Constant-pressure overflow device for pile sinking of bamboo joint pile and pile sinking method of bamboo joint pile

Abstract

The invention discloses a constant-pressure overflow device for pile sinking of a bamboo joint pile and a pile sinking method of the bamboo joint pile, the constant-pressure overflow device comprises a water bag assembly and a constant-pressure overflow valve, the water bag assembly comprises a soil bag and a framework pipe, and water is injected into the soil bag for providing support pressure for a pre-drilled hole; a counter weight lever type assembly of the constant-pressure overflow valve comprises a lever arm connected to a fulcrum shaft pin, the inner side of the lever arm is connected with a valve rod, the bottom end of the valve rod is connected with a blade valve element, when the constant-pressure overflow valve does not work, the blade valve element seals a water inlet, and when the constant-pressure overflow valve works, water flow in the water inlet can eject the blade valve element to flow out through a water outlet. A second balancing weight is arranged on the outer side of the lever arm, and the second balancing weight can hinder water flow in the water inlet through the lever effect. The supporting pressure in the water bag assembly can be ensured to be constant, and the problems that the geotechnical bag is burst and the pre-drilled hole collapses are avoided; due to the design of a large-diameter pipeline, pipeline blockage is avoided; and through cement-based grout replacement, the water bag assembly is converted into a geotextile bag concrete pile, and the foundation is permanently reinforced.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a constant pressure overflow device for driving bamboo-joint piles and a method for driving bamboo-joint piles using the device. Background Technology

[0002] As urbanization progresses into coastal and soft soil areas with complex geological conditions, bamboo-joint piles are widely used in engineering due to their excellent load-bearing capacity. However, their unique periodic variable cross-section joint design can trigger a severe soil squeezing effect during pile driving, leading to the accumulation of high excess pore water pressure within the soil and generating large deep radial deformation. This forces adjacent existing cast-in-place piles to bear additional lateral compression and vertical heave loads, which can easily cause problems such as pile cracking, shear fracture, or necking.

[0003] Existing technologies often employ stress relief holes, sandbag filling, or isolation piles for protection, but these methods have significant drawbacks in fluid plastic soft soil geology: traditional unsupported stress relief holes face the problems of poor hole formation stability and easy hole collapse failure; if mud slurry is used for wall protection, the volume compensation function is lost because the mud slurry is incompressible; although the sandbag filling method can support the hole wall, the compressibility of the sand is limited and it cannot achieve quantitative volume shrinkage, which easily leads to rigid stress transmission under the impact of pile driving; and rigid isolation measures such as steel sheet piles are not only costly, but their driving process also generates secondary soil displacement disturbance.

[0004] To resolve the contradiction between soft soil wall protection and pressure relief, using fluid-filled high-strength geotextile bags as active support media has become an effective technical approach. This method utilizes the isotropic pressure of the fluid to maintain borehole wall stability and the fluid's dischargeability to absorb soil displacement. However, to achieve the engineering effectiveness of this system, the core challenge of "transient constant pressure control" must be addressed: the instantaneous driving of bamboo-joint piles generates intense, pulsed, high-flow-rate soil displacement, requiring the barrier system (geotextile bags) to maintain absolute constant support pressure within the geotextile bags while simultaneously discharging large amounts of turbid fluid instantly. This is to prevent pressure spikes that could rupture the geotextile bags or sudden pressure drops that could lead to borehole collapse. Therefore, the crucial "pressure relief link" needs to ensure rapid passage of sediment and that the valves are not easily clogged. However, existing general-purpose valves are mostly based on Hooke's Law, such as springs, where the larger the valve opening, the greater the spring reaction force. During the instantaneous driving of bamboo-joint piles, the fluid inside the bladder needs to be discharged rapidly at a high flow rate. At this time, the spring valve causes a sharp increase in back pressure, which can easily rupture the flexible bladder and make it impossible to maintain a constant protective pressure. At the same time, the backflow fluid from the water bladder at the pile foundation construction site often contains silt, and the precision valve core of general valves can easily become stuck, resulting in either failure to close (loss of support force) or failure to open (loss of pressure relief function). Therefore, the industry urgently needs a complete construction process that combines a specific pressure relief device to simultaneously solve the problems of wall stability, unobstructed drainage, and constant pressure release in soft soil. Summary of the Invention

[0005] This invention provides a constant-pressure overflow device for bamboo-joint pile driving and a method for driving bamboo-joint piles using this device. It aims to resolve the contradiction between "hole wall stability" and "dynamic pressure relief effectiveness" in existing anti-displacement technologies for soft, fluid soil. Specifically, by improving the hardware configuration of the core pressure relief component, it overcomes the technical shortcomings of existing devices, such as easy clogging in mud environments and inconsistent pressure during high-flow discharge, which can damage the system. This invention achieves, through a complete process flow, active support for anti-collapse holes under static conditions, constant-pressure overflow to absorb displacement under dynamic conditions, and the conversion of the water-filled bladder assembly into part of a permanent foundation reinforcement pile after construction.

[0006] For the constant pressure overflow device, the technical solution of this application is as follows:

[0007] A constant pressure overflow device for bamboo-joint pile driving includes a water bladder assembly and a constant pressure overflow valve connected to the water bladder assembly. The water bladder assembly includes a geotextile bag with a skeleton tube inside. The constant pressure overflow valve includes a valve seat with an inlet and an outlet. The inlet is connected to the skeleton tube via a conduit. The outlet is connected to a sewage pipe. A counterweight lever assembly is installed between the inlet and outlet. The counterweight lever assembly includes a fulcrum pin connected to the valve seat and a fulcrum shaft. The valve has a lever arm on the pin, with a valve stem connected to the lever arm near the fulcrum pin. The valve stem is located inside the valve seat, and a blade valve core is connected to the bottom end of the valve stem. The blade valve core is located at the junction of the inlet and outlet, and the water flow from the inlet can push open the blade valve core and flow out through the outlet. A counterweight is provided on the lever arm away from the fulcrum pin. The counterweight can impede the water flow in the inlet through the lever action. The constant pressure relief valve also includes a pressure gauge, which is connected to the valve seat through an isolation valve.

[0008] The constant pressure overflow device of this invention uses a constant pressure overflow valve as a ground control unit, which is convenient for manual operation. It also employs the lever balance principle to control the support pressure within the water bladder assembly within a small range. When the constant pressure overflow valve is not in operation, the blade valve core seals the water inlet. When the constant pressure overflow valve is in operation, the water flow at the inlet can push open the blade valve core and flow out through the outlet. The counterweight of this invention maintains a constant double gravity, ensuring that regardless of changes in the opening degree of the constant pressure overflow valve, the support pressure of the water bladder assembly on the pre-drilled hole is always locked within a set threshold range, preventing excessive pressure from causing the geotextile bag to burst or insufficient pressure from causing hole collapse. When using a water pump to inject water into the geotextile bag, the pressure gauge allows for easy manual observation to ensure that the support pressure inside the geotextile bag is within the required range, preventing excessive or insufficient support pressure.

[0009] Preferably, in the aforementioned constant pressure overflow device for bamboo-joint pile driving, a flexible diaphragm is provided above the blade valve core. The flexible diaphragm is connected to the valve seat and seals the guide device connected to the blade valve core. By using the flexible diaphragm to isolate corrosive mud from the guide device, the problem of blockage caused by mud and sand entering the gap of the guide device is fundamentally eliminated.

[0010] Preferably, in the aforementioned constant pressure overflow device for bamboo-joint pile driving, the water bag assembly further includes a counterweight block, which is disposed at the bottom of the geotextile bag. The counterweight block facilitates manual operation, allowing the geotextile to be accurately placed in the pre-drilled hole.

[0011] Regarding the pile driving method, the technical solution of this application is as follows:

[0012] The bamboo-joint pile driving method, which uses the aforementioned constant pressure overflow device for bamboo-joint pile driving, includes the following steps:

[0013] Step 1, Waterbag Assembly Installation and Static Support: A pre-drilled hole is constructed between the existing cast-in-place piles and the newly constructed bamboo-joint piles. The waterbag assembly is then inserted into the pre-drilled hole, and a pressure relief valve is connected to the waterbag assembly. Water is pumped into the waterbag assembly until the pressure gauge reads [pressure value missing]. , The support pressure of the water bladder assembly on the pre-drilled borehole sidewall, wherein, With active earth pressure The relationship is:

[0014] =Ka×γ×H;

[0015] =1.1× ~1.2× ;

[0016] Where: Ka is the active earth pressure coefficient, γ is the unit weight of the soil, and H is the depth of the pre-drilled hole;

[0017] Then, a second counterweight is added to the constant pressure relief valve to balance the lever arm. The weight of the second counterweight is G, which is related to the support pressure. The relationship is:

[0018] ;

[0019] Where: S is the longitudinal projected area of ​​the blade valve core. It is the lever arm of the blade valve core. It is the lever arm of counterweight two;

[0020] Step 2, bamboo-joint pile driving, dynamic pressure relief via constant pressure overflow valve: During the bamboo-joint pile driving process, the soil around the pile is compressed, and the compression effect is transmitted to the water bladder assembly. The compressed water reduces the support pressure within the water bladder assembly. Increase, make When the lever arm becomes unbalanced, the water flow pushes open the blade valve core and flows out of the outlet. Due to the soil squeezing effect of the bamboo-joint piles inside the geotextile bag, the required water flow to be discharged decreases. Continue to decrease until This balances the lever arm, preventing water from draining out and thus ensuring the support pressure inside the geotextile bag. Constant;

[0021] Step three: After the bamboo-joint pile driving is completed, cement-based grout is injected into the geotextile bag to solidify it. After the bamboo-joint pile driving is finished, the grouting pump is connected to the skeleton pipe, and cement-based grout is injected into the geotextile bag through the skeleton pipe to drain the water inside, turning the geotextile bag into a geotextile formwork concrete pile. Utilizing the physical property that the density of cement-based grout (approximately 1.8-2.0 g / cm³) is greater than that of water (1.0 g / cm³), after the pile driving operation is completed, grout is injected through the bottom of the skeleton pipe using the replacement grouting method, completely squeezing out the temporarily stored water inside the geotextile bag from bottom to top. This step transforms the temporary flexible pressure-relieving water bag into a permanent rigid geotextile formwork concrete pile in situ, eliminating the potential for ground settlement caused by abandoned holes and enhancing the bearing capacity of the composite foundation using abandoned holes, achieving "zero waste" and "secondary utilization" of building materials.

[0022] To address the transient, high-flow-rate pulse drainage conditions generated during bamboo-joint pile driving, this invention innovatively employs a constant-pressure overflow valve as the ground control unit. Utilizing the lever principle and the constant force characteristic of gravity, it ensures that regardless of changes in the valve opening, the support pressure of the water-filled bladder assembly on the pre-drilled hole remains locked within a set threshold range. This prevents the geotextile bag from bursting due to a surge in pressure within the water-filled bladder assembly, and also avoids hole collapse caused by excessively low pressure within the water-filled bladder assembly reducing the support pressure. This invention utilizes the isobaric properties of fluids to generate active radial support force (support pressure), effectively overcoming the lateral earth pressure (active earth pressure) of fluid-plastic soft soil. It fundamentally solves the construction problems of traditional bare holes (pre-drilled holes) being prone to diameter reduction and collapse. During the dynamic impact phase of pile driving, the fluid medium's discharge characteristics instantly transform the originally rigid support body (water-filled bladder assembly) into a contractible "virtual cavity," achieving a technological breakthrough in soft soil by "bore preservation and pressure relief."

[0023] Preferably, in the aforementioned bamboo-joint pile driving method, the geotextile bag has a double-layer composite structure. The outer layer of the geotextile bag is made of polypropylene filament woven geotextile, and the inner layer is made of thermoplastic polyurethane coating. The outer load-bearing layer of the geotextile bag, made of polypropylene filament woven geotextile, utilizes its high warp and weft tensile strength and low elongation to effectively resist the huge bursting force generated during pile driving and prevent the geotextile bag from deforming out of control. The inner layer of the geotextile bag (thermoplastic polyurethane coating) forms an airtight and watertight structure, which has a seepage prevention function and can ensure that water pressure is not lost during static support pre-drilling.

[0024] Preferably, in the aforementioned bamboo-joint pile driving method, the skeleton pipe is a galvanized steel pipe with arrayed openings on its sidewall. The skeleton pipe has a triple function of guiding and positioning, fluid channel, and grouting. The galvanized steel pipe is strong and corrosion-resistant, and the arrayed openings on its sidewall facilitate water injection.

[0025] Preferably, in the aforementioned bamboo-joint pile driving method, the flexible diaphragm is made of terephthalic diisocyanate-based polyurethane material. Terephthalic diisocyanate-based polyurethane material has strong toughness and corrosion resistance, and can withstand the high-pressure impact of the mud pulse flowing into the inlet and resist the chemical erosion of groundwater, mud and subsequent trace cement slurry in geotechnical engineering.

[0026] Preferably, in the aforementioned bamboo-joint pile driving method, the base of the blade valve core is made of stainless steel, and the sealing surface of the blade valve core is overlaid with precipitation-hardened stainless steel. The blade-shaped valve seat design allows the blade valve core to effectively break or squeeze out large pieces of mud, sand, and debris when it re-seated, ensuring a tight seal of the inlet and system safety under harsh operating conditions. Precipitation-hardened stainless steel has extremely high hardness (HRC40+), which can cut or squeeze out gravel like a blade, ensuring the "sharpness" and long-lasting closure of the blade valve core sealing surface.

[0027] Preferably, in the aforementioned bamboo-joint pile driving method, the inner diameter of the inlet and outlet is 80-100mm. The constant pressure overflow valve of the present invention, combined with the design of the large-diameter inlet and outlet, can effectively allow sand-containing turbid water to pass through without obstruction, ensuring the absolute unobstructed flow of the pressure relief channel and system safety under harsh working conditions.

[0028] In summary, this invention can precisely control the soil stress level and reduce the lateral displacement and bending moment of adjacent existing cast-in-place piles by more than 50%. In the prior art, due to the influence of bamboo-joint pile driving, the lateral displacement of existing cast-in-place piles may be between 30-40 mm. After adopting this method, the lateral displacement of existing cast-in-place piles is reduced to below 15 mm. In the prior art, due to the influence of bamboo-joint pile driving, the additional bending moment of existing cast-in-place piles is around 400 kN·m. After adopting this method, the additional bending moment of existing cast-in-place piles is reduced to below 200 kN·m. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the constant pressure overflow device for bamboo-joint pile driving according to the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of the water bladder assembly of the present invention.

[0031] Figure 3 This is a schematic diagram of the constant pressure relief valve of the present invention.

[0032] Figure 4 This is a schematic diagram of the lever principle of the constant pressure relief valve of the present invention.

[0033] Figure 5 This is a flowchart illustrating the steps of the bamboo-joint pile driving method of the present invention.

[0034] The labels in the attached diagram are as follows: 1-Water bladder assembly; 11-Geotextile bag; 12-Skeleton pipe; 13-Counterweight block one; 2-Pressure relief valve; 21-Inlet; 22-Outlet; 23-Blade valve core; 24-Flexible diaphragm; 25-Valve stem; 26-Pillar pin; 27-Lever arm; 28-Counterweight block two; 29-Valve seat; 3-Injection pile; 4-Grouting pump; 5-Bamboo pile. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below through specific embodiments and with reference to the accompanying drawings, but this should not be construed as limiting the present invention. Contents not described in detail in the following embodiments are all common knowledge in the art or can be implemented using conventional technical means in the art.

[0036] Reference to embodiments of the present invention Figure 1-5 .

[0037] like Figure 1 As shown, the constant pressure overflow device for bamboo-joint pile driving of the present invention includes a water bladder assembly 1 and a constant pressure overflow valve 2. The water bladder assembly 1 is disposed below ground level and placed within the soil; the soil portion is omitted in the figure. The constant pressure overflow valve 2 is connected to the water bladder assembly 1 via a pipe and is disposed above ground level.

[0038] like Figure 2 As shown, the water bladder assembly 1 includes a geotextile bag 11, a skeleton tube 12, and a counterweight 13. The skeleton tube 12 is located inside the geotextile bag 11, and its top end is connected to a pressure relief valve 2 via a pipe. The counterweight 13 is located at the bottom inside the geotextile bag 11 to facilitate the smooth sinking of the geotextile bag 11. The pre-drilled hole is set between the existing cast-in-place pile 3 and the newly constructed bamboo-joint pile 5, and the diameter of the pre-drilled hole is typically between 30-60 cm.

[0039] The geotextile bag 11 is the core component that bears the soil displacement pressure and maintains constant internal pressure, adopting a composite structure design of "strong outside and dense inside". The outer load-bearing layer of the geotextile bag 11 is made of polypropylene (PP) woven geotextile, utilizing its high warp and weft tensile strength and low elongation to effectively resist the huge bursting force generated during pile driving and prevent uncontrolled deformation of the geotextile bag 11. The geotextile bag 11 has a thermoplastic polyurethane (TPU) coating, forming an airtight and watertight structure with seepage prevention function, ensuring that water pressure is not lost during static support pre-drilling.

[0040] The skeleton pipe 12 serves a triple function as a guiding and positioning device, a fluid channel, and a grouting device. The skeleton pipe 12 is a galvanized steel pipe with an array of perforations on its sidewalls. The "guiding and positioning device" refers to the skeleton pipe 12 guiding and positioning the geotextile bag 11 when it is placed into the pre-drilled hole. The "fluid channel" refers to the skeleton pipe 12 acting as a water flow channel when water is injected into or drained from the geotextile bag 11. The "grouting device" refers to the ability to inject cement-based grout into the geotextile bag 11 through the skeleton pipe 12 after the bamboo-joint pile driving operation is completed.

[0041] The counterweight 13 ensures that the lightweight geotextile bag 11 can be vertically and smoothly sunk into the designed depth of the pre-drilled hole. The counterweight 13 is made of cast iron cone.

[0042] like Figure 3As shown, the constant pressure relief valve 2 includes a valve seat 29, on which an inlet 21 and an outlet 22 are provided. The inlet 21 is connected to the top end of the skeleton pipe 12 via a conduit, and the outlet 22 is connected to a drain pipe. A counterweight lever assembly is provided between the inlet 21 and the outlet 22. The counterweight lever assembly includes a fulcrum pin 26 connected to the valve seat 29 of the constant pressure relief valve 2 and a lever arm 27 connected to the fulcrum pin 26. A valve stem 25 is connected to the lever arm 27 near the fulcrum pin 26. The bottom end of the valve stem 25 is connected to a blade valve core 23. The blade valve core 23 is located at the intersection of the inlet 21 and the outlet 22 and is fitted into the inlet 21. When water enters the inlet 21, the water flow can push open the blade valve core 23 and enter the outlet 22, and then flow out of the outlet 22. A flexible diaphragm 24 is disposed above the blade valve core 23. The flexible diaphragm 24 is connected to the valve seat 29 of the constant pressure relief valve 2. The flexible diaphragm 24 seals the guide device connected to the blade valve core 23, preventing the guide device from being contaminated by sewage, rusted, or blocked by dirt, thus reducing the guiding accuracy and preventing the constant pressure relief valve 2 from failing. A counterweight 28 is disposed on the lever arm 27 away from the fulcrum pin 26. The constant pressure relief valve 2 also includes a pressure gauge 210, which is connected to the valve seat 29 of the constant pressure relief valve 2 via an isolation valve. The function of the isolation valve is to close the isolation valve when the pressure gauge 210 is damaged or needs to be calibrated, allowing the pressure gauge 210 to be replaced or maintained without stopping the machine or depressurizing; at the same time, by adjusting the opening degree of the isolation valve, it can dampen and buffer the fluid pulses transmitted from the inlet 21, protecting the internal mechanism of the pressure gauge 210 and extending its service life.

[0043] In this embodiment, the flexible diaphragm 24 is made of terephthalic diisocyanate-based polyurethane material to withstand the high-pressure impact of the mud pulse flowing into the inlet 21 and resist the chemical erosion of groundwater, mud, and subsequent trace cement slurry in geotechnical engineering. The blade valve core 23 has a base of 316 stainless steel, and the sealing surface is overlaid with precipitation-hardened stainless steel. Precipitation-hardened stainless steel has extremely high hardness (HRC 40+), which can cut or squeeze out gravel like a blade, ensuring the "sharpness" of the sealing surface and long-term closure. The valve seat 29 of the constant pressure relief valve 2 is made of ductile iron (QT450-10), and the inner wall of the valve seat 29 needs to be coated with epoxy resin powder. The inner diameter of the inlet 21 and outlet 22 is 80-100mm.

[0044] Reference steps for the bamboo-joint pile driving method of the present invention Figure 4 and Figure 5 .

[0045] Step 1, Installation and Static Support of Water Bag Component 1: A pre-drilled hole is constructed between the existing cast-in-place pile 3 and the newly constructed bamboo-joint pile 5. The water bag component 1 is inserted into the pre-drilled hole, and the constant pressure overflow valve 2 is connected to the water bag component 1. Water is pumped into the water bag component 1 until the pressure gauge 210 displays a reading of [insert pressure value here]. Turn off the water pump. The support pressure of water bladder assembly 1 on the pre-drilled borehole sidewall, wherein, With active earth pressure The relationship is:

[0046] γ×H;

[0047] =1.1× ~1.2× ;

[0048] Where: Ka is the active earth pressure coefficient, γ is the unit weight of the soil, and H is the depth of the pre-drilled hole;

[0049] Then, a second counterweight 28 is configured for the constant pressure relief valve 2 to balance the lever arm 27. The weight of the second counterweight 28 is G, which is related to the support pressure. The relationship is:

[0050] ;

[0051] Where: S is the longitudinal projected area of ​​the blade valve core 23. It is the lever arm of the blade valve core 23. It is the lever arm of counterweight 28;

[0052] Step 2, driving bamboo-joint pile 5, dynamic pressure relief by constant pressure overflow valve 2: During the driving of bamboo-joint pile 5, the soil around the pile is squeezed, and the squeezing effect is transmitted to water bladder assembly 1. The squeezed water reduces the support pressure inside water bladder assembly 1. Increase, make When lever arm 27 becomes unbalanced, water flows out of outlet 22, pushing open the blade valve core 23. Due to the soil squeezing effect of the bamboo pile 5, the required water flow rate inside the geotextile bag 11 decreases. Continue to decrease until This balances the lever arm 27, preventing water from draining out and thus ensuring the support pressure within the geotextile bag 11. Constant;

[0053] Step 3: After the bamboo pile 5 is driven into the soil bag 11, cement-based grout is injected into the soil bag 11 to complete the solidification of the soil bag 11. After the bamboo pile 5 is driven into the soil bag 11, the grouting pump 4 is connected to the skeleton pipe 12. Cement-based grout is injected into the soil bag 11 through the skeleton pipe 12 to drain the water in the soil bag 11, so that the soil bag 11 becomes a geotextile concrete pile.

[0054] The table below provides four examples, detailing different soil conditions. , The relationship between G and G:

[0055]

[0056] The table above illustrates the counterweight configuration when installing a constant pressure overflow device in pre-drilled holes at different depths under two soil conditions. For example, in Examples 1 and 2, in silty soil, given the active earth pressure coefficient Ka and the unit weight γ of the silty soil, a counterweight of 110N is required when installing this constant pressure overflow device in a 10m pre-drilled hole; and a counterweight of 212.8N is required when installing this constant pressure overflow device in a 20m pre-drilled hole. Examples 3 and 4 illustrate that in soft clay, given the active earth pressure coefficient Ka and the unit weight γ of the soft clay, a counterweight of 86.4N is required when installing this constant pressure overflow device in a 10m pre-drilled hole; and a counterweight of 168.9N is required when installing this constant pressure overflow device in a 20m pre-drilled hole.

[0057] The foregoing general description of the invention and its specific embodiments should not be construed as a limitation on the technical solution of the invention. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the invention, to form other technical solutions within the scope of protection of this invention.

Claims

1. A constant pressure overflow device for bamboo-joint pile driving, characterized in that: The system includes a water bladder assembly (1) and a constant pressure overflow valve (2) connected to the water bladder assembly (1). The water bladder assembly (1) includes a geotextile bag (11) with a skeleton tube (12) inside. The constant pressure overflow valve (2) includes a valve seat (29) with an inlet (21) and an outlet (22). The inlet (21) is connected to the skeleton tube (12) via a conduit. The outlet (22) is connected to a sewage pipe. A counterweight lever assembly is provided between the inlet (21) and the outlet (22). The counterweight lever assembly includes a fulcrum pin (26) connected to the valve seat (29) and a lever arm (27) connected to the fulcrum pin (26). The lever arm (27) is supported by a... The valve stem (25) is connected to the position of the fulcrum pin (26). The valve stem (25) is located inside the valve seat (29). The bottom end of the valve stem (25) is connected to the blade valve core (23). The blade valve core (23) is located at the intersection of the inlet (21) and the outlet (22) and is fitted with the inlet (21). The water flow in the inlet (21) can push open the blade valve core (23) and flow out through the outlet (22). The counterweight block (28) is set on the lever arm (27) away from the fulcrum pin (26). The counterweight block (28) can impede the water flow in the inlet (21) through the lever action. The constant pressure relief valve (2) also includes a pressure gauge (210). The pressure gauge (210) is connected to the valve seat (29) through an isolation valve.

2. The constant pressure overflow device for bamboo-joint pile driving according to claim 1, characterized in that: A flexible diaphragm (24) is provided above the blade valve core (23). The flexible diaphragm (24) is connected to the valve seat (29). The flexible diaphragm (24) plays a sealing role for the guide device connected to the blade valve core (23).

3. The constant pressure overflow device for bamboo-joint pile driving according to claim 2, characterized in that: The water bladder assembly (1) also includes a counterweight (13), which is located at the bottom of the geotextile bag (11).

4. The bamboo-joint pile driving method, characterized by: This method uses the constant pressure overflow device for bamboo-joint pile driving as described in claim 2, and includes the following steps: Step 1, Waterbag Assembly (1) Installation and Static Support: A pre-drilled hole is constructed between the existing cast-in-place pile (3) and the newly built bamboo-joint pile (5). The waterbag assembly (1) is inserted into the pre-drilled hole, and a constant pressure overflow valve (2) is connected to the waterbag assembly (1). Water is pumped into the waterbag assembly (1) until the pressure gauge (210) displays a reading of [value missing]. , The support pressure of the water bladder assembly (1) on the pre-drilled borehole sidewall, wherein, With active earth pressure The relationship is: γ×H; =1.1× ~1.2× ； Where: Ka is the active earth pressure coefficient, γ is the unit weight of the soil, and H is the depth of the pre-drilled hole; Then, a counterweight block two (28) is configured for the constant pressure relief valve (2) to balance the lever arm (27). The weight of the counterweight block two (28) is G, which is related to the support pressure. The relationship is: ； Where: S is the longitudinal projected area of ​​the blade valve core (23), It is the lever arm of the blade valve core (23). It is the lever arm of counterweight two (28); Step 2, driving the bamboo-joint pile (5), and dynamically releasing pressure through the constant pressure overflow valve (2): During the driving process of the bamboo-joint pile (5), the soil around the pile is squeezed, and the squeezing effect is transmitted to the water bladder assembly (1). The squeezed water increases the support pressure inside the water bladder assembly (1). Increase, make When the lever arm (27) becomes unbalanced, the water flow pushes open the blade valve core (23) and flows out from the outlet (22). The water flow required to be discharged from the geotextile bag (11) is reduced due to the soil squeezing effect of the bamboo pile (5). Continue to decrease until This balances the lever arm (27), preventing water from flowing out and thus ensuring the support pressure inside the geotextile bag (11). Constant; Step 3: After the bamboo pile (5) is driven, cement-based grout is injected into the geotextile bag (11) to complete the solidification of the geotextile bag (11): After the bamboo pile (5) is driven, the grouting pump (4) is connected to the skeleton pipe (12), and cement-based grout is injected into the geotextile bag (11) through the skeleton pipe (12) to drain the water in the geotextile bag (11) and make the geotextile bag (11) into a geotextile formwork concrete pile.

5. The bamboo-joint pile driving method according to claim 4, characterized in that: The geotextile bag (11) has a double-layer composite structure. The outer layer of the geotextile bag (11) is a woven geotextile with polypropylene filaments, and the inner layer of the geotextile bag (11) is a thermoplastic polyurethane coating.

6. The bamboo-joint pile driving method according to claim 4, characterized in that: The skeleton tube (12) is a galvanized steel pipe, and the side wall of the skeleton tube (12) has an array of openings.

7. The bamboo-joint pile driving method according to claim 4, characterized in that: The flexible diaphragm (24) is made of terephthalic diisocyanate-based polyurethane material.

8. The bamboo-joint pile driving method according to claim 4, characterized in that: The base of the blade valve core (23) is made of stainless steel, and the sealing surface of the blade valve core (23) is overlaid with precipitation-hardened stainless steel.

9. The bamboo-joint pile driving method according to claim 4, characterized in that: The inner diameter of the inlet (21) and outlet (22) is 80-100mm.

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