CN115976947A - UHPC grouting dual-corrugated-pipe prefabricated pier with slots and construction method thereof - Google Patents

Abstract

The invention relates to a UHPC grouting dual-corrugated pipe prefabricated pier with slots, which comprises a reinforced concrete bearing platform, prefabricated reinforced concrete pier columns and prefabricated reinforced concrete capping beams, wherein the reinforced concrete bearing platform is cast in situ; longitudinal ribs extend out of the upper end and the lower end of each pier stud; embedding a large-caliber metal corrugated pipe at the upper part of the bearing platform to form an inserting groove, embedding a plurality of small-caliber metal corrugated pipes matched with longitudinal ribs at the lower end of the pier stud, placing the lower end of the pier stud into the inserting groove, and inserting the extending longitudinal ribs into the corresponding corrugated pipes; a plurality of small-caliber metal corrugated pipes matched with the longitudinal bars at the upper ends of the pier studs are embedded in the bent caps; the corrugated pipe is positioned by positioning steel bars or connecting steel bars, and UHPC is poured into the spliced pipe. And also relates to a construction method of the UHPC grouting double-corrugated-pipe prefabricated pier with the slots. The invention enhances the force transmission effect, reduces the depth of the slot and avoids the brittle failure of the splicing interface; the integral stress is more reliable; the bellows centering required precision is low, and the construction is convenient, belongs to assembled bridge technical field.

Description

A UHPC grouted double bellows prefabricated pier with slots and its construction method

technical field

The invention relates to the technical field of prefabricated bridges, in particular to a UHPC grouting double bellows prefabricated pier with slots and a construction method thereof.

Background technique

Prefabricated bridge technology is a construction method in which the bridge structure is divided into several sections and prefabricated separately, and then transported to the site to form the main body of the bridge through connection, which can greatly reduce the wet work of site construction, reduce the impact on ground traffic, and reduce Carbon emissions, reduced energy consumption, shortened construction period, green and environmental protection, in line with my country's "double carbon" goal, has become an inevitable trend in the development of bridge construction in recent years. The prefabricated assembly technology of the bridge substructure has not been widely used in my country. The connection between components is the key to the overall force of the bridge pier. A new connection method that is reliable in force transmission, good in seismic performance, and convenient in construction needs to be explored urgently.

Whether the components of the prefabricated bridge piers can effectively transmit the force through the connection to achieve the overall force, and the seismic performance of the joints between the pier columns, caps, and cap beams are the most concerned safety issues in the engineering field. At present, the connection technology in the actual engineering of prefabricated bridge piers has the defects of high precision requirements, difficulty in detecting the fullness of grouting in the embedded sleeve, and the inability to replenish grout, which poses a safety hazard to the overall force between components. On the other hand, the connection between the root of the pier column and the upper surface of the cap is the weakest position for earthquake resistance. In existing projects, the prefabricated pier is usually provided with a connection interface at this position, and the interface is connected by using grout or grouting material. However, these two materials harden quickly, and the interface bond strength between the upper and lower members is not high. Under earthquake load, brittle failure of the connection interface is very easy to occur, which greatly reduces the seismic performance of the bridge pier.

A new type of dense cement-based engineering material - Ultra-High Performance Concrete (UHPC for short), has the advantages of high strength, high toughness, self-compacting, and stronger bonding performance with ordinary concrete and steel bars. The inventors found that if the material can be used for the connection of prefabricated bridges, it can not only enhance the anchorage of steel bars, but also improve the bonding force between the connection interfaces, which is beneficial to the effective transmission of forces between components and the seismic resistance of prefabricated bridge piers. Very favorable.

Contents of the invention

In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a belt with strong bonding performance, preventing brittle failure of the connection interface between components, ensuring compact grouting, little impact on the bearing structure of the cap, and convenient construction. Slotted UHPC grouted double bellows prefabricated pier and its construction method.

In order to achieve the above object, the present invention adopts following technical scheme:

A UHPC grouted double bellows prefabricated bridge pier with slots, including a reinforced concrete cap platform cast on site, a prefabricated reinforced concrete pier column, and a prefabricated reinforced concrete cap beam; longitudinal bars protrude from both ends of the pier column; A large-diameter metal bellows is pre-embedded in the upper part of the cap to form a slot, and a number of small-diameter metal bellows are pre-embedded to match the longitudinal reinforcement at the lower end of the pier column, and the lower end of the pier column is placed in the slot; A number of small-diameter metal bellows that match the longitudinal reinforcement at the upper end of the pier are buried, and the small-diameter metal bellows run through the cover beam up and down; both the small-diameter metal bellows and the large-diameter metal bellows are perfused with UHPC.

As a preference, there is a mesh-type steel bar inside the cap, and the mesh-type steel bar is connected with the steel bar skeleton of the cap, and the small-diameter metal bellows is fixed on the mesh-type steel bar; The steel skeleton of the cover beam is connected by binding or welding, and the small-diameter metal bellows are fixed on the grid-shaped steel bars.

As a preference, the grid-type steel bars include a plurality of positioning steel bars, and the multiple positioning steel bars are criss-crossed on the horizontal plane to form a plane grid, and the multi-layer plane grids are arranged in sequence in the height direction to form a space grid.

As a preference, there are multiple connecting steel bars inside the cap, and the connecting steel bars and the steel skeleton of the cap are connected by binding or welding, and the multiple connecting steel bars are arranged around large-diameter metal bellows, and the large-diameter metal bellows are fixed on the connecting steel bars Above; the connecting reinforcement includes a horizontal section and a downwardly bent bent section, the inner side of the horizontal section is connected with the large-diameter metal bellows, and the bent section is located outside the horizontal section.

As a preference, the cross-section of the piers is circular or rectangular; the metal bellows with large diameters are circular or rectangular; and the metal bellows with small diameters are arranged in circular or rectangular rings.

A construction method for UHPC grouting double bellows prefabricated bridge piers with slots, comprising the following steps: a. prefabricating reinforced concrete pier columns and reinforced concrete cap beams; b. pouring reinforced concrete caps on site; c. The column is hoisted, and the longitudinal rib protruding from the lower end of the pier column is inserted into the pre-buried small-diameter metal bellows in the cap. d. Hoisting the cover beam, inserting the longitudinal reinforcement protruding from the upper end of the pier column into the pre-buried small-diameter metal bellows in the cover beam, after leveling and positioning, pour UHPC into the small-diameter metal bellows from the upper end, Maintenance, complete the assembly of the upper node of the pier column.

As a preference, in step b, in order to prevent the concrete grout from flowing into the slot when the cap is poured, the upper end of the large-diameter metal bellows is higher than the upper surface of the cap, and the upper end of the small-diameter metal bellows is higher than the large-diameter The lower end of the metal bellows, and the upper and lower nozzles of the large-diameter metal bellows and small-diameter metal bellows should be temporarily closed, and the excess pipe section at the upper end should be cut off before splicing; in step a, when prefabricating the cover beam, in order to avoid concrete pouring When the concrete slurry flows in, the upper end of the small-diameter metal bellows is higher than the upper surface of the cover beam, and the upper and lower nozzles of the small-diameter metal bellows should be temporarily closed, and the excess pipe section at the upper end should be cut off before splicing.

As a preference, when the pier column is placed in the slot, the bottom of the slot is covered with UHPC to realize the function of UHPC seat grout; effect.

As a preference, in order to enhance the cohesive force of the connection interface, before the connection, all the connection interfaces of the piers are chiseled; the floating dust and the cleaning surface of the connection interface of the prefabricated pier are cleaned.

As a preference, the maintenance of UHPC is as follows: according to the temperature conditions of the construction site, choose to use natural condition curing or steam curing; when the site temperature exceeds 10°C, use timely watering and film covering natural curing; when the site temperature is lower than 10°C , using steam curing.

The present invention has the following advantages:

1) The fullness of grouting is guaranteed. The UHPC material is poured in the open type, that is, the grout is directly grouted from the mouth of the bellows, and the self-compacting characteristics of the UHPC material are used to ensure the fullness of the grouting.

2) The bonding force between the interfaces is stronger to avoid brittle failure of the interface. It is mainly reflected in the following aspects:

① The setting of double bellows prevents the pier column from being pulled out and damaged due to insufficient anchorage. At present, the connection interface between the prefabricated pier column and the cap is only treated by chiseling or tooth key, which is prone to bond failure; for the weakest lower node of seismic resistance, double bellows are installed to make full use of the bonding force between the bellows and concrete Stronger advantages, enhance the bonding force of the vertical connection interface between the pier column and the cap, and ensure reliable anchoring.

② UHPC materials have stronger bonding properties with steel bars than ordinary concrete, which can enhance the anchoring performance of longitudinal steel bars, strengthen the force transmission effect of steel bars between pier columns, caps, and cap beams, and realize effective force transmission between components.

③The bonding force between UHPC material and ordinary concrete is stronger. UHPC is used as a sitting grout layer to ensure sufficient contact between the bottom of the pier column and the connecting interface between the cap, the top of the pier column and the cover beam, and the bonding force of the connecting interface is stronger. powerful.

3) Better seismic performance. The lower node is connected by slots combined with grouted bellows. The connection interface between the pier column and the cap is located at the bottom of the slot, avoiding the weakest position for seismic resistance (the junction between the pier column and the upper surface of the cap), and using steel bars in UHPC. Strong anchoring performance, reducing the depth of the slot, reducing the adverse impact on the force of the cap structure, and improving the seismic performance (the deeper the slot, the disconnection of the cap reinforcement, the unfavorable force).

4) Construction is more convenient.

① The connecting steel bars and grid-type positioning steel bars of the bellows are short steel bars, which are convenient for construction and have little impact on the design and construction of the steel skeleton of the cap and cover beam itself. By binding or welding, they form a whole with the steel bars of the cap or cover beam , the overall stress effect is good.

②The construction of slots and longitudinal ribs inserted into bellows has low precision requirements, is convenient and quick, and is more suitable for site conditions.

Description of drawings

Figure 1 is an assembly rendering of the prefabricated bridge piers.

Figure 2 is a schematic diagram of components of a prefabricated bridge pier.

Fig. 3 is a sectional view of the first embodiment along the direction A-A in Fig. 1 .

Fig. 4 is a sectional view of the first embodiment along the B-B direction in Fig. 1 .

Fig. 5 is a sectional view of the first embodiment along the line C-C in Fig. 1 .

Fig. 6 is a cross-sectional view of the second embodiment along the direction A-A in Fig. 1 .

Fig. 7 is a cross-sectional view of the second embodiment along the B-B direction in Fig. 1 .

Fig. 8 is a sectional view of the second embodiment along the direction C-C in Fig. 1 .

Figure 9 is the hysteresis curves of the two specimens.

Among them, 1 is the pier column, 2 is the cap, 3 is the cover beam, 4 is the longitudinal reinforcement of the pier column, 5 is the small-diameter metal bellows, 6 is the large-diameter metal bellows, 7 is UHPC, 8 is the connecting steel bar, 9 For positioning reinforcement.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments.

Embodiment one

A UHPC grouted double bellows prefabricated bridge pier with slots, including a reinforced concrete cap platform cast on site, a prefabricated reinforced concrete pier column, and a prefabricated reinforced concrete cap beam; longitudinal bars protrude from both ends of the pier column; A large-diameter metal bellows is pre-embedded in the upper part of the cap to form a slot, and a number of small-diameter metal bellows are pre-embedded to match the longitudinal reinforcement at the lower end of the pier column, and the lower end of the pier column is placed in the slot; A number of small-diameter metal bellows that match the longitudinal reinforcement at the upper end of the pier are buried, and the small-diameter metal bellows run through the cover beam up and down; both the small-diameter metal bellows and the large-diameter metal bellows are perfused with UHPC.

There are mesh-type steel bars inside the cap, and the mesh-type steel bars are connected with the steel frame of the cap, and the small-diameter metal bellows are fixed on the mesh-type steel bars; there are mesh-type steel bars in the cover beam, and the mesh-type steel bars are connected to the steel frame of the cover beam Connection, the small-diameter metal bellows are fixed on the grid steel bars.

The grid-type reinforcement includes a plurality of positioning reinforcements, which are criss-crossed on the horizontal plane to form a plane grid, and the multi-layer plane grids are arranged in sequence in the height direction to form a space grid.

There are multiple connecting steel bars inside the cap, the connecting steel bars are connected with the steel frame of the cap, and the multiple connecting steel bars are set around the large-diameter metal bellows, and the large-diameter metal bellows are fixed on the connecting steel bars; the connecting steel bars include horizontal sections and In the bending section of the downward bending, the inner side of the horizontal section is connected with the large-diameter metal bellows, and the bending section is located outside the horizontal section.

In this embodiment, the cross-section of the piers is rectangular; the metal bellows with large diameters are rectangular pipes; and the metal bellows with small diameters are arranged in rectangular rings.

A construction method for a UHPC grouted double bellows prefabricated bridge pier with slots, comprising the following steps:

a. Prefabricated reinforced concrete piers and reinforced concrete cap beams: when prefabricating reinforced concrete piers, the longitudinal bars at both ends protrude by a certain length La (La≥30d, d is the diameter of the longitudinal bars of the pier column), in order to prevent the reinforcement If rusted or damaged, it can be wrapped in plastic film for protection. When the cover beam is prefabricated, a corresponding number of small-diameter metal bellows is pre-embedded at the corresponding position of the longitudinal reinforcement of the pier column. The length of the bellows is equal to the height of the cover beam. The top surface is higher than the upper surface of the cover beam, and the upper and lower nozzles shall be temporarily closed. The small-diameter metal bellows is fixed by grid-type steel bars, and connected with the steel bar frame of the cover beam itself.

b. On-site pouring of reinforced concrete caps: Set slots corresponding to the cross-sectional shape of the pier columns (depth H ₁ ≤ 300mm) at the connection between the caps and the pier columns. The edge of the slots is about 150-200mm larger than the size of the pier columns. Around the slot, there are pre-embedded rectangular metal bellows, which are fixed with connecting steel bars, and the connecting steel bars are connected with the steel frame of the cap itself by binding or welding. When pouring caps, corrugated pipes are pre-embedded at the positions corresponding to the longitudinal reinforcements of pier columns, and the depth H ₂ of embedding caps is ≥30d. Tube. In order to prevent the concrete grout from flowing into the bellows during pouring of the platform, the top surface of the bellows can be higher than the upper surface of the platform, and the upper and lower nozzles should be temporarily closed. The small-diameter metal bellows is fixed by grid-type steel bars, and connected with the steel bar skeleton of the cap itself.

c. Lift the pier column with a crane, insert the longitudinal reinforcement protruding from the lower end of the pier column into the small-diameter metal bellows pre-buried in the cap, pour UHPC into the small-diameter metal bellows and large-diameter metal bellows, maintain, and complete The assembly of the lower node of the pier column is as follows: before splicing the prefabricated pier column and the cap, use a high-pressure air pump or a vacuum cleaner to clean the inside of the slot and the inside of the small-diameter metal bellows, and cut off the protruding part of the small-diameter metal bellows , keeping it flush with the bottom of the tank. With the help of a crane, lift the pier column, insert the longitudinal reinforcement protruding from the bottom into the small-diameter metal bellows inside the cap, and slowly pour UHPC into the mouth of the small-diameter metal bellows until it overflows the nozzle and flows to the socket. Half the depth of the groove. Adjust the verticality and elevation of the pier column, fix the pier column temporarily, and continue to pour UHPC into the slot until it is full.

d. Hoist the cover beam, insert the longitudinal reinforcement protruding from the upper end of the pier column into the pre-buried small-diameter metal bellows in the cover beam, pour UHPC into the small-diameter metal bellows from the upper end, and perform maintenance to complete the assembly of the upper node of the pier column. Specifically: after the UHPC compressive strength at the lower node reaches 60 MPa or more (it takes about 48 hours for normal temperature curing, and about 24 hours for steam curing), the upper node is spliced; before splicing, use a high-pressure air pump or a vacuum cleaner to splice the pier top and the bottom of the cover beam Clean up the floating dust at the position, cut off the protruding part of the small-diameter metal bellows, and keep it flush with the top and bottom surfaces of the cover beam. Steel or wood formwork is used around the top of the pier, with a height of 2cm, and a layer of UHPC with a thickness of 2cm is evenly spread on the pier column; when hoisting the cover beam, insert the steel bar protruding from the pier column into the corresponding small-diameter metal bellows, and slowly place it Press the top of the pier to the UHPC; adjust the verticality and elevation of the cover beam and fix it temporarily. From the small-diameter metal bellows on the top of the cover beam, pour UHPC until it overflows. During the pouring process, use thin steel bars for slight agitation to ensure the fluidity and compactness of UHPC.

In step b, in order to prevent the concrete grout from flowing into the platform during pouring, the upper end of the large-diameter metal bellows is higher than the upper surface of the platform, the upper end of the small-diameter metal bellows is higher than the lower end of the large-diameter metal bellows, and the large-diameter metal bellows is higher than the lower end of the large-diameter metal bellows. The upper and lower nozzles of the metal bellows and small-diameter metal bellows should be temporarily closed, and the excess pipe section at the upper end should be cut off after the pouring is completed; The upper end of the metal bellows is higher than the upper surface of the cover beam, and the upper and lower nozzles of the small-diameter metal bellows should be temporarily closed, and the excess pipe section at the upper end should be cut off after the pouring is completed.

In order to enhance the bonding strength of the interface, all the bellows above are made of metal.

When the pier column is placed in the slot, the bottom of the slot is covered with UHPC to realize the function of UHPC seat grout; when the cover beam is placed on the pier column, the upper end of the pier column is covered with UHPC to realize the function of UHPC seat grout. When splicing, when the upper member falls, the bottom surface must be pressed against the UHPC until it overflows.

In order to enhance the cohesive force of the connection interface, before the connection, all the connection interfaces of the pier column shall be chiseled; the floating dust and the cleaning surface of the connection interface of the prefabricated pier shall be cleaned.

The maintenance of UHPC is: according to the temperature conditions of the construction site, choose to use natural condition curing or steam curing; when the site temperature exceeds 10°C, use timely watering and film covering natural curing; when the site temperature is lower than 10°C, use steam curing. Measure the compressive strength of the same batch of UHPC materials, and if it reaches more than 60MPa, the temporary fixing measures can be removed and the next step of splicing can be carried out.

The leveling and positioning of the pier columns can be realized by placing steel pads locally, and the size should not be too large.

Through experimental research, it is verified that the effect of cast-in-place connection can be achieved by adopting the fabricated technology of the present invention.

Design two scaled-scale models of pier columns with the same size and reinforcement, A1 adopts the integral cast-in-place connection, B3 adopts the slot combined with grouting UHPC metal bellows connection proposed by the present invention, and conducts pseudo-static experiments. The results show that the two test The hysteretic curves of the components basically overlap, and it can be seen that the seismic effect equivalent to that of cast-in-place can be achieved by using the technology of the present invention to connect the assembled piers.

The invention utilizes UHPC to have stronger bonding performance with steel bars and bellows, enhance the effect of force transmission, reduce the depth of slots, and reduce damage to the cap structure; by positioning the steel bars and connecting the steel bars to the steel bar skeletons of the caps and cover beams, The overall force is more reliable; the bellows requires low centering accuracy and the construction is convenient.

Embodiment two

In this embodiment, the cross-section of the piers is circular; the metal bellows with large diameters are circular pipes; and the metal bellows with small diameters are arranged in a ring shape.

The parts not mentioned in this embodiment are the same as those in Embodiment 1.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. A UHPC grouting double bellows prefabricated bridge pier with slots is characterized in that: it includes a reinforced concrete cap platform cast on site, a prefabricated reinforced concrete pier column, and a prefabricated reinforced concrete cap beam; the upper and lower ends of the pier column are There are longitudinal ribs protruding; a large-diameter metal bellows is pre-embedded in the upper part of the cap to form a slot, and several small-diameter metal bellows are pre-embedded to match the longitudinal ribs at the lower end of the pier column, and the lower end of the pier column is placed in the slot Inside; a number of small-diameter metal bellows are pre-embedded in the cover beam to cooperate with the longitudinal reinforcement at the upper end of the pier column, and the small-diameter metal bellows run through the cover beam up and down; both the small-diameter metal bellows and the large-diameter metal bellows are perfused with UHPC. 2. A UHPC grouting double bellows prefabricated bridge pier with slots according to claim 1, characterized in that: grid steel bars are arranged in the cap, and the grid steel bars are connected with the steel skeleton of the cap, and the small-diameter metal The corrugated pipe is fixed on the grid steel bar; there is a grid steel bar inside the cover beam, and the grid steel bar and the steel skeleton of the cover beam are connected by binding or welding, and the small-diameter metal bellows is fixed on the grid steel bar. 3. A UHPC grouted double bellows prefabricated bridge pier with slots according to claim 2, characterized in that: the grid steel bars include multiple positioning steel bars, and the multiple positioning steel bars are criss-crossed on the horizontal plane to form a layer of planar network The multi-layer planar grids are arranged sequentially in the height direction to form a spatial grid. 4. A UHPC grouted double bellows prefabricated pier with slots according to claim 1, characterized in that: a plurality of connecting steel bars are arranged in the cap, and the connecting steel bars and the steel skeleton of the cap are connected by binding or welding , a plurality of connecting steel bars are set around the large-diameter metal bellows, and the large-diameter metal bellows are fixed on the connecting steel bars; the connecting steel bars include a horizontal section and a downwardly bent bending section, and the inner side of the horizontal section is connected to the large-diameter metal bellows Then, the bent section is located on the outside of the horizontal section. 5. A UHPC grouted double bellows prefabricated bridge pier with slots according to claim 1, characterized in that: the cross section of the pier column is circular or rectangular; the large-diameter metal bellows is a round tube or a rectangular tube; The small-diameter metal bellows are arranged in a circular ring or a rectangular ring. 6. According to the construction method of a UHPC grouting double bellows prefabricated bridge pier with a slot according to any one of claims 1 to 5, it is characterized in that it comprises the steps of: a. Prefabricated reinforced concrete piers and reinforced concrete cap beams; b. On-site pouring of reinforced concrete caps; c. Lift the pier column with a crane, insert the longitudinal ribs protruding from the lower end of the pier column into the small-diameter metal bellows embedded in the cap, after leveling and positioning, pour into the small-diameter metal bellows and large-diameter metal bellows UHPC, maintenance, complete the assembly of the lower node of the pier column; d. Hoist the cover beam, insert the longitudinal reinforcement protruding from the upper end of the pier column into the pre-buried small-diameter metal bellows in the cover beam, after leveling and positioning, pour UHPC into the small-diameter metal bellows from the upper end for maintenance, and complete the pier column The assembly of the upper node. 7. According to the construction method of a UHPC grouting double bellows prefabricated bridge pier with a slot according to claim 6, it is characterized in that: in step b, in order to avoid the concrete grout flowing into the slot when the cap is poured, The upper end of the large-diameter metal bellows is higher than the upper surface of the platform, the upper end of the small-diameter metal bellows is higher than the lower end of the large-diameter metal bellows, and the upper and lower nozzles of the large-diameter metal bellows and small-diameter metal bellows should be temporarily fixed. Close, and cut off the excess pipe section at the upper end before splicing; in step a, when prefabricating the cover beam, in order to avoid the inflow of concrete slurry when the cap is poured, the upper end of the small-diameter metal bellows is higher than the upper surface of the cover beam, and the small-diameter metal bellows The upper and lower nozzles of the bellows should be temporarily closed, and the excess pipe section at the upper end should be cut off before splicing. 8. The construction method of UHPC grouting double bellows prefabricated pier with slots according to claim 6, characterized in that: when the pier column is placed in the slot, the bottom of the slot is covered with UHPC to realize UHPC grouting When the cover beam is spliced with the pier column, the upper surface of the pier column is covered with UHPC to realize the function of UHPC seat grout. 9. According to the construction method of a UHPC grouting double bellows prefabricated bridge pier with slots according to claim 6, it is characterized in that: in order to enhance the cohesive force of the connection interface, before the connection, all the connection interfaces of the pier column are chiseled ; Clean up the floating dust and clean the surface of the connection interface of the prefabricated pier. 10. According to the construction method of a UHPC grouting double bellows prefabricated pier with slots according to claim 6, it is characterized in that the maintenance of UHPC is: according to the temperature conditions of the construction site, natural condition maintenance or steam maintenance is selected ;When the site temperature exceeds 10°C, use timely watering and film covering for natural maintenance; when the site temperature is lower than 10°C, use steam curing.

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