Steel casing cofferdam construction device and construction method thereof

Abstract

The present application relates to the technical field of cofferdam, and particularly discloses a steel casing cofferdam construction device and a construction method thereof, the steel casing cofferdam construction device comprises a casing and a deviation prevention assembly, the casing is used for waterproofing, the deviation prevention assembly is arranged on the casing, the deviation prevention assembly comprises movable plates and sliding seats, a plurality of sliding seats are arranged on the inner wall of the casing and are distributed along the circumference of the casing at intervals, one movable plate is slidably connected to each sliding seat, the movable plate can move up and down relative to the casing, the movable plate is an arc plate, the curvature of the movable plate is the same as that of the casing, and the movable plate is attached to the inner wall of the casing; the steel casing cofferdam construction device and the construction method thereof can dig a foundation pit first, then put the casing into the foundation pit, support the casing by inserting the movable plates into the bottom of the foundation pit, and prevent the casing from tilting, so as to avoid the problem that it is difficult to drive the cofferdam into the foundation pit due to a large number of stones.

Description

TECHNICAL FIELD

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

[0002] Cofferdam pile cap construction is a common construction process in bridge, wharf or hydraulic structure, wherein the pile cap is a support platform of the bridge or structure, usually located at the top of the pile foundation, for transmitting the load of the upper structure to the pile foundation, and the cofferdam is a temporary or permanent water retaining structure commonly used in the fields of water conservancy projects, bridge construction and port construction, mainly used for forming a closed water retaining space around the construction area to facilitate foundation excavation, structure construction and other operations.

[0003] In bridge foundation construction, when the bridge pier and platform foundation is below the ground water level, various forms of earth cofferdams are built according to local materials; in deep and fast-flowing rivers, wooden sheet piles or steel sheet piles (single or double layer) cofferdams can be used, which can prevent and retain water and support the pit wall of the foundation pit.

[0004] Steel sheet pile cofferdam is the most commonly used type of sheet pile cofferdam. Steel sheet pile is a type of steel with a locking port, which has the advantages of high strength, easy to drive into hard soil, can be constructed in deep water, good water resistance, can be formed into various shapes of cofferdams as needed, and can be reused multiple times, so it is commonly used in bridge construction for cofferdams on top of open caissons, pipe column foundations, pile foundations and open excavation foundations.

[0005] A Chinese patent application with publication number CN116950102A discloses a water retaining cofferdam device, which comprises a first water retaining structure, a support structure and a top protection structure. The first water retaining structure includes a water retaining side plate and a top plate. The water retaining side plate has a cofferdam area enclosed inside. The cofferdam area has an opening at the top. The water retaining side plate has a connecting assembly at the bottom. 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 support structure is installed on the ground and fixed with the first water retaining structure through the connecting assembly. The top protection structure is arranged on the top of the water retaining side plate to shield the opening at the top of the cofferdam area and provide shielding protection.

[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;

[0010] The casing is used for waterproofing, and the anti-deflection component is arranged on the casing;

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The effect of the supporting ring is to improve the structural strength of the steel casing, so that the steel casing can bear the lateral pressure of the stone blocks and various additional loads generated during construction, prevent the cofferdam from deforming and collapsing, and ensure smooth construction.

[0022] Preferably, the bottom section of the movable plate is conical.

[0023] The effect of the conical bottom section of the movable plate is to reduce the resistance when the movable plate is inserted into the bottom surface of the foundation pit, thereby facilitating the insertion of the movable plate into the foundation pit, enabling the movable plate to penetrate deeper into the bottom surface of the foundation pit, and preventing the movable plate from tilting.

[0024] Preferably, the bottom of the movable plate is provided with a sawtooth structure.

[0025] Preferably, the top end of the steel casing is provided with an ear.

[0026] A construction method of a steel casing cofferdam construction device, which is applied to any one of the above-mentioned steel casing cofferdam construction devices, comprises the following steps:

[0027] Firstly, excavate the foundation pit, and use an external excavator to excavate the pile cap foundation pit to the corresponding size and depth;

[0028] Secondly, lower the cofferdam device, use an external crane to lift the steel casing, and vertically place the steel casing into the foundation pit;

[0029] Thirdly, backfill, use clay to backfill the gap between the foundation pit and the steel casing.

[0030] Fourthly, lay the cushion layer, after the water in the steel casing is drained, first lay the gravel cushion layer, level and waterproof the bottom surface of the foundation pit in the steel casing, then lay the concrete cushion layer, and reinforce the bottom surface of the foundation pit in the steel casing.

[0031] By adopting the above technical scheme, the present application has the following advantages:

[0032] 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

[0033] Figure 1 It is a structural schematic diagram of a steel casing cofferdam construction device according to an embodiment of the present invention.

[0034] Figure 2 It is a cross-sectional view of a steel casing cofferdam construction device according to an embodiment of the present invention.

[0035] Figure 3 2 is a front view of a movable panel according to an embodiment of the present invention.

[0036] Figure 4 2 is a side view of a movable panel according to an embodiment of the present invention.

[0037] Figure 5 yes Figure 2 Enlarged view of point A in the middle.

[0038] Figure 6 It is a front view of the support plate and the support rod according to an embodiment of the present invention.

[0039] Figure 7 It is a bottom view of the support plate according to an embodiment of the present invention.

[0040] Figure 8 4 is a front view of a slider according to an embodiment of the present invention.

[0041] Reference numerals:

[0042] 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

[0043] 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.

[0044] 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.

[0045] like Figure 1 and Figure 2 As 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.

[0046] like Figures 1 to 4As shown, the anti-deviation assembly comprises the movable plate 22 and the sliding seat 21, a plurality of sliding seats 21 are fixedly arranged on the inner wall of the casing 1 and evenly spaced along the inner wall of the casing 1, each sliding seat 21 forms a sliding channel extending along the axial direction of the casing 1 with the casing 1, and each sliding channel is slidably fitted with a movable plate 22, the movable plate 22 is an arc plate with the same curvature as the casing 1, the movable plate 22 is made of copper-nickel alloy and has a density greater than that of the casing 1, the movable plate 22 comprises a first section 221 and a second section 222, the width of the first section 221 is less than that of the second section 222, the bottom end of the first section 221 is fixedly connected to the top end of the second section 222, the first section 221 is slidably fitted in the sliding channel, the second section 222 is located below the sliding seat 21, the thickness of the second section 222 is greater than that of the first section 221 and the casing 1, and the bottom section of the second section 222 is tapered, and the bottom section of the second section 222 is further provided with a sawtooth structure, and the second section 222 can be inserted into the soil.

[0047] When the casing 1 is vertically distributed and the bottom end of the casing 1 is in contact with the soil, the movable plate 22 slides downward under the action of its own gravity and is inserted into the soil, and when the movable plate 22 stops moving downward, the soil can fix the movable plate 22, thereby fixing the casing 1 and preventing the casing 1 from deviating, if the bottom of the foundation pit is uneven, part of the casing 1 may be in a suspended state, by inserting the movable plate 22 into the soil and supporting the casing 1 from the inside, the casing 1 can be prevented from falling due to the suspended state of the bottom region.

[0048] As shown in Figure 1 , Figure 2 , Figures 5 to 7 The support assembly 3 comprises a support seat 31, a support rod 32 and a support plate 33, a plurality of support seats 31 are fixedly arranged at the upper region of the outer wall of the casing 1, the plurality of support seats 31 are evenly spaced along the circumferential direction of the casing 1, the number of support seats 31 is the same as that of sliding seats 21, and each support seat 31 is located outside the corresponding sliding seat 21, the support rod 32 is slidably fitted at the outer end of the support seat 31, the support rod 32 is vertically distributed, a return spring 34 is arranged between the bottom end of the support rod 32 and the support seat 31, the return spring 34 is sleeved on the support rod 32, the bottom end of the return spring 34 is fixedly connected to the bottom end of the support rod 32, and the top end of the return spring 34 is fixedly connected to the support seat 31, the support rod 32 can move up and down along its axial direction relative to the support seat 31, and the support plate 33 is fixedly connected to the bottom end of the support rod 32, and a plurality of downward extending conical spike structures 331 are arranged on the bottom surface of the support plate 33, which can be inserted into the ground.

[0049] By arranging the support assembly 3, the top of the casing 1 can be supported and fixed, and the pressure on the movable plate 22 can be shared, so that the movable plate 22 is not bent due to the heavy weight of the casing 1.

[0050] 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.

[0051] like Figure 1 and Figure 2 As 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.

[0052] 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:

[0053] 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.

[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 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.

[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] 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:

[0058] 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.

[0059] 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.

[0060] 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.

[0061] Fourthly, laying the cushion, waiting for the cofferdam area to ebb tide, two hours before the ebb tide to the mud surface, the water in the pile 1 is pumped out by the external pumping device, and then the sand cushion is laid at the bottom of the foundation pit, so as to level the bottom of the foundation pit. The sand cushion is laid layer by layer. When a layer of sand cushion is compacted, the next layer of sand cushion is laid. After the sand cushion is laid, the concrete cushion is laid, so as to enhance the bearing capacity of the foundation.

[0062] In other embodiments, the soil in the cofferdam area is soft. The construction method of the steel pile cofferdam construction device applied to the soft soil in the cofferdam area comprises the following steps:

[0063] Firstly, excavating the foundation pit. Firstly, the size of the pile 1 is determined, and then the position of the pile cap is measured and laid out. The installation position of the cofferdam construction device is determined. The long-arm excavator is used in cooperation with the short-arm excavator to carry out the excavation of the foundation pit. The depth of the foundation pit is greater than the depth of the soil. After the excavation is completed, the reinforcing plates are arranged around the foundation pit, so as to prevent the collapse of the foundation pit. A small amount of stones are put into the bottom of the foundation pit, so that the depth of the foundation pit is consistent with the depth of the soil.

[0064] Secondly, lowering the cofferdam device. A steel cable is installed on each lifting lug 7. Each steel cable is fixed to the hook of the external crane. The pile 1 is lifted into the foundation pit by the external crane. During the lowering process, the pile 1 is always kept in a vertical state. The support plates 33 gradually approach the bottom surface around the foundation pit during the lowering process. When the support plates 33 abut against the bottom surface, the conical spike structure 331 at the bottom surface of the support plate 33 is inserted into the bottom surface, so as to fix the support plate 33. The plurality of support plates 33 around the pile 1 are fixed to the ground, so as to realize the positioning of the pile 1. Then the pile 1 continues to be lowered. The support seat 31 moves synchronously with the pile 1, so that the support rod 32 moves upward relative to the support seat 31. The reset spring 34 is compressed. When the support rod 32 moves upward relative to the support seat 31, the support rod 32 can drive the sliding block 4 to move outward along the support seat 31 through the connecting plate 5, so as to make the sliding block 4 and the movable plate 22 disengage, and then release the limiting of the sliding block 4 to the movable plate 22. The movable plate 22 slides downward under the action of gravity. Since the pile 1 is slowly lowered by the external crane, the downward movement speed of the movable plate 22 is greater than the downward movement speed of the pile 1. The movable plate 22 is inserted into the bottom of the foundation pit earlier than the pile 1. When the bottom of the movable plate 22 is blocked by the stones in the soil and cannot move downward, the movable plate 22 stops moving downward. If the stones in the soil are unevenly distributed, the depth of each movable plate 22 inserted into the soil is different. Each movable plate 22 is vertically distributed. When the pile 1 abuts against the bottom surface of the foundation pit, the bottom surface of the foundation pit can support the pile 1. Even if there is part of soft soil in the foundation pit, the pile 1 can still keep a vertical posture due to the limiting of the movable plate 22 to the pile 1, so as to prevent the pile 1 from being deflected. Finally, the steel cable on the lifting lug 7 is released. Then the position of the pile 1 is reviewed to ensure that the center position of the pile cap meets the requirements.

[0065] The third step is backfilling, the waterproof board around the foundation pit is removed, the gap between the steel casing 1 and the side wall of the foundation pit is filled with clay and stone, the clay is fixed by the stone to prevent the clay from being washed away by the water flow, the stability of the steel casing 1 is ensured, and the water leakage between the bottom of the steel casing 1 and the riprap area foundation pit bottom gap is prevented.

[0066] The fourth step is to lay the cushion, wait for the cofferdam area to ebb tide, two hours before the ebb tide to the mud surface, the accumulated water in the steel casing 1 is pumped out by an external water pumping device, and then a sand and stone cushion is laid on the bottom of the foundation pit, thereby leveling the bottom of the foundation pit, the sand and stone cushion is laid layer by layer, and each time a layer of sand and stone cushion is compacted, the next layer of sand and stone cushion is started to be laid, after the sand and stone cushion is laid, a concrete cushion is laid, thereby enhancing the bearing capacity of the foundation.

[0067] Compared with the traditional steel sheet pile cofferdam construction method, the construction method of the steel casing cofferdam construction device of the present application can effectively reduce the construction difficulties caused by the obstruction of the riprap area stone, and can better adapt to the complex geology of the riprap area, and can also solve the problem of the stability of the riprap area cofferdam, the cylindrical structure of the steel casing 1 in the present application makes the integrity of the steel casing 1 better, the lateral sealing property is higher, the leakage of water is effectively prevented, in the riprap area, the connection of the cofferdam can be avoided from being damaged due to the extrusion and damage of the stone, thereby causing the waterproof performance to be reduced, and the stability can be improved by increasing the depth of the soil, which can withstand larger water and soil pressure and external impact force, ensure the safety of the project, and is more suitable for the geological conditions of the riprap area, the installation of the steel casing 1 of the present application can adopt various ways, thereby facilitating the cofferdam construction in the riprap area, and the influence of the terrain and the stone can be avoided.

[0068] Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

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; The anti-deflection assembly is characterized in that the anti-deflection assembly includes a movable plate and a sliding seat, a plurality of the sliding seats are provided on the inner wall of the casing and are spaced apart along the circumference of the casing, each of the sliding seats 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, the curvature of the movable plate is the same as that of the casing, the movable plate is in contact with the inner wall of the casing, the bottom cross-section of the movable plate is conical, and the movable plate can be inserted into the soil; The casing is also provided with a support assembly, which includes a support seat, a support rod and a support plate. A plurality of the support seats are arranged at the upper area of ​​the outer wall of the casing, and the plurality of the support seats are spaced apart along the circumference of the casing. Each of the support seats 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 provided at the bottom end of the support rod, and the support plate can stop at the ground. The support seat is provided with a slide groove, 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. 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.

2. The steel casing cofferdam construction device according to claim 1, 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.

3. The steel casing cofferdam construction device according to claim 1, 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.

4. 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.

5. The steel casing cofferdam construction device according to claim 1, characterized in that: The bottom of the movable plate is provided with a sawtooth structure.

6. 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.

7. 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 6, 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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