A removable round assembled precast caisson and construction method

Abstract

The application discloses a removable circular assembled prefabricated well and a construction method thereof, and belongs to the technical field of well construction. The prefabricated well comprises a prefabricated well shaft which is formed by annularly splicing a plurality of longitudinally arranged supporting columns, the supporting column comprises a superposition part and a blade foot part, the superposition part is fixedly installed by connecting a plurality of superposition splicing blocks in an up-down mode, and the blade foot part is fixedly installed at the lower end of the superposition part. At least one longitudinal grouting hole is arranged in the middle of the superposition splicing block, and flow guide holes are arranged on the inner and outer sidewalls of the superposition splicing block and are communicated with the grouting hole. The prefabricated well is assembled on the ground, is sunk by using the well sinking method, is pulled out after backfilling in the prefabricated well shaft is completed, and the time for cast-in-situ production of the well is greatly shortened. Meanwhile, the prefabricated well is sunk by using the well sinking method, and can adapt to different geological requirements. After the construction is completed, the removable characteristic solves the problems of difficulty in removing the cast-in-situ well, occupation of underground space and waste of resources.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of prefabricated caisson, in particular to a circular prefabricated caisson capable of being removed and a construction method thereof. BACKGROUND

[0002] The caisson is a structure in the shape of a well, which is excavated in the well and sinks to the design elevation by relying on its own gravity to overcome the frictional resistance of the well wall, and then the bottom is sealed by concrete and the well hole is filled, so that it becomes the foundation of a bridge pier or other structure. It is generally used in the construction of foundation pits of large bridge piers, sewage pumping stations, large equipment foundations, civil air defense shelters, shield assembly wells, underground road and station water conservancy foundation construction enclosure devices.

[0003] During the construction process of municipal rainwater and sewage pipe network engineering, pipe jacking construction is required, and the pipe jacking working well and the receiving well are generally constructed by reverse construction method or caisson method. Both methods have advantages and disadvantages, and the common disadvantages are: (1) the municipal pipe network engineering construction occupies the road and needs to close the road, the construction period of the caisson is relatively long, generally more than one month, which causes great influence on road traffic; (2) the occupied area is large, after the pipe jacking construction is completed, it is difficult to remove, and the underground space is occupied after that, many well positions are located on municipal trunk roads and important intersections, which is not conducive to the utilization of urban underground space; (3) the amount of reinforced concrete of the caisson is large, the materials cannot be reused, and the resources of steel bars, cement and ground materials are wasted. SUMMARY

[0004] The technical problem to be solved by the present application is to solve the problems in the background art, and to provide a circular prefabricated caisson capable of being removed, which is assembled on the ground, sunk by the caisson method, removed after the backfilling of the prefabricated well hole is completed, greatly shortens the time of cast-in-situ production of the caisson, and can adapt to different geological requirements by sinking by the caisson method. The characteristics of being capable of being removed solve the problems of difficulty in removing the cast-in-situ caisson, occupation of underground space and waste of resources.

[0005] Another technical problem to be solved by the present application is to provide a construction method using the circular prefabricated caisson capable of being removed, which is used for the installation and removal of the prefabricated well hole in the pipe jacking construction.

[0006] In order to realize the above technical features, the purpose of the present application is realized as follows: a circular prefabricated caisson capable of being removed, comprising a prefabricated well hole, the prefabricated well hole is formed by annularly splicing a plurality of longitudinally arranged support columns, the support column comprises a superposition part and a blade foot part, the superposition part is formed by connecting and fixing a plurality of superposition splicing blocks in an up-down manner, and the blade foot part is fixedly installed at the lower end of the superposition part; at least one longitudinal through grouting hole is arranged in the middle part of the superposition splicing block, and flow guide holes are arranged on the inner and outer side walls of the superposition splicing block respectively, and the flow guide holes are communicated with the grouting hole.

[0007] The left and right sides of the superimposed splicing block are respectively provided with a protrusion and a groove matched with the protrusion, and the upper and lower sides are respectively provided with bolt mounting holes, and the bolt mounting holes are arranged on the inner and outer sides of the superimposed splicing block, one end of the bolt mounting hole is located on the inner wall or the outer wall of the superimposed splicing block, the other end is located on the end face of the superimposed splicing block, the bolt mounting hole positions of the upper and lower adjacent superimposed splicing blocks correspond, and the arc-shaped bolt passes through the bolt mounting holes of the upper and lower adjacent superimposed splicing blocks to connect and fix the upper and lower adjacent superimposed splicing blocks.

[0008] The gap filler and / or expansion water stop strip is arranged between the left and right adjacent superimposed splicing blocks; and the water stop gasket is arranged between the upper and lower adjacent superimposed splicing blocks.

[0009] The left and right sides of the blade foot part are respectively provided with the same protrusion and groove as the superimposed splicing block, the upper side is provided with a corresponding hole matched with the bolt mounting hole on the superimposed splicing block, the blade foot part is located inside the prefabricated shaft, and the lower side of the blade foot part is provided with an inclined surface, the inclined surface forms a sharp end at the lower end of the blade foot part, and the outer circumference of the cast-in-place bottom plate for supporting equipment in the prefabricated shaft abuts against the inclined surface.

[0010] The support column further comprises a tension detection device; the tension detection device comprises a tension rod and a tension sensor, a pre-buried nut is pre-set at the upper end of the blade foot part, the tension rod is inserted into the grouting hole of the superimposed splicing block, the lower end of the tension rod is screwed with the high-strength nut, the upper end of the tension rod extends out of the superimposed splicing block, one end of the tension sensor is connected and fixed with the support arranged on the superimposed splicing block, and the other end of the tension sensor is connected and fixed with the upper end of the tension rod.

[0011] The support column further comprises a reinforcing structure, the reinforcing structure comprises a high-strength rod, a pre-buried nut is pre-set at the upper end of the blade foot part, the high-strength rod is inserted into the grouting hole of the superimposed splicing block, the lower end of the high-strength rod is screwed with the pre-buried nut, the upper end of the high-strength rod extends out of the superimposed splicing block, a pressing plate is sleeved on the upper end of the high-strength rod extending out of the superimposed splicing block, and a high-strength nut is arranged on the upper end of the high-strength rod and abuts against the pressing plate.

[0012] The prefabricated shaft further comprises a portal assembly, the portal assembly comprises steel columns on both sides and steel beams arranged above and below the steel columns, a portal is formed between the steel columns and the steel beams, and a closing plate is arranged in the portal, the steel columns and the steel beams are bolted, and the steel columns, the steel beams and the closing plate are bolted.

[0013] At least one inner support ring is arranged on the inner wall of each layer of the superimposed splicing block in the prefabricated shaft.

[0014] A construction method of a circular assembled prefabricated sinking well which can be removed comprises the following steps:

[0015] S1. The site is leveled at a place where pipe jacking well construction is needed to meet the needs of prefabricated sinking well assembly;

[0016] S2. Assembling the first layer of the open caisson lower part through the pre-assembled ring 6; sequentially placing the blade feet in the pre-assembled ring 6, and assembling the blade feet into a ring as a whole;

[0017] S2. Assembling the superimposed part of the prefabricated open caisson; sequentially installing the superimposed splicing blocks layer by layer, synchronously installing the water stop gaskets, gap fillers and expansion water stop strips, and fixing the superimposed splicing blocks through the installation of the arc-shaped bolts between the adjacent superimposed splicing blocks and between the adjacent superimposed splicing blocks and the blade feet; after assembling the superimposed part into a ring, the inner support ring is synchronously installed, the soil in the prefabricated well shaft is excavated, the prefabricated well shaft is sunk, and the pre-assembled ring 6 is removed; the superimposed part is installed until the final elevation, and the sinking construction of the working well is completed; during the process of assembling the prefabricated well shaft, the portal assembly is synchronously installed according to the elevation and position of the pipe jacking;

[0018] S3. After the sinking of the prefabricated well shaft is completed, the construction of the cast-in-place bottom plate is started, and after the construction is completed, the pipe jacking construction is started;

[0019] S4. During the pipe jacking construction, the steel columns and steel beams of the closure plate or portal assembly are removed according to the size of the culvert, so as to facilitate the pipe jacking construction;

[0020] S5. After the pipe jacking construction and the pipe inspection well are completed, the soil is backfilled layer by layer, and the inner support ring 4 is synchronously removed; if the steel columns and steel beams are not removed during the pipe jacking construction, the steel columns and steel beams are synchronously removed; after the soil in the well is completed, the support column of the prefabricated well shaft is pulled out one by one by using the pile pulling machine; before the support column of the prefabricated well shaft is pulled out, mud is injected into both sides of the superimposed splicing block through the grouting hole.

[0021] In S5, when the support column of the prefabricated well shaft is pulled out, the step of tension monitoring is further included:

[0022] S51. After the mud is injected into both sides of the superimposed splicing block through the grouting hole, the lower end of the tension rod of the tension detection device is screwed into the pre-buried nut at the upper end of the blade foot, the upper end of the tension rod extends out of the superimposed splicing block, one end of the tension sensor is fixedly connected with the support, and the other end is fixedly connected with the upper end of the tension rod; when the support column is pulled out by the pile pulling machine, the size of the tension is monitored in real time through the instrument matched with the tension sensor;

[0023] S52. When the tension is about to exceed the tensile strength threshold of the support column, the pulling out is stopped, the structure of the support column is reinforced, the reinforcing structure is installed in the grouting hole in the support column, and then the pulling out construction is performed again.

[0024] The present application has the following beneficial effects:

[0025] 1. Precast manholes are manufactured off-site or in factories, allowing for direct on-site installation. This reduces the time spent on on-site formwork assembly, rebar installation, and concrete pouring and curing, significantly shortening the construction cycle and minimizing road and land occupation, thus facilitating rapid site restoration and traffic recovery. Precast manholes are assembled from individual support columns. After backfilling, they can be removed using a pile extractor. The piles can be reused, reducing resource waste. Furthermore, the removal of the original working manhole does not occupy additional underground space beyond the main pipeline network, increasing the utilization rate of urban underground space, especially for important roads.

[0026] 2. Through the protrusions and grooves, when the stacked splicing blocks are enclosed into a ring, under the pressure of the outer soil and rock, the ring-shaped stacked splicing blocks can maintain a stable shape. The arc bolts pass through the bolt mounting holes of the upper and lower adjacent stacked splicing blocks to connect and fix the upper and lower adjacent stacked splicing blocks. The connection is stable and reliable, and it is easy to pull out later.

[0027] 3. The cutting edge is equipped with corresponding holes to facilitate connection with the superimposed part. The outer circumference of the cast-in-place base plate abuts against the inclined surface. This is to facilitate the removal of the support column and because groundwater will generate an upward buoyancy force on the cast-in-place base plate. With the outer circumference of the cast-in-place base plate abutting against the inclined surface, the stability of the cast-in-place base plate is better.

[0028] 4. By setting up a tensile testing device, the tensile force value when the support column is pulled out is detected in real time to prevent the support column from breaking due to excessive friction exceeding the tensile strength when pulled out.

[0029] 5. Install a reinforced structure. If the pulling force is about to reach the tensile strength of the support column and it still cannot be pulled out, inject mud or bentonite into the support column and then install a high-strength rod to ensure that the support column is pulled out intact.

[0030] 6. Installing an inner support ring to support the support column from the inside prevents the soil and rock from squeezing the support column. This not only improves the stability of the support column but also prevents excessive squeezing of adjacent support columns, which could make the support column impossible to pull out.

[0031] 7. By using water-stopping gaskets, gap fillers, and expansion water-stopping strips installed between columns, the waterproof performance of the caisson can be increased, which can resist a certain height of groundwater and has a certain ability to be implemented in areas with abundant groundwater. Attached Figure Description

[0032] Figure 1 This is a schematic cross-sectional view of the overall structure of the present invention.

[0033] Figure 2 This is a side view of the structure of the present invention.

[0034] Figure 3 This is a top view of the support column structure of the present invention.

[0035] Figure 4 This is a schematic diagram of the side cross-sectional structure of the support column of the present invention.

[0036] Figure 5 This is a side view cross-sectional structural diagram of the cutting edge of the present invention.

[0037] Figure 6 This is a schematic diagram of the main structure of the portal frame assembly of the present invention.

[0038] Figure 7 This is a top view of the portal frame assembly of the present invention.

[0039] Figure 8 This is a schematic diagram of the tensile testing device for the support column installation of the present invention.

[0040] Figure 9 This is a schematic diagram of the support column installation and reinforcement structure of the present invention.

[0041] In the diagram: 7. Support column, 1. Overlapping part, 11. Overlapping splice block, 111. Protrusion, 112. Groove, 12. Grouting hole, 121. Water-stop gasket, 13. Bolt mounting hole, 14. Gap filler, 15. Expansion water-stop strip, 16. Arc bolt, 17. Cutting foot, 2. Corresponding hole, 21. Inclined surface, 22. Cast-in-place base plate, 3. Inner support ring, 4. Tunnel portal assembly, 5. Steel column, 51. Steel beam, 52. Sealing plate, 53. Pre-assembled ring, 6. Tension detection device, 8. Embedded nut, 81. Tension rod, 82. Tension sensor, 83. Support, 84. Reinforcing structure, 9. High-strength rod, 91. Pressure plate, 92. High-strength nut, 93. Detailed Implementation

[0042] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0043] Example 1:

[0044] See Figures 1-9A removable circular prefabricated caisson includes a prefabricated shaft, which is formed by arranging several longitudinally arranged support columns 7 in a ring. Each support column 7 includes a stacking part 1 and a cutting edge part 2. The stacking part 1 is formed by connecting and fixing several stacked splicing blocks 11 vertically. The cutting edge part 2 is installed and fixed at the lower end of the stacking part 1. Both the stacked splicing blocks 11 and the cutting edge part 2 are prefabricated concrete. At least one longitudinally penetrating grouting hole 12 is provided in the middle of the stacked splicing block 11. The inner and outer walls of the stacked splicing block 11 are respectively provided with guide holes 121, which are connected to the grouting hole 12. The caisson is assembled on the ground and sunk using the caisson method. After backfilling is completed, the caisson is removed, which greatly shortens the time for cast-in-place caisson construction. At the same time, the caisson method can adapt to different geological requirements. After construction, the removable feature solves the problems of difficult demolition, occupation of underground space, and waste of resources associated with cast-in-place caissons. The grouting hole 12 is used to inject mud or bentonite into the inner and outer sides of the support column 7 during extraction, so as to reduce the friction between the support column 7 and the soil layer and facilitate extraction.

[0045] See Figure 3 The overlapping splicing blocks 11 have protrusions 111 and grooves 112 that mate with the protrusions 111 on both sides of the left and right splicing. Bolt mounting holes 14 are provided on both sides of the upper and lower connections, located on the inner and outer sides of the overlapping splicing blocks 11. One end of the bolt mounting hole 14 is located on the inner or outer wall of the overlapping splicing block 11, and the other end is located on the end face of the overlapping splicing block 11. The bolt mounting holes 14 of adjacent upper and lower overlapping splicing blocks 11 are aligned. Arc-shaped bolts 17 pass through the bolt mounting holes 14 of adjacent upper and lower overlapping splicing blocks 11 to connect and fix them. Through the protrusions 111 and grooves 112, when the overlapping splicing blocks 11 are formed into a ring, under the pressure of the outer soil and rock, the ring-shaped overlapping splicing blocks 11 can maintain a stable shape. The arc-shaped bolts 17 pass through the bolt mounting holes 14 of adjacent upper and lower overlapping splicing blocks 11 to connect and fix them, ensuring a stable and reliable connection and facilitating later removal.

[0046] See Figure 3 , 4 The overlapping splicing blocks 11 on the left and right sides are provided with gap filler 15 and / or expansion waterstop strips 16; the overlapping splicing blocks 11 on the top and bottom are provided with waterstop gaskets 13. The gap filler 15 can be made of foam board, and the waterstop gasket 13 is made of rubber. The gap filler 15, expansion waterstop strips 16 and waterstop gaskets 13 can prevent water seepage in the gaps. In addition, the gap filler 15 and expansion waterstop strips 16 between the overlapping splicing blocks 11 on the left and right sides can reduce friction with adjacent support columns when the support column 7 is pulled out later, and prevent the support column 7 from breaking when pulled out, especially the first one.

[0047] See Figure 5The cutting edge 2 has protrusions 111 and grooves 112 on both sides of the left and right splicing parts, which are the same as those on the superimposed splicing block 11. The upper side has corresponding holes 22 that mate with the bolt mounting holes 14 on the superimposed splicing block 11. The cutting edge 2 has a slope 22 on its lower side inside the precast well shaft, which forms a pointed tip at the lower end. The outer circumference of the cast-in-place base plate 3, used to support the equipment inside the precast well shaft, abuts against the slope 22. The corresponding holes 22 on the cutting edge 2 facilitate connection with the superimposed part 1. The outer circumference of the cast-in-place base plate 3 abuts against the slope 22, which facilitates the removal of the support column 7 and allows the groundwater to generate upward buoyancy, thus improving the stability of the cast-in-place base plate 3.

[0048] See Figure 8 The support column 7 is also equipped with a tensile testing device 8. The tensile testing device 8 includes a tension rod 82 and a tension sensor 83. A pre-embedded nut 81 is pre-set at the upper end of the cutting foot 2. The tension rod 82 is inserted into the grouting hole 12 of the stacked splicing block 11. The lower end of the tension rod 82 is screwed to the pre-embedded nut 81, and the upper end extends out of the stacked splicing block 11. One end of the tension sensor 83 is connected and fixed to the support 84 set on the stacked splicing block 11, and the other end is connected and fixed to the upper end of the tension rod 82. By setting the tensile testing device 8, the tensile force value when the support column 7 is pulled out is detected in real time, preventing the support column 7 from breaking due to excessive tensile force exceeding the tensile strength of the support column 7 when it is pulled out.

[0049] See Figure 9 The support column 7 is further equipped with a reinforcing structure 9, which includes a high-strength rod 91. A pre-embedded nut 81 is pre-installed at the upper end of the cutting edge 2. The high-strength rod 91 is inserted into the grouting hole 12 of the overlapping splicing block 11. The lower end of the high-strength rod 91 is screwed to the pre-embedded nut 81, and the upper end extends out of the overlapping splicing block 11. A pressure plate 92 is fitted onto the upper end of the high-strength rod 91 extending out of the overlapping splicing block 11. A high-strength nut 93 is installed on the upper end of the high-strength rod 91 and abuts against the pressure plate 92. By setting up the reinforcing structure 9, if the pulling force during pull-out is about to reach the tensile strength of the support column 7 and the support column 7 still cannot be pulled out, further injection of mud or bentonite is performed, and then the high-strength rod 91 is installed, thereby ensuring that the support column 7 is pulled out completely.

[0050] See Figure 6 , 7 The precast shaft is also equipped with a portal assembly 5, which includes steel columns 51 on both sides and steel beams 52 installed at the upper and lower ends of the steel columns 51. A portal is formed between the steel columns 51 and the steel beams 52, and a sealing plate 53 is installed inside the portal. The steel columns 51 and steel beams 52 are bolted together, and the steel columns 51, steel beams 52, and sealing plate 53 are also bolted together. The portal assembly 5 facilitates pipe jacking construction. Specifically, depending on the size of the culvert, the sealing plate 53 or the steel columns 51 and steel beams 52 of the portal assembly 5 can be removed.

[0051] See Figure 1 Inside the prefabricated well shaft, at least one inner support ring 4 is installed on the inner wall of each layer of the stacked splicing blocks 11. The inner support ring 4 provides support to the support column 7 from the inside, preventing the rock and soil from squeezing the support column 7. This not only improves the stability of the support column 7, but also prevents excessive squeezing of adjacent support columns 7, which would make it impossible to pull out the support column 7.

[0052] Example 2:

[0053] A construction method for a removable circular prefabricated caisson includes the following steps:

[0054] S1. Level the site where pipe jacking shaft construction is required to meet the needs of prefabricated caisson assembly;

[0055] S2. Assemble the first layer of the lower part of the caisson using the pre-assembly ring 6; place the cutting edge 2 into the pre-assembly ring 6 in sequence, and assemble the cutting edge 2 into a ring as a whole;

[0056] S2. Assemble the superimposed part 1 of the precast caisson; install the superimposed splicing blocks 11 one by one layer, and simultaneously install the water-stopping gaskets 13, gap fillers 15 and expansion water-stopping strips 16. Connect and fix the superimposed splicing blocks 11 between the upper and lower adjacent superimposed splicing blocks 11, and between the superimposed splicing blocks 11 between the upper and lower adjacent superimposed splicing blocks 11 and the cutting foot part 2 by installing arc bolts 17; after each layer of superimposed part 1 is assembled into a ring, install the inner support ring 4 simultaneously, excavate the soil inside the precast caisson, sink the assembled precast caisson, and remove the pre-assembled ring 6; install the superimposed part 1 until the final elevation, and complete the sinking construction of the working caisson; during the assembly of the precast caisson, install the portal assembly 5 simultaneously according to the elevation and position of the jacking pipe; specifically, the portal assembly 5 is located on the upper side of the cutting foot part 2, and the upper and lower sides of the portal assembly 5 are bolted to the superimposed part 1 and the cutting foot part 2 respectively.

[0057] S3. After the precast shaft is sunk, the construction of the cast-in-place base slab 3 will begin, and the pipe jacking construction will begin after that.

[0058] S4. During pipe jacking construction, depending on the size of the culvert, remove the steel columns 51 and steel beams 52 of the sealing plate 53 or the portal assembly 5 to facilitate pipe jacking construction;

[0059] S5. After the pipe jacking construction and pipeline inspection well are completed, backfill the soil layer by layer and remove the inner support ring 4 at the same time. If the steel column 51 and steel beam 52 were not removed during the pipe jacking construction, remove the steel column 51 and steel beam 52 at the same time. After the soil in the well is completed, use a pile extractor to start removing the support column 7 of the precast well cylinder one by one. Before removing the support column 7 of the precast well cylinder, inject mud into both sides of the superimposed splicing block 11 through the grouting hole 12.

[0060] In S5, when removing the support column 7 of the prefabricated wellbore, a tensile force monitoring step is also included:

[0061] S51. After injecting mud into both sides of the superimposed splicing block 11 through the grouting hole 12, the lower end of the tension rod 82 of the tension detection device 8 is inserted into the grouting hole 12 and screwed into the pre-embedded nut 81 at the upper end of the cutting foot 2. The upper end of the tension rod 82 extends out of the superimposed splicing block 11. One end of the tension sensor 83 is connected and fixed to the support 84, and the other end is connected and fixed to the upper end of the tension rod 82. When the pile extractor lifts and removes the support column 7, the magnitude of the tension is monitored in real time by the instrument matched with the tension sensor 83.

[0062] S52. When the pulling force is about to exceed the tensile strength threshold designed for the support column 7, stop pulling out, strengthen the structure of the support column 7, install the reinforcing structure 9 in the grouting hole 12 inside the support column 7, and then pull out the work again.

[0063] Precast manholes are manufactured off-site or in factories and then installed directly on-site, reducing the time spent on on-site formwork assembly, rebar installation, and concrete pouring and curing. This significantly shortens the construction cycle, reduces road and land occupation time, and facilitates rapid site or traffic restoration. The precast manhole is assembled from seven supporting columns. After backfilling, it can be removed using a pile extractor. The piles can be recycled, reducing resource waste. Furthermore, the original working manhole location does not occupy additional underground space beyond the main pipeline network after removal, increasing the utilization rate of urban underground space, especially the underground space of important roads.

Claims

1. A construction method for a removable circular prefabricated caisson, characterized in that, This invention relates to a removable circular prefabricated caisson, comprising: a prefabricated well shaft, wherein the prefabricated well shaft is formed by annular splicing of several longitudinally arranged support columns (7), the support column (7) comprising a stacked part (1) and a cutting edge part (2), the stacked part (1) being formed by connecting and fixing several stacked splicing blocks (11) vertically, and the cutting edge part (2) being installed and fixed at the lower end of the stacked part (1); the middle part of the stacked splicing block (11) is provided with at least one longitudinally penetrating grouting hole (12), the inner and outer walls of the stacked splicing block (11) are respectively provided with guide holes (121), the guide holes (121) are connected to the grouting hole (12); the left and right sides of the stacked splicing block (11) are respectively provided with protrusions (111) and grooves (112) that cooperate with the protrusions (111). The support column (7) is equipped with a tension detection device (8); the tension detection device (8) includes a tension rod (82) and a tension sensor (83). The upper end of the cutting foot (2) is pre-embedded with a nut (81). The tension rod (82) is inserted into the grouting hole (12) of the stacked splicing block (11). The lower end of the tension rod (82) is screwed to the pre-embedded nut (81), and the upper end extends out of the stacked splicing block (11). One end of the tension sensor (83) is connected and fixed to the support (84) set on the stacked splicing block (11), and the other end is connected and fixed to the upper end of the tension rod (82). The support column (7) is provided with a reinforcing structure (9), which includes a high-strength rod (91). The upper end of the blade foot (2) is pre-embedded with a nut (81). The high-strength rod (91) is inserted into the grouting hole (12) of the stacked splicing block (11). The lower end of the high-strength rod (91) is screwed to the pre-embedded nut (81), and the upper end extends out of the stacked splicing block (11). The pressure plate (92) is fitted on the upper end of the high-strength rod (91) extending out of the stacked splicing block (11). The high-strength nut (93) is installed on the upper end of the high-strength rod (91) and abuts against the pressure plate (92). The removal of the support column (7) of the precast wellbore includes a step of tension monitoring: S51. After injecting mud into both sides of the superimposed splicing block (11) through the grouting hole (12), insert the lower end of the tension rod (82) of the tension detection device (8) into the grouting hole (12) and screw it into the pre-embedded nut (81) at the upper end of the cutting foot (2). The upper end of the tension rod (82) extends out of the superimposed splicing block (11). One end of the tension sensor (83) is connected and fixed to the support (84), and the other end is connected and fixed to the upper end of the tension rod (82). When the pile extractor pulls the support column (7) upward, the magnitude of the tension is monitored in real time by the instrument matched with the tension sensor (83). S52. When the tension is about to exceed the tensile strength threshold designed for the support column (7), stop pulling out and strengthen the structure of the support column (7). Install the reinforcing structure (9) in the grouting hole (12) inside the support column (7), and then pull out the construction again.

2. The construction method for a removable circular prefabricated caisson according to claim 1, characterized in that: Includes the following steps: S1. Level the site where pipe jacking shaft construction is required to meet the needs of prefabricated caisson assembly; S2. Assemble the first layer of the lower part of the caisson using the pre-assembly ring (6); place the cutting edge (2) into the pre-assembly ring (6) in sequence, and assemble the cutting edge (2) into a ring as a whole; S2. Assemble the superimposed part (1) of the precast caisson; install the superimposed splicing blocks (11) one by one layer, and simultaneously install the water-stop gaskets (13), gap fillers (15) and expansion water-stop strips (16). Connect and fix the superimposed splicing blocks (11) between the upper and lower adjacent superimposed splicing blocks (11) and between the superimposed splicing blocks (11) and the cutting foot part (2) by installing arc bolts (17); after each layer of superimposed part (1) is assembled into a ring, install the inner support ring (4) simultaneously, excavate the soil inside the precast caisson, sink the assembled precast caisson, and remove the pre-assembled ring (6); install the superimposed part (1) until the final elevation, and complete the sinking construction of the working caisson; during the assembly of the precast caisson, install the portal assembly (5) simultaneously according to the elevation and position of the jacking pipe. S3. After the precast shaft is sunk, the construction of the cast-in-place base slab (3) begins, and the pipe jacking construction begins after the base slab is completed. S4. During pipe jacking construction, depending on the size of the culvert, remove the steel columns (51) and steel beams (52) of the sealing plate (53) or the portal assembly (5) to facilitate pipe jacking construction; S5. After the pipe jacking construction and pipeline inspection well are completed, backfill the soil layer by layer and remove the inner support ring 4 at the same time. If the steel column (51) and steel beam (52) are not removed during the pipe jacking construction, remove the steel column (51) and steel beam (52) at the same time. After the soil in the well is completed, use a pile extractor to start removing the support column (7) of the precast well cylinder one by one. Before removing the support column (7) of the precast well cylinder, inject mud into both sides of the superimposed splicing block (11) through the grouting hole (12).

3. The construction method for a removable circular prefabricated caisson according to claim 1, characterized in that: The stacked splicing block (11) is provided with bolt mounting holes (14) on both sides of the upper and lower connection. The bolt mounting holes (14) are located on the inner and outer sides of the stacked splicing block (11). One end of the bolt mounting hole (14) is located on the inner or outer wall of the stacked splicing block (11), and the other end is located on the end face of the stacked splicing block (11). The bolt mounting holes (14) of the upper and lower adjacent stacked splicing blocks (11) are in corresponding positions. The arc bolt (17) passes through the bolt mounting holes (14) of the upper and lower adjacent stacked splicing blocks (11) to connect and fix the upper and lower adjacent stacked splicing blocks (11).

4. The construction method for a removable circular prefabricated caisson according to claim 1, characterized in that: The overlapping splicing blocks (11) on the left and right sides are provided with gap filler (15) and / or expansion waterstop strip (16); the overlapping splicing blocks (11) on the top and bottom sides are provided with waterstop gasket (13).

5. The construction method for a removable circular prefabricated caisson according to claim 1, characterized in that: The left and right sides of the blade foot (2) are respectively provided with the same protrusion (111) and groove (112) as the superimposed splicing block (11). The upper side is provided with a corresponding hole (21) that matches the bolt mounting hole (14) on the superimposed splicing block (11). The blade foot (2) is located on the lower side of the precast well barrel with a slope (22). The slope (22) makes the lower end of the blade foot (2) form a point. The outer circumference of the cast-in-place base plate (3) used to support the equipment in the precast well barrel abuts against the slope (22).

6. The construction method for a removable circular prefabricated caisson according to claim 1, characterized in that: The precast shaft is also provided with a portal assembly (5). The portal assembly (5) includes steel columns (51) on both sides and steel beams (52) installed on the upper and lower sides of the steel columns (51). A portal is formed between the steel columns (51) and the steel beams (52). A sealing plate (53) is installed inside the portal. The steel columns (51) are bolted to the steel beams (52), and the steel columns (51), steel beams (52) and sealing plate (53) are bolted to each other.

7. The construction method for a removable circular prefabricated caisson according to claim 1, characterized in that: Inside the prefabricated well shaft, at least one inner support ring (4) is installed on the inner wall of each layer of the stacked splicing block (11).

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