Steel cofferdam construction method for deepwater high-rise pile cap reinforcement construction

Abstract

The invention belongs to the technical field of steel cofferdam construction, and particularly relates to a steel cofferdam construction method for deepwater high pile cap reinforcing construction. The method comprises the steps that S1, a double-wall steel jacket box is manufactured, lock catch steel pipe piles are lengthened, and a top layer support and surrounding purlins are manufactured; s2, positioning piles of the double-wall steel jacket box are inserted into the two limited sides below the old bridge, the whole double-wall steel jacket box is hoisted to the operation position, and the positioning piles on the inner side and the outer side serve as guides and are used for clamping the double-wall steel jacket box after installation is completed; S3, CT type connectors are reserved in the two sides of the double-wall steel jacket box, and lock catch steel pipe piles are inserted into the connector positions on the two sides in sequence till the two sides are closed; s4, top enclosing purlins and inner supports in the double-wall steel jacket box are installed; s5, underwater bottom sealing concrete is poured at the bottom in the double-wall steel jacket box; s6, mounting a bottom template at the bottom of the bearing platform; s7, after the bearing platform is reinforced, opening the communicating vessel to inject water into the double-wall steel jacket box, dismantling the top support, pulling out the lock catch steel pipe pile, and dismantling and recycling the double-wall steel jacket box; the construction efficiency and the construction safety can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel cofferdam construction, and in particular relates to a steel cofferdam construction method for deep-water high-pile cap reinforcement construction. Background Art

[0002] As a temporary water retaining structure, cofferdams are widely used in water conservancy, bridges, construction and other projects. When constructing in rivers, lakes and other water bodies, in order to prevent water flow from scouring and eroding the construction area, it is necessary to build cofferdams to isolate the construction area from the external environment. The cofferdam used to reinforce the old bridge cap is different from the cofferdam used in the construction of a normal new bridge cap. The reinforcement of the old bridge cap requires increasing the height, width and length of the cap. The original cap and pile foundation have a great impact on the cofferdam construction, especially for the deep-water high-pile cap with a very tight construction period for emergency repairs. It is necessary to comprehensively consider the water stopping of the cofferdam side walls, the bottom closure, the current status of the old cap disease and the response measures for the uncertainties that have not been discovered, etc., which makes the construction more difficult.

[0003] Generally, cofferdam construction requires several steel sheet piles or steel pipe piles to be assembled and enclosed on the construction platform to form a rectangular or circular cofferdam. However, when steel sheet piles are used in deep-water high-pile caps, although they can be assembled as a whole before being installed at the bottom, the height space for inserting steel sheet piles in the bottom area of ​​the bridge during the reinforcement of the old bridge cap is insufficient, and multiple extensions are required, which affects the construction efficiency. In addition, the structural strength is relatively low, making it difficult to use in areas with fast water flow. Although the steel pipe pile cofferdam has high strength, when used in areas with fast water flow, each surface of the steel pipe pile is subject to a large impact force from the water flow, so it is difficult to assemble as a whole and then sink to the bottom of the river. It is easy to deviate or overturn under the action of the water flow, and the steel pipe piles can only be inserted and driven to the bottom of the river one by one, which also affects the construction efficiency.

[0004] Therefore, in order to improve the construction efficiency and safety when constructing the reinforcement cofferdam for the old bridge pier, a steel cofferdam construction method for deep-water high-pile pier reinforcement construction is proposed. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a steel cofferdam construction method for deep-water high-pile cap reinforcement construction.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for constructing a steel cofferdam for reinforcing a deepwater high pile cap comprises the following steps:

[0008] S1: Construction preparation: making double-walled steel casing, locking steel pipe pile extension, top floor support and surrounding purlin;

[0009] S2: Installation of double-walled steel casing: Insert and drive positioning piles of the double-walled steel casing on both sides of the restricted area under the old bridge, and hoist the double-walled steel casing as a whole to the working position. At this time, the connecting valve of the outer wall of the double-walled steel casing is normally open, and water is injected into the double-walled steel casing. The double-walled steel casing is hoisted close to the positioning piles, the top is hung and fixed, and the bottom is pulled close with steel wire ropes. The positioning piles on both sides of the inside and outside are used as guides and are used to clamp the double-walled steel casing after the installation is completed. The double-walled steel casing sinks to 1m below the riverbed by its own weight, and is assisted by vibrating hammers;

[0010] S3: CT-type interfaces are reserved on both sides of the double-walled steel casing. Locking steel pipe piles are inserted in sequence at the interface positions on both sides. The two sides of several locking steel pipe piles are connected in sequence until they are closed at the corner piles;

[0011] S4: Install the top purlin and inner support in the double-walled steel casing. After the purlin and inner support are pre-assembled, they are assembled in two parts at the bridge location;

[0012] S5: pouring underwater bottom sealing concrete at the bottom of the double-walled steel casing;

[0013] S6: After the bottom seal concrete reaches the design strength requirement, pump water to 0.5m below the lowest elevation of the cap reinforcement, install the bottom formwork at the bottom of the cap, and arrange the bottom formwork only on the outside of the cap to reinforce the cap and control the water head difference inside and outside the double-wall steel casing according to the tide level;

[0014] S7: Dismantling of the double-walled steel casing: After the reinforcement of the foundation is completed, open the connecting valve and inject water into the double-walled steel casing to keep the water head inside and outside the double-walled steel casing consistent, remove the top support and pull out the locking steel pipe piles, and dismantle and recycle the double-walled steel casing.

[0015] Furthermore, in S2, firstly, the inner positioning piles on the inner side of the double-walled steel casing are installed, and the double-walled steel casing is placed to a predetermined height along the inner positioning piles. After adjusting the plane position and the overall verticality of the double-walled steel casing, the outer positioning piles are inserted into the corresponding positions of the inner positioning piles on the other side of the double-walled steel casing. After the inner positioning piles and the outer positioning piles are installed, they are used to clamp the double-walled steel casing.

[0016] Furthermore, in S2, blade feet are provided at the bottom of the double-walled steel casing. After being lowered to the riverbed, a vibrating hammer is used to insert the double-walled steel cofferdam portion as a whole into the bottom of the riverbed by 1m, and fixed sandbags are suspended outside the double-walled steel cofferdam as counterweight feet.

[0017] Furthermore, in S4, the gap between the surrounding purlin and the locking steel pipe pile is filled with a curved steel plate.

[0018] Furthermore, in S6, a corbel is welded on the locking steel pipe pile and abuts against the bottom of the bottom form, and a hanging beam and a lower longitudinal beam are respectively arranged on the top and bottom surfaces of the pedestal and connected to the bottom form for suspending and supporting the bottom form of the pedestal reinforcement area.

[0019] Furthermore, in S7, communicating vessels are provided on both the inner and outer walls of the double-walled steel box. When the inner wall communicating vessel is closed, a waterless working environment is created inside the double-walled steel box. When it is opened, water is injected into the double-walled steel box. The outer wall communicating vessel is always open, and the water head inside the double-walled steel box remains basically consistent with the water head outside the double-walled steel box.

[0020] The beneficial effects of the present invention are as follows: two sections of double-walled steel casings parallel to the direction of water flow are first assembled before construction, and can be quickly hoisted into place during construction, thereby reducing the construction time; and the connection of the locking steel pipe piles that are sequentially buckled on both sides of the double-walled steel casing can provide partial support and bearing capacity for the double-walled steel casing, thereby preventing the double-walled steel casing from collapsing due to insufficient bearing capacity; and the locking steel pipe piles are not under the bridge and have higher strength themselves, requiring fewer extensions, so they can be quickly inserted and driven; through the rapid installation of the prefabricated double-walled steel casing and the coordinated use with the locking steel pipe piles, the structural strength of the cofferdam can be improved while ensuring construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0022] Figure 1 It is a construction flow chart of the present invention;

[0023] Figure 2 It is a schematic diagram of the side structure of the steel cofferdam of the present invention;

[0024] Figure 3 It is a schematic diagram of the top view structure of the steel cofferdam of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the connection between the double-wall steel casing and the locking steel pipe pile of the present invention;

[0026] Figure 5 It is a structural schematic diagram of the double-wall steel casing and two positioning piles of the present invention;

[0027] Explanation of the reference numerals: 1. Double-walled steel casing; 2. Positioning piles; 3. Internal support; 4. Purlin; 5. Hanging beam; 6. Lower longitudinal beam; 7. Threaded steel bar; 8. U-tube; 9. Fixed sandbags; 10. Bottom sealing concrete; 11. Arc steel plate; 12. Locking steel pipe piles. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0029] like Figure 1-5As shown, a steel cofferdam construction method for deep-water high-pile cap reinforcement construction of the present invention comprises the following steps:

[0030] S1: Construction preparation: making double-walled steel casing 1, extending locking steel pipe piles 12, top floor support and surrounding purlin 4;

[0031] S2: Install the double-walled steel casing 1: insert and drive the positioning piles 2 of the double-walled steel casing 1 on both sides of the old bridge, and hoist the double-walled steel casing 1 as a whole to the working position. At this time, the outer wall connecting vessel 8 of the double-walled steel casing 1 is normally open, and water is injected into the double-walled steel casing 1. The double-walled steel casing 1 is hoisted and moved close to the positioning piles 2, the top is hung and fixed, and the bottom is pulled close with a steel wire rope. The positioning piles 2 on both sides of the inside and outside are used as guides and are used to clamp the double-walled steel casing 1 after the installation is completed. The double-walled steel casing 1 sinks to 1m below the riverbed by its own weight, and is assisted by a vibrating hammer for insertion and driving;

[0032] S3: CT-type interfaces are reserved on both sides of the double-walled steel casing 1, and locking steel pipe piles 12 are inserted in sequence at the interface positions on both sides, and the two sides of several locking steel pipe piles 12 are connected in sequence until the corner piles are closed;

[0033] Among them, the CT type interface is mainly composed of a C-type joint and a T-type joint, and the connection between the steel pipe piles and between the steel pipe piles and the double-walled steel casing 1 is realized through the cooperation of these two joints.

[0034] C-type connector: usually composed of multiple plates (such as two first plates, two second plates and one third plate) to form a cavity with an opening. These plates are arranged in parallel or vertically to accommodate the insertion of the T-type connector.

[0035] T-joint: It consists of an insertion section with a right angle and a straight section that is consistent with the radial direction of the steel pipe pile body, forming a T-shaped structure rotated 90° counterclockwise. The insertion section is used to insert into the cavity of the C-joint, while the straight section provides additional stability and support.

[0036] The connection through the CT type interface not only enables rapid construction, but also enables a plurality of locking steel pipe piles 12 to form a whole with the double-walled steel casing 1, thereby improving the structural strength of the cofferdam and reducing water seepage in the gaps between the locking steel pipe piles 12.

[0037] S4: Install the top purlin 4 and the inner support 3 in the double-walled steel casing 1. After the purlin 4 and the inner support 3 are pre-assembled, they are assembled in two pieces at the bridge position;

[0038] S5: pouring underwater bottom sealing concrete 10 at the bottom of the double-walled steel casing 1;

[0039] S6: After the bottom sealing concrete 10 reaches the design strength requirement, pump water to 0.5m below the lowest elevation of the pedestal reinforcement, install the bottom formwork at the bottom of the pedestal, and arrange the bottom formwork only on the outside of the pedestal to reinforce the pedestal and control the water head difference inside and outside the double-walled steel casing 1 according to the tide level; tie steel bars on the bottom formwork and pour concrete for pedestal reinforcement or expansion construction.

[0040] S7: Dismantling of the double-walled steel casing 1: After the foundation reinforcement is completed, open the connecting vessel 8 to inject water into the double-walled steel casing 1 to keep the water head inside and outside the double-walled steel casing 1 consistent, dismantle the top support and pull out the locking steel pipe piles 12, and dismantle and recycle the double-walled steel casing 1.

[0041] The double-walled steel box 1 is formed by a number of steel sheet piles that are interlocked and connected, and the double-walled steel box 1 is divided into two sections. In order to avoid the steel sheet piles that constitute the double-walled steel box 1 from being extended multiple times under the bridge, the height of the double-walled steel box 1 is set to only be able to be inserted 1m below the riverbed. The two sections of the double-walled steel box 1 are partially below the vertical projection plane of the bridge projection, and their setting direction is parallel to the direction of the water flow, so the impact force of the flowing water is small. Although it is not inserted into a deeper position of the riverbed, it can also meet the requirements of water bearing capacity. At the same time, in order to ensure the bearing capacity of the cofferdam and avoid water seepage during construction, locking steel pipe piles 12 are sequentially fastened on both sides of the double-walled steel casing 1. The locking steel pipe piles 12 can form a stable wall structure due to their unique locking structure, and have high bearing capacity and earthquake resistance. In bridge engineering, the locking steel pipe piles 12 can be used for the construction of piers, abutments and cofferdams. A stable supporting structure is formed through locking connection to improve the bearing capacity and stability of the cofferdam. The locking steel pipe piles 12 can quickly build a support system.

[0042] Therefore, two sections of double-walled steel casing 1 parallel to the direction of water flow are first assembled before construction, and can be quickly hoisted into place during construction to reduce construction time. The connection of the locking steel pipe piles 12 that are sequentially buckled on both sides of the double-walled steel casing 1 can provide partial support and bearing capacity for the double-walled steel casing 1, thereby preventing the double-walled steel casing 1 from collapsing due to insufficient bearing capacity. The locking steel pipe piles 12 are not under the bridge and have higher strength, requiring fewer extensions, so they can be quickly inserted. Through the rapid installation of the prefabricated double-walled steel casing 1 and the coordinated use with the locking steel pipe piles 12, the structural strength of the cofferdam can be improved while ensuring construction efficiency.

[0043] Since the water flow rate is generally fast during the construction of deep-water high pile caps, the installation accuracy of the double-walled steel casing 1 is difficult to control. In order to improve the installation accuracy of the double-walled steel casing 1 and improve the construction efficiency, in one embodiment, in S2, the inner positioning piles 2 on the inner side of the double-walled steel casing 1 are first installed, and the double-walled steel casing 1 is placed to a predetermined height position along the inner positioning piles 2. After adjusting the plane position and the overall verticality of the double-walled steel casing 1, the outer positioning piles 2 are inserted at the corresponding positions of the inner positioning piles 2 on the other side of the double-walled steel casing 1. After the inner positioning piles 2 and the outer positioning piles 2 are installed, they are used to clamp the double-walled steel casing 1;

[0044] That is, the positioning piles 2 are divided into inner positioning piles 2 and outer positioning piles 2, which are respectively located on the inner and outer sides of the double-walled steel casing 1. At the same time, the inner positioning piles 2 and the outer positioning piles 2 are arranged relatively to each other. During installation, the inner positioning piles 2 are installed first to assist the installation and positioning of the double-walled steel casing 1, and at the same time, the influence of water flow impact on the installation accuracy of the double-walled steel casing 1 can be reduced. A steel wire rope is arranged at the bottom of the inner positioning piles 2 to be connected to the bottom of the double-walled steel casing 1 and gradually tightened to guide the double-walled steel casing 1 to be installed in place, and then the outer positioning piles 2 are inserted to the outside of the double-walled steel casing 1 to correct the position of the double-walled steel casing 1 after installation, and to reinforce it at the same time to prevent the double-walled steel casing 1 from having insufficient bearing capacity due to being inserted into the shallow bottom of the riverbed.

[0045] Further, in S2, a blade foot is provided at the bottom of the double-walled steel casing 1, and after being lowered to the riverbed, a vibrating hammer is used to insert the double-walled steel casing 1 part as a whole into the riverbed bottom 1m, and a fixed sandbag 9 is suspended outside the double-walled steel cofferdam as a counterweight foot guard;

[0046] When the double-walled steel casing 1 is inserted into the bottom of the riverbed, it is necessary to remove the soil at the insertion position at the same time. The soil removal inside the double-walled steel casing 1 should be evenly and symmetrically removed from the middle to the blade foot. Pay attention to the correct sinking of the double-walled steel casing 1 at any time. Generally, it should be checked once every 1.0m of sinking, and corrected in time. At the same time, the abandoned soil outside the weir should be arranged reasonably, and the soil should be mainly abandoned downstream to prevent moisture erosion. During the sinking process of the double-walled steel casing 1, it is necessary to carry out meteorological and tidal bore detection and forecasting work, and reasonably control and utilize the interval time of tidal bore to organize construction as soon as possible. If a large tidal bore occurs when the double-walled steel casing 1 is sinking, construction should be stopped to ensure the safety of equipment and personnel. When removing mud and soil within the scope of the double-walled steel casing 1, attention should be paid to the changes in the elevation of the riverbed soil layer at any time and records should be kept. Arrange special personnel to observe the changes in the water head inside and outside the casing to prevent the water head difference from causing the water inside and outside the double-walled steel casing 1 at the bottom of the blade to penetrate or cause sand to turn over. A large amount of sand turning over will cause serious adverse consequences. First, it may cause the cofferdam to tilt. Second, due to the rapid influx of quicksand into the cofferdam, the water head inside the cofferdam rises rapidly, forming a large difference in the height of the water head inside and outside the cofferdam. When the sinking is close to the design elevation of about 2.0m, the sinking speed should be appropriately slowed down, and the amount and position of soil removal in the cofferdam should be controlled so that the double-walled steel casing 1 can sink steadily and be correctly positioned. After the double-walled steel casing 1 sinks to the design elevation by sucking mud, the divers will remove the mud and dirt within the thickness range of the bottom seal, throw in slabs and gravel, and the divers will level the slabs and gravel, and hang fixed sandbags 9 on the outside of the double-walled steel cofferdam as a counterweight foot guard.

[0047] In order to prevent water leakage at the CT-type interface of the locking steel pipe pile 12 , the gap between the surrounding purlin 4 and the locking steel pipe pile 12 is filled with an arc-shaped steel plate 11 .

[0048] In S6, a corbel is welded on the locking steel pipe pile 12 and abutted against the bottom of the bottom formwork. A hanging beam 5 and a lower longitudinal beam 6 are respectively arranged on the top and bottom surfaces of the pedestal and connected to the bottom formwork for suspending and supporting the bottom formwork of the pedestal reinforcement area. The hanging beam 5 and the lower longitudinal beam 6 are connected by threaded steel bars 7 to improve their connection stability and structural strength.

[0049] Finally, in S7, communicating vessels 8 are provided on both the inner and outer walls of the double-walled steel casing 1. When the inner wall communicating vessel 8 is closed, a waterless working environment is created inside the double-walled steel casing 1. When it is opened, water is injected into the double-walled steel casing 1. The outer wall communicating vessel 8 is always open, and the water head inside the double-walled steel casing 1 is kept basically consistent with the water head outside the double-walled steel casing 1.

[0050] After the bottom concrete 10 is poured and the strength meets the requirements, water can be pumped out at low tide. The inner support 3 is installed during the pumping process. Partial brackets and reinforcement braces are set at the end of the support to avoid local stress concentration effects. After the two layers of support are installed, the columns between the two layers of support are welded to form a frame system with two layers of inner support 3.

[0051] After the support is installed, continue pumping until all the water in the cofferdam is drained. During the pumping process, pay attention to the deformation of the cofferdam. If there are abnormal conditions such as leakage, stop the construction and check and solve them before continuing to pump. After the water in the cofferdam is basically drained, the pile head can be broken. First, cut off the locking steel pipe piles 12 above the bottom concrete 10 and lift them off in blocks.

[0052] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A steel cofferdam construction method for deep-water high-pile cap reinforcement construction, Features: The following steps are involved: S1: Construction preparation: making double-walled steel casing, locking steel pipe pile extension, top floor support and surrounding purlin; S2: Installation of double-walled steel casing: Insert and drive positioning piles of the double-walled steel casing on both sides of the restricted area under the old bridge, and hoist the double-walled steel casing as a whole to the working position. At this time, the connecting valve of the outer wall of the double-walled steel casing is normally open, and water is injected into the double-walled steel casing. The double-walled steel casing is hoisted close to the positioning piles, the top is hung and fixed, and the bottom is pulled close with steel wire ropes. The positioning piles on both sides of the inside and outside are used as guides and are used to clamp the double-walled steel casing after the installation is completed. The double-walled steel casing sinks to 1m below the riverbed by its own weight, and is assisted by vibrating hammers; S3: CT-type interfaces are reserved on both sides of the double-walled steel casing. Locking steel pipe piles are inserted in sequence at the interface positions on both sides. The two sides of several locking steel pipe piles are connected in sequence until they are closed at the corner piles; S4: Install the top purlin and inner support in the double-walled steel casing. After the purlin and inner support are pre-assembled, they are assembled in two parts at the bridge location; S5: pouring underwater bottom sealing concrete at the bottom of the double-walled steel casing; S6: After the bottom seal concrete reaches the design strength requirement, pump water to 0.5m below the lowest elevation of the cap reinforcement, install the bottom formwork at the bottom of the cap, and arrange the bottom formwork only on the outside of the cap to reinforce the cap, and control the water head difference inside and outside the double-wall steel casing according to the tide level; S7: Dismantling of the double-walled steel casing: After the reinforcement of the foundation is completed, open the connecting valve and inject water into the double-walled steel casing to keep the water head inside and outside the double-walled steel casing consistent, remove the top support and pull out the locking steel pipe piles, and dismantle and recycle the double-walled steel casing.

2. A steel cofferdam construction method for deep-water high-pile cap reinforcement construction according to claim 1, Features: In S2, first, the inner positioning piles on the inner side of the double-walled steel casing are installed, and the double-walled steel casing is placed to a predetermined height along the inner positioning piles. After adjusting the plane position and the overall verticality of the double-walled steel casing, the outer positioning piles are inserted into the corresponding positions of the inner positioning piles on the other side of the double-walled steel casing. After the inner positioning piles and the outer positioning piles are installed, they are used to clamp the double-walled steel casing.

3. A steel cofferdam construction method for deep-water high-pile cap reinforcement construction according to claim 1, Features: In S2, blade feet are set at the bottom of the double-walled steel casing. After being lowered to the riverbed, the double-walled steel casing is inserted into the riverbed bottom 1m with a vibrating hammer, and fixed sandbags are hung outside the double-walled steel cofferdam as counterweight feet.

4. A steel cofferdam construction method for deep-water high-pile cap reinforcement construction according to claim 1, Features: In the above S4, the gap between the surrounding purlin and the locking steel pipe pile is filled with a curved steel plate.

5. A steel cofferdam construction method for deep-water high-pile cap reinforcement construction according to claim 1, Features: In S6, a corbel is welded on the locking steel pipe pile and abuts against the bottom of the bottom formwork, and a hanging beam and a lower longitudinal beam are respectively arranged on the top and bottom surfaces of the pedestal and connected to the bottom formwork for suspending and supporting the bottom formwork of the pedestal reinforcement area.

6. A steel cofferdam construction method for deep-water high-pile cap reinforcement construction according to claim 1, Features: In S7, communicating vessels are provided on both the inner and outer walls of the double-walled steel casing. When the inner wall communicating vessel is closed, a waterless working environment is created inside the double-walled steel casing. When it is opened, water is injected into the double-walled steel casing. The outer wall communicating vessel is always open, and the water head inside the double-walled steel casing is kept basically consistent with the water head outside the double-walled steel casing.

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