Auxiliary device and method for cofferdam steel pipe pile forming

Abstract

The application provides a cofferdam steel pipe pile forming auxiliary device and a pile forming method. When the hard clay layer is formed into a steel pipe pile, the super-high pressure deflection angle water jet of the water flow rotary cutting device can cut and peel the hard clay at the front end of the steel pipe pile, and the mud formed by the hard clay is removed by the air-lift reverse circulation device, so that the pile end occlusion effect that is prone to occur in the process of the steel pipe pile entering the hard clay layer is broken, and the cofferdam steel pipe pile is smoothly penetrated to the preset elevation. The application can effectively solve the problem that the traditional high-frequency vibration hammer insertion and pile forming construction technology is only applicable to conventional construction environment and cannot adapt to the complex geological environment mainly composed of hard clay layer and soft fine sand layer, and can quickly form the cofferdam steel pipe pile, thereby effectively improving the construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and more specifically, to an auxiliary device and method for forming steel pipe piles for cofferdams. Background Technology

[0002] While the types and construction techniques of modern bridges are constantly being updated, cofferdam construction remains the mainstream method for bridge foundation construction when the bridge abutment and pier foundations are below the surface water level. A cofferdam is a temporary retaining structure built around the permanent structure of a bridge in hydraulic engineering, based on the site environment and available materials. Its function is to prevent water and soil from entering the construction site during construction, creating a dry working environment for the bridge abutment foundation and other structures. Depending on the construction materials, cofferdams can be classified as earthen cofferdams, timber cofferdams, and steel cofferdams. Among these, interlocking steel pipe pile cofferdams or steel sheet pile cofferdams are the most widely used in bridge foundation construction due to their convenient installation, high structural rigidity, strong stability, and excellent water-stopping effect.

[0003] A steel pipe pile cofferdam is constructed by driving a ring of steel pipe piles around the bridge abutment. These piles, along with interlocking mechanisms, create a sealed, water-stopping environment. The water inside the cofferdam is then pumped out, creating a dry construction environment. This results in a significant water-soil pressure difference between the inside and outside of the cofferdam. This pressure difference causes the cofferdam to collapse inwards and also creates piping at the base of the steel pipe piles, pulling them upwards. The inward collapse force is primarily counteracted by the layered installation of internal supports and walers within the cofferdam. The pull-out resistance of the steel pipe piles mainly comes from the friction between the piles and the surrounding soil, as well as the cohesion between the piles and the bottom concrete. The pile friction resistance is directly related to the driving depth and the surrounding geological conditions. Therefore, the water-stopping effect of a steel pipe pile cofferdam is primarily determined by the driving depth of the steel pipe piles in the soil. In other words, rapid pile driving technology is a crucial aspect of cofferdam construction, directly determining the quality and construction period of the cofferdam, and consequently affecting the overall bridge construction schedule.

[0004] Currently, the main method for constructing cofferdams relies on high-powered vibratory hammers or hydraulic hammers to drive steel pipe piles to the designated elevation. Guide frames are then installed to control the driving accuracy and verticality of the steel pipe piles. This conventional construction method is simple to operate and has mature technology, making it the most commonly used steel pipe pile construction method among construction teams. However, when geological conditions are complex, it is often difficult to drive the steel pipe piles to the designated elevation, or the driving process takes a long time, severely delaying the overall construction schedule.

[0005] Therefore, it is evident that traditional high-frequency vibratory hammer pile driving technology is only suitable for conventional construction environments and cannot adapt to complex geological environments dominated by hard clay layers and soft fine sand layers. Due to the high viscosity and hardness of hard clay layers, steel pipe piles will gradually accumulate increasing side friction and end resistance during the crossing process. Furthermore, some clay will enter the steel pipe, forming a pile end blockage effect, further increasing the difficulty of steel pipe pile crossing. Simply using vibratory hammer driving cannot reduce the pipe side resistance and end resistance, nor can it solve the end blockage effect. On the contrary, due to the huge reaction force exerted on the steel pipe pile by the hard clay layer, the steel pipe pile itself will be damaged after a long driving time. The excessive slenderness ratio will cause a more significant second-order P-Δ effect, resulting in a large amount of heat generated by friction between the vibratory hammer and the fixed position of the steel pipe pile, melting the pipe opening. In addition, the verticality and accuracy of the steel pipe pile itself become difficult to control during the driving process. The steel pipe piles cannot form a good closed working surface, resulting in a decrease in the overall water-stopping effect of the cofferdam. It is easy to cause bottom piping after sealing the bottom, making it impossible to form dry construction conditions. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide an auxiliary device and method for the pile formation of steel pipe piles for cofferdams, so as to solve the problem that the traditional high-frequency vibratory hammer pile driving construction technology in the prior art is only suitable for conventional construction environments and cannot adapt to complex geological environments dominated by hard clay layers and soft fine sand layers.

[0007] This invention provides an auxiliary device for the pile formation of steel pipe piles for cofferdams, comprising a cylindrical shell, a water flow rotary cutting device, and an air lift reverse circulation device; wherein, the cylindrical shell includes an inner cylindrical shell and an outer shell sleeved on the top outer periphery of the inner cylindrical shell, the upper inner sidewall of the outer shell and the upper outer sidewall of the inner cylindrical shell are fixedly connected by a horizontal stiffening plate, and the inner sidewall of the bottom port of the outer shell is fixed to the upper outer sidewall of the inner cylindrical shell; the water flow rotary cutting device includes a main water flow pipe disposed between the outer sidewall of the inner cylindrical shell and the inner sidewall of the outer shell, and a branch pipe connected to the outlet of the main water flow pipe; The inlet of the main water flow pipe is located outside the outer shell, and the inlet of the main water flow pipe is connected to an inlet pipe; the inlet end of the inlet pipe is connected to an external ultra-high pressure water supply system; the branch pipes are arranged vertically along the outer side wall of the inner cylindrical shell, and the outlet of the branch pipes is fixed on the outer side wall of the bottom port of the inner cylindrical shell; the air-lift reverse circulation device is located inside the inner cylindrical shell, the lower sludge inlet of the air-lift reverse circulation device is located at the bottom port of the inner cylindrical shell, and the upper sludge outlet of the air-lift reverse circulation device passes through the top of the outer shell and is located on one side of the outer shell.

[0008] In addition, a preferred embodiment is that the main water flow pipe is arranged horizontally around the outer periphery of the inner cylindrical shell, and at least four water outlets are provided on the main water flow pipe, each of which is connected to a branch pipe; the branch pipes are evenly distributed around the outer periphery of the inner cylindrical shell.

[0009] Furthermore, a preferred embodiment is that a first nut interface is provided at the outlet of the main water flow pipe; a first connecting screw interface is provided at the inlet of the branch pipe; the first connecting screw interface is fixedly connected to the first nut interface by threads; and / or, a second nut interface is provided at the inlet of the main water flow pipe; a second connecting screw interface is provided at the outlet of the inlet pipe; the second connecting screw interface is fixedly connected to the second nut interface by threads.

[0010] Furthermore, a preferred embodiment is that a first fixing buckle is provided on the upper outer side wall of the outer shell; the water inlet pipe is fixed to the outer side wall of the outer shell by the first fixing buckle; and / or, a second fixing buckle and a third fixing buckle are respectively provided on the upper outer side wall of the inner cylindrical shell and on the outer side wall of the bottom port of the inner cylindrical shell; the upper and lower ends of the branch pipe are respectively fixed to the upper outer side wall of the inner cylindrical shell and the outer side wall of the bottom port of the inner cylindrical shell by the second fixing buckle and the third fixing buckle.

[0011] Furthermore, a preferred embodiment is that the water inlet pipe is a high-strength rubber hose.

[0012] Furthermore, a preferred embodiment is to fix a triangular stiffening plate at the bottom port of the outer shell and the upper outer side wall of the inner cylindrical shell.

[0013] In addition, a preferred embodiment is to provide a hook hanging opening on the outer wall of the top port of the housing.

[0014] Furthermore, a preferred embodiment is that a stiffening steel plate is provided on the outer wall of the top port of the outer casing; the hook attachment point is provided on the stiffening steel plate.

[0015] Furthermore, a preferred embodiment is that a reserved maintenance port is provided on the outer casing; the location of the reserved maintenance port corresponds to the connection between the main water flow pipe and the branch pipe.

[0016] This invention provides a method for constructing steel pipe piles for cofferdams, utilizing the auxiliary device described above to assist in the construction of steel pipe piles, comprising the following steps:

[0017] S1. Insert the steel pipe pile to be piled into the soil layer, so that the steel pipe pile has stability at the preset pile position, and obtain a stable steel pipe pile.

[0018] S2. Hoist the auxiliary device into the inside of the stable steel pipe pile, and adjust the bottom of the auxiliary device to a preset distance from the front soil layer. Turn on the ultra-high pressure water supply external system so that the water flow rotary cutting device can perform rotary cutting operation on the front soil layer.

[0019] S3. When the water flow rotary cutting device performs rotary cutting operation on the front soil layer for a preset time, the ultra-high pressure water supply external system is shut down and the air lift reverse circulation device is turned on. The air lift reverse circulation device is used to discharge the silt generated in the stabilized steel pipe pile after the rotary cutting operation from the silt outlet at the upper end of the air lift reverse circulation device.

[0020] S4. Repeat steps S2 to S3 until the stable steel pipe piles are driven to the predetermined elevation, thus completing the pile construction of the cofferdam steel pipe piles.

[0021] As can be seen from the above technical solution, the auxiliary device and method for cofferdam steel pipe pile formation provided by this invention combines a water-jet cutting device and an air-lift reverse circulation device on a cylindrical shell. When forming steel pipe piles in hard clay layers, the ultra-high pressure deflection angle water jet of the water-jet cutting device can cut and peel off the hard clay at the front end of the steel pipe pile. Then, the air-lift reverse circulation device removes the mud formed by the hard clay, breaking the pile end blockage effect that easily occurs when the steel pipe pile enters the hard clay layer, helping the cofferdam steel pipe pile to smoothly penetrate to the preset elevation. This invention can effectively solve the problem that traditional high-frequency vibratory hammer pile driving construction technology is only suitable for conventional construction environments and cannot adapt to complex geological environments dominated by hard clay layers and soft fine sand layers. It can quickly form cofferdam steel pipe piles and effectively improve construction efficiency.

[0022] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0023] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings. In the drawings:

[0024] Figure 1 This is a schematic diagram of the auxiliary device for pile forming of cofferdam steel pipe piles according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 Enlarged view of the upper part of the auxiliary device in the diagram;

[0026] Figure 3for Figure 1 Enlarged view of the lower part of the auxiliary device;

[0027] Figure 4 This is a top plan view of the auxiliary device for pile forming of cofferdam steel pipe piles according to an embodiment of the present invention;

[0028] Figure 5 This is a bottom plan view of the auxiliary device for pile forming of cofferdam steel pipe piles according to an embodiment of the present invention;

[0029] Figure 6 This is a flowchart of a cofferdam steel pipe pile forming method according to an embodiment of the present invention;

[0030] Figure 7 This is a top view schematic diagram of a steel pipe pile cofferdam or steel sheet pile cofferdam in the prior art;

[0031] Figure 8 This is a side view schematic diagram of a steel pipe pile cofferdam or steel sheet pile cofferdam in the prior art.

[0032] In the attached drawings, 11-inner cylindrical shell, 12-outer shell, 13-horizontal stiffening plate, 21-main water flow pipe, 22-branch pipe, 23-inlet pipe, 3-air lift reverse circulation device, 31-lower sludge inlet, 32-upper sludge outlet, 41-first nut interface, 42-first connecting screw interface, 43-second nut interface, 44-second connecting screw interface, 51-first fixing lock, 52-second fixing lock, 53-third fixing lock, 6-triangular stiffening plate, 7-hook hanging port, 71-stiffening steel plate, 8-reserved maintenance port, 91-steel pipe pile, 92-bridge pile foundation, 93-inner support waler, 94-steel pipe pile closure lock, 95-bridge abutment.

[0033] In all the accompanying drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed Implementation

[0034] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details.

[0035] To address the issue that the traditional high-frequency vibratory hammer pile driving technology in the prior art is only suitable for conventional construction environments and cannot adapt to complex geological environments dominated by hard clay layers and soft fine sand layers, an auxiliary device and pile driving method for cofferdam steel pipe pile construction is proposed.

[0036] like Figure 7As shown, in existing technologies, when the bridge abutment 95 and bridge pile foundation 92 are below the surface water level during bridge foundation construction, cofferdam construction remains the mainstream method. A cofferdam is a temporary retaining structure built around the permanent structure of a bridge in hydraulic engineering, based on the site environment and available materials. Its function is to prevent water and soil from entering the construction site during construction in a hydraulic environment, creating a dry working environment for the bridge abutment 95, bridge pile foundation 92, and other structures. Depending on the construction materials, cofferdams can be classified as earthen cofferdams, timber cofferdams, and steel cofferdams. Among these, interlocking steel pipe pile cofferdams or sheet pile cofferdams are the most widely used in bridge foundation construction due to their convenient installation, high structural rigidity, strong stability, and excellent water-stopping effect. Generally, steel pipe piles 91 are installed around the outer perimeter of the bridge abutment 95 and fixed to the soil layer by driving them in. An inner supporting waler 93 is installed within the pile, and a steel pipe pile closure interlocking 94 is installed at the joints of the steel pipe piles 91 at both ends. By relying on steel pipe piles 91 and interlocking to form a closed, water-stopping environment, and then pumping out the water inside the cofferdam to create a dry construction environment, a huge water-soil pressure difference will be formed inside and outside the cofferdam. This pressure difference will cause the cofferdam to collapse inward on the one hand, and on the other hand, it will cause piping at the bottom of the steel pipe piles, pulling the steel pipe piles upward. The external force causing the cofferdam to collapse inward is mainly offset by the inner supporting walers 93 installed layer by layer inside the cofferdam. The pull-out resistance of the steel pipe piles 91 mainly comes from the pile-side friction between the steel pipe piles 91 and the surrounding soil layers, and the cohesion between the steel pipe piles 91 and the bottom sealing concrete. The pile-side friction resistance of the steel pipe piles 91 is directly related to the driving depth of the steel pipe piles 91 and the surrounding geological conditions. The water-stopping effect of the steel pipe pile cofferdam is mainly determined by the driving depth of the steel pipe piles 91 in the geological soil layers. That is, the rapid driving technology of steel pipe piles 91 is a key link in the cofferdam construction, which will directly determine the quality of the cofferdam and the construction period, and thus affect the overall construction period of the bridge.

[0037] Currently, the construction of cofferdams mainly relies on high-powered vibratory hammers or hydraulic hammers to drive steel pipe piles to the designated elevation. Figure 8 As shown, the installation of guide frames to control the driving accuracy and verticality of the steel pipe piles for the cofferdam is a conventional construction method that is simple to operate and has mature technology, making it the most commonly used steel pipe pile construction scheme by construction teams. However, when the geological conditions are complex, it is often difficult to drive the steel pipe piles to the designated elevation, or the driving process takes a long time, seriously delaying the overall construction period.

[0038] For example, during the construction of a bridge, a cross-city boundary bridge with a total length of 1.6135 kilometers, corresponding to route chainage K5+988-K7+619.5, has a 1015.55-meter section located in City X and a 615.95-meter section located in City Y. The main river channel is a 3x110-meter under-deck simply supported truss composite arch bridge, while the approach bridges on both sides are constructed of steel-concrete composite beams, cast-in-place box girders, and prefabricated small box girders. The approach bridges cross the left and right embankment roads and connect with the planned roadbed section. The four sets of piers #25-28 of the main bridge are located within the river channel, with the pier caps #25 and #28 located on the main channel bank slope. The pier cap dimensions are 9.1x9.1x4m, and the construction method adopted is an 18m steel sheet pile cofferdam. The main piers 26# and 27# are located at the bottom of the main channel of the river. The dimensions of the piers are 14.6x9.1x4m. The water depth at the location of the piers is 9.5m. The construction method adopts 24m steel pipe pile cofferdam.

[0039] Following actual geological exploration, the geological conditions at the location of piers 26 and 27 of the main bridge, from top to bottom, are as follows: water depth 8.15m, 3.3m silt layer, 3.6m fine sand layer, 1.2m hard clay layer, 1.7m fine sand layer, 7.5m hard clay layer, 1.9m fine sand layer, 1.8m hard clay layer, and 9.6m fine sand layer. It can be seen that the geological conditions at this location are very complex, exhibiting an alternating layering of hard clay and soft fine sand layers. The hard clay is a type of refractory clay that is hard, does not easily disperse in water, and has low plasticity. Based on the design elevation of the main bridge pier foundation, the embedment depth of the steel pipe pile cofferdam was calculated, determining that the steel pipe piles need to penetrate multiple layers of hard clay and fine sand, ultimately being fixed within the 7.5m hard clay layer. Because the design of steel pipe piles needs to simultaneously meet the requirements of the local water level and pier cap, and the fine sand layer cannot meet the bearing capacity requirements of the steel pipe piles, the length of the steel pipe piles is designed to be longer than the conventional value. Driving steel pipe piles with a large slenderness ratio into the hard clay layer using conventional methods in this complex geological environment is technically challenging and involves many uncontrollable factors. The excessively large slenderness ratio also makes the second-order P-Δ effect more significant. During the driving process, the reaction force of the hard clay and other soil layers on the steel pipe piles further exacerbates the horizontal displacement of the steel pipe piles, leading to a larger bending moment. This places higher demands on the material properties of the steel pipe piles and the driving process. In actual construction, repeated problems arose, including the difficulty of the steel pipe piles penetrating the hard clay layer, long driving time, heat melting of the pipe ends due to prolonged friction, and large-scale sand inrush after the cofferdam is sealed, which greatly slowed down the overall construction period. Based on the aforementioned construction difficulties, an auxiliary device and method for cofferdam steel pipe pile construction are proposed to solve these problems.

[0040] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] To illustrate the auxiliary device and pile-forming method for cofferdam steel pipe piles provided by this invention, Figure 1 The structure of an auxiliary device for cofferdam steel pipe pile foundation construction according to an embodiment of the present invention is shown; Figure 2 It shows Figure 1 The upper enlarged structure of the auxiliary device in the middle; Figure 3 It shows Figure 1 The lower enlarged structure of the auxiliary device in the middle; Figure 4 The top plan structure of the auxiliary device for cofferdam steel pipe pile pile forming according to an embodiment of the present invention is shown; Figure 5 The bottom plan structure of the auxiliary device for cofferdam steel pipe pile pile forming according to an embodiment of the present invention is shown; Figure 6 The flowchart of a cofferdam steel pipe pile forming method according to an embodiment of the present invention is shown; Figure 7 The diagram shows a top view of a steel pipe pile cofferdam or steel sheet pile cofferdam in the prior art; Figure 8 The side view of a steel pipe pile cofferdam or steel sheet pile cofferdam in the prior art is shown.

[0042] like Figures 1 to 8 As shown in the figure, the auxiliary device for cofferdam steel pipe pile formation provided by the present invention includes: a cylindrical shell, a water flow rotary shearing device, and an air lift reverse circulation device 3; wherein,

[0043] The cylindrical shell includes an inner cylindrical shell 11 and an outer shell 12 fitted around the top outer periphery of the inner cylindrical shell 11. The upper inner sidewall of the outer shell 12 is fixedly connected to the upper outer sidewall of the inner cylindrical shell 11 by a horizontal stiffening plate 13. The inner sidewall of the bottom port of the outer shell 12 is fixed to the upper outer sidewall of the inner cylindrical shell 11. The water flow rotary cutting device includes a main water flow pipe 21 disposed between the outer sidewall of the inner cylindrical shell 11 and the inner sidewall of the outer shell 12, and a branch pipe 22 connected to the outlet of the main water flow pipe 21. The inlet of the main water flow pipe 21 is located outside the outer shell 12. The inlet of channel 21 is connected to an inlet pipe 23; the inlet end of the inlet pipe 23 is connected to an external ultra-high pressure water supply system (not shown in the figure); the branch pipe 22 is set vertically along the outer side wall of the inner cylindrical shell 11, and the outlet of the branch pipe 22 is fixed on the outer side wall of the bottom port of the inner cylindrical shell 11; the air-lift reverse circulation device 3 is set inside the inner cylindrical shell 11, the lower sludge inlet 31 of the air-lift reverse circulation device 3 is set at the bottom port of the inner cylindrical shell 11, and the upper sludge outlet 32 ​​of the air-lift reverse circulation device 3 passes through the top of the outer shell 12 and is set on one side of the outer shell 12.

[0044] The inner cylindrical shell 11 and the outer shell 12 are preferably cylindrical in shape, with the diameter of the outer shell 12 being larger than that of the inner cylindrical shell 11, and the upper port of the outer shell 12 being larger than the lower port. This is to facilitate the installation of the air-lift reverse circulation device 3, and to increase the pressure difference between the inside and outside of the cylindrical shell, facilitating the discharge of bottom sludge; the outer shell 12 also protects the connection between the main water flow pipe 21 and the branch pipe 22. For example, the diameter of the inner cylindrical shell 11 is 64 cm, the upper port diameter of the outer shell 12 is 82 cm, and the lower port diameter is slightly larger than that of the inner cylindrical shell 11. Both the inner cylindrical shell 11 and the outer shell 12 are made of 10 mm thick steel. The material and thickness of the cylindrical shell, as well as the shape of the inner cylindrical shell 11 and the outer shell 12, can be selected according to actual needs, and this invention does not impose any particular limitations on them.

[0045] The horizontal stiffening plate 13 is preferably made of steel and is fixed between the inner cylindrical shell 11 and the outer shell 12 by welding. The connection is integrally welded around the perimeter.

[0046] The air-lift reverse circulation device 3 can be any existing air-lift reverse circulation system, which will not be described in detail in this invention.

[0047] The ultra-high pressure water supply external system preferably adopts the TYJP-90 high pressure water jet, which is connected to an external variable frequency three-phase asynchronous motor and mainly supplies water to the main water flow pipeline 21.

[0048] The main water flow pipe 21 is preferably made of 30mm high-strength alloy pipe. The branch pipe 22 can be divided into upper and lower sections. The upper section is connected to the outlet of the main water flow pipe 21 as the upper branch pipe, and the lower section can be seamlessly connected to the upper branch pipe with the help of shock-resistant rubber hose.

[0049] By combining a water-jet cutting device and an air-lift reverse circulation device 3 onto a cylindrical shell, when constructing steel pipe piles 91 in hard clay layers, the ultra-high pressure deflection angle water jet of the water-jet cutting device can cut and peel off the hard clay at the front end of the steel pipe pile 91. Then, the air-lift reverse circulation device 3 removes the mud formed by the hard clay, breaking the pile end blockage effect that easily occurs when the steel pipe pile enters the hard clay layer, and helping the cofferdam steel pipe pile to successfully penetrate to the preset elevation. This invention can effectively solve the problem that traditional high-frequency vibratory hammer pile driving construction technology is only suitable for conventional construction environments and cannot adapt to complex geological environments dominated by hard clay layers and soft fine sand layers. It can quickly construct cofferdam steel pipe piles and effectively improve construction efficiency.

[0050] In a preferred embodiment of the present invention, the main water flow pipe 21 is arranged horizontally around the outer periphery of the inner cylindrical shell 11, and at least four water outlets are provided on the main water flow pipe 21, each of which is connected to a branch pipe 22; the branch pipes 22 are evenly distributed around the outer periphery of the inner cylindrical shell 11. The number of water outlets can be set according to actual needs, such as four, five, six, etc.; of course, without considering the optimal rotary cutting effect, it is also feasible to provide one, two, or three water outlets, and the present invention does not particularly limit this.

[0051] As a preferred embodiment of the present invention, a first nut interface 41 is provided at the outlet of the main water flow pipe 21; a first connecting screw interface 42 is provided at the inlet of the branch pipe 22; the first connecting screw interface 42 is fixedly connected to the first nut interface 41 by threads; and / or, a second nut interface 43 is provided at the inlet of the main water flow pipe 21; a second connecting screw interface 44 is provided at the outlet of the inlet pipe 23; the second connecting screw interface 44 is fixedly connected to the second nut interface 43 by threads.

[0052] The preferred method for connecting pipes is to use a 40mm nut interface and a 30mm threaded rod connection interface, which facilitates replacement and maintenance.

[0053] In a preferred embodiment of the present invention, a first fixing buckle 51 is provided on the upper outer side wall of the outer casing 12; the water inlet pipe 23 is fixed to the outer side wall of the outer casing 12 by the first fixing buckle 51; and / or, a second fixing buckle 52 and a third fixing buckle 53 are respectively provided on the upper outer side wall of the inner cylindrical shell 11 and on the outer side wall of the bottom port of the inner cylindrical shell 11; the upper and lower ends of the branch pipe 23 are respectively fixed to the upper outer side wall of the inner cylindrical shell 11 and the outer side wall of the bottom port of the inner cylindrical shell 11 by the second fixing buckle 52 and the third fixing buckle 53. The fixing buckles facilitate the fixation of the water inlet pipe 23 and the branch pipe 22 to the cylindrical shell as a whole.

[0054] As a preferred embodiment of the present invention, the water inlet pipe 23 is a high-strength rubber hose. It is sturdy, durable, and easy to replace. The number of water inlet pipes 23 can be set according to actual construction needs, and the present invention does not impose any particular limitation on this.

[0055] As a preferred embodiment of the present invention, a triangular stiffening plate 6 is fixed at the bottom port of the outer shell 12 and the upper outer side wall of the inner cylindrical shell 11. Preferably, a 10mm triangular stiffening plate is used to make the fixation between the outer shell 12 and the inner cylindrical shell 11 more secure.

[0056] As a preferred embodiment of the present invention, a hook hanging opening 7 is provided on the outer wall of the top port of the outer casing 12.

[0057] As a preferred embodiment of the present invention, a stiffening steel plate 71 is provided on the outer wall of the top port of the outer casing 12; the hook hanging port 7 is provided on the stiffening steel plate 71.

[0058] The top of the outer casing 12 has a 5cm hook interface 7, and the opening of the hook is on a 10mm stiffening steel plate 71 to prevent the hook from damaging the outer casing 12 and to enhance the overall stability.

[0059] As a preferred embodiment of the present invention, a reserved maintenance port 8 is provided on the outer casing 12; the reserved maintenance port 8 is located at the connection between the main water flow pipe 21 and the branch pipe 22, which facilitates device maintenance.

[0060] The cofferdam steel pipe pile forming method provided by the present invention utilizes the auxiliary device for cofferdam steel pipe pile forming as described above to assist in the steel pipe pile forming construction, and includes the following steps:

[0061] S1. Insert the steel pipe pile 91 to be piled into the soil layer, so that the steel pipe pile 91 has stability at the preset pile position, and obtain a stable steel pipe pile.

[0062] S2. Hoist the auxiliary device into the inside of the stable steel pipe pile, and adjust the bottom of the auxiliary device to a preset distance from the front soil layer. Turn on the ultra-high pressure water supply external system so that the water flow rotary cutting device can perform rotary cutting operation on the front soil layer.

[0063] S3. When the water flow rotary cutting device performs rotary cutting operation on the front soil layer for the preset time, the ultra-high pressure water supply external system is shut down and the air lift reverse circulation device 3 is turned on. The air lift reverse circulation device 3 is used to discharge the silt generated in the stabilized steel pipe pile after the rotary cutting operation from the silt outlet at the upper end of the air lift reverse circulation device 3.

[0064] S4. Repeat steps S2 to S3 until the stable steel pipe piles are driven to the predetermined elevation, thus completing the pile construction of the cofferdam steel pipe piles.

[0065] The preset distance, preset time, and preset elevation can all be set according to actual construction needs.

[0066] The hard clay at the front end of the cofferdam steel pipe piles is removed using a water-jet cutting device, and then the silt is removed by an air-lift reverse circulation device 3 before the steel pipe piles are driven into the cofferdam, thus enabling the steel pipe piles to reach the designated elevation smoothly. During operation, the ultra-high pressure deflection angle water flow of the water-jet cutting device is first used to cut the hard clay at the front end of the steel pipe piles, destroying the original geological structure of the clay layer. At the same time, the water flow reduces the viscosity of the clay, thereby cutting the whole piece of hard clay into smaller water-soil mixtures. Then, the air-lift reverse circulation device 3 is used to inject high-pressure gas into the hard clay, forming a gas-solid-liquid three-phase mixture. A huge pressure difference is formed at the branch pipe 22 and the bottom port of the inner cylindrical shell 11, and then the silt is cleared out using the reverse circulation principle.

[0067] Because hard clay layers are characterized by their dense structure, hard texture, and high viscosity, direct-angle ultra-high pressure water jet cutting easily creates a reaction force at the front end of the ultra-high pressure water jet. The rebounding water flow cancels out the original water flow, forming turbulence and weakening the shear force of the water flow, thus failing to achieve the ideal cutting effect. Therefore, the water jet cutting device is arranged close to the steel pipe pile at a large deflection angle, thereby forming a jet cutting water jet at the front end of the steel pipe pile. This avoids energy loss and expands the cutting area, increasing the number of concentrated points from the four straight cutting points to four tangents, enhancing the cutting effect of the ultra-high pressure water flow. This facilitates subsequent steps to remove hard clay, break the pile end blockage effect of the steel pipe pile, disrupt the internal force balance of the soil at the pile head, and redistribute the internal forces, thereby reducing the end resistance caused by the clay cohesion and helping the steel pipe pile to quickly penetrate to the designated elevation.

[0068] When using the auxiliary device provided by this invention, the entire device is installed inside the steel pipe piles of the cofferdam. After the preparatory work is completed, the steel pipe piles are first driven into the soil to give them a certain degree of stability. If necessary, a guide frame can be used to assist in ensuring that the steel pipe piles have sufficient rigidity and to prevent energy loss caused by excessive deflection of the steel pipe piles themselves, which would prevent the impact force generated by the subsequent vibratory hammer or hydraulic hammer from being effectively transmitted to the bottom of the steel pipe piles. After the steel pipe piles have achieved initial rigidity, the auxiliary device is then hoisted into the steel pipe piles. The bottom end of the device can be spliced ​​in sections, and the overall length should preferably be 2-3 meters longer than the steel pipe piles, which can be flexibly adjusted according to the actual conditions of the construction site.

[0069] After the device is installed, check the installation location of external equipment and the length of pipelines, and secure the pipelines firmly with locks to prevent them from falling off during use. Use a crane to hoist the auxiliary device to a water surface far from the equipment and people for an ultra-high pressure water jet test to check pipeline flow and equipment operational stability. After the equipment is tested and adjusted appropriately, hoist the auxiliary device into the steel pipe pile. Note that during hoisting, the auxiliary device should not be in close contact with the front soil layer to prevent the ultra-high pressure water jet from affecting the device itself. After adjusting the auxiliary device to a suitable height, begin ultra-high pressure rotary cutting to remove hard clay from the pile end. Then, turn off the ultra-high pressure water jet and use the air-lift reverse circulation device 3 to discharge the silt. After working continuously for 15 minutes, use a crane to lift it out and continue driving the steel pipe pile. Observe whether there is still significant obstruction. If the steel pipe pile does not descend significantly for a long time during driving, continue using the auxiliary device to remove hard silt from the pile end. Repeat the operation until the steel pipe pile is successfully driven to the designated elevation.

[0070] As can be seen from the above specific embodiments, the auxiliary device and method for cofferdam steel pipe pile formation provided by the present invention, by combining a water-jet cutting device and an air-lift reverse circulation device on a cylindrical shell, allows for the cutting and peeling of the hard clay at the front end of the steel pipe pile during steel pipe pile formation in hard clay layers using the ultra-high pressure deflection angle water jet of the water-jet cutting device. Then, the air-lift reverse circulation device removes the mud formed by the hard clay, breaking the pile end blockage effect that easily occurs during the steel pipe pile's entry into the hard clay layer, thus helping the cofferdam steel pipe pile to smoothly penetrate to the preset elevation. The present invention effectively solves the problem that traditional high-frequency vibratory hammer pile driving construction technology is only suitable for conventional construction environments and cannot adapt to complex geological environments dominated by hard clay layers and soft fine sand layers. It enables rapid cofferdam steel pipe pile formation, effectively improving construction efficiency.

[0071] The auxiliary device and method for pile formation of cofferdam steel pipe piles according to the present invention have been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various modifications can be made to the auxiliary device and method for pile formation of cofferdam steel pipe piles according to the present invention without departing from the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. An auxiliary device for the pile formation of steel pipe piles for cofferdams, characterized in that, include: Cylindrical shell, water flow swirl cutting device, and air lift reverse circulation device; among which, The cylindrical shell includes an inner cylindrical shell and an outer shell fitted around the top outer periphery of the inner cylindrical shell. The upper inner sidewall of the outer shell is fixedly connected to the upper outer sidewall of the inner cylindrical shell by a horizontal stiffening plate. The inner sidewall of the bottom port of the outer shell is fixed to the upper outer sidewall of the inner cylindrical shell. The water flow rotary cutting device includes a main water flow pipe disposed between the outer side wall of the inner cylindrical shell and the inner side wall of the outer shell, and a branch pipe connected to the outlet of the main water flow pipe; the inlet of the main water flow pipe is disposed outside the outer shell, and the inlet of the main water flow pipe is connected to an inlet pipe; the inlet end of the inlet pipe is connected to an external ultra-high pressure water supply system; the branch pipe is disposed along the vertical direction of the outer side wall of the inner cylindrical shell, and the outlet of the branch pipe is fixed on the outer side wall of the bottom port of the inner cylindrical shell; The air-lift reverse circulation device is located inside the inner cylindrical shell. The lower sludge inlet of the air-lift reverse circulation device is located at the bottom port of the inner cylindrical shell, and the upper sludge outlet of the air-lift reverse circulation device passes through the top of the outer shell and is located on one side of the outer shell.

2. The auxiliary device for cofferdam steel pipe pile formation according to claim 1, characterized in that, The main water flow pipe is arranged horizontally around the outer periphery of the inner cylindrical shell, and at least four water outlets are provided on the main water flow pipe, each of which is connected to the branch pipe. The sub-pipes are evenly distributed around the outer periphery of the inner cylindrical shell.

3. The auxiliary device for cofferdam steel pipe pile pile formation according to claim 1, characterized in that, A first nut interface is provided at the outlet of the main water flow pipe; A first connecting screw interface is provided at the water inlet of the branch pipe; The first connecting screw interface is fixedly connected to the first nut interface via threads; and / or, A second nut interface is provided at the inlet of the main water flow pipe; A second connecting screw interface is provided at the outlet of the water inlet pipe; The second connecting screw interface is fixedly connected to the second nut interface by threads.

4. The auxiliary device for cofferdam steel pipe pile formation according to claim 1, characterized in that, A first fixing latch is provided on the upper outer side wall of the outer casing; the water inlet pipe is fixed to the outer side wall of the outer casing by the first fixing latch; and / or, A second fixing latch and a third fixing latch are respectively provided on the upper outer side wall of the inner cylindrical shell and on the outer side wall of the bottom port of the inner cylindrical shell; The upper and lower ends of the branch pipe are respectively fixed to the upper outer wall of the inner cylindrical shell and the outer wall of the bottom port of the inner cylindrical shell by the second fixing buckle and the third fixing buckle.

5. The auxiliary device for cofferdam steel pipe pile formation according to claim 1, characterized in that, The water inlet pipe is a high-strength rubber hose.

6. The auxiliary device for cofferdam steel pipe pile pile formation according to claim 1, characterized in that, A triangular stiffening plate is fixed at the bottom port of the outer shell and at the upper outer side wall of the inner cylindrical shell.

7. The auxiliary device for cofferdam steel pipe pile pile formation according to claim 1, characterized in that, A hook opening is provided on the outer wall of the top port of the outer casing.

8. The auxiliary device for cofferdam steel pipe pile formation according to claim 7, characterized in that, A stiffening steel plate is provided on the outer wall of the top port of the outer casing; The hook attachment point is located on the stiffening steel plate.

9. The auxiliary device for cofferdam steel pipe pile formation according to claim 1, characterized in that, A maintenance port is provided on the outer casing; The location of the reserved maintenance port corresponds to the connection between the main water flow pipe and the branch pipe.

10. A method for constructing steel pipe piles for cofferdams, characterized in that, The auxiliary device for cofferdam steel pipe pile construction as described in any one of claims 1-9 is used to assist in the construction of steel pipe piles, comprising the following steps: S1. Insert the steel pipe pile to be piled into the soil layer, so that the steel pipe pile has stability at the preset pile position, and obtain a stable steel pipe pile. S2. Hoist the auxiliary device into the inside of the stable steel pipe pile, and adjust the position of the auxiliary device so that the bottom of the auxiliary device is at a preset distance from the front soil layer. Turn on the ultra-high pressure water supply external system so that the water flow rotary cutting device can perform rotary cutting operation on the front soil layer. S3. When the water flow rotary cutting device performs rotary cutting operation on the front soil layer for a preset time, the ultra-high pressure water supply external system is shut down and the air lift reverse circulation device is turned on. The air lift reverse circulation device is used to discharge the silt generated in the stabilized steel pipe pile after the rotary cutting operation from the silt outlet at the upper end of the air lift reverse circulation device. S4. Repeat steps S2 to S3 until the stable steel pipe piles are driven to the predetermined elevation, thus completing the pile construction of the cofferdam steel pipe piles.

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