Steel casing cofferdam construction device and construction method thereof

Abstract

The invention relates to the technical field of cofferdams, in particular to a steel casing cofferdam construction device and a construction method.The steel casing cofferdam construction device comprises a casing and an anti-deviation assembly, the casing is used for preventing water, and the anti-deviation assembly is arranged on the casing and comprises a movable plate and a sliding seat; the multiple sliding seats are arranged on the inner wall of the pile casing and distributed at intervals in the circumferential direction of the pile casing, each sliding seat is in sliding fit with one movable plate, the movable plates can move up and down relative to the pile casing, the movable plates are arc-shaped plates, the radian of the arc-shaped plates is the same as that of the pile casing, and the movable plates can move up and down relative to the pile casing. The movable plate is attached to the inner wall of the pile casing. According to the steel pile casing cofferdam construction device and the construction method thereof, the foundation pit is excavated firstly, then the pile casing is placed in the foundation pit, the movable plate is inserted into the bottom of the foundation pit to support the pile casing, the pile casing is prevented from inclining, and therefore the problem that the cofferdam is difficult to be driven into the foundation pit due to the existence of a large number of stones is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of cofferdams, and in particular to a steel casing cofferdam construction device and a construction method thereof. Background Art

[0002] Cofferdam cap construction is a common construction process in bridges, docks or hydraulic structures. The cap is the supporting platform of the bridge or structure, usually located on top of the pile foundation, used to transfer the load of the superstructure to the pile foundation. The cofferdam is a common temporary or permanent water retaining structure in the fields of water conservancy projects, bridge construction and port construction. It is mainly used to form an enclosed water-proof space around the construction area to facilitate foundation excavation, structure construction and other operations.

[0003] During bridge foundation construction, when bridge piers and platform foundations are located below the surface water level, various forms of earthen weirs are built using local materials. In rivers with deeper water and faster flow rates, wooden or steel sheet piles (single or double layers) can be used to form cofferdams. The cofferdams can not only prevent water from entering and retain water, but also support the walls of the foundation pit.

[0004] Steel sheet pile cofferdams are the most commonly used. Steel sheet piles are a type of steel with a locking joint. Their advantages include high strength and ease of driving into hard soil; they can be constructed in deep water and offer excellent waterproofing properties; they can be formed into various shapes and reused multiple times. Therefore, they are often used in bridge construction for cofferdams at the top of caissons, as well as for pipe column foundations, pile foundations, and open-cut foundations.

[0005] A Chinese patent application with application publication number CN116950102A discloses a water retaining cofferdam device, which includes: a first water retaining structure, a supporting structure and a top protective structure. The first water retaining structure includes a water retaining side plate and a top plate. The water retaining side plate is surrounded by a cofferdam area, and the top of the cofferdam area has an opening. A connecting component is provided at the bottom of the water retaining side plate. The top plate is laid on the top of the water retaining side plate to protect the top of the water retaining side plate; the supporting structure is installed on the ground, and the supporting structure and the first water retaining structure are fixed by a connecting component; the top protective structure is provided on the top of the water retaining side plate to cover the top opening of the cofferdam area to play a shielding and protective role.

[0006] The above patent application blocks the water flow by setting a first water retaining structure to prevent the water from entering or flowing out of the cofferdam area, and forms a cofferdam area for construction by enclosing the water retaining side panels; by setting a supporting structure, the first water retaining structure is firmly connected to the ground to prevent it from collapsing or shifting; by setting a top protective structure that can block the top opening, the internal area of ​​the cofferdam is shielded and protected. The top protective structure can be a steel plate structure that is resistant to erosion and wear, or a polymer material with good weather resistance and aging resistance, which is lighter. By setting a top protective structure, the cofferdam area can be prevented from being eroded by rainwater or oxidized by ultraviolet radiation, forming a more stable construction environment and improving construction efficiency and project quality.

[0007] However, if there are a large number of irregular stones in the cofferdam area, the steel sheet piles may be easily obstructed by the stones during the driving process, making it difficult or even impossible to drive them in. At the same time, if there are large riprap or complex riprap accumulation, the steel sheet pile cofferdam structure may not be able to fit tightly to the foundation, and there is a problem that the bottom of the cofferdam lacks support and is prone to tipping over, thereby affecting the water-stopping effect of the cofferdam and the overall structural safety. Summary of the Invention

[0008] The present invention provides a steel casing cofferdam construction device and a construction method thereof, aiming to solve the problem in the related art that a large number of stones exist in the cofferdam area, making it difficult to drive steel sheet piles into the ground.

[0009] The steel casing cofferdam construction device of the present invention comprises: a casing and an anti-deflection component; The casing is used for waterproofing, and the anti-deflection component is arranged on the casing; The anti-deflection assembly includes a movable plate and a sliding seat. Multiple sliding seats are arranged on the inner wall of the casing and are distributed at intervals along the circumference of the casing. Each sliding seat is slidably fitted with a movable plate. The movable plate can move up and down relative to the casing. The movable plate is an arc-shaped plate with the same curvature as that of the casing. The movable plate fits against the inner wall of the casing and can be inserted into the soil.

[0010] Preferably, the casing is also provided with a support assembly, which includes a support seat, a support rod and a support plate. Multiple support seats are arranged at the upper area of ​​the outer wall of the casing, and multiple support seats are distributed at intervals along the circumference of the casing. Each support seat is slidably fitted with a support rod, and the support rod can move up and down relative to the support seat. The support plate is arranged at the bottom end of the support rod, and the support plate can stop at the ground.

[0011] The effect is that by arranging the support assembly on the peripheral side of the top end of the casing, when the casing is placed in the foundation pit, the support assembly can be supported on the ground around the foundation pit, thereby further preventing the casing from deflecting.

[0012] Preferably, a plurality of spaced-apart cone structures are provided on the bottom surface of the support plate, and the cone structures can be inserted into the ground.

[0013] The effect is that by arranging multiple cone-shaped thorn structures on the bottom surface of the support plate, when the support plate stops at the ground, the cone-shaped thorn structures at the bottom of the support plate can be inserted into the ground, thereby fixing the support plate on the ground and further preventing the casing from deflecting.

[0014] Preferably, a slide groove is provided on the support seat, and a slider is slidably fitted in the slide groove. The slider can pass through the side wall of the protective tube and extend into the protective tube. A matching groove is provided on the top of the movable plate, and the slider can extend into the matching groove to be clamped with the movable plate. A connecting plate is provided between the slider and the top of the support rod, and the two ends of the connecting plate are hinged to the slider and the support rod respectively.

[0015] The effect is that by extending the slider into the matching groove, the movable plate is engaged with the slider, and the slider can limit the movable plate to prevent the movable plate from moving downward, and then keep the movable plate retracted into the casing under normal conditions. Only when the casing is lowered to the foundation pit, the support plate stops at the bottom surface and the support rod moves upward relative to the support seat. The support rod pulls the slider through the connecting plate, thereby disengaging the slider from the movable plate, releasing the limit on the movable plate, and the movable plate can move downward under the action of gravity.

[0016] Preferably, a return spring is provided between the support rod and the support seat, and the return spring is connected to the support rod and the support seat respectively.

[0017] When recovering the cofferdam device, the movable plate is first lifted upward and reset using the external lifting device, and then the casing is lifted upward as a whole. When the support plate is out of contact with the bottom surface, the reset spring releases the elastic force, so that the support rod moves downward relative to the support seat. The support rod pushes the slider inward through the connecting plate, so that the slider extends into the matching groove of the movable plate, realizing the clamping connection between the slider and the movable plate, and limiting the downward movement of the movable plate.

[0018] Preferably, a support ring is further provided in the casing, and the support ring is located in the middle area of ​​the casing, and the support ring is in contact with the inner wall of the casing.

[0019] The effect is that the support ring can improve the structural strength of the casing, so that the casing can withstand the lateral pressure of the stones and various additional loads generated during the construction process, prevent the cofferdam from deformation and collapse, and ensure smooth construction.

[0020] Preferably, the bottom cross-section of the movable plate is conical.

[0021] The effect is that by setting the bottom cross-section of the movable plate to a cone, the resistance encountered when the movable plate is inserted into the bottom surface of the foundation pit is reduced, thereby facilitating the insertion of the movable plate into the foundation pit, allowing the movable plate to penetrate deeper into the bottom surface of the foundation pit and preventing the movable plate from tilting.

[0022] Preferably, a serrated structure is provided at the bottom of the movable plate.

[0023] Preferably, a lifting lug is provided at the top end of the casing.

[0024] A construction method for a steel casing cofferdam construction device, applied to any of the above-mentioned steel casing cofferdam construction devices, comprises the following steps: The first step is to dig the foundation pit. Use an external excavator to excavate the foundation pit of the foundation to the corresponding size and depth; The second step is to lower the cofferdam device, lift the casing using an external crane, and place it vertically into the foundation pit; The third step is backfilling, using clay to backfill the gap between the foundation pit and the casing.

[0025] The fourth step is to lay the cushion layer. After draining the water in the casing, first lay the sand and gravel cushion layer, level and waterproof the bottom surface of the foundation pit in the casing, and then lay the concrete cushion layer to reinforce the bottom surface of the foundation pit in the casing.

[0026] By adopting the above technical solution, the beneficial effects of the present invention are: The present invention relates to a method for constructing a steel casing cofferdam. The method first uses an external excavator to dig a foundation pit, then uses an external lifting device to lift the casing and slowly put it into a predetermined position in the foundation pit. During the process of lowering the casing, the casing is always kept in a vertical state. Under the action of gravity, the movable plate moves downward relative to the casing, and the bottom end of the movable plate extends downwardly from the casing and is inserted into the bottom of the foundation pit until the bottom of the movable plate stops contacting with the stones in the soil. Due to the uneven distribution of stones in the soil, the depth of each movable plate inserted into the soil is different. When the casing stops contacting the bottom surface of the foundation pit, the casing is separated from the external lifting device. If there is a situation where part of the casing is in a suspended state due to the unevenness of the foundation pit bottom, the multiple movable plates in the casing can support the casing from the inside, and even if the bottom of the casing is suspended, the casing can always be kept in a vertical state to prevent the casing from deflecting. At the same time, the movable plate can also improve the structural strength of the casing, and when backfilling clay, the casing can be supported from the inside to prevent the casing from being squeezed and deformed. The steel casing cofferdam construction device and construction method of the present invention can prevent the casing from tilting due to complex riprap accumulation in the foundation pit when the casing is placed, thereby ensuring the water-stopping effect of the cofferdam and the safety of the overall structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1It is a structural schematic diagram of a steel casing cofferdam construction device according to an embodiment of the present invention.

[0028] Figure 2 It is a cross-sectional view of a steel casing cofferdam construction device according to an embodiment of the present invention.

[0029] Figure 3 2 is a front view of a movable panel according to an embodiment of the present invention.

[0030] Figure 4 2 is a side view of a movable panel according to an embodiment of the present invention.

[0031] Figure 5 yes Figure 2 Enlarged view of point A in the middle.

[0032] Figure 6 It is a front view of the support plate and the support rod according to an embodiment of the present invention.

[0033] Figure 7 It is a bottom view of the support plate according to an embodiment of the present invention.

[0034] Figure 8 4 is a front view of a slider according to an embodiment of the present invention.

[0035] Reference numerals: 1. Casing; 21. Sliding seat; 211. Mounting groove; 22. Movable plate; 221. First section; 2211. Matching groove; 222. Second section; 3. Support assembly; 31. Support seat; 32. Support rod; 33. Support plate; 331. Cone structure; 34. Return spring; 4. Slider; 5. Connecting plate; 6. Support ring; 7. Lifting ear. DETAILED DESCRIPTION

[0036] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0037] like Figures 1 to 8 As shown, the steel casing cofferdam construction device of the present invention comprises: a casing 1, an anti-deflection assembly and a support assembly 3. The casing 1 is used to separate the water in the foundation pit, the anti-deflection assembly is used to prevent the casing 1 from deflecting, and the support assembly 3 is used to fix the casing 1 to prevent the casing 1 from shaking.

[0038] like Figure 1 and Figure 2As shown, specifically, the casing 1 is a cylindrical structure. The casing 1 is formed by bending and splicing standard steel plates. The steel plates are bent and connected end to end to form a cylindrical structure. The head and tail ends of the casing 1 are welded and fixed using internal and external submerged arc welding to form the casing 1 structure. The diameter and height of the casing 1 can be adjusted by the number of steel plates spliced, so as to meet the construction requirements of different heights and diameters, thereby reducing construction costs. Manual ultrasonic testing and physical and chemical inspection of the appearance ensure that there are no gaps in the welding position of the casing 1. The top and bottom of the casing 1 are thickened and reinforced within 50 cm to prevent deformation of the blade foot during construction. The casing 1 is then sprayed with an anti-corrosion coating. The top of the casing 1 is also fixed with a lifting lug 7 that can cooperate with the hook of an external crane to facilitate lifting the casing 1.

[0039] like Figures 1 to 4 As shown, the anti-deflection assembly includes a movable plate 22 and a sliding seat 21. A plurality of sliding seats 21 are fixedly arranged on the inner wall of the casing 1 and are evenly spaced along the inner wall of the casing 1. Each sliding seat 21 forms a slideway extending along the axial direction of the casing 1 with the casing 1. A movable plate 22 is slidably fitted in each slideway. The movable plate 22 is an arc-shaped plate with the same curvature as that of the casing 1. The movable plate 22 is made of copper-nickel alloy, and its density is greater than that of the casing 1. The movable plate 22 includes a first Segment 221 and the second segment 222, wherein the width of the first segment 221 is smaller than the width of the second segment 222, the bottom end of the first segment 221 is fixedly connected to the top end of the second segment 222, the first segment 221 slides in the slide, the second segment 222 is located below the sliding seat 21, the thickness of the second segment 222 is greater than the thickness of the first segment 221 and the casing 1, the bottom cross-section of the second segment 222 is conical, and the bottom of the second segment 222 is also provided with a serrated structure, and the second segment 222 can be inserted into the soil.

[0040] When the casing 1 is distributed vertically and the bottom end of the casing 1 contacts the soil, the movable plate 22 slides downward under the action of its own gravity and is inserted into the soil. When the movable plate 22 stops moving downward, the soil can fix the movable plate 22, and then the movable plate 22 fixes the casing 1 to prevent the casing 1 from tilting. If the bottom of the foundation pit is uneven, part of the casing 1 may be in a suspended state. The movable plate 22 is inserted into the soil and supports the casing 1 from the inside, thereby preventing the casing 1 from tipping over due to the bottom area being in a suspended state.

[0041] like Figure 1 、 Figure 2 、 Figures 5 to 7The support assembly 3 includes a support seat 31, a support rod 32 and a support plate 33. The support seats 31 are fixedly arranged at the upper area of ​​the outer wall of the casing 1, and the support seats 31 are evenly spaced along the circumference of the casing 1. The number of support seats 31 is the same as the number of sliding seats 21, and each support seat 31 is located at the outer side of the corresponding sliding seat 21. The support rod 32 is vertically distributed and a return spring 34 is provided between its bottom end and the support seat 31. The return spring 34 is sleeved on the support rod 32, and the bottom end of the return spring 34 is fixedly connected to the bottom end of the support rod 32. The top end of the return spring 34 is fixedly connected to the support seat 31, and the support rod 32 can move up and down relative to the support seat 31 along its axial direction. The support plate 33 is fixedly connected to the bottom end of the support rod 32, and a plurality of downwardly extending cone thorn structures 331 are provided on the bottom surface of the support plate 33, which can be inserted into the ground.

[0042] By providing the support assembly 3 , the top of the casing 1 can be supported and fixed, the pressure on the movable plate 22 can be shared, and the movable plate 22 can be prevented from being bent due to the heavy weight of the casing 1 itself.

[0043] like Figure 3 、 Figure 5 and Figure 8 As shown, a matching groove 2211 is provided at the top of the first section 221 of the movable plate 22, and a sliding groove extending along its length direction is provided on the support seat 31. A slider 4 is provided in the sliding groove, and the slider 4 slides with the support seat 31. The slider 4 can slide along the sliding groove, and a connecting hole is provided on the side wall of the casing 1. The inner end of the slider 4 can pass through the connecting hole and extend into the inner wall of the casing 1, and the slider 4 can extend into the matching groove 2211, thereby realizing the card connection with the movable plate 22, and then realizing the limiting of the movable plate 22, preventing the movable plate 22 from moving downward relative to the casing 1. A connecting plate 5 is provided between the slider 4 and the support rod 32. One end of the connecting plate 5 is hinged to the top end of the support rod 32, and the other end of the connecting plate 5 is hinged to the slider 4. When the support rod 32 moves up and down relative to the support seat 31, the support rod 32 can drive the slider 4 to slide in the slide groove through the connecting plate 5. When the support rod 32 moves upward relative to the support seat 31, the support rod 32 pulls the connecting plate 5, thereby moving the slider 4 away from the movable plate 22. When the support rod 32 moves downward relative to the support seat 31, the support rod 32 pushes the connecting plate 5, thereby moving the slider 4 closer to the movable plate 22. A flange is provided at the top end of the movable plate 22, which can stop against the slider 4. The flange can improve the structural strength of the movable plate 22 and prevent the movable plate 22 from breaking.

[0044] like Figure 1 and Figure 2As shown, the casing 1 is further provided with a support ring 6, which is located in the middle area inside the casing 1. The inner sidewall of the sliding seat 21 is provided with a mounting groove 211, and the outer sidewall of the support ring 6 is provided with a mating key that can fit into the mounting groove 211. The mounting groove 211 extends along the axial direction of the casing 1 and passes through the top of the sliding seat 21. The mating key can slide within the mounting groove 211. The support ring 6 is used to support the casing 1 and prevent the casing 1 from being squeezed by external forces and thus deformed. The staff can insert a corresponding number of support rings 6 into the casing 1 as needed. The greater the squeezing force on the casing 1, the more support rings 6 are required.

[0045] The construction method of the steel casing cofferdam construction device according to the embodiment of the present invention is applied to the steel casing cofferdam construction device according to the embodiment of the present invention, and includes the following steps: The first step is to dig the foundation pit. First, determine the size of the casing 1. In the embodiment of the present invention, the size of the casing 1 is 3 meters in diameter, 1.2 centimeters in wall thickness, 6.2 meters in height, the cofferdam construction device weighs 7 tons, and the depth of burial is 3.9 meters. Then measure the position of the pedestal and determine the installation position of the cofferdam construction device. Use a long-arm excavator in conjunction with a short-arm excavator to excavate the riprap area of ​​the foundation pit to the bottom elevation of the casing 1. The excavation depth is 3.9 meters and the foundation pit diameter is 4 meters.

[0046] When the support plate 33 stops contacting with the bottom surface, the cone thorn structure 331 on the bottom surface of the support plate 33 is inserted into the bottom surface, thereby fixing the support plate 33. The multiple support plates 33 around the casing 1 are all fixed on the ground, thereby realizing the positioning of the casing 1. Then the casing 1 continues to be lowered, and the support seat 31 moves synchronously with the casing 1, so that the support rod 32 moves upward relative to the support seat 31, the return spring 34 is compressed, and the support rod 32 can drive the slider 4 to move outward along the support seat 31 through the connecting plate 5 when it moves upward relative to the support seat 31, thereby causing the slider 4 to disengage from the movable plate 22, and then Finally, the steel cable on the lifting lug 7 is released, and the position of the casing 1 is checked again to ensure that the center position of the foundation platform meets the requirements.

[0047] The third step is backfilling. The gap between the casing 1 and the side wall of the foundation pit is filled with clay to ensure the stability of the casing 1 and prevent water leakage from the gap between the bottom of the casing 1 and the bottom of the foundation pit in the riprap area.

[0048] The fourth step is to lay the cushion layer and wait for the tide to recede in the cofferdam area. Two hours before the tide recedes to the mud surface, drain the accumulated water in the casing 1 through an external pumping device, and then lay a sand and gravel cushion layer at the bottom of the foundation pit to level the bottom of the foundation pit. The sand and gravel cushion layer is laid layer by layer. After each layer of sand and gravel cushion layer is compacted, the next layer of sand and gravel cushion layer is laid. After the sand and gravel cushion layer is laid, the concrete cushion layer is laid to enhance the bearing capacity of the foundation.

[0049] In some other embodiments, there are a large number of rocks in the cofferdam area, and the construction method of the steel casing cofferdam construction device applied to the cofferdam area having a large number of rocks includes the following steps: The first step is to dig a foundation pit. First, the size of the casing 1 is determined. In the embodiment of the present invention, the casing 1 has a diameter of 4.2 meters, a height of 6.2 meters, a weight of 7.7 tons, and a depth of 4 meters in the ground. Then, the position of the foundation plate is measured and staked out, and the installation position of the cofferdam construction device is determined. A long-arm excavator is used in conjunction with a short-arm excavator to carry out foundation pit excavation operations. The depth of the foundation pit is 4.5 meters and the diameter of the foundation pit is 5.5 meters. After the foundation pit excavation is completed, clay is backfilled into the foundation pit to fill the foundation pit to a depth of 4 meters.

[0050] When the support plate 33 stops contacting with the bottom surface, the cone thorn structure 331 on the bottom surface of the support plate 33 is inserted into the bottom surface, thereby fixing the support plate 33. The multiple support plates 33 around the casing 1 are all fixed on the ground, thereby realizing the positioning of the casing 1. Then the casing 1 continues to be lowered, and the support seat 31 moves synchronously with the casing 1, so that the support rod 32 moves upward relative to the support seat 31, the return spring 34 is compressed, and the support rod 32 can drive the slider 4 to move outward along the support seat 31 through the connecting plate 5 when it moves upward relative to the support seat 31, thereby causing the slider 4 to disengage from the movable plate 22, and then Finally, the steel cable on the lifting lug 7 is released, and the position of the casing 1 is checked again to ensure that the center position of the foundation platform meets the requirements.

[0051] The third step is backfilling. The gap between the casing 1 and the side wall of the foundation pit is filled with clay to ensure the stability of the casing 1 and prevent water leakage from the gap between the bottom of the casing 1 and the bottom of the foundation pit in the riprap area.

[0052] The fourth step is to lay the cushion layer and wait for the tide to recede in the cofferdam area. Two hours before the tide recedes to the mud surface, drain the accumulated water in the casing 1 through an external pumping device, and then lay a sand and gravel cushion layer at the bottom of the foundation pit to level the bottom of the foundation pit. The sand and gravel cushion layer is laid layer by layer. After each layer of sand and gravel cushion layer is compacted, the next layer of sand and gravel cushion layer is laid. After the sand and gravel cushion layer is laid, the concrete cushion layer is laid to enhance the bearing capacity of the foundation.

[0053] In some other embodiments, the soil in the cofferdam area is relatively soft, and the construction method of the steel casing cofferdam construction device applied to the cofferdam area with relatively soft soil includes the following steps: The first step is to dig the foundation pit. First, determine the size of the casing 1, then measure the position of the foundation platform, determine the installation position of the cofferdam construction device, and use a long-arm excavator in conjunction with a short-arm excavator to carry out foundation pit excavation. The depth of the foundation pit is greater than the burial depth. After the excavation is completed, reinforcement plates are set around the foundation pit to prevent the foundation pit from collapsing, and a small amount of stones are placed at the bottom of the foundation pit to keep the depth of the foundation pit consistent with the burial depth.

[0054] When the support plate 33 stops contacting with the bottom surface, the cone thorn structure 331 on the bottom surface of the support plate 33 is inserted into the bottom surface, thereby fixing the support plate 33. The multiple support plates 33 around the casing 1 are all fixed on the ground, thereby realizing the positioning of the casing 1. Then the casing 1 continues to be lowered, and the support seat 31 moves synchronously with the casing 1, so that the support rod 32 moves upward relative to the support seat 31, the return spring 34 is compressed, and the support rod 32 can drive the slider 4 to move outward along the support seat 31 through the connecting plate 5 when it moves upward relative to the support seat 31, thereby causing the slider 4 to disengage from the movable plate 22, and then Finally, the steel cable on the lifting lug 7 is released, and the position of the casing 1 is checked again to ensure that the center position of the foundation platform meets the requirements.

[0055] The third step is backfilling. The waterproof board around the foundation pit is removed. The gap between the casing 1 and the side wall of the foundation pit is filled with clay and stones. The clay is fixed by stones to prevent it from being washed away by water flow. The casing 1 is ensured to be stable to prevent water leakage from the gap between the bottom of the casing 1 and the bottom of the foundation pit in the riprap area.

[0056] The fourth step is to lay the cushion layer and wait for the tide to recede in the cofferdam area. Two hours before the tide recedes to the mud surface, drain the accumulated water in the casing 1 through an external pumping device, and then lay a sand and gravel cushion layer at the bottom of the foundation pit to level the bottom of the foundation pit. The sand and gravel cushion layer is laid layer by layer. After each layer of sand and gravel cushion layer is compacted, the next layer of sand and gravel cushion layer is laid. After the sand and gravel cushion layer is laid, the concrete cushion layer is laid to enhance the bearing capacity of the foundation.

[0057] Compared with the traditional steel sheet pile cofferdam construction method, the construction method of the steel casing cofferdam construction device of the present invention can effectively reduce the construction difficulties caused by the obstruction of stones in the riprap area, and can better adapt to the complex geology of the riprap area; it can also solve the problem of the stability of the cofferdam operation in the riprap area. The cylindrical casing 1 structure adopted in the present invention makes the casing 1 have better integrity and higher lateral sealing, which effectively prevents water leakage. In the riprap area, it can also avoid the damage to the connection of the cofferdam due to the squeezing and destruction of stones, thereby causing the waterproof performance to decline, and the stability can be improved by increasing the depth of soil burial, etc., and it can withstand greater water and soil pressure and external impact force, ensuring the safety of the project is more suitable for the geological conditions of the riprap area; the casing 1 of the present invention can be installed in a variety of ways, so that it is convenient to carry out cofferdam construction in the riprap area, and at the same time avoid the influence of terrain and stones.

[0058] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A steel casing cofferdam construction device, comprising: Casing and anti-deflection components; The casing is used for waterproofing, and the anti-deflection component is arranged on the casing; It is characterized in that the anti-deflection assembly includes a movable plate and a sliding seat, multiple sliding seats are arranged on the inner wall of the casing, and are distributed at intervals along the circumference of the casing, each sliding seat is slidably fitted with a movable plate, the movable plate can move up and down relative to the casing, the movable plate is an arc-shaped plate, and its curvature is the same as that of the casing, the movable plate is in contact with the inner wall of the casing, and the movable plate can be inserted into the soil.

2. The steel casing cofferdam construction device according to claim 1, characterized in that: The casing is also provided with a support assembly, which includes a support seat, a support rod and a support plate. Multiple support seats are arranged at the upper area of ​​the outer wall of the casing, and multiple support seats are distributed at intervals along the circumference of the casing. Each support seat is slidably fitted with a support rod, and the support rod can move up and down relative to the support seat. The support plate is arranged at the bottom end of the support rod, and the support plate can stop at the ground.

3. The steel casing cofferdam construction device according to claim 2, characterized in that: A plurality of spaced-apart cone structures are provided on the bottom surface of the support plate, and the cone structures can be inserted into the ground.

4. The steel casing cofferdam construction device according to claim 2, characterized in that: The support seat is provided with a sliding groove, and a slider is slidably fitted in the sliding groove. The slider can pass through the side wall of the protective tube and extend into the protective tube. The top of the movable plate is provided with a matching groove, and the slider can extend into the matching groove to be clamped with the movable plate. A connecting plate is provided between the slider and the top of the support rod, and the two ends of the connecting plate are hinged to the slider and the support rod respectively.

5. The steel casing cofferdam construction device according to claim 4, characterized in that: A return spring is provided between the support rod and the support seat, and the return spring is connected to the support rod and the support seat respectively.

6. The steel casing cofferdam construction device according to claim 1, characterized in that: A support ring is further provided in the casing. The support ring is located in the middle area of ​​the casing and fits the inner wall of the casing.

7. The steel casing cofferdam construction device according to claim 1, characterized in that: The bottom cross section of the movable plate is tapered.

8. The steel casing cofferdam construction device according to claim 7, characterized in that: The bottom of the movable plate is provided with a sawtooth structure.

9. The steel casing cofferdam construction device according to claim 1, characterized in that: The top end of the casing is provided with a lifting lug.

10. A construction method for a steel casing cofferdam construction device, applied to the steel casing cofferdam construction device according to any one of claims 1 to 9, characterized in that: The following steps are involved: The first step is to dig the foundation pit. Use an external excavator to excavate the foundation pit of the foundation to the corresponding size and depth; The second step is to lower the cofferdam device, lift the casing using an external crane, and place it vertically into the foundation pit; The third step is backfilling, using clay to backfill the gap between the foundation pit and the casing; The fourth step is to lay the cushion layer. After draining the water in the casing, first lay the sand and gravel cushion layer, level and waterproof the bottom surface of the foundation pit in the casing, and then lay the concrete cushion layer to reinforce the bottom surface of the foundation pit in the casing.

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