Self-anchored steel casing temporary construction support and rapid dismounting and mounting method thereof

Abstract

The invention relates to the technical field of self-anchored steel casing supports, in particular to a self-anchored steel casing temporary construction support and a quick disassembly and assembly method thereof.The self-anchored steel casing temporary construction support comprises a top frame and a bottom frame, steel pipe bases are installed at the four corners between the top frame and the bottom frame, and a steel pipe stand column is jointly installed between every two upper and lower steel pipe bases; a plurality of distribution beams are obliquely arranged at the upper end of the top frame and the upper end of the bottom frame, the top frame, the bottom frame, the steel pipe bases, the steel pipe stand columns, the distribution beams and other structures form a guide frame, lifting lugs are arranged in the middles of the distribution beams, and jack sleeve frames are installed at the upper ends of the distribution beams above. According to the self-anchored steel casing temporary construction support, system conversion and top changing can be achieved at the same time by adjusting the nuts, the position of a distribution beam does not need to be changed, the jacks and finish rolling deformed steel bars do not need to be disassembled and assembled, the structure is simple, the cost is low, and the construction efficiency is high. Operation is convenient and fast.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of self-anchored steel casing support, in particular to a self-anchored steel casing temporary construction support and a quick dismounting method thereof. BACKGROUND

[0002] With the continuous development of bridge construction technology, deep water pile foundation engineering is increasing, and the construction demand of deep water large-diameter super-long steel casing is increasingly widespread. Deep water bored pile construction needs to first drive a steel casing, and then perform bored pile construction. Due to deep water level and long casing, the steel casing needs to be connected and lowered in sections until the casing bottom is bedded.

[0003] A Chinese patent with patent number ZL200810142990.7 has the technical solution as follows: the patent connects the finished rolled threaded steel with the steel hoop ear plate of the steel casing, lowers the steel casing, places the casing on the lower two distribution beams, dismounts and installs the through-hole jack with the finished rolled threaded steel on the upper two distribution beams, removes the lower two distribution beams, connects the through-hole jack with the steel hoop ear plate of the steel casing, continues to lower, and alternately repeats the above steps until the entire steel casing is welded. In the patent, the jack needs to complete system conversion by moving the distribution beams, and dismounts and reassembles the jack and the finished rolled threaded steel to complete the jack replacement operation. The dismounting and reassembling of the jack and the threaded steel involves the steel hoop ear plate, and the process is extremely complex.

[0004] At present, the existing self-anchored steel casing temporary construction support has the following deficiencies in use: the existing technology mostly welds lifting points on the steel casing and lowers it by using steel wire ropes, but this method is only suitable for projects with short and light steel casings. In the case of steel casings weighing dozens of tons, a winch and a block set are needed to cooperate. On the one hand, the lifting point problem of the block set needs to be solved, and on the other hand, the lifting point conversion problem of the steel casing during lengthening needs to be solved. The on-site operation is relatively complicated. To solve the problems of lengthening and lowering the deep water large-diameter super-long steel casing, a simple, quick and efficient method is needed to solve the system conversion during lengthening of the steel casing and the overall lowering after lengthening.

[0005] Therefore, the present application provides a self-anchored steel casing temporary construction support and a quick dismounting method thereof to solve the problems in the background art. SUMMARY

[0006] In view of the deficiencies of the prior art, the self-anchored steel casing temporary construction support and the quick dismounting method thereof are provided, which solve the problem that the prior art adopts more welding of lifting points on the steel casing and uses a steel wire rope to lower the steel casing, but this method is only applicable to projects with short steel casings and light weight, and in the case that the steel casing weighs dozens of tons, a winch and a block set are needed to cooperate, on the one hand, the lifting point problem of the block set is solved, and on the other hand, the lifting point conversion problem during the lengthening of the steel casing is solved, and the on-site operation is relatively complicated, in order to solve the problems of lengthening and lowering of the deep water large-diameter super-long steel casing, a simple, quick and efficient method is needed to solve the system conversion during the lengthening of the steel casing and the overall lowering after the lengthening.

[0007] The present application is realized by the following technical solutions:

[0008] A self-anchored steel casing temporary construction support comprises a top frame and a bottom frame, steel pipe bases are installed at four corners between the top frame and the bottom frame, steel pipe columns are jointly installed between every two steel pipe bases, a plurality of distribution beams are obliquely arranged at upper ends of the top frame and the bottom frame, the top frame, the bottom frame, the steel pipe bases, the steel pipe columns, the distribution beams and other structures constitute a guide frame, lug ears are arranged at middle portions of the distribution beams, jack sleeve frames are installed at upper ends of the upper distribution beams, through-hole jacks are installed at inner sides of the jack sleeve frames, upper nuts are installed at upper ends of the through-hole jacks, a first section of a steel casing is arranged at an inner side of the top frame and between the upper distribution beams, a first section of a casing is arranged at an inner side of the bottom frame and between the lower distribution beams, the first section of the casing is connected with the first section of the steel casing, a fine rolled threaded steel is arranged at a middle portion of the through-hole jack, a hanging assembly is connected to a bottom end of the fine rolled threaded steel, and four notches are formed in outer walls of the first section of the casing and the first section of the steel casing.

[0009] Preferably, a pressure pipe is fixedly connected to an upper outer surface of the through-hole jack.

[0010] Preferably, an oil return pipe is fixedly connected to a lower outer surface of the through-hole jack.

[0011] Preferably, a plurality of steel supports are fixedly connected to an outer surface of the bottom frame, hollow branch pipes are arranged on upper surfaces of the steel supports, and the hollow branch pipes are used in cooperation with the distribution beams.

[0012] Preferably, a plurality of lower nuts are arranged at the upper end of the bottom frame and are sleeved with the fine rolled threaded steel.

[0013] Preferably, the hanging assembly comprises a double-ply board sleeved on an outer side of the fine rolled threaded steel, a matched bolt clamp is threadedly sleeved with the fine rolled threaded steel at one end of the double-ply board, a hanger is fixedly connected to an outer side of the double-ply board, and a through-hole rod is arranged at a lower portion of the hanger.

[0014] Preferably, the through rod is inserted into the hanger, a limiting screw is sleeved on one side of the hanger, and a limiting clamp is inserted into one end of the through rod.

[0015] A quick dismounting method of a self-anchored steel casing temporary construction support, specifically comprising the following steps:

[0016] S1: after the positioning and installation of the guide frame are completed, the first section of the casing is hoisted into place by using hoisting equipment, and is suspended at a position 1m above the bottom frame of the guide frame, so that the upper end of the second section of the casing is slightly higher than the bottom frame of the guide frame, the center position and the perpendicularity of the casing are adjusted, the lifting lug 15 is inserted into the notch, and then the casing is lowered to be suspended on the bottom frame of the guide frame;

[0017] S2: the second section of the casing is hoisted above the first section of the casing, the upper and lower casings are welded, the horizontal jack is used to level the upper and lower casings, the through-type jack top is aligned with the protruding part of the casing, the through-type jack base is clamped on the angle steel welded with the recessed part of the lower casing, and when the through-type jack is filled with oil, a pair of counter forces of one compression and one tension are generated, so that the recessed part is expanded outward and the protruding part is contracted inward, until the joint is leveled and then welded;

[0018] S3: after the casing is lengthened, it is hoisted by 5-10 cm, the lifting lug in the notch is pulled out, the second section of the casing is lowered to be suspended at a position 1m above the bottom frame of the guide frame, the lifting lug is inserted and suspended on the bottom frame, the lengthening and lowering operations are repeated until the top of the casing is suspended on the bottom frame;

[0019] S4: when the weight of the lengthened casing exceeds the rated hoisting weight of the hoisting equipment, the through-type jack is used for lowering and construction, strip distribution beams are arranged at the upper and lower frames of the guide frame, and components such as the through-type jack, the finished rolled threaded steel, the upper nut, the lower nut, the hanging assembly and the lifting lug are installed, so as to prepare for the lowering of the through-type jack;

[0020] S5: the maximum stroke of the through-type jack is 60 cm, and the actual stroke is 50 cm; the upper nut of the through-type jack is adjusted to be higher than the through-type jack by 45 cm, the through-type jack is lifted by 50 cm after oil return, and the nut is lifted by 5 cm, at this time the weight of the casing is borne by the through-type jack, and the lifting lug suspended on the bottom frame is removed;

[0021] S6: the lower nut of the through-type jack is adjusted so that the nut is higher than the distribution beam on the bottom frame of the guide frame by 50 cm;

[0022] S7: the lower nut is adjusted to release the pressure of the through-type jack, and the through-type jack falls back by 50 cm, so that the lower nut falls on the distribution beam of the bottom frame, at this time the weight of the casing is borne by the bottom frame distribution beam, and the system conversion is completed.

[0023] S8: By adjusting the upper nut of the through jack, it is higher than the through jack by 50 cm, the through jack is lifted by 50 cm to resist the upper nut, the system conversion is completed, then the lower nut is adjusted, the through jack is depressurized, the lower nut is placed on the distribution beam, the upper nut is adjusted, and the through jack returns oil;

[0024] S9: By repeating the above steps 1-8, the steel casing is lowered, after the self-anchored steel casing is lowered and connected through the support, the distribution beam can be removed, the tool is used to open the steel pipe base, the upper top frame is removed, and the steel pipe column is removed and transported away;

[0025] S10: With the lowering of the casing, the length of the fine rolled threaded steel above the through jack is gradually reduced, and the distance between the lifting lug insertion hole and the water surface is closer and closer. In order to solve the problem of insufficient length of the fine rolled threaded steel and avoid underwater welding and plugging in the later stage, the casing needs to be hung on the bottom frame, the lifting lug is unhooked, the threaded steel is lifted, and the lifting lug insertion hole plugging construction is carried out.

[0026] Compared with the prior art, the advantages and beneficial effects of the present application are:

[0027] 1. The self-anchored steel casing temporary construction support and the quick disassembly and assembly method thereof, which positions and lowers the steel casing by using a crawler crane, a jack, fine rolled threaded steel, fine rolled nuts and a guide frame, and is especially suitable for long steel casing extension and lowering in deep water.

[0028] 2. The self-anchored steel casing temporary construction support and the quick disassembly and assembly method thereof, wherein the guide frame is a double-layer derrick structure, the upper layer is provided with a through jack, the steel casing is lowered through fine rolled threaded steel and fine rolled nuts, and the lower layer is a steel casing suspension load-bearing bottom frame, so that the system conversion problem during steel casing extension and top replacement is solved.

[0029] 3. The self-anchored steel casing temporary construction support and the quick disassembly and assembly method thereof, wherein the lifting lug of the steel casing is a hole-inserted lifting lug, field welding of the lifting lug is avoided, the problems of low field welding efficiency and uncontrollable quality are solved, and the construction efficiency and safety of the casing lowering are improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application will be further described below in combination with the drawings and examples.

[0031] Figure 1 It is a whole structure schematic view of the embodiment of the present application;

[0032] Figure 2 It is a whole structure schematic view of the embodiment of the present application; Figure 1 It is a front view structure schematic view of the embodiment of the present application;

[0033] Figure 3 for the present application Figure 1 the overall sectional structure schematic diagram in the present application;

[0034] Figure 4 for the present application Figure 1 the overall sectional structure schematic diagram in the present application;

[0035] Figure 5 for the present application Figure 1 the overall sectional structure schematic diagram in the present application;

[0036] Figure 6 for the present application Figure 1 the overall sectional structure schematic diagram in the present application;

[0037] In the figure: 1, top frame; 2, bottom frame; 3, steel pipe stand; 4, hollow branch pipe; 5, steel support; 6, the first section of the casing; 7, the second section of the steel casing; 8, jack set; 9, through center jack; 10, pressure pipe; 11, oil return pipe; 12, distribution beam; 13, upper nut; 14, fine rolling threaded steel; 15, lifting lug; 18, steel pipe base; 19, lower nut; 20, hanging assembly; 201, limit card; 202, limit thread; 203, through center rod; 205, matching bolt card; 206, double spliced board; 207, hanging bracket. DETAILED DESCRIPTION

[0038] The applicant will make a brief introduction to the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] The present application will be further described below in combination with the drawings and embodiments.

[0040] As Figures 1-6As shown, a self-anchored steel casing temporary construction support of the present invention comprises a top frame 1 and a bottom frame 2, wherein steel pipe bases 18 are installed at the four corners between the top frame 1 and the bottom frame 2, and steel pipe columns 3 are installed between each two steel pipe bases 18 above and below. A plurality of distribution beams 12 are obliquely arranged at the upper ends of the top frame 1 and the bottom frame 2. The top frame 1, the bottom frame 2, the steel pipe base 18, the steel pipe columns 3, and the distribution beams 12 constitute a guide frame. The middle part of the plurality of distribution beams 12 is provided with The upper ends of the multiple distribution beams 12 above are all equipped with jack brackets 8, the inner side of the jack brackets 8 is equipped with a through-type jack 9, the upper end of the through-type jack 9 is equipped with an upper nut 13, the inner side of the top frame 1 and the multiple distribution beams 12 above are interspersed with the second section of steel casing 7, the inner side of the bottom frame 2 and the multiple distribution beams 12 below are interspersed with the first section of casing 6, the first section of casing 6 is connected to the second section of steel casing 7, the through-type The middle part of the jack 9 is interspersed with a finely rolled threaded steel bar 14, and the bottom end of the finely rolled threaded steel bar 14 is connected to a hanging assembly 20. The outer walls of the first section casing 6 and the second section steel casing 7 are each provided with four notches. The upper outer surface of the through-type jack 9 is fixedly connected to a pressure pipe 10, and the lower outer surface of the through-type jack 9 is fixedly connected to an oil return pipe 11. The upper end of the bottom frame 2 is provided with a plurality of lower nuts 19 that are fitted with the finely rolled threaded steel bar 14. The hanging assembly 20 includes a sleeve. On the outer side of the fine-rolled threaded steel bar 14, the fine-rolled threaded steel bar 14 passes through the double-piece plate 206 and is threaded with a matching bolt clip 205 at one end. The outer side of the double-piece plate 206 is fixedly connected to the hanger 207. A through rod 203 is inserted into the lower part of the hanger 207. The through rod 203 and the hanger 207 are inserted. The through rod 203 passes through one side of the hanger 207 and is sleeved with a limiting thread 202. A limiting clip 201 is inserted into one end of the through rod 203.

[0041] The specific steps for using the above technical solution are as follows: after the guide frame is positioned and installed, the first section of the casing 6 is hoisted in using a lifting device, and lowered until the top of the second section of the steel casing 7 is 21 meters above the bottom frame of the guide frame, so that the pre-cut notch on the upper end of the second section of the steel casing 7 is slightly higher than the bottom frame 2 of the frame body, the center position and verticality of the casing section are adjusted, the lifting lug 15 is inserted into the notch, and the casing is lowered so that it is suspended on the bottom frame of the guide frame;

[0042] Further, by hoisting the second section of steel casing 7 to the top of the first section of casing 6, the upper and lower casings are welded neatly, and the upper and lower casings are leveled with a horizontal jack where they cannot be aligned. The head of the through-type jack 9 is aligned with the protruding part of the casing, and the base of the through-type jack 9 is stuck on the angle steel welded to the concave part of the lower casing. When the through-type jack 9 is filled with oil, a pair of reaction forces of one pressing and one pulling are generated, causing the concave part to expand outward and the protruding part to shrink inward, until the joints are flush and then welding is performed;

[0043] Further, after the lengthening of the pile casing, hoist 5-10 cm, pull out the lifting lug 15 in the notch, lower the second section of the pile casing 7 to the position where the top of the pile casing is higher than the bottom frame 21 m of the frame, hang on the bottom frame 2 by inserting the lifting lug 15, repeat the lengthening and lowering operation until the top of the third section of the pile casing is hung on the bottom frame 2;

[0044] When the weight of the lengthened pile casing exceeds the rated lifting capacity of the lifting equipment, use the through-type jack 9 for lowering construction, set up 4 distribution beams 12 at the upper and lower frames of the guide frame, and install the through-type jack 9, the fine rolled threaded steel 14, the upper nut 13, the lower nut 19, the hanging assembly 20, the lifting lug 15 and other components to prepare for the lowering of the through-type jack 9;

[0045] Then through the maximum stroke of the through-type jack 9 in the present scheme, the actual stroke is 50 cm. Adjust the upper nut 13 above the through-type jack 9 to be 45 cm higher than the through-type jack 9, the through-type jack 9 is lifted by 50 cm, and the upper nut 13 is lifted by 5 cm. At this time, the weight of the pile casing is borne by the through-type jack 9, and the lifting lug 15 hanging on the bottom frame 2 is removed;

[0046] Then adjust the lower nut 19 of the through-type jack 9 so that the nut is 50 cm higher than the distribution beam 12 on the bottom frame 2 of the frame;

[0047] Then adjust the lower nut 19 below to release the pressure of the through-type jack 9, and make the through-type jack 9 fall back by 50 cm, so that the lower nut 19 falls on the distribution beam 12 of the bottom frame 2. At this time, the weight of the pile casing is borne by the distribution beam 12 of the bottom frame 2, and the system conversion is completed;

[0048] Then adjust the upper nut 13 of the through-type jack 9 so that it is 50 cm higher than the through-type jack 9, and the through-type jack 9 is lifted by 50 cm to stop the upper nut 13. Complete the system conversion, then adjust the lower nut 19, release the pressure of the through-type jack 9, and make the lower nut 19 fall on the distribution beam 12. Adjust the upper nut 13 and the through-type jack 9 to release the oil;

[0049] Then repeat the above steps to lower the steel pile casing. After the self-anchored steel pile casing is lowered and connected by the support, the distribution beam 12 can be removed, the steel pipe base 18 can be opened with tools, the top frame 1 can be removed, and the steel pipe column 3 can be removed and transported away;

[0050] Further, as the casing is lowered, the length of the fine rolled threaded steel 14 above the through-type jack 9 gradually decreases, and the distance between the lug 15 and the water surface becomes closer. To solve the problem of insufficient length of the fine rolled threaded steel, and to avoid underwater welding and plugging in the later stage, the casing needs to be hung on the bottom frame 2, so that the lug 15 is unhooked, the threaded steel is lifted, and the lug 15 plug hole plugging construction is carried out. The method specifically includes the following steps: the guide frame is a double-layer derrick structure, the upper layer is provided with a through-type jack, and the steel casing is lowered by the fine rolled threaded steel and the fine rolled nut; the lower layer is a steel casing hanging load-bearing bottom frame, which solves the system conversion problem during the lengthening and replacement of the steel casing.

[0051] The steel casing lug adopts a hole insertion type lug, which avoids on-site welding of the lug, solves the problems of low on-site welding efficiency and uncontrollable quality, and improves the construction efficiency and safety of the casing lowering.

[0052] The steel casing hanging assembly is used to connect the fine rolled threaded steel and the casing lug. The thickness and size of the hanging assembly need to be designed in combination with the load size and stress condition. The length and strength of the weld need to be reduced in combination with the on-site welding quality, and sufficient safety reserve is reserved.

[0053] The steel casing is pre-fabricated in sections according to a certain length, transported to the site for lengthening and lowering, which is beneficial to the lengthening and lowering of deep water large diameter super-long steel casings that cannot be accessed by large lifting and lowering equipment.

[0054] Further, the self-anchored steel casing temporary construction support and the quick disassembly method thereof of the present application, the outer surface of the bottom frame 2 is fixedly connected with a plurality of steel braces 5, the upper surfaces of the plurality of steel braces 5 are provided with hollow branch pipes 4, and the plurality of hollow branch pipes 4 are used in cooperation with the distribution beam 12.

[0055] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application.

Claims

1. A self-anchored steel casing temporary construction support, characterized by: The invention comprises a top frame (1) and a bottom frame (2), wherein steel pipe bases (18) are installed at the four corners between the top frame (1) and the bottom frame (2), and a steel pipe column (3) is installed between each two steel pipe bases (18) at the top and bottom. The upper ends of the top frame (1) and the bottom frame (2) are both obliquely provided with a plurality of distribution beams (12). The top frame (1), the bottom frame (2), the steel pipe base (18), the steel pipe column (3), and the distribution beams (12) constitute a guide frame. A lifting lug (15) is provided in the middle of the plurality of distribution beams (12). The upper ends of the plurality of distribution beams (12) are all provided with a jack sleeve (8), and the inner side of the jack sleeve (8) is provided with a through-hole. The invention relates to a through-type jack (9), wherein an upper nut (13) is installed on the upper end of the through-type jack (9), a second section of steel casing (7) is inserted between the inner side of the top frame (1) and the plurality of distribution beams (12) above, a first section of casing (6) is inserted between the inner side of the bottom frame (2) and the plurality of distribution beams (12) below, the first section of casing (6) is connected to the second section of steel casing (7), a fine-rolled threaded steel (14) is inserted in the middle of the through-type jack (9), the bottom end of the fine-rolled threaded steel (14) is connected to a hanging assembly (20), and the outer walls of the first section of casing (6) and the second section of steel casing (7) are both provided with four notches.

2. A self-anchored steel casing temporary construction support according to claim 1, characterized in that: The upper outer surface of the through-type jack (9) is fixedly connected with a pressure pipe (10).

3. The self-anchored steel casing temporary construction support according to claim 1, characterized in that: An oil return pipe (11) is fixedly connected to the lower outer surface of the through-type jack (9).

4. The self-anchored steel casing temporary construction support according to claim 1, characterized in that: The outer surface of the bottom frame (2) is fixedly connected with a plurality of steel supports (5), and the upper surfaces of the plurality of steel supports (5) are all provided with hollow branch pipes (4), and the plurality of hollow branch pipes (4) are used in conjunction with the distribution beam (12).

5. The self-anchored steel casing temporary construction support according to claim 1, characterized in that: The upper end of the bottom frame (2) is provided with a plurality of lower layer nuts (19) fitted with the finished rolled threaded steel bars (14).

6. The self-anchored steel casing temporary construction support according to claim 1, characterized in that: The hanging assembly (20) includes a double-jointed plate (206) sleeved on the outside of the fine-rolled threaded steel (14); the fine-rolled threaded steel (14) passes through one end of the double-jointed plate (206) and is threadedly sleeved with a matching bolt clamp (205); the outer side of the double-jointed plate (206) is fixedly connected to a hanger (207); and a through-rod (203) is inserted into the lower part of the hanger (207).

7. The self-anchored steel casing temporary construction support according to claim 6, characterized in that: The core-penetrating rod (203) is interlaced with the hanger (207); one side of the core-penetrating rod (203) passing through the hanger (207) is sleeved with a limiting thread (202); and one end of the core-penetrating rod (203) is interlaced with a limiting clip (201).

8. A method for quickly disassembling and assembling a self-anchored steel casing temporary construction support according to any one of claims 1 to 7, characterized in that: The specific steps include: S1: After the guide frame is positioned and installed, the first section of the casing (6) is hoisted in using a lifting device, and lowered until the top of the second section of the steel casing (7) is 1m higher than the guide frame bottom frame (2) and hovered, so that the pre-cut notch on the upper end of the second section of the steel casing (7) is slightly higher than the frame bottom frame (2), the center position and verticality of the casing are adjusted, the lifting lug (15) is inserted into the notch, and the casing is lowered to be suspended on the guide frame bottom frame; S2: hoist the second section of steel casing (7) above the first section of casing (6), weld the upper and lower casings together, use a horizontal jack to level the parts where the upper and lower casings cannot be aligned, align the head of the through-type jack (9) with the protruding part of the casing, and clamp the base of the through-type jack (9) on the angle steel welded to the concave part of the lower casing. When the through-type jack (9) is filled with oil, a pair of reaction forces of one pressing and one pulling are generated, causing the concave part to expand outward and the protruding part to shrink inward, until the joints are flush and then welding is performed; S3: After the casing is extended, lift it 5-10cm, pull out the lifting lug (15) in the notch, lower the second section of casing (7) until the top of the casing is 1m higher than the bottom frame (2) of the frame, insert the lifting lug (15) and hang it on the bottom frame (2), repeat the extension and lowering operation until the top of the third section of casing is hung on the bottom frame (2); S4: When the weight of the casing after extension exceeds the rated lifting weight of the lifting equipment, the through-type jack (9) is used for lowering construction. Four distribution beams (12) are respectively set up at the upper and lower frames of the guide frame, and the through-type jack (9), the finished rolled threaded steel (14), the upper nut (13), the lower nut (19), the hanging assembly (20), and the lifting lug (15) are installed to prepare for the lowering of the through-type jack (9); S5: The maximum stroke of the through-type jack (9) is 60cm, and the actual stroke is 50cm; the upper nut (13) above the through-type jack (9) is adjusted to 45cm above the through-type jack (9), the through-type jack (9) is lifted by 50cm through oil return, and the layer nut (13) is lifted by 5cm. At this time, the weight of the casing is borne by the through-type jack (9), and the lifting lug (15) hanging at the bottom frame (2) is removed; S6: Adjust the lower nut (19) of the through-type jack (9) so that the nut is 50 cm higher than the distribution beam (12) on the bottom frame (2); S7: By adjusting the lower nut (19), the through-type jack (9) is depressurized and dropped back 50 cm, so that the lower nut (19) falls on the distribution beam (12) of the bottom frame (2). At this time, the weight of the casing is borne by the distribution beam (12) of the bottom frame (2), and the system conversion is completed; S8: By adjusting the upper nut (13) of the through-type jack (9) to make it 50 cm higher than the through-type jack (9), the through-type jack (9) returns oil and lifts it 50 cm to support the upper nut (13), completing the system conversion, then adjusting the lower nut (19) and the through-type jack (9) to release pressure, so that the lower nut (19) falls on the distribution beam (12), adjusting the upper nut (13), and the through-type jack (9) returns oil; S9: By repeating the above steps 1-8, the steel casing is lowered. After the self-anchored steel casing is lowered and docked through the bracket, the distribution beam (12) can be removed, and the steel pipe base (18) can be opened with a tool, the upper top frame (1) can be removed, and the steel pipe column (3) can be dismantled and loaded and transported away; S10: As the casing is lowered, the length of the finished rolled threaded steel bar (14) above the through-type jack (9) gradually decreases, and the insertion hole of the lifting lug (15) is closer and closer to the water surface. In order to solve the problem of insufficient length of the finished rolled threaded steel bar and avoid underwater welding plugging in the later stage, the casing needs to be hung on the bottom frame (2), the lifting lug (15) is unhooked, the threaded steel bar is lifted, and the insertion hole of the lifting lug (15) is sealed.

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