Lightweight caisson and its construction method for high-pile cap construction of bridges in water

Abstract

This invention relates to a lightweight caisson and its construction method suitable for the construction of high-pile foundations for bridges in water. The caisson includes a base plate and side plates installed around the base plate. The base plate is composed of multiple precast blocks, which are connected as a whole by wet-joint concrete pouring. The base plate has multiple inverted arched grooves, each covered by a cover plate. The base plate also has through-holes for steel casings. For each pile foundation construction, a steel casing is inserted into one of these through-holes, and circumferential sealing concrete is poured into the gap between the inner wall of the through-hole and the outer wall of the steel casing. The inverted arched cavity in the base plate of this invention reduces the weight of the base plate without reducing its thickness, thus ensuring sufficient bonding force between the base plate and the steel casing. This effectively enhances the seismic performance of bridges in water in high-intensity seismic zones.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, and relates to the construction of high pile caps for bridges in water. Specifically, it relates to a lightweight caisson structure and its construction method suitable for the construction of high pile caps for bridges in water. Background Technology

[0002] Underwater high-pile foundations are generally constructed using a bottomed caisson. The caisson's bottom slab is typically assembled from steel trusses and plates. After the foundation piles are constructed, a lowering device is installed on the steel casing used for pile construction to lower the caisson to the designed height. A certain thickness of sealing concrete is then poured inside the caisson. Once the sealing concrete has reached a certain strength, the water inside the caisson is pumped out. The caisson's side panels and the sealing concrete form a waterless working environment, where the reinforcement of the foundation structure is tied and the concrete is poured. After the foundation construction is completed, the sealing concrete bonds with the foundation concrete, becoming part of the permanent structure of the foundation.

[0003] During construction, after the water inside the caisson is drained and during the initial stage of pier cap construction, the caisson needs to overcome the buoyancy of the water to prevent it from floating. Later in the pier cap construction and after its completion, the caisson must withstand the load of the pier cap and its own weight to prevent it from sinking. The caisson overcomes these two forces mainly by relying on the tension and compression rods welded between the base plate and the steel casing, and the bond force between the bottom sealing concrete and the steel casing. The load-bearing capacity of the tension and compression rods is relatively fixed, while the magnitude of the bond force mainly depends on the thickness of the bottom sealing concrete.

[0004] The thickness of the bottom sealing concrete typically requires comprehensive calculation considering various factors, including the pier cap's immersion depth in water, the clear distance between piles, the pier cap pouring load, the self-weight of the caisson, and construction costs. Seismic resistance levels also need to be considered, making the calculation process quite complex. While a thicker bottom sealing concrete results in greater bond strength with the steel casing, it also increases the amount of concrete poured, thus raising construction costs. Currently, for ordinary bridge high-pile pier caps in water, the thickness of the bottom sealing concrete is generally no less than 1.5 meters, while for large bridge pier caps, the thickness can reach 2-4 meters. The volume of bottom sealing concrete accounts for 30-50% of the total pier cap concrete volume, resulting in higher costs.

[0005] Increasing the thickness of the bottom sealing concrete also leads to an increase in its self-weight. In areas with low seismic intensity, the self-weight of the bottom sealing concrete has little impact. However, in areas with high seismic intensity, the weight of the bottom sealing concrete has a significant impact on the seismic design of bridges, especially bridges in deep water or deep silt geology. Due to the large free length of the foundation piles, the seismic impact is more pronounced. To resist the seismic impact of the weight of the bottom sealing concrete, it is often necessary to increase the diameter and number of foundation piles, further increasing construction costs.

[0006] In addition, the bottom sealing concrete is poured underwater, which places higher demands on the quality of the concrete and the pouring process, and the construction risk is relatively high. If there are problems with the quality of the bottom sealing concrete pouring, resulting in water leakage inside the casing, or if it cannot generate sufficient bonding force with the steel casing, it will directly affect the safety of subsequent construction.

[0007] Considering all the above factors, current research on the construction of high-pile foundations in water focuses on using prefabricated assembled caisson structures to reduce the amount of cast-in-place bottom concrete, and using lightweight caisson structures to increase the seismic resistance of bridges.

[0008] In the prior art, CN100591863C discloses a patent entitled "An Underwater Bottomless Cofferdam and Its Application Method". The cofferdam of this solution adopts a precast concrete structure. The bottom plate and side plates of the cofferdam are precast as a whole and then lowered as a whole. This eliminates the need for the cast-in-place concrete for sealing the bottom of the cofferdam. However, the bottom plate of the cofferdam and the steel casing use a capsule-shaped water-stopping method. Not only is the water-stopping effect poor, but there is also almost no bonding force between the bottom plate of the cofferdam and the steel casing. It cannot effectively prevent the cofferdam from floating. Therefore, it is only suitable for construction environments in shallow seas or when the water level is lower than the bottom plate of the cofferdam during low tide. In addition, since the cofferdam is a concrete structure, it has a large self-weight. The side plates of the cofferdam cannot be removed. The cofferdam is finally cast as a whole with the foundation concrete, which further increases the volume and weight of the foundation, resulting in poor seismic performance.

[0009] Patent CN105951856B discloses a construction method for an underwater bottomless concrete-steel composite cofferdam, in which the bottom slab is made of precast concrete and the side slabs are made of steel. This method requires only the pouring of sealing concrete into the circumferential joint between the bottom slab and the steel casing after the cofferdam is lowered into place, thus requiring less concrete to be poured in place. However, to ensure sufficient bond strength between the sealing concrete and the steel casing, the bottom slab must be of sufficient thickness. Since the bottom slab in this method is a solid structure, the weight of the cofferdam bottom slab is relatively large, necessitating measures such as increasing the diameter and number of foundation piles to improve seismic resistance, thereby increasing construction costs. Summary of the Invention

[0010] The purpose of this invention is to address the above-mentioned problems by providing a lightweight caisson and its construction method suitable for the construction of high-pile abutments for bridges in water. While ensuring that the caisson has sufficient anti-buoyancy capacity, the self-weight of the caisson is reduced, thereby improving the seismic resistance of the bridge.

[0011] The technical solution of the present invention is as follows:

[0012] A lightweight caisson suitable for the construction of high-pile bridge piers in water includes a caisson base plate and caisson side plates fixedly installed around the caisson base plate. The caisson base plate has corresponding through holes for steel casings according to the number and layout of the steel casings used for the pier pile foundation construction. Each steel casing for the pier pile foundation construction is inserted into a through hole in the caisson base plate. Circumferential sealing concrete is poured into the gap between the inner wall of the through hole and the outer wall of the steel casing. The caisson base plate is characterized by having multiple inverted arched grooves, each groove opening covered by a cover plate. The caisson base plate is assembled from multiple precast blocks, including four corner modules, at least four side modules, and at least one intermediate module. Each precast block has one through hole for the steel casing. A portion of the inverted arched groove is also provided on each precast block according to the distribution of the inverted arched grooves on the caisson base plate. The precast blocks are connected as a whole by pouring wet-joint concrete.

[0013] The above-mentioned construction method for lightweight caissons applicable to the construction of high-pile caps for bridges in water is characterized by comprising the following steps:

[0014] (1) After the pile foundation construction is completed, a casing assembly platform is erected on the steel casing of the pile foundation construction. The precast blocks of each casing bottom plate are hoisted onto the assembly platform in sequence according to their installation positions on the casing bottom plate. Each steel casing is inserted into the through hole of the steel casing on the precast block.

[0015] (2) Pour wet joint concrete between the joints of each precast block to connect the precast blocks into an integral casing bottom plate; install casing side plates around the bottom plate to form an integral casing.

[0016] (3) Install a casing lowering device on the top of the steel casing and lower the casing to the designed underwater installation height;

[0017] (4) Seal the circumferential gap between the bottom of the through hole of the steel casing and the steel casing;

[0018] (5) Pour concrete to seal the circumferential joint inside the through hole of the steel casing;

[0019] (6) After the circumferential joint sealing concrete has solidified and formed sufficient bonding force between it and the outer wall of the steel casing, drain the water from the casing and install a cover plate on the groove of the inverted arch groove on the bottom plate of the casing to completely seal the inverted arch groove and make the bottom plate form a cavity structure.

[0020] (7) Cut off the steel casing inside the cofferdam, tie the foundation reinforcement inside the cofferdam, and pour the foundation concrete.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The bottom plate of the caisson has a cavity, which reduces the weight of the bottom plate without reducing the thickness of the bottom plate to ensure sufficient gripping force with the steel casing, and can effectively enhance the seismic performance of bridges in water in high seismic intensity areas.

[0023] 2. The cavity on the bottom plate of the casing adopts an inverted arch structure, which can make full use of the arch force principle and ensure that the bottom surface of the bottom plate can effectively withstand the upward pressure of water; the overall structure can reduce the amount of concrete and steel bars used, and reduce the project cost.

[0024] 3. The bottom plate of the casing is assembled from multiple precast blocks. The precast blocks can be manufactured in a factory to ensure the quality of the bottom plate. The circumferential joint between the bottom plate and the steel casing is first sealed with annular sandbags, and then the circumferential joint sealing concrete is poured. The concrete can be poured by vibration to ensure the bonding force and sealing effect, and to ensure the safety of the foundation construction. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the planar structure of the present invention;

[0026] Figure 2 This invention follows Figure 1 Elevation view of the central section II;

[0027] Figure 3 This invention follows Figure 1 Elevation view along the middle II-II direction;

[0028] Figure 4 This is a plan view of one corner module of the base plate of the housing;

[0029] Figure 5 This is an elevation view of one corner module of the base plate of the housing;

[0030] Figure 6 This is a plan view of one side module of the bottom plate of the casing;

[0031] Figure 7 This is an elevation view of one side module of the base plate of the casing;

[0032] Figure 8 This is a plan view of an intermediate module of the base plate of the casing;

[0033] Figure 9 This is an elevation view of an intermediate module of the base plate of the casing;

[0034] Figure 10 yes Figure 3 The enlarged view at point A mainly shows the circumferential joint sealing structure between the bottom plate of the casing and the steel casing for pile foundation construction;

[0035] Figure 11 yes Figure 3 The enlarged view at point B mainly shows the fixing structure between the side panel and the bottom plate of the housing;

[0036] Figure 12 A schematic diagram of the assembly method of the bottom plate of the container on the lowering platform;

[0037] Figure 13 This is a schematic diagram showing the installation method of the side panel of the casing on the bottom plate;

[0038] Figure 14 This is a schematic diagram showing the state of the entire set of boxes after they have been lowered into place.

[0039] Figure 15 This is a schematic diagram showing the installation of sandbags to seal the circumferential seam of the casing.

[0040] Figure 16 This is a schematic diagram showing the state of the circumferential joint sealing concrete after it has been poured.

[0041] Figure 17 This is a schematic diagram showing the state of the cover plate installed at the bottom opening of the cavity of the casing.

[0042] Figure 18 This is a schematic diagram showing the state of pouring concrete for the foundation within the casing. Detailed Implementation

[0043] like Figures 1 to 11 As shown, the present invention includes a base plate 1 and side plates 2 fixedly installed around the base plate. The base plate 1 has corresponding through holes 11 for steel casings according to the number and layout of the steel casings for the pile foundation construction. Each steel casing 3 for pile foundation construction is inserted into a through hole 11 on the base plate. Circumferential sealing concrete 4 is poured into the gap between the inner wall of the through hole 11 and the outer wall of the steel casing 3. The base plate 1 has multiple inverted arched grooves 12, and a cover plate 13 covers the opening of each inverted arched groove 12. The base plate 1 is assembled from multiple precast blocks. The multiple precast blocks include four corner modules 14, at least four side modules 15, and at least one intermediate module 16. Each precast block has a through hole 11 for the steel casing. Each precast block has a portion of an inverted arched groove 12 according to the distribution of the inverted arched grooves on the base plate. The precast blocks are connected as a whole by pouring wet joint concrete 17.

[0044] like Figures 3 to 9 As shown, in a specific implementation of the present invention, to facilitate the sealing of the through holes of the steel casing, an inwardly protruding circumferential edge 111 is provided at the bottom opening of each through hole 11 of the steel casing on the bottom plate of the casing, forming a constricted opening structure; as shown Figure 10 As shown, each steel casing 3 is fitted with an annular sealing sandbag 5. The sealing sandbag 5 is supported on the annular edge 111 at the bottom of the through hole of the steel casing and is in close contact with the outer wall of the steel casing. The annular joint sealing concrete 4 is poured into the top of the sealing sandbag 5 inside the through hole 11 of the steel casing.

[0045] like Figures 3 to 10 As shown, in a specific implementation of the present invention, in order to prevent the cover plate 13 from moving and to ensure that the cover plate completely seals the inverted arched groove, a lowered cover plate positioning step 121 can be provided around the groove opening of each inverted arched groove 12 on the bottom plate of the sleeve box, and the cover plate 13 is supported on the cover plate positioning step 121.

[0046] like Figures 1 to 7 and Figure 11 As shown, in a specific implementation of the present invention, to facilitate the installation and fixing of the side plate 2 of the housing and the disassembly of the side plate after the construction of the support platform, a set of side plate positioning steps 18 that descend from the inside to the outside are respectively provided on the top surface of the four sides of the bottom plate 1 of the housing. The bottom of the side plate 2 of the housing is supported on the side plate positioning steps 18, and the inner wall of the side plate 2 of the housing is in close contact with the inner side wall of the side plate positioning steps 18. Multiple embedded steel plates 181 are provided on the top surface of the side plate positioning steps. A limiting device 6 is fixedly connected to each embedded steel plate 181. Each limiting device 6 includes a vertical plate 61 and a limiting plate 62. The bottom of the vertical plate 61 is welded to the embedded steel plate 181. One end of the limiting plate 62 is rotatably connected to the vertical plate 61 through a pin 63, and the other end of the limiting plate 62 is pressed against the outer wall of the side plate 2 of the housing.

[0047] like Figure 1 Figure 2 , Figure 3 As shown, in order to prevent the inverted arched groove 12 on the bottom plate of the casing from being deformed outward due to the upward pressure of water, at least two tie rods 19 can be installed between the two opposite side walls of each inverted arched groove 12 on the bottom plate of the casing, and each tie rod is anchored at both ends in the concrete of the bottom plate of the casing.

[0048] Furthermore, to facilitate tie rod installation, each tie rod 19 can be configured as two tie rod segments 191; such as Figures 4 to 9 As shown, an internally threaded sleeve 192 is pre-embedded in the sidewall concrete of each inverted arch groove 12 on each precast block according to the installation position of the tie rod; one end of each of the two segments 191 of the tie rod is screwed to the pre-embedded internally threaded sleeve 192 on the two opposite sidewalls of the inverted arch groove, and the other ends of the two tie rod segments are connected by an externally threaded sleeve 193.

[0049] The above-mentioned construction method for lightweight caissons applicable to the construction of high-pile caps for bridges in water includes the following steps:

[0050] (1) As Figure 12 As shown, after the pile foundation construction is completed, a casing assembly platform 7 is erected on the steel casing 3 of the pile foundation construction. The precast blocks 14, 15, and 16 of the casing bottom plate are hoisted onto the assembly platform 7 in sequence according to their installation positions on the casing bottom plate. Each steel casing 3 is inserted into the steel casing through hole 11 on the precast block.

[0051] (2) Figure 13As shown, wet joint concrete 17 is poured between the joints of each precast block to connect the precast blocks into an integral casing bottom plate 1; casing side plates 2 are installed around the bottom plate to form an integral casing.

[0052] When tie rods 19 are installed between the two opposite side walls of each inverted arch groove on the bottom plate of the casing, the tie rods are installed after the wet joint concrete is poured. When installing tie rods 19, first connect one end of each of the two segments of each tie rod to two opposite pre-embedded threaded sleeves on the side wall of the inverted arch groove, and then connect the other ends of the two tie rod segments with threaded sleeves.

[0053] With the side plate positioning steps 18 on the top surface of the four sides of the bottom plate of the housing, when installing the side plate of the housing, the bottom of the side plate 2 is supported on the side plate positioning steps 18, and the inner wall of the side plate is tightly attached to the inner side wall of the side plate positioning steps. Then, a limiting device 6 is fixedly installed on each pre-embedded steel plate. Each limiting device includes a vertical plate 61 and a limiting plate 62. One end of the limiting plate is rotatably connected to the vertical plate through a pin 63. First, the vertical plate is placed on the pre-embedded steel plate 181 on the side plate positioning steps. The limiting plate is rotated to a horizontal state and the other end of the limiting plate is pressed against the outer wall of the side plate of the housing. Then, the bottom of the vertical plate is welded to the pre-embedded steel plate, and the side plate 2 of the housing is pressed and fixed by the limiting device 6.

[0054] (3) Figure 14 As shown, a casing lowering device 8 is installed on the top of the steel casing 3 to lower the casing as a whole to the designed underwater installation height. The lowering method is the same as that of ordinary steel casing. Before lowering the casing, a cross brace is installed between the two opposite side plates inside the casing to ensure that the side plates of the casing can withstand the water pressure after the water inside the casing is pumped out.

[0055] (4) Figure 15 As shown, after the casing is lowered into place, the circumferential gap between the bottom of the through hole of the steel casing and the steel casing is sealed.

[0056] The purpose of sealing the circumferential joint between the bottom opening of the through hole and the steel casing is to prevent grout leakage when pouring the concrete for sealing the circumferential joint. In ordinary casing systems, circumferential joint sealing typically involves welding a ring-shaped steel plate to the steel casing. This method requires underwater welding and cannot guarantee a tight seal. In this invention, during the prefabrication of the casing bottom plate, a ring edge 111 protrudes inward from the bottom opening of each through hole 11 of the steel casing on the casing bottom plate, forming a constricted structure. When sealing the circumferential joint between the bottom opening of the through hole and the steel casing, a ring-shaped sealing sandbag 5 is first fitted tightly against the inner wall of the steel casing. The sealing sandbag 5 is then slid down from the top of the steel casing into the through hole and supported on the ring edge 111 at the bottom opening of the through hole, ensuring complete sealing of the circumferential joint between the bottom opening of the through hole and the outer wall of the steel casing.

[0057] (5) Figure 16As shown, circumferential joint sealing concrete 4 is poured into the through hole 11 of the steel casing. Since the sandbag can completely seal the bottom of the steel casing and ensure that there is no leakage of grout during pouring, the circumferential joint sealing concrete can be poured while vibrating to ensure that the concrete is poured densely and tightly bonded to the steel casing.

[0058] (6) Figure 17 As shown, after the circumferential joint sealing concrete 4 has solidified and formed sufficient bonding force between it and the outer wall of the steel casing, the lowering device is removed, the water in the casing is drained, and a cover plate 13 is installed on the groove of the inverted arched groove 12 on the bottom plate of the casing to completely seal the inverted arched groove, so that the bottom plate forms a cavity structure.

[0059] To prevent the cover plate 13 from moving and to ensure that the cover plate completely seals the inverted arched groove, a lowered cover plate positioning step 121 is provided around the groove opening of each inverted arched groove 12 on the bottom plate of the casing. When installing the cover plate, the cover plate 13 is supported on the cover plate positioning step 121.

[0060] (7) Figure 18 As shown, the steel casing inside the casing is cut off, and the foundation reinforcement is tied inside the casing and the foundation concrete is poured.

[0061] After the foundation construction is completed, the side panel 2 of the caisson is removed. Since the bottom of the side panel is secured by a limiting device 6, when removing the side panel, a crane is used to lift it upwards. The limiting plate 62 of the limiting device can rotate upwards, separating the side panel from the bottom plate. The side panel can be reused after removal.

Claims

1. A light-weight sleeve box suitable for construction of a high-pile cap of a bridge in water, comprising a sleeve box bottom plate and sleeve box side plates fixedly installed around the sleeve box bottom plate, the sleeve box bottom plate being provided with corresponding steel casing through holes according to the number and layout of the steel casings for pile foundation construction, each steel casing for pile foundation construction being inserted into a steel casing through hole on the sleeve box bottom plate, and annular gap sealing concrete being cast in the gap between the inner wall of the steel casing through hole and the outer wall of the steel casing, characterized in that: The bottom plate of the sleeve box is provided with a plurality of inverted-arch-shaped grooves, and the groove opening of each inverted-arch-shaped groove is covered by a cover plate; the bottom plate of the sleeve box is spliced by a plurality of prefabricated blocks, the plurality of prefabricated blocks include four corner modules, at least four edge modules and at least one middle module, a steel casing through hole is arranged on each prefabricated block, and a part of the inverted-arch-shaped groove is arranged on each prefabricated block according to the position of the inverted-arch-shaped groove on the bottom plate of the sleeve box, and the prefabricated blocks are connected into a whole by wet joint concrete pouring.

2. The light-weight box suitable for the construction of a high-pile cap of a bridge in water according to claim 1, characterized in that: The bottom opening of each steel casing through hole on the bottom plate of the sleeve box protrudes inwardly and circularly by a ring edge, forming a necked structure; an annular sand bag is sleeved on each steel casing, the sand bag is supported on the ring edge of the bottom opening of the steel casing through hole and tightly abuts against the outer wall of the steel casing, and the annular joint sealing concrete is poured on the top of the sand bag.

3. The light-weight box suitable for the construction of a high-pile cap of a bridge in water according to claim 1, characterized in that: The groove opening of each inverted-arch-shaped groove on the bottom plate of the sleeve box is provided with a first cover plate positioning step which is lowered downwardly, and the cover plate periphery is supported on the cover plate positioning step.

4. The light-weighted box suitable for the construction of a high-pile cap of a bridge in water according to claim 1, characterized in that: The top surface of the four peripheries of the bottom plate of the sleeve box is respectively provided with a first side plate positioning step which is lowered downwardly from inside to outside, the bottom of the sleeve side plate is supported on the side plate positioning step, and the inner wall of the sleeve side plate abuts against the inner side wall of the side plate positioning step; a plurality of embedded steel plates are arranged on the top surface of the side plate positioning step, a limiting device is fixedly connected to each embedded steel plate, each limiting device comprises a vertical plate and a limiting plate, the bottom of the vertical plate is welded to the embedded steel plate, one end of the limiting plate is rotatably connected to the vertical plate through a pin shaft, and the other end of the limiting plate abuts against the outer wall of the sleeve side plate.

5. The light-weight box suitable for the construction of a high-pile cap of a bridge in water according to claim 1, characterized in that: At least two pull rods are arranged between the two opposite side walls of each inverted-arch-shaped groove on the bottom plate of the sleeve box, and the two ends of each pull rod are respectively anchored in the concrete of the bottom plate of the sleeve box.

6. The light-weighted box suitable for the construction of a high-pile cap of a bridge in water according to claim 5, characterized in that: Each pull rod comprises two pull rod segments, and an internally-threaded sleeve is embedded in the concrete of the side wall of each inverted-arch-shaped groove according to the installation position of the pull rod; one end of each segment of the pull rod is respectively screwed with the internally-threaded sleeve on the two opposite side walls of the inverted-arch-shaped groove, and the other ends of the two pull rod segments are connected through an externally-threaded sleeve.

7. A construction method of the light-weighted sleeve box for the construction of a high-pile cap of a bridge in water according to claim 1, characterized in that, The method comprises the following steps: (1) after the pile foundation construction is completed, a sleeve box assembly platform is erected on the steel casing of the pile foundation construction, the prefabricated blocks of the bottom plate of the sleeve box are hoisted onto the assembly platform in sequence according to the installation positions of the prefabricated blocks on the bottom plate of the sleeve box, and each steel casing is inserted into the steel casing through hole on the prefabricated block; (2) wet joint concrete is poured in the joints between the prefabricated blocks to connect the prefabricated blocks into an integral bottom plate of the sleeve box, and the sleeve side plates are installed around the bottom plate to form an integral sleeve box; (3) a sleeve box lowering device is installed on the top of the steel casing, and the sleeve box is lowered to the designed installation height under water; (4) the annular joint between the bottom opening of the steel casing through hole and the steel casing is sealed; (5) annular joint sealing concrete is poured in the steel casing through hole; (6) after the annular joint sealing concrete is solidified and sufficient gripping force is formed between the annular joint sealing concrete and the outer wall of the steel casing, the water in the sleeve box is drained, the cover plates are installed on the groove openings of the inverted-arch-shaped grooves on the bottom plate of the sleeve box to completely seal the inverted-arch-shaped grooves, so that the bottom plate forms a cavity structure; (7) the steel casing in the sleeve box is cut off, the pile cap steel bars are bound in the sleeve box, and the pile cap concrete is poured.

8. The construction method of a lightweight jacket suitable for the construction of a high-pile cap of a bridge in water according to claim 7, characterized in that: The bottom opening of each steel casing through hole on the sleeve box bottom plate is protruded inwardly and circularly by a ring edge, forming a necked structure; when the annular gap between the steel casing through hole bottom opening and the steel casing is blocked, a ring-shaped sand bag is tightly sleeved on the inner wall of the steel casing, the sand bag is slid down from the upper end of the steel casing into the steel casing through hole and supported on the ring edge of the steel casing through hole bottom opening, ensuring that the annular gap between the steel casing through hole bottom opening and the outer wall of the steel casing is completely closed, then the annular gap blocking concrete is poured into the steel casing through hole, and the concrete is poured while vibrating to ensure that the concrete is densely poured.

9. The construction method of a lightweight jacket suitable for the construction of a high-pile cap of a bridge in water according to claim 7, characterized in that: The top surface of the sleeve box bottom plate is provided with a side plate positioning step which is lowered from inside to outside, and the top surface of the side plate positioning step is provided with a plurality of embedded steel plates; when installing the sleeve box side plate, the bottom of the sleeve box side plate is supported on the side plate positioning step, and the inner wall of the sleeve box side plate is tightly attached to the outer side wall of the side plate positioning step, then a limiting device is fixedly arranged on each embedded steel plate, each limiting device includes a vertical plate and a limiting plate, one end of the limiting plate is rotatably connected with the vertical plate through a pin shaft, the vertical plate is placed on the embedded steel plate first, the limiting plate is rotated to a horizontal state and the other end of the limiting plate is tightly pressed against the outer wall of the sleeve box side plate, then the bottom of the vertical plate is welded with the embedded steel plate, and the sleeve box side plate is fixed through the limiting device.

10. The construction method of a lightweight jacket suitable for the construction of a high-pile cap of a bridge in water according to claim 7, characterized in that: At least two pull rods are arranged between the two opposite side walls of each inverted arch-shaped groove on the sleeve box bottom plate, each pull rod includes two pull rod segments, and the two pull rod segments are connected through a threaded sleeve; according to the installation position of each pull rod, a threaded sleeve is embedded in the side wall concrete of each inverted arch-shaped groove, when assembling the sleeve box bottom plate, after the wet joint concrete pouring is completed, one end of each pull rod segment is connected with two opposite embedded threaded sleeves on the side wall of the inverted arch-shaped groove, and the other end of the two pull rod segments is connected through a threaded sleeve.

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