Double-wall steel cofferdam construction method for first pile foundation and second cofferdam floating transportation construction

Abstract

The invention provides a double-wall steel cofferdam construction method for first pile foundation and second cofferdam floating transportation construction. The double-wall steel cofferdam construction method comprises the following steps that a steel trestle for construction is built, and a floating platform is assembled; a bottom section cofferdam is assembled on the floating platform; overall assembly of the double-wall steel cofferdam is completed on the bottom section cofferdam; pile foundation construction at the pier position is synchronously conducted, underwater cutting is conducted on a pile foundation steel casing, and the top end of the cut pile foundation steel casing is lower than the bottom end of the double-wall steel cofferdam; the assembled double-wall steel cofferdam is transported to a pier position in a floating mode, and wall cabin concrete is poured to enable the double-wall steel cofferdam to sink slowly after the double-wall steel cofferdam is in place; an inner guide device, a middle positioning device and an upper fine adjustment device are used for precise positioning and sinking; and foundation cleaning and bottom sealing are conducted in the double-wall steel cofferdam, after the strength of bottom sealing concrete meets the requirement, water in the double-wall steel cofferdam is drained, a bearing platform and a pier body are constructed, and after construction of the pier body is completed, water returning is conducted, and the double-wall steel cofferdam is dismantled. The method has the advantages of being short in construction period, convenient and fast to install and construct and low in construction cost.

Description

Technical Field

[0001] The invention relates to the technical field of cofferdam construction, and in particular to a double-wall steel cofferdam construction method that first constructs a pile foundation and then floats the cofferdam. Background Art

[0002] With the rapid development of bridge construction technology, more and more difficult foundation construction techniques have achieved breakthroughs, among which deepwater foundation engineering, especially double-walled steel cofferdam construction technology, has become increasingly mature. In the construction organization of abutments and piers of various deepwater large bridges, double-walled steel cofferdam construction has become the only choice after comprehensive consideration of all aspects.

[0003] In the special occasion where there are 110KV high-voltage wires above the bridge, there are some adverse effects on the construction of double-wall steel cofferdams. Because there are 110KV high-voltage wires above the bridge, the site does not have the conditions for large floating cranes to enter the site, so the construction of double-wall steel cofferdams can only adopt the traditional construction technology of segmented and block-by-block in-situ splicing. The existing in-situ loose assembly construction steps are as follows: dismantle the drilling platform, weld and assemble the corbels on the steel casing, and assemble the bottom side panels as a whole on the assembled corbels; install the bottom internal support, connect the steel casings at the four corners of the high cap and install the hanging equipment; install the guide device under the cofferdam, and use the hanging equipment to slowly raise the steel cofferdam below to a self-floating state; loosely assemble the second-layer high cofferdam and the corresponding internal supports, pour the blade foot and wall compartment concrete, and lower them with water; loosely assemble the subsequent side wall segments and internal supports in turn, inject water, suck mud, lower them and level them, pour the bottom concrete, and after the bottom concrete reaches the design strength, pump out water to chisel the pile head, construct the cap and pier body, and after the pier body construction is completed, return water and remove the cofferdam.

[0004] When adopting the above-mentioned double-wall steel cofferdam in-situ loose assembly construction process, after the drilling platform is dismantled, it is necessary to install the assembled brackets and hanging system, and the cofferdam side walls need to be assembled in sections and blocks. The process is cumbersome and complicated, the construction period is long, and the resource investment is greatly increased. The construction cost is high, resulting in a tight construction period for the subsequent abutment, pier body and upper structure. Therefore, there is an urgent need in the art to provide a rapid construction and installation process suitable for double-wall steel cofferdams under high-voltage lines to solve the deficiencies in the existing technology. Summary of the invention

[0005] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a double-wall steel cofferdam construction method of first constructing the pile foundation and then floating the cofferdam, which can solve the problems of complicated procedures, long construction period, high construction cost and tight construction period in the existing in-situ loose assembly construction process of double-wall steel cofferdams under high-voltage lines, and has the advantages of short construction period, convenient and fast installation and construction, and low construction cost.

[0006] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:

[0007] A double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction, comprising the following steps:

[0008] S1. Build a steel trestle for construction in the waters far away from the high-voltage wires above the bridge, and assemble a floating platform in the water using a pontoon on one side of the steel trestle; assemble the bottom section of the double-walled steel cofferdam on the floating platform using a crane, and fix temporary steel supports at the top corners of the bottom section of the cofferdam;

[0009] S2. Fill the pontoon in the floating platform with water to make the floating platform sink until the bottom cofferdam floats in the water, and then separate the bottom cofferdam from the floating platform; assemble the other upper cofferdam segments on the bottom cofferdam to complete the overall assembly of the double-walled steel cofferdam, and install internal supports in the double-walled steel cofferdam. The assembled double-walled steel cofferdam floats on the water surface as a whole. The height of the bottom end of the double-walled steel cofferdam from the water surface is recorded as H. 1 ;

[0010] S3, while steps S1 and S2 are being performed, the pile foundation construction at the pier position is carried out synchronously. After the construction is completed, the drilling platform is removed, and the pile foundation steel casing is cut underwater. The height of the top of the pile foundation steel casing from the water surface after cutting is recorded as H 2 , H 2 >H 1 ;

[0011] S4. Use a tugboat to float the assembled double-walled steel cofferdam to the pier position. After it is in place, pour the wall compartment concrete into the double-walled steel cofferdam to make the double-walled steel cofferdam sink slowly;

[0012] S5. During the slow sinking of the double-walled steel cofferdam, the inner guide device, the middle positioning device and the upper fine adjustment device are used to accurately position and sink the double-walled steel cofferdam until the double-walled steel cofferdam sinks to the designed elevation and is leveled;

[0013] S6. Carry out bottom sealing and clearing inside the double-walled steel cofferdam. When the strength of the bottom concrete reaches the requirement, drain the water inside the double-walled steel cofferdam and construct the abutment and pier body. After the pier body construction is completed, return the water and dismantle the double-walled steel cofferdam.

[0014] Furthermore, the floating platform in step S1 is in a U-shaped structure, and a bottom platform for supporting the bottom cofferdam is arranged on the floating platform using sleepers or steel sections, and an iron chain for fixing the floating platform and the steel trestle is arranged between the floating platform and the steel trestle.

[0015] Furthermore, in step S3, H 2 H 1 25 to 30cm in size.

[0016] Furthermore, in step S4, after the double-walled steel cofferdam is floated away, air is inflated into the buoyancy box of the floating platform to press out the water inside the buoyancy box so that the floating platform floats to the surface, thereby realizing the reuse of the floating platform.

[0017] Furthermore, when the double-walled steel cofferdam is towed and floated by a tugboat in step S4, tires or rubber cushions are hung on the side walls of the tugboat close to the double-walled steel cofferdam to protect the double-walled steel cofferdam.

[0018] Furthermore, in step S4, before floating by tugboat, a floating route is determined, the floating route avoids obstacles above and below the water while keeping the distance shortest, and the distribution position of the tugboat is determined by calculation.

[0019] Furthermore, in step S4, in order to facilitate the tugboat to float the double-walled steel cofferdam, a towing lug is welded on the double-walled steel cofferdam, and the position where the towing lug is welded is reinforced.

[0020] Furthermore, in step S5, the inner guide device is composed of a wedge block, a connecting support steel, and a guide steel plate, corresponding to the position of the pile foundation steel casing; one end of the connecting support steel is welded to the inner wall of the double-walled steel cofferdam, and the other end is connected to the guide steel plate; the guide steel plate is made of Q235 steel plate and processed into an arc-shaped sheet metal part that fits the outer wall of the pile foundation steel casing, and the inner diameter of the arc is larger than the outer diameter of the steel casing; a wedge block is welded at the bottom of the inner guide device to facilitate the smooth sinking of the cofferdam, so that the inner guide device can smoothly support the pile foundation steel casing.

[0021] Furthermore, the middle positioning device in step S5 is composed of a first positioning steel casing and a positioning ring. The first positioning steel casing is arranged on the downstream outer side of the double-walled steel cofferdam and is constructed together with the drilling platform. The positioning ring is made of Q235 steel plate, and its inner diameter is larger than the outer diameter of the first positioning steel casing. It withstands the impact of water flow force on the double-walled steel cofferdam during the sinking process of the double-walled steel cofferdam.

[0022] Furthermore, the upper fine-adjustment device in step S5 is composed of a second positioning steel casing, an outer guide block, a jack and an outer guide platform. The second positioning steel casing is arranged on both sides of the double-walled steel cofferdam perpendicular to the water flow direction and is constructed together with the drilling platform; the outer guide platform is fixed on the second positioning steel casing, and the outer guide platform is a box-type structure made of steel sections and steel plates, in which a jack is placed, and an outer guide block is arranged on the top of the jack. The outer guide block contacts the side wall of the double-walled steel cofferdam, and the double-walled steel cofferdam is fine-tuned by the jack.

[0023] Compared with the prior art, the technical solution provided by the present invention has the following advantages:

[0024] 1. The double-wall steel cofferdam construction method provided in the present invention, which comprises first piling foundation and then cofferdam floating construction, can realize the rapid construction and installation of the double-wall steel cofferdam when a large floating crane under a high-voltage line cannot enter the site.

[0025] 2. The double-wall steel cofferdam construction method provided in the present invention of first pile foundation and then cofferdam floating construction does not require assembly of corbels and installation of hanging system on the pile foundation steel casing during the whole process, thus avoiding the occupation of construction period by these two processes.

[0026] 3. The double-wall steel cofferdam construction method provided in the present invention of first constructing the pile foundation and then floating the cofferdam can realize the simultaneous construction of the cofferdam assembly and the pile foundation, avoid the large amount of construction time occupied by the cofferdam assembly, and effectively shorten the construction period of the cofferdam.

[0027] 4. The positioning and guiding device for sinking and positioning the steel cofferdam provided in the present invention realizes the rapid and accurate sinking of the double-walled steel cofferdam. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the splicing of the floating platform and the bottom cofferdam of the present invention;

[0029] Figure 2 for Figure 1 Sectional view of the main view;

[0030] Figure 3 This is a schematic diagram of floating double-wall steel cofferdam;

[0031] Figure 4 This is a schematic diagram of positioning guide fine adjustment;

[0032] Figure 5 is a schematic diagram of the layout of the inner guide device;

[0033] Figure 6 This is a schematic diagram of the layout of the positioning device;

[0034] Figure 7 This is a schematic diagram of the layout of the upper fine-tuning device;

[0035] Figure 8 This is a schematic diagram of the pier body during construction;

[0036] In the figure: 1-steel trestle, 2-floating platform, 21-bottom platform, 3-bottom section cofferdam, 31-temporary steel support, 4-double-wall steel cofferdam, 41-inner support, 5-tugboat, 6-pile foundation steel casing, 7-towing lifting lug, 8-inner guide device, 81-wedge block, 82-guide steel plate, 9-middle positioning device, 91-first positioning steel casing, 92-positioning ring, 10-upper fine adjustment device, 101-jack, 102-outer guide block, 103-outer guide platform, 104-second positioning steel casing, 11-bottom sealing concrete, 12-wall cabin concrete, 13-pile foundation, 14-cap, 15-pier body. DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0038] The specific construction process in this embodiment is as follows

[0039] S1. A steel trestle 1 is constructed in a water area far away from the high-voltage wires above the bridge. A floating platform 2 is assembled in water on one side of the steel trestle 1 using a pontoon. The floating platform 2 is in a U-shaped structure. An iron chain is arranged between the floating platform 2 and the steel trestle 1 to fix the floating platform 2. A crane is driven onto the steel trestle 1. A bottom platform 21 for supporting the bottom cofferdam is arranged on the floating platform 2 using sleepers or steel sections. A bottom cofferdam 3 of a double-walled steel cofferdam is assembled on the floating platform 2 using a crane. A temporary steel support 31 is fixed at the top corner of the bottom cofferdam 3. Figure 1 and Figure 2 shown.

[0040] S2. Fill the pontoon in the floating platform 2 with water to make the floating platform sink until the bottom cofferdam 3 floats in the water, thereby separating the bottom cofferdam 3 from the floating platform 2; assemble the other upper cofferdam segments on the bottom cofferdam 3, complete the overall assembly of the double-walled steel cofferdam 4, and install the inner support 41 in the double-walled steel cofferdam 4. The assembled double-walled steel cofferdam 4 floats on the water surface as a whole. The height of the bottom end of the double-walled steel cofferdam 4 from the water surface is recorded as H. 1 .

[0041] S3, while steps S1 and S2 are being performed, the pile foundation 13 at the pier position is constructed synchronously, the drilling platform is removed after the construction is completed, and the pile foundation steel casing 6 is cut underwater, and the height of the top of the pile foundation steel casing 6 from the water surface after cutting is recorded as H 2 , H 2 >H 1 , usually H 2 H 1 25 to 30cm in size.

[0042] S4. Use tugboat 5 to float the assembled double-wall steel cofferdam 4 to the pier position. Figure 3As shown. After the double-walled steel cofferdam 4 is floated away, air is inflated into the pontoon of the floating platform 2 to press out the water inside the pontoon so that the floating platform 2 can be floated to the surface, and the floating platform 2 can be used again. Before using the tugboat 5 for floating, the floating route is determined. The floating route avoids obstacles on and under the water under the premise of the shortest distance, and the distribution position of the tugboat 5 is determined by calculation. In order to facilitate the tugboat 5 to float the double-walled steel cofferdam 4, a towing lug 7 is welded on the double-walled steel cofferdam 4, and the position where the towing lug 7 is welded is reinforced. When the tugboat 5 is used to tow and float the double-walled steel cofferdam 4, a tire or a rubber cushion is hung on the side wall of the tugboat 5 close to the double-walled steel cofferdam 4 to protect the double-walled steel cofferdam 4. After floating in place, the wall cabin concrete 12 is poured into the double-walled steel cofferdam 4 to make the double-walled steel cofferdam 4 sink slowly.

[0043] S5. During the slow sinking of the double-walled steel cofferdam 4, the inner guide device 8, the middle positioning device 9 and the upper fine adjustment device 10 are used to accurately position and sink the cofferdam. Figure 4 As shown. Until the double-walled steel cofferdam 4 sinks to the designed elevation and the double-walled steel cofferdam 4 is leveled. Figure 5 As shown, it is composed of a wedge block 81, a connecting support steel, and a guide steel plate 82, which corresponds to the position of the pile foundation steel casing 6; one end of the connecting support steel is welded to the inner wall of the double-walled steel cofferdam 4, and the other end is connected to the guide steel plate 82; the guide steel plate 82 is made of Q235 steel plate and processed into an arc-shaped sheet metal part that fits the outer wall of the pile foundation steel casing, and the inner diameter of the arc is larger than the outer diameter of the steel casing; a wedge block 81 is welded at the bottom of the inner guide device to facilitate the smooth sinking of the cofferdam, so that the inner guide device 8 can smoothly support the pile foundation steel casing 6.

[0044] The middle positioning device 9 is as Figure 6 As shown, it is composed of a first positioning steel casing 91 and a positioning ring 92. The first positioning steel casing 91 is arranged on the downstream outer side of the double-walled steel cofferdam 4 and is constructed together with the drilling platform. The positioning ring 92 is made of Q235 steel plate, and its inner diameter is larger than the outer diameter of the first positioning steel casing 91. It withstands the impact of water flow force on the double-walled steel cofferdam 4 during the sinking process of the double-walled steel cofferdam 4.

[0045] The upper fine adjustment device 10 is as follows Figure 7 As shown, it is composed of a second positioning steel casing 104, an outer guide block 102, a jack 101 and an outer guide platform 103. The second positioning steel casing 104 is arranged on both sides of the double-walled steel cofferdam 4 perpendicular to the water flow direction and is constructed together with the drilling platform; the outer guide platform 103 is fixed on the second positioning steel casing 104, and the outer guide platform 103 is a box-type structure made of steel sections and steel plates, in which a jack 101 is placed, and an outer guide block 102 is arranged at the end of the jack 101, and the outer guide block 102 contacts the side wall of the double-walled steel cofferdam 4, and the double-walled steel cofferdam 4 is fine-tuned by the jack 101.

[0046] S6, clean the bottom of the double-walled steel cofferdam 4, and after the strength of the bottom concrete 11 reaches the required level, drain the water in the double-walled steel cofferdam 4, and construct the cap 14 and the pier 15. After the construction of the pier 15 is completed, return the water and dismantle the double-walled steel cofferdam 4. Figure 8 shown.

Claims

1. A double-wall steel cofferdam construction method with pile foundation first and cofferdam floating construction later, characterized in that The following steps are involved: S1. Build a steel trestle for construction in the waters far away from the high-voltage wires above the bridge, and assemble a floating platform in the water using a pontoon on one side of the steel trestle; assemble the bottom section of the double-walled steel cofferdam on the floating platform using a crane, and fix temporary steel supports at the top corners of the bottom section of the cofferdam; S2. Fill the pontoon in the floating platform with water to make the floating platform sink until the bottom cofferdam floats in the water, thereby separating the bottom cofferdam from the floating platform; assemble the other upper cofferdam segments on the bottom cofferdam to complete the overall assembly of the double-walled steel cofferdam, and install internal supports in the double-walled steel cofferdam. The assembled double-walled steel cofferdam floats on the water surface as a whole, and the height of the bottom end of the double-walled steel cofferdam from the water surface is recorded as H1; S3, while steps S1 and S2 are being performed, the pile foundation construction at the pier position is carried out synchronously, the drilling platform is removed after the construction is completed, and the pile foundation steel casing is cut underwater, and the height of the top of the pile foundation steel casing from the water surface after cutting is recorded as H2, H2>H1; S4. Use a tugboat to float the assembled double-walled steel cofferdam to the pier position. After it is in place, pour the wall compartment concrete into the double-walled steel cofferdam to make the double-walled steel cofferdam sink slowly; S5. During the slow sinking of the double-walled steel cofferdam, the inner guide device, the middle positioning device and the upper fine adjustment device are used to accurately position and sink the double-walled steel cofferdam until the double-walled steel cofferdam sinks to the designed elevation and is leveled; S6. Carry out bottom sealing and clearing inside the double-walled steel cofferdam. When the concrete strength of the bottom seal reaches the requirement, drain the water inside the double-walled steel cofferdam and construct the abutment and pier body. After the pier body construction is completed, return the water and dismantle the double-walled steel cofferdam.

2. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: The floating platform described in step S1 is in a U-shaped structure, and a bottom platform for supporting the bottom cofferdam is arranged on the floating platform using sleepers or steel sections, and an iron chain for fixing is arranged between the floating platform and the steel trestle.

3. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: In step S3, H2 is 25 to 30 cm larger than H1.

4. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: In step S4, after the double-walled steel cofferdam is floated away, air is inflated into the buoyancy box of the floating platform to press out the water inside the buoyancy box so that the floating platform floats to the surface, thereby realizing the reuse of the floating platform.

5. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: When the double-walled steel cofferdam is towed and floated by a tugboat in step S4, tires or rubber cushions are hung on the side walls of the tugboat close to the double-walled steel cofferdam to protect the double-walled steel cofferdam.

6. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: In step S4, before floating by tugboat, a floating route is determined. The floating route avoids obstacles above and below the water while keeping the distance to the shortest possible, and the distribution position of the tugboat is determined by calculation.

7. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: In step S4, in order to facilitate the tugboat to float the double-walled steel cofferdam, a towing lug is welded on the double-walled steel cofferdam, and the position where the towing lug is welded is reinforced.

8. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: In step S5, the inner guide device is composed of a wedge block, a connecting support steel, and a guide steel plate, which corresponds to the position of the pile foundation steel casing; one end of the connecting support steel is welded to the inner wall of the double-walled steel cofferdam, and the other end is connected to the guide steel plate; the guide steel plate is made of Q235 steel plate and processed into an arc-shaped sheet metal part that fits the outer wall of the pile foundation steel casing, and the inner diameter of the arc is larger than the outer diameter of the steel casing; a wedge block is welded at the bottom of the inner guide device to facilitate the smooth sinking of the cofferdam, so that the inner guide device can smoothly support the pile foundation steel casing.

9. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: The middle positioning device in step S5 is composed of a first positioning steel casing and a positioning ring. The first positioning steel casing is arranged on the downstream outer side of the double-walled steel cofferdam and is constructed together with the drilling platform. The positioning ring is made of Q235 steel plate. The inner diameter is larger than the outer diameter of the first positioning steel casing. It withstands the impact of water flow force on the double-walled steel cofferdam during the sinking process of the double-walled steel cofferdam.

10. The double-wall steel cofferdam construction method of first pile foundation and then cofferdam floating construction according to claim 1 is characterized by: The upper fine-adjustment device in step S5 is composed of a second positioning steel casing, an outer guide block, a jack and an outer guide platform. The second positioning steel casing is arranged on both sides of the double-walled steel cofferdam perpendicular to the water flow direction and is constructed together with the drilling platform; the outer guide platform is fixed on the second positioning steel casing. The outer guide platform is a box-type structure made of steel sections and steel plates. A jack is placed inside the box. An outer guide block is arranged on the top of the jack. The outer guide block is in contact with the side wall of the double-walled steel cofferdam, and the double-walled steel cofferdam is fine-tuned by the jack.

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