Steel pipe pile cofferdam and cofferdam construction method

Abstract

The invention relates to the technical field of underwater engineering, and discloses a steel pipe pile cofferdam and a cofferdam construction method.The steel pipe pile cofferdam comprises a plurality of steel pipe columns, the two sides of each steel pipe column are each provided with a first lock catch and a second lock catch which extend in the length direction of the steel pipe column, and steel pipe piles are buckled in pairs through the corresponding first lock catches and second lock catches; a sealing cavity is formed between the first lock catch and the second lock catch, and the sealing cavity is sequentially divided into a sealing cavity, an induction cavity and a grouting cavity from the outer side to the inner side of the cofferdam; the sealing cavity and the sensing cavity are separated through the elastic water stop lips, and shape memory alloy wires are arranged in the elastic water stop lips. The cofferdam has the beneficial effects that the first layer of sealing structure is formed by arranging the mechanical seal, then the second layer of sealing structure and the third layer of sealing structure are formed by the elastic water stop lip and the grouting area, and water located on the outer side of the cofferdam is prevented from entering the inner side of the cofferdam step by step through the three layers of sealing.

Description

Technical Field

[0001] The present invention relates to the field of underwater engineering technology, and in particular to a steel pipe pile cofferdam and a cofferdam construction method. Background Art

[0002] During road construction, more and more routes need to cross major rivers and reservoirs. Due to navigation and flood restrictions, bridge abutments need to be buried in the riverbed and embedded in the rock layer. During the construction of the abutment, a deep water foundation pit cofferdam is required.

[0003] In cofferdam projects, locking steel pipe piles can quickly construct enclosed spaces, which is more efficient than ordinary steel pipe pile welding and other connection methods, and has the characteristics of high connection strength and high stability. Existing locking steel pipe piles generally use CT-type buckle steel pipe piles. Since the T-shaped lock of the CT-type buckle steel pipe pile cannot be sealed on the C-shaped steel pipe, it is easy to cause water seepage, causing water outside the cofferdam to leak into the inside of the cofferdam through the gap of the CT-type lock, affecting the construction of the foundation inside the cofferdam. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the sealing effect of the current CT-type buckle steel pipe pile cofferdam is poor, which easily causes water seepage and affects the construction of the pedestal inside the cofferdam. The purpose is to provide a steel pipe pile cofferdam and a cofferdam construction method, in which a first locking buckle and a second locking buckle are buckled together to form a first layer of sealing structure to prevent water from the outside from entering the inside, and then a second layer of sealing structure is formed by an elastic water-stop lip. When the second layer of sealing leaks, a third layer of sealing structure is constructed. The three layers of sealing gradually prevent water on the outside of the cofferdam from entering the inside of the cofferdam.

[0005] The present invention is achieved through the following technical solutions: A steel pipe pile cofferdam comprises several steel pipe columns, both sides of which are provided with a first lock buckle and a second lock buckle extending along the length direction of the steel pipe columns, the steel pipe piles are fastened in pairs by the corresponding first lock buckle and the second lock buckle, a sealed cavity is formed between the first lock buckle and the second lock buckle, and the sealed cavity is sequentially divided into a sealing cavity, a sensing cavity and a grouting cavity from the outside to the inside of the cofferdam; several elastic water-stop lips, the sealing cavity and the sensing cavity are separated by the elastic water-stop lips, shape memory alloy wire is provided in the elastic water-stop lips, a grouting pipe is installed in the grouting cavity, the grouting pipe is connected to the output end of the grouting pump, and when there is a leakage at the elastic water-stop lip, grouting is injected into the grouting cavity to form a grouting sealing layer.

[0006] The beneficial effect of the present invention is that the steel pipe piles are fastened together by the corresponding first lock buckle and the second lock buckle to form a first layer of sealing structure that blocks water from the outside of the cofferdam from entering the inside of the cofferdam, and then a sealed cavity is formed between the first lock buckle and the second lock buckle, and the sealed cavity is sequentially divided into a sealing cavity, a sensing cavity and a grouting cavity along the outside to the inside of the cofferdam, so that when the first layer of sealing structure is not enough to block the water from the outside of the cofferdam, a second layer of sealing structure is formed by the elastic water-stop lip after radial expansion to block the water from the outside of the cofferdam from entering the inside; and by setting a sensing cavity, when the pressure fluctuation range in the sensing cavity is detected to be greater than the set threshold, the grouting equipment is started to grout the grouting cavity to form a third layer of sealing (grouting sealing layer), and rapid grouting is achieved, and the three layers of sealing prevent the water on the outside of the cofferdam from entering the inside of the cofferdam step by step, thereby improving the anti-seepage level of the joint.

[0007] In some embodiments, the cross-section of the first lock buckle is Ω-shaped, and two first connecting buckles are provided on the side of the first lock buckle away from the steel pipe column. The two first connecting buckles are symmetrically arranged and located on the outside of the first lock buckle. The cross-section of the second lock buckle is C-shaped, and the open end of the second lock buckle is provided with a second connecting buckle. The two second connecting buckles respectively cooperate with the corresponding first connecting buckles to form a first sealing structure, and the first sealing structure is located on the outside of the sealing cavity. By setting the cross-section of the first buckle to Ω-shape and cooperating with the second lock buckle with a C-shaped cross-section, the first sealing structure is located on the outside of the sealing cavity, providing installation space for the subsequent second and third sealing structures, and further fixing and enhancing the connection stability between the lock buckle and the steel pipe pile, ensuring that under complex water pressure and external forces, the lock buckle and the steel pipe pile will not undergo relative displacement, thereby ensuring the sealing and safety of the entire cofferdam structure.

[0008] In some embodiments, the first and second connecting buckles are each provided with a concave-convex stopper where they interlock, and the stopper extends along the length of the corresponding connecting buckle. Providing the concave-convex stopper on the first and second connecting buckles further prevents relative displacement of the first and second connecting buckles during operation, further ensuring the sealing and safety of the entire cofferdam structure.

[0009] In some embodiments, the inner cavity of the second lock buckle is provided with a first sealing portion, the two ends of the first sealing portion are respectively sealedly connected to the inner side of the second lock buckle, and a semicircular closed cavity is formed on the inner side of the second lock buckle. A support portion extending toward the first connection buckle is provided on the side of the first sealing portion away from the closed cavity, and the elastic water stop lip is located between the support portion and the first lock buckle. By providing the first sealing portion on the inner side of the second lock buckle, a semicircular closed cavity is formed on the inner side of the second lock buckle, thereby improving the strength and rigidity of the second lock buckle and providing support force for the support portion. The provision of the support portion reduces the gap distance with the outer side of the first lock buckle and provides installation space for the elastic water stop lip.

[0010] In some embodiments, a second sealing portion extending toward the first connecting buckle is provided on a side of the first sealing portion away from the closed cavity, and a flexible sealing portion is provided at a free end of the second sealing portion, the flexible sealing portion abutting against the outer side of the corresponding first locking buckle to separate the sensing cavity and the grouting cavity. By providing the second sealing portion and providing a flexible sealing portion at the free end of the second sealing portion abutting against the outer side of the first locking buckle, a certain contact stress is generated between the flexible sealing portion and the first locking buckle, thereby separating the sensing cavity from the grouting cavity and preventing the grouting liquid from contaminating the sensing equipment.

[0011] In some embodiments, a first mounting groove is provided on the outer side of the first connecting buckle, and a second mounting groove corresponding to the first mounting groove is provided on the free end of the support portion. The first mounting groove and the second mounting groove both have arc-shaped cross-sections, and the two sides of the elastic water-stop lip respectively cooperate with the first mounting groove and the second mounting groove. By providing the first mounting groove on the outer side of the first connecting buckle and the second mounting groove on the free end of the support portion, installation of the elastic water-stop lip is facilitated.

[0012] In some embodiments, the elastic water-stop lip is a hollow cylinder as a whole, the material of the elastic water-stop lip is EPDM rubber, and a shape memory alloy wire is arranged inside the EPDM rubber. The material of the shape memory alloy wire is Ni-Ti alloy, and the pre-set shape of the shape memory alloy is a circular ring. The shape memory alloy wires include several and are evenly distributed along the length direction of the elastic water-stop lip. The shape memory alloy wires are all spiral and arranged along the circumference of the elastic water-stop lip. The elastic waterstop lip is made of EPDM rubber, which is convenient for taking advantage of the excellent ozone aging resistance and high elasticity of EPDM. It has no cracking for 500 hours under an ozone concentration of 50pphm. It also has good weather resistance and can work for a long time in an environment of -40℃ to 80℃, thereby improving the overall life of the elastic waterstop lip. In addition, several spiral shape memory alloy wires are arranged in the EPDM rubber, so that when water is poured into the sealing cavity, the shape memory alloy wires of the elastic waterstop lip trigger phase change under the action of water pressure, driving the elastic waterstop lip to expand radially, thereby forming a dynamic extrusion seal with the first mounting groove and the second mounting groove.

[0013] In some embodiments, multiple pressure-sensing membranes are provided and electrically connected to the control terminal. The membranes are evenly distributed along the length of the support portion. Each membrane is a PVDF piezoelectric film, and the spacing between each membrane is 250 mm. By evenly distributing the pressure-sensing membranes along the length of the support portion, pressure detection at a corresponding height is achieved.

[0014] The present invention also provides a cofferdam construction method, which is based on the above-mentioned steel pipe pile cofferdam and includes the following steps: S1. First, install the pressure-sensing membrane and calibrate the installation position. Then, drive the steel pipe piles and fasten the first and second connectors of adjacent steel pipe piles. Pump out the water in the sealed cavity and install the elastic waterstop lip. Install the grouting pipe in the grouting cavity. Install a grouting pump outside the cofferdam and connect the output of the grouting pump to the grouting pipe. Electrically connect the pressure-sensing membrane and the grouting pump to the control terminal. S2. Install a support structure inside the cofferdam and pump water from the inside to the outside of the cofferdam; S3. Water is poured into the sealing chamber, and the elastic waterstop lip expands radially under the action of water pressure and forms a dynamic extrusion seal with the side walls of the first and second mounting grooves; S4. When the value detected by the pressure sensing membrane is greater than the preset pressure fluctuation value, the control terminal sends an opening command to the grouting pump to perform grouting in the grouting area, and the grouting height is greater than the elevation of the pressure sensing membrane that detects the pressure fluctuation value greater than the preset pressure fluctuation value.

[0015] By installing the pressure-sensing membrane first and then driving the steel pipe piles, the difficulty of installing the pressure-sensing membrane is reduced. The water in the sealed cavity is pumped out before installing the elastic water-stop lip and the grouting pipe to prevent the elastic water-stop lip from radially expanding under the action of water pressure when it is installed. The pressure-sensing membrane and the grouting pump are also electrically connected to the control terminal, so that when the value detected by the pressure-sensing membrane is greater than the preset pressure fluctuation value, the control terminal sends an open command to the grouting pump to grout the grouting area.

[0016] In some embodiments, the contact stress of the dynamic extrusion seal is 1.2 MPa-1.5 MPa, and the preset pressure fluctuation value is ≥0.05 MPa. By setting the contact stress of the dynamic extrusion seal to 1.2 MPa-1.5 MPa, the sealing effect of the elastic water stop lip is ensured.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The first connecting buckle and the second connecting buckle are interlocked to form a first layer of sealing structure that prevents water from the outside of the cofferdam from entering the inside. When water is poured into the sealing cavity, the shape memory alloy wire of the elastic water-stop lip triggers a phase change under the action of water pressure, driving the elastic water-stop lip to expand radially, forming a second layer of sealing structure that prevents water from the outside of the cofferdam from entering the inside. In addition, by setting a sensing cavity, when the sensing cavity detects that the pressure fluctuation range in the cavity is greater than the set threshold, the grouting equipment is started to grout the grouting cavity to form a third layer of sealing, thereby improving the anti-seepage level of the joint.

[0018] 2. By electrically connecting the PVDF piezoelectric film and the grouting pump to the control terminal, a real-time perception-analysis-response closed-loop management of leakage is achieved, allowing the grouting system to complete grouting within 30 seconds, improving the grouting effect and further enhancing the joint anti-seepage grade.

[0019] 3. Concave and convex limiting parts are provided on the first connecting buckle and the second connecting buckle to prevent relative displacement between the first connecting buckle and the second connecting buckle, thereby further ensuring the sealing and safety of the entire cofferdam structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings: Figure 1 is a cross-sectional view of the steel pipe column in the present invention; Figure 2It is a cross-sectional view of the first lock buckle and the second lock buckle in the present invention when they are matched; Figure 3 is a cross-sectional view of the second lock buckle in the present invention; Figure 4 is a cross-sectional view of the first lock buckle in the present invention; Figure 5 This is a partial structural diagram of the elastic water stop lip in the present invention.

[0021] Markings and corresponding parts names in the accompanying drawings: Steel pipe column 10, first locking buckle 11, first connecting buckle 12, limiting part 13, first mounting groove 14, second locking buckle 21, sealing cavity 211, first sealing part 22, supporting part 23, second mounting groove 28, pressure sensing membrane 25, grouting cavity 26, sensing cavity 27, second sealing part 29, flexible seal 291, second connecting buckle 24, elastic water-stop lip 30, memory alloy 31. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0023] Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment," "an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combinations and / or subcombinations. Furthermore, it will be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes only and are not necessarily drawn to scale. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] In the description of the present invention, the terms "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0025] The terms "first" and "second" used in the present invention are only used to distinguish corresponding components for the sake of clarity of description and are not intended to limit any order or emphasize importance. In addition, the term "connected" used in this article can refer to direct connection or indirect connection via other components unless otherwise specified.

[0026] Example 1 See also Figure 1-Figure 5 , this embodiment 1 provides a steel pipe pile cofferdam, including several steel pipe columns 10, both sides of the steel pipe columns 10 are provided with a first lock buckle 11 and a second lock buckle 21 extending along the length direction thereof, the steel pipe piles are buckled in pairs through the corresponding first lock buckle 11 and the second lock buckle 21, and a sealed cavity is formed between the first lock buckle 11 and the second lock buckle 21, and the sealed cavity is sequentially divided into a sealing cavity 211, a sensing cavity 27 and a grouting cavity 26 along the outside to the inside of the cofferdam; several elastic water-stop lips 30, the sealing cavity 211 and the sensing cavity 27 are separated by the elastic water-stop lips 30, a shape memory alloy 31 wire is provided in the elastic water-stop lip 30, a grouting pipe is installed in the grouting cavity 26, the grouting pipe is connected to the output end of the grouting pump, and when there is a leakage at the elastic water-stop lip 30, grouting is injected into the grouting cavity 26 to form a grouting sealing layer.

[0027] See also Figures 1-4 The cross section of the first lock buckle 11 is Ω-shaped. Two first connecting buckles 12 are provided on the side of the first lock buckle 11 away from the steel pipe column 10. The two first connecting buckles 12 are symmetrically arranged and located on the outside of the first lock buckle 11. The cross section of the second lock buckle 21 is C-shaped. The open ends of the second lock buckle 21 are each provided with a second connecting buckle 24. The two second connecting buckles 24 respectively cooperate with the corresponding first connecting buckles 12 to form a first sealing structure. The first sealing structure is located on the outside of the sealing cavity. By setting the cross section of the first buckle to Ω-shaped and cooperating with the second lock buckle 21 with a C-shaped cross section, the first sealing structure is located on the outside of the sealing cavity, providing installation space for the subsequent second and third sealing structures, and further fixing and enhancing the connection stability between the lock buckle and the steel pipe pile, ensuring that under complex water pressure and external forces, the lock buckle and the steel pipe pile will not undergo relative displacement, thereby ensuring the sealing and safety of the entire cofferdam structure.

[0028] See also Figures 1-4The first and second connecting buckles 12, 24 are each provided with a concave-convex stopper 13 at their interlocking locations. The stopper 13 extends along the length of the corresponding buckle. The provision of these concave-convex stoppers 13 on the first and second connecting buckles 12, 24 enhances the mechanical engagement between the first and second connecting buckles 12, 24, further preventing relative displacement between the two buckles and ensuring the sealing and safety of the entire cofferdam structure. Specifically, the stopper 13 can be configured in a serrated shape.

[0029] See also Figures 1-4 The inner cavity of the second lock buckle 21 is provided with a first sealing portion 22. The two ends of the first sealing portion 22 are respectively sealed and connected to the inner side of the second lock buckle 21, and a semicircular closed cavity is formed on the inner side of the second lock buckle 21. A support portion 23 extending toward the first connecting buckle 12 is provided on the side of the first sealing portion 22 away from the closed cavity. The elastic water-stop lip 30 is located between the support portion 23 and the first lock buckle 11. By providing the first sealing portion 22 on the inner side of the second lock buckle 21, a semicircular closed cavity is formed on the inner side of the second lock buckle 21, thereby improving the strength and rigidity of the second lock buckle 21 and providing support force for the support portion 23. The support portion 23 is provided to reduce the gap distance with the outer side of the first lock buckle 11 and provide installation space for the elastic water-stop lip 30.

[0030] See also Figures 1-4 A second sealing portion 29 extending toward the first connecting buckle 12 is provided on the side of the first sealing portion 22 away from the closed cavity. A flexible sealing portion 291 is provided at the free end of the second sealing portion 29. The flexible sealing portion 291 abuts against the outer side of the corresponding first locking buckle 11 to separate the sensing cavity 27 from the grouting cavity 26. By providing the second sealing portion 29 and providing the flexible sealing portion 291 at the free end of the sealing portion to abut against the outer side of the first locking buckle 11, a certain contact stress is generated between the flexible sealing portion 291 and the first locking buckle 11, thereby separating the sensing cavity 27 from the grouting cavity 26.

[0031] See also Figures 1-4 The first connecting buckle 12 is provided with a first mounting groove 14 on its outer side, and the support portion 23 is provided with a second mounting groove 28 corresponding to the first mounting groove 14 on its free end. The cross-sections of the first mounting groove 14 and the second mounting groove 28 are both arc-shaped. The two sides of the elastic water stop lip 30 respectively cooperate with the first mounting groove 14 and the second mounting groove 28. By providing the first mounting groove 14 on the outer side of the first connecting buckle 12 and the second mounting groove 28 on the free end of the support portion 23, the installation of the elastic water stop lip 30 is facilitated.

[0032] See also Figure 1 and Figure 5 The elastic water-stop lip 30 is hollow cylindrical as a whole. The material of the elastic water-stop lip 30 is EPDM rubber. A shape memory alloy 31 wire is arranged in the EPDM rubber. The material of the shape memory alloy 31 wire is Ni-Ti alloy. The preset shape of the shape memory alloy 31 is a circular ring. The shape memory alloy 31 wires include several and are evenly distributed along the length direction of the elastic water-stop lip 30. The shape memory alloy 31 wires are all spiral and are arranged along the circumference of the elastic water-stop lip 30. The elastic waterstop lip 30 is made of EPDM rubber, which is convenient for taking advantage of the excellent ozone aging resistance and high elasticity of EPDM. It has no cracking for 500 hours under an ozone concentration of 50pphm. It also has good weather resistance and can work for a long time in an environment of -40°C to 80°C, thereby improving the overall life of the elastic waterstop lip 30. In addition, several spiral shape memory alloy wires 31 are arranged in the EPDM rubber, so that when water is poured into the sealing cavity 211, the shape memory alloy wires 31 of the elastic waterstop lip 30 are triggered to phase change under the action of water pressure, driving the elastic waterstop lip 30 to expand radially, thereby forming a dynamic extrusion seal with the first mounting groove 14 and the second mounting groove 28, effectively preventing water leakage.

[0033] See also Figure 1 and Figure 5 The device also includes a plurality of pressure-sensing membranes 25 , each electrically connected to the control terminal. The membranes 25 are evenly distributed along the length of the support portion 23 and are constructed of PVDF piezoelectric film. Each membrane 25 is spaced 250 mm apart. By evenly distributing the pressure-sensing membranes 25 along the length of the support portion 23 , pressure detection at a corresponding height is achieved.

[0034] Example 2 See also Figure 1-Figure 5 This embodiment 2 provides a cofferdam construction method based on the above-mentioned steel pipe pile cofferdam, including the following steps: S1. First, install the pressure-sensing membrane 25 and calibrate the installation position. Then, drive the steel pipe piles and engage the first connecting buckles 12 and second connecting buckles 24 of adjacent steel pipe piles. Pump out the water in the sealed cavity and install the elastic waterstop lip 30. Install the grouting pipe in the grouting cavity 26. Install a grouting pump outside the cofferdam and connect the output end of the grouting pump to the grouting pipe. Electrically connect the pressure-sensing membrane 25 and the grouting pump to the control terminal. Among them, the inner diameter of the micro-grouting pipe can be set to 2 mm -3 mm, and connected to the external micro-grouting pump with a flow rate of 2L / min through a quick-plug connector, and the grouting pressure is 0.5-1.0MPa.

[0035] When installing the pressure-sensing membrane 25, conductive silver glue (bonding strength ≥3 MPa) is used to completely adhere the membrane 25 to the inner wall of the support 23, ensuring a bonded surface area of ≥80%. The edges are sealed with silicone rubber (1 mm thick) to prevent moisture from intruding into the back of the sensor. A 5 μm thick polyimide coating is applied to the surface of the pressure-sensing membrane 25, which is resistant to water pressures ≥2 MPa and temperatures ranging from -40°C to 80°C. The pressure-sensing membrane 25 is connected to an IP68-rated waterproof connector on the top of the locking buckle via four silver-plated wires. The connector incorporates a built-in signal amplification circuit (gain 10 dB) to enhance interference resistance for weak charge signals (≤10 pC).

[0036] S2. Install a support structure inside the cofferdam and pump water from the inside to the outside of the cofferdam; S3. Water is poured into the sealing chamber 211, and the elastic water stop lip 30 expands radially under the action of water pressure and forms a dynamic extrusion seal with the side walls of the first mounting groove 14 and the second mounting groove 28; S4. When the value detected by the pressure-sensing membrane 25 exceeds the preset pressure fluctuation value, the control terminal issues an on command to the grouting pump to inject grout into the grouting area, with the grouting height being greater than the elevation of the pressure-sensing membrane 25 at which the pressure fluctuation value greater than the preset pressure fluctuation value was detected. Grouting is only performed in the corresponding position of the grouting cavity when leakage occurs between the elastic waterstop lip 30 and the sidewalls of the first and second mounting grooves 14 and 28, thus saving grouting volume. Grouting is also performed immediately upon detection of a leak, preventing grouting from being injected only after the leak has increased. This improves the sealing effect of the grouting and further saves grouting volume.

[0037] The difficulty of installing the pressure sensing membrane 25 is reduced by first installing the pressure sensing membrane 25 and then inserting the steel pipe piles. The water in the sealed cavity is pumped out before installing the elastic water stop lip 30 and the grouting pipe to prevent radial expansion under the action of water pressure when the elastic water stop lip 30 is installed. The pressure sensing membrane 25 and the grouting pump are also electrically connected to the control terminal, so that when the value detected by the pressure sensing membrane 25 is greater than the preset pressure fluctuation value, the control terminal sends an open command to the grouting pump to grout the grouting area.

[0038] In some embodiments, the contact stress of the dynamic extrusion seal is 1.2 MPa-1.5 MPa, and the preset pressure fluctuation value is ≥0.05 MPa. By setting the contact stress of the dynamic extrusion seal to 1.2 MPa-1.5 MPa, the sealing effect of the elastic water stop lip 30 is ensured.

[0039] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A steel pipe pile cofferdam, characterized in that: include: Several steel pipe columns, each of which is provided with a first lock buckle and a second lock buckle extending along its length on both sides, wherein the steel pipe piles are fastened in pairs by the corresponding first lock buckle and the second lock buckle, and a sealed cavity is formed between the first lock buckle and the second lock buckle, and the sealed cavity is sequentially divided into a sealing cavity, a sensing cavity, and a grouting cavity from the outside to the inside of the cofferdam; Several elastic water-stop lips are provided, and the sealing cavity and the sensing cavity are separated by the elastic water-stop lips. Shape memory alloy wire is provided in the elastic water-stop lips. A grouting pipe is installed in the grouting cavity. The grouting pipe is connected to the output end of the grouting pump. When there is a leakage at the elastic water-stop lips, grouting is injected into the grouting cavity to form a grouting sealing layer.

2. The steel pipe pile cofferdam according to claim 1, characterized in that: The cross-section of the first lock buckle is Ω-shaped, and two first connecting buckles are provided on the side of the first lock buckle away from the steel pipe column. The two first connecting buckles are symmetrically arranged and located on the outside of the first lock buckle. The cross-section of the second lock buckle is C-shaped, and the open ends of the second lock buckle are each provided with a second connecting buckle. The two second connecting buckles respectively cooperate with the corresponding first connecting buckle to form a first sealing structure, and the first sealing structure is located on the outside of the sealing cavity.

3. The steel pipe pile cofferdam according to claim 2, characterized in that: The engaging positions of the first connecting buckle and the second connecting buckle are both provided with concave-convex matching limiting parts, and the limiting parts extend along the length direction of the corresponding connecting buckle.

4. The steel pipe pile cofferdam according to claim 1, characterized in that: The inner cavity of the second lock buckle is provided with a first sealing part, the two ends of the first sealing part are respectively sealed and connected to the inner side of the second lock buckle, and a semicircular closed cavity is formed on the inner side of the second lock buckle. The first sealing part is provided with a support part extending toward the direction of the first connecting buckle on the side away from the closed cavity, and the elastic water-stop lip is located between the support part and the first lock buckle.

5. The steel pipe pile cofferdam according to claim 4, characterized in that: A second sealing portion extending toward the first connecting buckle is provided on the side of the first sealing portion away from the closed cavity, and a flexible sealing portion is provided at the free end of the second sealing portion. The flexible sealing portion abuts against the outer side of the corresponding first lock buckle to separate the sensing cavity and the grouting cavity.

6. The steel pipe pile cofferdam according to claim 4, characterized in that: A first mounting groove is provided on the outer side of the first connecting buckle, and a second mounting groove corresponding to the first mounting groove is provided at the free end of the support portion. The cross-sections of the first mounting groove and the second mounting groove are both arc-shaped, and the two sides of the elastic water-stop lip are respectively matched with the first mounting groove and the second mounting groove.

7. The steel pipe pile cofferdam according to claim 4, characterized in that: The elastic water-stop lip is hollow cylindrical as a whole. The material of the elastic water-stop lip is EPDM rubber. A shape memory alloy wire is arranged inside the EPDM rubber. The material of the shape memory alloy wire is Ni-Ti alloy. The preset shape of the shape memory alloy is a circular ring. The shape memory alloy wires include several and are evenly distributed along the length direction of the elastic water-stop lip. The shape memory alloy wires are all spiral and are arranged along the circumference of the elastic water-stop lip.

8. The steel pipe pile cofferdam according to claim 4, characterized in that: It also includes a pressure sensing membrane, which is provided in plurality and electrically connected to the control terminal. The plurality of pressure sensing membranes are evenly distributed along the length direction of the support portion. The pressure sensing membrane is a PVDF piezoelectric film, and the spacing between each pressure sensing membrane is 250mm.

9. A cofferdam construction method, characterized in that: The implementation of the steel pipe pile cofferdam according to any one of claims 1 to 8 comprises the following steps: S1. First, install the pressure-sensing membrane and determine the installation position elevation. Then, drive the steel pipe piles and fasten the first and second connectors of adjacent steel pipe piles. Pump out the water in the sealed cavity and install the elastic waterstop lip. Install the grouting pipe in the grouting cavity. Install a grouting pump outside the cofferdam and connect the output of the grouting pump to the grouting pipe. Electrically connect the pressure-sensing membrane and the grouting pump to the control terminal. S2. Install a support structure inside the cofferdam and pump water from the inside to the outside of the cofferdam; S3. Water is poured into the sealing chamber, and the elastic waterstop lip expands radially under the action of water pressure and forms a dynamic extrusion seal with the side walls of the first and second mounting grooves; S4. When the value detected by the pressure sensing membrane is greater than the preset pressure fluctuation value, the control terminal sends an opening command to the grouting pump to perform grouting in the grouting area, and the grouting height is greater than the elevation of the pressure sensing membrane that detects the pressure fluctuation value greater than the preset pressure fluctuation value.

10. The cofferdam construction method according to claim 9, characterized in that: The contact stress of the dynamic extrusion seal is 1.2 MPa-1.5 MPa, and the preset pressure fluctuation value is ≥0.05 MPa.

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