of ultra-high performance concrete, the bridge pier inner core being cast on-site from ordinary concrete, and the bridge pier outer ring being prefabricated in a processing plant.

[0007] This type of composite pier uses higher-priced ultra-high performance concrete only on the outer ring of the pier. This not only meets the pier's freeze-thaw resistance requirements but also reduces the amount of ultra-high performance concrete used, thus balancing project costs. At the same time, the outer ring of the pier is prefabricated in the factory, and the prefabricated outer ring of the pier is used directly as pier formwork on the construction site, saving the material costs and installation and dismantling costs of pier formwork in traditional construction.

[0008] To increase the reliability of the connection between the inner core of the pier and the outer ring of the pier, the inner surface of the outer ring of the pier is provided with a pit.

[0009] This invention also discloses a construction method for composite bridge piers suitable for high-altitude and cold regions, comprising the following steps:

[0010] Step 1: Use ultra-high performance concrete to precast the outer ring of the bridge pier at the processing plant;

[0011] Step 2: Transport the prefabricated outer ring of the bridge pier to the construction site for installation and fixation;

[0012] Step 3: Arrange the steel reinforcement cage inside the outer ring of the pier, and then pour ordinary concrete to form the inner core of the pier. The outer ring of the pier is used as a formwork for pouring the inner core of the pier.

[0013] The outer ring of the bridge pier is essentially a type of concrete pipe, and its prefabrication method is consistent with existing concrete pipe technologies. This involves installing a reinforcing cage within an inner and outer mold, pouring concrete, curing it, and then dismantling the mold. In existing concrete pipe prefabrication processes, the inner mold is removed laterally from the inside of the concrete pipe. The inner surface of the bridge pier outer ring of this invention requires recesses. However, considering the demolding process, the inner mold used in this invention cannot simply have raised points on its surface; otherwise, demolding would be difficult. This invention provides two methods for prefabricating recesses on the inner surface of the bridge pier outer ring. The first method involves wrapping the inner mold surface of the prefabricated bridge pier outer ring with uniformly applied bubble wrap in step 1. Bubble wrap is a common and inexpensive item used in the packaging industry, readily available and inexpensive. Using bubble wrap, recesses can be formed on the inner surface of the bridge pier outer ring. This method does not require changing the existing concrete pipe production molds and is low-cost. However, this method involves extensive bubble wrap wrapping and cleaning operations, and the bubble wrap itself is filled with compressible air, which will lead to unstable quality of the recesses on the inner surface of the bridge pier outer ring.

[0014] The second method involves using a dedicated inner mold to prefabricate the outer ring of the bridge pier in step 1. The dedicated inner mold includes an outer ring, an inner ring, telescopic columns, and springs. The inner ring is concentric with the outer ring and located inside it. The outer ring has multiple annularly distributed through holes on its surface, each containing a telescopic column. One end of the telescopic column is spherical, and the other end has a first arc surface. A shoulder is provided on the telescopic column, and a spring is fitted onto it. The two ends of the spring abut against the shoulder and the inner wall of the outer ring, respectively. The outer surface of the inner ring has multiple protrusions corresponding to the telescopic columns. The surface of each protrusion has a second arc surface, and the first arc surface contacts the second arc surface. When the inner ring rotates relative to the outer ring in a forward stroke, the protrusions drive the telescopic columns to extend outward from the through holes. It should be noted that the forward stroke rotation here does not specifically refer to clockwise or counterclockwise rotation. The inner ring has only two rotational directions relative to the outer ring; the direction that causes the telescopic columns to extend outward is the forward stroke rotation direction, and the other is the counterclockwise rotation direction.

[0015] The special inner mold is equipped with telescopic columns. Before the outer ring of the pier is poured, the telescopic columns extend outward to form a pit on the inner surface of the outer ring of the pier. After the outer ring of the pier is cured and formed, the telescopic columns retract into the through hole, and the entire special inner mold can be pulled out laterally from the outer ring of the pier to achieve demolding, just like a normal inner mold.

[0016] In this invention, the telescopic column retracts into the through hole using the elastic force of a spring. This retraction method has a certain degree of unreliability because the telescopic column and the outer ring of the pier may adhere after the concrete is poured and dried. To prevent a small number of telescopic columns from failing to retract using the spring, the telescopic column of this invention has a third arc surface on its side, and the convex column has a fourth arc surface on its side. When the inner ring of the mold rotates in the opposite direction to the outer ring of the mold, the fourth arc surface of the convex column contacts the third arc surface of the adjacent telescopic column and drives the telescopic column to retract inward into the through hole. This means that even if some telescopic columns adhere to the outer ring of the pier, the impact between the third and fourth arc surfaces can cause the telescopic column to separate from the outer ring of the pier.

[0017] Furthermore, the special inner mold also includes an end plate and an inner shaft. The end plate is installed at both ends of the outer ring of the mold. The inner shaft is concentric with the inner ring and the outer ring of the mold. The inner shaft is connected to the inner ring of the mold through a support rod. The two ends of the inner shaft are inserted into the end plate. The inner ring of the mold can be driven to rotate by driving the inner shaft to rotate.

[0018] Specifically, the special inner mold also includes a cylinder and a sleeve. The cylinder is fixed on the inner surface of the end plate. One end of the inner shaft is provided with a radial sleeve rod. The sleeve is sleeved on the sleeve rod and the end of the sleeve is hinged to the telescopic rod of the cylinder. The cylinder drives the inner shaft and the inner ring of the mold to rotate forward and backward by a certain angle through the sleeve and the sleeve rod.

[0019] Furthermore, there are two types of protrusions on the inner ring surface of the mold: type I protrusions and type II protrusions. The difference between type I protrusions and type II protrusions lies in the specific shape of the second arc surface.

[0020] The second arc surface of a type of convex pillar satisfies the following condition: when the inner ring of the mold rotates to make the telescopic pillar extend to its farthest position, if the inner ring of the mold continues to rotate, the telescopic pillar will no longer extend.

[0021] The second arc surface of the second type of convex column satisfies the following: after the inner ring of the mold rotates to make the telescopic column extend to its farthest position, if the inner ring of the mold continues to rotate, the telescopic column will continue to extend; the farthest position refers to the position that the telescopic column should reach in order to form the recess when the outer ring of the bridge pier is poured.

[0022] The inner ring surface of the mold has N consecutive protrusions that are of type II, and the rest are of type I; N is greater than or equal to 3 and less than or equal to 5;

[0023] In this invention, the inner ring rotates a certain angle during its forward stroke to drive the telescopic column to extend, and rotates a certain angle during its reverse stroke to drive the telescopic column to retract. Although theoretically, the inner ring only needs to perform one forward stroke rotation and one reverse stroke rotation during each pouring process, this is not the case in practical applications. During demolding, repeated rotation of the inner ring can achieve vibration of the entire dedicated inner mold, making the dedicated inner mold and the outer ring of the pier more thoroughly separated during vibration, facilitating demolding. To enhance this demolding capability, this invention divides the protruding columns into Class I and Class II protruding columns. During demolding, each forward stroke rotation of the inner ring will appropriately increase the stroke angle. This operation will cause the telescopic column corresponding to the Class II protruding column to further push against the outer ring of the pier, promoting the creation of a gap between the outer ring of the pier and the outer ring of the mold, which is beneficial for demolding.

[0024] Beneficial effects: (1) The composite pier of the present invention uses only the more expensive ultra-high performance concrete on the outer ring of the pier, which can meet the requirements of the pier for freeze-thaw resistance and reduce the amount of ultra-high performance concrete used, thus taking into account the engineering cost. (2) The prefabricated outer ring of the pier in the composite pier of the present invention can be directly used as the pier template on the construction site, saving the material cost of the pier template and the installation and dismantling construction cost of the pier template in traditional construction, which can save costs and shorten the construction period. (3) The inner surface of the outer ring of the pier of the present invention is provided with pits, which improves the strength of the composite pier. (4) The present invention provides a method for producing a pier outer ring containing pits by wrapping bubble film on a traditional inner mold, without changing the existing production mold, and the cost is low. (5) The present invention provides a special inner mold with telescopic columns, which makes the quality of the pits of the prefabricated pier outer ring more stable and controllable and does not affect demolding. (6) The present invention sets two kinds of protruding columns in the inner ring of the mold, which causes the outer ring of the pier to vibrate in a biased manner, so that a gap is generated between the outer ring of the pier and the outer ring of the mold, which is beneficial to demolding. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the combined bridge pier in Example 1.

[0026] Figure 2 This is a perspective view of the special inner mold in Example 2.

[0027] Figure 3 This is a cross-sectional view of the special inner mold in Example 2.

[0028] Figure 4 yes Figure 3 Enlarged view of A.

[0029] Figure 5 This is a schematic diagram of the working principle of the special inner mold in Example 2 (one of them).

[0030] Figure 6 This is a schematic diagram of the working principle of the special inner mold in Example 2 (Part Two).

[0031] Figure 7 This is the working principle diagram of the special inner mold in Example 2 (Part 3).

[0032] Figure 8 This is an application state diagram of the special inner mold in Example 2.

[0033] Among them: 100, inner core of pier; 200, outer ring of pier; 210, recess; 300, special inner mold; 310, outer ring of mold; 311, through hole; 320, inner ring of mold; 321, protruding column; 321A, first type of protruding column; 321B, second type of protruding column; 321-1, second arc surface; 321-2, fourth arc surface; 330, telescopic column; 331, first arc surface; 332, protruding shoulder; 333, third arc surface; 340, spring; 350, end plate; 360, inner shaft; 361, support rod; 362, sleeve rod; 370, cylinder; 380, sleeve; 400, outer mold. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments.

[0035] Example 1

[0036] like Figure 1 As shown, the composite bridge pier suitable for high-altitude and cold regions in this embodiment includes an inner pier core 100 and an outer pier ring 200. The outer pier ring 200 encloses the inner pier core 100. The outer pier ring 200 is made of ultra-high performance concrete, while the inner pier core 100 is cast in place with ordinary concrete. The outer pier ring 200 is prefabricated in a factory. Multiple recesses 210 are provided on the inner surface of the outer pier ring 200. During casting, the inner pier core 100 forms corresponding protrusions that embed into the recesses 210, thus enhancing the overall integrity of the outer pier ring 200 and the inner pier core 100.

[0037] In this embodiment, the composite pier uses only the more expensive ultra-high performance concrete in the outer ring 200 of the pier. This not only meets the pier's freeze-thaw resistance requirements but also reduces the amount of ultra-high performance concrete used, thus balancing project costs. At the same time, the outer ring 200 of the pier is prefabricated in the factory, and the prefabricated outer ring 200 of the pier is directly used as the pier formwork on the construction site, saving the material costs of pier formwork and the installation and dismantling costs of pier formwork in traditional construction.

[0038] The construction method for composite bridge piers applicable to high-altitude and cold regions in this embodiment includes the following steps:

[0039] Step 1: Use ultra-high performance concrete to precast the outer ring of the bridge pier at the processing plant;

[0040] Step 2: Transport the prefabricated outer ring of the bridge pier 200 to the construction site for installation and fixation;

[0041] Step 3: Arrange a steel cage inside the outer ring 200 of the pier, and then pour ordinary concrete to form the inner core 100 of the pier. The outer ring 200 of the pier is used as a casting template for the inner core 100 of the pier.

[0042] In this embodiment, the mold used for prefabricating the outer ring 200 of the bridge pier is the same as that used for prefabricating concrete pipes in the prior art. However, when prefabricating the outer ring 200 of the bridge pier, the surface of the inner mold should be wrapped with a uniform bubble film so as to form multiple pits 210 on the inner surface of the outer ring 200 of the bridge pier.

[0043] Example 2

[0044] like Figure 2 As shown, this embodiment provides a dedicated inner mold 300 for prefabricating the outer ring 200 of the bridge pier.

[0045] like Figure 3 and Figure 4 As shown, the dedicated inner mold 300 includes an outer mold ring 310, an inner mold ring 320, a telescopic column 330, a spring 340, an end plate 350, an inner shaft 360, a cylinder 370, and a sleeve 380. The inner mold ring 320 is concentric with the outer mold ring 310 and is located inside the outer mold ring 310. The surface of the outer mold ring 310 is provided with a plurality of annularly distributed through holes 311, and a telescopic column 330 is installed in each through hole 311. One end of the telescopic column 330... The other end of the spherical part has a first arc surface 331. The telescopic column 330 has a shoulder 332 and a spring 340 fitted onto it. The two ends of the spring 340 respectively abut against the shoulder 332 and the inner wall of the outer mold ring 310. The outer surface of the inner mold ring 320 has multiple protrusions 321 corresponding to the telescopic column 330. The surface of each protrusion 321 has a second arc surface 321-1, and the first arc surface 331 contacts the second arc surface 321-1. Figure 4 As shown, when the inner ring 320 rotates relative to the outer ring 310 during its positive stroke, the protrusion 321 drives the telescopic column 330 to extend outward from the through hole 311.

[0046] like Figure 5 As shown, when the inner ring 320 rotates in the reverse direction relative to the outer ring 310, that is... Figure 5 When rotated clockwise, the telescopic column 330 retracts into the through hole 311 due to the elastic force of the spring 340; this retraction method has a certain degree of unreliability because after the concrete is poured and dried, adhesion may occur between the telescopic column 330 and the outer ring 200 of the pier. To avoid a small number of telescopic columns 330 failing to retract due to the spring 340, such as... Figure 6 As shown, the telescopic column 330 in this embodiment has a third arc surface 333 on its side, and the protruding column 321 has a fourth arc surface 321-2 on its side. When the inner ring 320 rotates in the reverse direction relative to the outer ring 310, if the following occurs... Figure 6If a telescopic post 330 does not retract, the fourth arc surface 321-2 of the adjacent protrusion 321 will contact the third arc surface 333 of the telescopic post 330 and drive the telescopic post 330 to retract inward into the through hole 311.

[0047] like Figure 2 and Figure 3 As shown, end plates 350 are installed at both ends of the outer ring 310. The inner shaft 360 is concentric with the inner ring 320 and the outer ring 310. The inner shaft 360 is connected to the inner ring 320 through a support rod 361. Both ends of the inner shaft 360 are inserted into the end plate 350. The inner ring 320 can be driven to rotate by driving the inner shaft 360 to rotate. The cylinder 370 is fixed on the inner surface of the end plate 350. One end of the inner shaft 360 is provided with a radial sleeve rod 362. The sleeve 380 is sleeved on the sleeve rod 362 and the end of the sleeve 380 is hinged to the telescopic rod of the cylinder 370. The cylinder 370 drives the inner shaft 360 and the inner ring 320 to rotate by a certain angle in both the forward and reverse strokes through the sleeve 380 and the sleeve rod 362.

[0048] like Figure 7 As shown, there are two types of protrusions 321 on the surface of the inner ring 320: type 1 protrusion 321A and type 2 protrusion 321B. The difference between type 1 protrusion 321A and type 2 protrusion 321B lies in the specific shape of the second arc surface 321-1. The second arc surface 321-1 of type 1 protrusion 321A is more gentle than the second arc surface 321-1 of type 2 protrusion 321B.

[0049] The second arc surface 321-1 of a type of protruding post 321A satisfies the following: when the inner ring 320 rotates to make the telescopic post 330 extend to its farthest position, if the inner ring 320 continues to rotate, the telescopic post 330 will no longer extend.

[0050] The second arc surface 321-1 of the second type of protruding post 321B satisfies the following: when the inner ring 320 rotates to make the telescopic post 330 extend to its farthest position, if the inner ring 320 continues to rotate, the telescopic post 330 continues to extend.

[0051] This embodiment sets up as follows: Figure 7 The three consecutive Class II convex pillars 321B shown, and the rest being Class I convex pillars 321A, clearly indicate that... Figure 7 When the inner ring of the mold continues to rotate counterclockwise, only the telescopic post 330 corresponding to the second type of protrusion 321B continues to rise, while the telescopic post 330 corresponding to the first type of protrusion 321A remains in its original position.

[0052] In this embodiment, the dedicated inner mold 300 is arranged in a position such as... Figure 8In the outer mold 400 shown, cylinder 370 drives the inner ring 320 to rotate, causing all telescopic columns 330 to extend. A reinforcing cage is placed between the special inner mold 300 and the outer mold 400, and ultra-high performance concrete is poured. After curing, the pier outer ring 200 is obtained. After the pier outer ring 200 hardens, cylinder 370 should drive the inner ring 320 to rotate forward and backward repeatedly. The telescopic columns 330 corresponding to the second type of convex column 321B drive the pier outer ring 200 to vibrate to avoid adhesion between the pier outer ring 200 and the special inner mold 300 and the outer mold 400. Finally, cylinder 370 drives the inner ring 320 to rotate, causing all telescopic columns 330 to retract. The special inner mold 300 can then be pulled out laterally to achieve demolding.

[0053] Although embodiments of the present invention have been described in the specification, these embodiments are merely illustrative and should not be construed as limiting the scope of protection of the present invention. Various omissions, substitutions, and modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A construction method for composite bridge piers suitable for high-altitude and cold regions, characterized in that: The composite pier includes an inner core (100) and an outer ring (200), the outer ring (200) enclosing the inner core (100), and the outer ring (200) is made of ultra-high performance concrete; Includes the following steps: Step 1: Use ultra-high performance concrete to precast the outer ring of the bridge pier (200). Step 2: Transport the prefabricated outer ring of the bridge pier (200) to the construction site for installation and fixation; Step 3: Arrange a steel cage inside the outer ring (200) of the pier, and then pour ordinary concrete to form the inner core (100) of the pier. The outer ring (200) of the pier is used as a casting template for the inner core (100) of the pier. In step 1, the outer ring (200) of the bridge pier is prefabricated using a special inner mold (300). The dedicated inner mold (300) includes an outer mold ring (310), an inner mold ring (320), a telescopic column (330), and a spring (340). The inner mold ring (320) is concentric with the outer mold ring (310) and located inside the outer mold ring (310). The surface of the outer mold ring (310) is provided with a plurality of annularly distributed through holes (311). Each through hole (311) is equipped with a telescopic column (330). One end of the telescopic column (330) is spherical and the other end is provided with a first arc surface (331). The telescopic column (330) is provided with a shoulder (332) and... A spring (340) is fitted on the inner wall of the outer ring (310) and the shoulder (332) are respectively abutted by the two ends of the spring (340). The outer surface of the inner ring (320) is provided with a plurality of protrusions (321) corresponding to the telescopic column (330). The surface of the protrusion (321) is provided with a second arc surface (321-1). The first arc surface (331) contacts the second arc surface (321-1). When the inner ring (320) rotates relative to the outer ring (310) in the forward stroke, the protrusion (321) drives the telescopic column (330) to extend outward from the through hole (311).

2. The construction method for composite bridge piers suitable for high-altitude and cold regions according to claim 1, characterized in that: The inner core (100) of the pier is cast in place from ordinary concrete, while the outer ring (200) of the pier is prefabricated in the processing plant.

3. The construction method for combined bridge piers suitable for high-altitude and cold regions according to claim 1, characterized in that: The inner surface of the outer ring (200) of the pier is provided with a pit (210).

4. The construction method for combined bridge piers suitable for high-altitude and cold regions according to claim 1, characterized in that: The telescopic column (330) has a third arc surface (333) on its side, and the protruding column (321) has a fourth arc surface (321-2) on its side. When the inner ring (320) rotates in the opposite direction to the outer ring (310), the fourth arc surface (321-2) of the protruding column (321) contacts the third arc surface (333) of the adjacent telescopic column (330) and drives the telescopic column (330) to retract inward into the through hole (311).

5. The construction method for composite bridge piers suitable for high-altitude and cold regions according to claim 4, characterized in that: The special inner mold (300) also includes an end plate (350) and an inner shaft (360). The end plate (350) is installed at both ends of the outer ring (310). The inner shaft (360) is concentric with the inner ring (320) and the outer ring (310). The inner shaft (360) is connected to the inner ring (320) through a support rod (361).

6. The construction method for composite bridge piers suitable for high-altitude and cold regions according to claim 5, characterized in that: The special inner mold (300) also includes a cylinder (370) and a sleeve (380). The cylinder (370) is fixed on the inner surface of the end plate (350). One end of the inner shaft (360) is provided with a radial sleeve rod (362). The sleeve (380) is sleeved on the sleeve rod (362) and the end of the sleeve (380) is hinged to the telescopic rod of the cylinder (370).

7. The construction method for composite bridge piers suitable for high-altitude and cold regions according to claim 6, characterized in that: There are two types of protrusions (321) on the surface of the inner ring (320): a type I protrusion (321A) and a type II protrusion (321B). The difference between the type I protrusion (321A) and the type II protrusion (321B) lies in the specific shape of the second arc surface (321-1). The second arc surface (321-1) of a type of protruding post (321A) satisfies the following: when the inner ring (320) rotates to make the telescopic post (330) extend to its farthest position, if the inner ring (320) continues to rotate, the telescopic post (330) will no longer extend. The second arc surface (321-1) of the second type of protruding post (321B) satisfies the following: when the inner ring (320) rotates to make the telescopic post (330) extend to the farthest position, if the inner ring (320) continues to rotate, the telescopic post (330) continues to extend. The protrusions (321) on the surface of the inner ring (320) have N consecutive protrusions of type II (321B) and the rest are protrusions of type I (321A); N is greater than or equal to 3 and less than or equal to 5.

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