Tubular pile circumferential restraint device and construction method

Abstract

The invention relates to the technical field of tubular pile construction, in particular to a tubular pile circumferential restraint device and a construction method. The device comprises a driving mechanism and a radial telescopic assembly, the driving mechanism is used for outputting linear driving force in the axial direction of the pipe pile, and the output end of the driving mechanism is connected with the radial telescopic assembly and provided with a lifting point; the radial telescopic assembly comprises a plurality of telescopic parts which are coaxially arranged side by side, each telescopic part has an expansion state capable of abutting against the inner wall of the pipe pile and a contraction state capable of being separated from the inner wall of the pipe pile, and the telescopic parts make rolling contact with the inner wall of the pipe pile. When the driving mechanism drives the telescopic part to be far away from the lifting point, the telescopic part is switched to an expansion state; and when the driving mechanism drives the telescopic part to be close to the lifting point, the telescopic part is switched to a contraction state. According to the scheme provided by the invention, through the synergistic effect of the driving mechanism and the radial telescopic assembly, the telescopic part can apply active and dynamic circumferential stress compensation to the inner wall of the pipe pile in the whole pile sinking process, so that the damage problems of pile body cracking, local deformation and the like are solved.

Description

Technical Field

[0001] This application relates to the field of pipe pile construction technology, and in particular to a pipe pile circumferential restraint device and construction method. Background Technology

[0002] Dynamic impact pile driving, as a core construction method for precast pipe piles such as steel pipe piles and concrete pipe piles, occupies an irreplaceable position in the construction of major marine infrastructure such as port terminals, cross-sea bridges, and deep-sea wind power. As marine engineering expands into the deep sea, the technical challenges of offshore pile driving are becoming increasingly severe. This is because pipe piles are trending towards larger diameters and longer lengths, and need to penetrate complex and hard strata such as dense sand layers and weathered rock layers to obtain sufficient vertical bearing capacity. This places extremely high demands on the impact resistance of the pile structure.

[0003] However, during pile driving in complex and hard strata, the dynamic impact load generated by hammering can reach thousands of tons, inducing extremely high driving stress within the pile. When this stress exceeds the material's limits, it can easily cause damage and deformation to the pipe pile. For example, steel pipe piles are prone to buckling, while concrete pipe piles are prone to vertical and diagonal cracks or even breakage. These damage and deformations directly threaten the integrity and long-term durability of the pile foundation, with concrete pipe piles being particularly vulnerable due to their brittle nature. Summary of the Invention

[0004] To overcome the problems existing in related technologies, this application provides a circumferential restraint device for pipe piles. Through the precise coordination and linkage of the drive mechanism and the radial telescopic component, the telescopic part applies active and dynamic circumferential stress compensation to the inner wall of the pipe pile throughout the entire pile driving process, thereby eliminating the problem of circumferential stress concentration caused by uneven construction loads and solving the damage problems such as pile cracking and local deformation.

[0005] The first aspect of this application provides a circumferential restraint device for pipe piles, including a drive mechanism and a radial telescopic assembly; The drive mechanism is used to output a linear driving force along the axial direction of the pipe pile. Its output end is connected to a radial telescopic component, and the drive mechanism is provided with a lifting point. The radial telescopic assembly includes several telescopic parts arranged coaxially side by side. Each telescopic part has an expanded state that can press against the inner wall of the pipe pile and a contracted state that can detach from the inner wall of the pipe pile, and the telescopic part is in rolling contact with the inner wall of the pipe pile. When the drive mechanism drives the telescopic part away from the lifting point, the telescopic part switches to the expanded state; when the drive mechanism drives the telescopic part closer to the lifting point, the telescopic part switches to the retracted state.

[0006] In some embodiments, the drive mechanism includes a plurality of axial drive members, and a telescopic portion is provided between two adjacent axial drive members; The axial drive component at the first end is provided with the lifting point, and the axial drive component at the last end is provided with a conical base, and a pressure sensor is provided on the outer side of the conical base.

[0007] In some embodiments, the axial drive includes a hydraulic jack, an upper loading plate, and a lower loading plate, wherein the output end of the hydraulic jack is connected to the upper loading plate, and the fixed end is connected to the lower loading plate; Between adjacent axial drive components, the lower loading plate of the previous axial drive component and the upper loading plate of the next axial drive component are simultaneously connected to both ends of a telescopic part.

[0008] In some embodiments, the upper loading plate is provided with a plurality of guide rods extending along the axial direction of the pipe pile, and the lower loading plate is provided with guide through holes corresponding to the guide rods one by one.

[0009] In some embodiments, the telescopic portion includes a first transmission member, a second transmission member, an elastic constraint ring, and a plurality of inclined support rods: The elastic constraint ring abuts against the inner wall of the pipe pile in the expanded state, and several support rods are evenly distributed along the circumference of the elastic constraint ring. One end of the support rod is hinged to the elastic constraint ring, and the other end is divided into two groups, one group is hinged to the first transmission component, and the other group is hinged to the second transmission component. The outer circumferential surface of the elastic constraint ring is fitted with several rolling bearings.

[0010] In some embodiments, both the first transmission member and the second transmission member include a transmission ring and a plurality of axial connecting rods, wherein the transmission ring is fixedly connected to an adjacent axial driving member through the axial connecting rods; The support rod is hinged to the transmission ring, and the outer diameter of the transmission ring is smaller than the inner diameter of the elastic constraint ring when it is in a contracted state.

[0011] In some embodiments, the drive mechanism includes a servo motor; The telescopic part includes a cylindrical base, a rotating rod, a nut, a transmission rod, and a slider: The cylindrical base has an internal cavity and at least four grooves that communicate with the cavity in the circumferential direction. The rotating rod passes through the receiving cavity axially, the nut is located in the receiving cavity, and the rotating rod and the nut are threaded together. The two ends of the transmission rod are respectively hinged to the nut and the slider, and the slider is slidably disposed in the slide groove. The slider has several rollers arranged in an array on one side away from the rotating rod; The rotating rods between adjacent telescopic sections are coaxially connected by a coupling, and the rotating rod located at the first telescopic section is connected to the output shaft of the servo motor by a coupling.

[0012] In some embodiments, the cylindrical base includes a base plate, an end plate, and at least four blocking columns, the blocking columns being arranged in a circular array around the central axis of the rotating rod, and the two ends of the blocking columns being fixedly connected to the base plate and the end plate, respectively. The gap between adjacent blocking posts forms the sliding groove. Each blocking post is provided with a guide bar perpendicular to the axis of the rotating rod, and the slider is provided with a guide groove that mates with the guide bar. The second aspect of this application provides a construction method for a circumferential restraint device for pipe piles, comprising the following steps: S1. Hoist the circumferential restraint device of the pipe pile into the inner cavity of the pipe pile, load the preset circumferential restraint stress model into the servo controller, and connect the circumferential restraint device of the pipe pile to the pile driving equipment. S2. Start the pile driving equipment to carry out pile driving operations, and simultaneously monitor the hammer bounce value of the pile driving equipment and the penetration depth of the pipe pile per blow. S3. The servo controller determines whether the circumferential stress of the current pipe pile has reached the preset monitoring threshold based on the current hammer bounce height, penetration depth per blow, and preset penetration efficiency coefficient. S4. If the stress of the pipe pile reaches the threshold, the circumferential constraint device of the pipe pile is first positioned in the stress section of the pipe pile; then, based on the jump value of the previous hammer blow, the servo controller calculates the current required circumferential constraint stress value and the corresponding target load in combination with the hammer impact load and the circumferential constraint stress model; then, the drive mechanism is controlled to output the target load, driving all telescopic parts to expand synchronously and press against the inner wall of the pipe pile; then, steps S2 to S3 are repeated until the pile driving depth meets the design requirements. If the stress of the pipe pile does not reach the threshold, steps S2 to S3 are repeated. The servo controller maintains the contraction state of the telescopic part until the pile driving depth meets the design requirements.

[0013] In some implementations, step S1 specifically includes: S11. An installation hole is opened on the top side wall of the pipe pile, and the circumferential restraint device of the pipe pile is hoisted to the preset position inside the pipe pile cavity by the main lifting equipment. S12. The steel rope of the automatic lifting control device is threaded through the installation hole and wound around the pulley block, and then connected to the lifting point of the circumferential restraint device of the pipe pile. S13. Lead the power line of the drive mechanism out of the pipe pile through the mounting hole and connect it to the servo controller. S13. Establish a communication connection between the servo controller and the control system of the pile driving equipment.

[0014] The technical solution provided in this application may include the following beneficial effects: The circumferential constraint device for pipe piles provided in this application, through the coordinated design of the drive mechanism and radial telescopic components, combined with the intelligent control of the servo controller, can apply active and controllable circumferential constraint stress to the inner wall of the pipe pile during pile driving operations. During operation, the lifting equipment hoists the entire device into the inner cavity of the pipe pile through the lifting points on the drive mechanism. The servo system collects real-time data on the pile driving conditions (such as hammer bounce and penetration per blow) and dynamically adjusts the output load of the drive mechanism accordingly, driving multiple telescopic parts to expand or contract synchronously. This precisely matches the stress changes of the pipe pile in complex strata, solving technical problems such as pile cracking and local damage caused by encountering complex geological conditions such as hard interlayers and boulders, and filling the technical gap in active pile protection during pile driving. Attached Figure Description

[0015] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals denote the same components in the exemplary embodiments thereof.

[0016] Figure 1 This is a schematic diagram of the stress distribution of a pipe pile during pile driving construction, as shown in the embodiments of this application. Figure 2 This is a three-dimensional schematic diagram of the circumferential restraint device for pipe piles shown in Embodiment 2 of this application; Figure 3 This is a front view of the circumferential restraint device for pipe piles shown in Embodiment 2 of this application; Figure 4 This is a schematic diagram of the assembly of the axial drive member and the telescopic part shown in Embodiment 2 of this application; Figure 5 This is a schematic diagram of the telescopic part shown in Embodiment 2 of this application; Figure 6 This is a schematic diagram of the telescopic part shown in Embodiment 4 of this application; Figure 7 This is an exploded view of the telescopic part shown in Embodiment 4 of this application; Figure 8 This is a schematic diagram of the hoisting of the circumferential restraint device for pipe piles shown in Embodiment 5 of this application.

[0017] 1. Drive mechanism; 10. Lifting point; 11. Axial drive component; 110. Hydraulic jack; 111. Upper loading plate; 112. Lower loading plate; 113. Guide rod; 2. Radial telescopic assembly; 20. Telescopic part; 200. First transmission component; 201. Second transmission component; 202. Elastic constraint ring; 203. Support rod; 204. Columnar base; 205. Rotating rod; 206. Nut; 207. Transmission rod; 208. Slider; 3. Conical base; 4. Pipe pile; 5. Soil layer. Detailed Implementation

[0018] Preferred embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0019] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0020] Regarding the issue of pile driving stress, existing construction monitoring systems primarily focus on the assessment and control of vertical stress, such as verifying standard formulas and conducting dynamic pile driving tests. However, both theory and practice show that the stress waves generated by hammering induce complex expansion effects within the cavity of the pipe pile 4, causing significant circumferential tensile stress in the pile material. Once this stress exceeds the material's limit, the concrete pipe pile 4 will develop fatal longitudinal cracks, while the thin-walled steel pipe pile 4 will experience local buckling. Traditional vertical stress control methods completely ignore the hazards of circumferential tensile stress and cannot comprehensively guarantee construction quality. Figure 1 As shown, during the pile driving process, soil layer 5 has a natural restraining effect on the pile body in the soil section, which can effectively disperse the impact stress. However, the free section above the mud line lacks the restraint of soil layer 5, so the impact stress cannot be dissipated, forming a stress concentration area, which becomes a high-incidence area for pile damage.

[0021] Existing prevention and control measures are mostly passive and fixed protective measures. For steel pipe pile 4, the wall thickness of section 4 of the pipe pile is thickened; for PHC pipe pile 4, the pile body stirrups are reinforced. These measures are designed only for the final pile driving elevation, completely ignoring the dynamic changes of the free section as the pile penetrates during the pile driving process. In actual pile driving, the free section is constantly changing, and traditional measures cannot provide real-time protection for the high-stress zone throughout the entire pile driving process.

[0022] To address the aforementioned issues, this application provides a circumferential constraint device for pipe piles. Through the coordinated action of the drive mechanism 1 and the radial telescopic component 2, the telescopic part 20 can compensate for the radial circumferential constraint stress of the pipe pile 4 during the pile driving process, thus solving the problem of pile damage caused by the inability to control circumferential stress in real time.

[0023] Example 1 Please see Figure 2 or Figure 6 Embodiment 1 of this application proposes a circumferential restraint device for pipe piles, including a drive mechanism 1 and a radial telescopic assembly 2.

[0024] The drive mechanism 1 outputs a linear driving force along the axial direction of the pipe pile 4. Its output end is connected to the radial telescopic assembly 2, and the drive mechanism 1 is provided with a lifting point 10. The radial telescopic assembly 2 includes several coaxially arranged telescopic parts 20. Each telescopic part 20 has an expanded state that can press against the inner wall of the pipe pile 4 and a contracted state that can detach from the inner wall of the pipe pile 4. The telescopic part 20 is in rolling contact with the inner wall of the pipe pile 4. When the drive mechanism 1 drives the telescopic part 20 away from the lifting point 10, the telescopic part 20 switches to the expanded state; when the drive mechanism 1 drives the telescopic part 20 closer to the lifting point 10, the telescopic part 20 switches to the contracted state.

[0025] Specifically, the drive mechanism 1 generates a linear driving force that is transmitted along the axis of the pipe pile 4. This linear driving force can be generated in various ways, such as through a hydraulic cylinder, a pneumatic cylinder, a lead screw and nut 206 transmission mechanism, or a gear and rack transmission mechanism. The output end of the drive mechanism 1 is connected to the radial telescopic component 2, thereby transmitting the generated linear driving force to the radial telescopic component 2. The drive mechanism 1 is provided with a lifting point 10, which can be an annular lifting lug, a U-shaped lifting ring, or a connecting seat with a threaded hole, so as to facilitate the circumferential constraint and positioning of the pipe pile 4 into the inner cavity of the pipe pile 4 by lifting equipment.

[0026] The radial expansion joint 2 consists of multiple sets of expansion joints 20 equidistantly arranged along the axis of the pipe pile 4. In the expanded state, the central axis of each set of expansion joints 20 is coaxial with the axis of the pipe pile 4, forming a uniform circumferential constraint stress field. Each expansion joint 20 can be an independent unit or a combination of multiple sub-units. For example, the expansion joint 20 can be composed of multiple radially expandable wedges, an inflatable annular airbag, or a connecting rod in conjunction with an elastic constraint ring 202. In the expanded state, the radial dimension of the expansion joint 20 increases to the design value, allowing the outer surface of the expansion joint 20 to form a tight surface contact with the inner wall of the pipe pile 4. The uniformly distributed contact stress provides active circumferential constraint, effectively suppressing radial deformation of the pile body. In the contracted state, the radial dimension of the expansion joint 20 shrinks to a size smaller than the inner wall dimension of the pipe pile 4.

[0027] To reduce the moving resistance of the device and achieve dynamic constraint stability, the telescopic part 20 and the inner wall of the pipe pile 4 are designed with a low-friction rolling contact pair. For example, several rollers can be evenly distributed on the outer circumference of the telescopic part 20, or rolling bearings can be installed. During the pile driving process, when the pipe pile 4 penetrates the soil layer 5, a compacted soil plug layer will be formed inside the pile body. After the bottom of the radial telescopic component 2 contacts the soil plug layer, the reaction force of the soil plug and the axial force of the sinking pipe pile 4 will first form a dynamic balance, so that the telescopic part 20 maintains the circumferential constraint force while keeping relatively stationary with the inner wall of the pipe pile 4, avoiding synchronous downward movement with the pipe pile 4, thereby preventing the soil plug from directly impacting the radial telescopic component 2 and preventing damage to the device structure.

[0028] In this embodiment, through the closed-loop coordinated control of the drive mechanism 1 and the radial telescopic component 2, a dynamically adjustable active circumferential constraint force can be applied to the inner wall of the pipe pile 4 throughout the entire pile driving process. Firstly, when the pipe pile 4 passes through complex and hard strata such as dense sand layers and moderately weathered rock layers, the high-frequency impact load induced by hammering or vibration during pile driving can cause localized high stress concentrations. Active circumferential constraint can reduce the maximum stress in the pile body, preventing structural damage such as pile buckling instability, circumferential cracking, or even pile breakage. This is particularly suitable for thin-walled prestressed concrete pipe piles 4. Secondly, the active circumferential constraint provided by the telescopic component 20 is equivalent to providing a dynamic stirrup effect for the pipe pile 4, which can improve the impact bearing capacity of the pipe pile 4 and thus increase the ultimate penetration resistance. For large-diameter (≥1200mm) and ultra-long (≥60m) pipe piles 4, this can effectively solve the problem of penetration difficulties caused by insufficient pile stiffness in traditional construction. Furthermore, active circumferential restraint can reduce initial damage during pile driving, thereby lowering the risk of stress corrosion and fatigue failure of the pipe pile 4 during long-term use. The durability improvement effect is even more significant in highly corrosive coastal areas or bridge pile foundations subjected to dynamic loads. Finally, the pipe pile circumferential restraint device provided in this application does not require additional pile reinforcement procedures and can achieve real-time protection directly during pile driving, avoiding rework and pile replacement due to pile damage.

[0029] Example 2 To achieve the goal of synchronously outputting uniform circumferential constraint force from multiple telescopic parts 20, thereby improving the structural stability and force transmission accuracy of the device under complex working conditions, Embodiment 2 of this application, based on Embodiment 1, innovatively optimizes the distributed architecture of the drive mechanism 1. For details, please refer to... Figures 2-5 The drive mechanism 1 includes several axial drive components 11, and a telescopic part 20 is provided between two adjacent axial drive components 11. The axial drive component 11 at the first end is provided with the suspension point 10, and the axial drive component 11 at the end end is provided with a conical base 3. A pressure sensor is provided on the outer side of the conical base 3.

[0030] Specifically, the axial drive component 11 is an independently controllable axial force output unit. It can be flexibly selected from servo hydraulic cylinders, high-thrust pneumatic cylinders, or precision electric push rod / screw mechanisms according to requirements such as large load constraints, rapid response, or high-precision positioning. In this embodiment 2, by adopting a series modular layout of the axial drive component 11, the telescopic part 20, and the axial drive component 11, the drive mechanism 1 is decomposed into several independent units. Adjacent drive components are rigidly connected by the telescopic part 20, achieving distributed drive control. This structural design avoids force transmission attenuation over long distances, ensuring that each telescopic part 20 is directly and precisely driven by the drive components on both sides. Simultaneously, the resulting rigid overall structure can effectively resist vibration and impact loads during pile driving.

[0031] During pile driving, the device is hoisted and positioned to the stress concentration zone of the pipe pile 4 using lifting equipment. The stress concentration zone of the pipe pile 4 is the upper part of the exposed soil layer 5. Simultaneously, for the open-type pipe pile 4, the compacted soil plug layer formed inside during pile driving serves as a passive support structure, providing stable reaction force fulcrums for each expansion joint 20 and driving component, forming an axial force balance system between the hoisting force of the lifting point 10 and the reaction force of the soil plug. In specific implementation, to ensure that each expansion joint 20 outputs uniform circumferential constraint stress, a layered progressive expansion and contraction control logic from bottom to top can be adopted. First, the last driving component triggers the expansion of the bottom expansion joint 20. After it reaches the design constraint stress, the upper driving components are activated layer by layer upwards. Under this driving strategy, it avoids both the lower expansion joint 20 lacking deformation space due to premature expansion of the upper expansion joint and the upper expansion joint 20 expanding too early, causing the base to be suspended. The conical base 3, in surface contact with the soil plug layer, provides stable end support, maintaining the stability of the device's posture. It also allows for real-time assessment of the device's operating status through changes in contact pressure; for example, it can warn of jamming risks when the pressure exceeds the design threshold, while zero pressure indicates the device is suspended. Pressure sensors, either resistance strain gauges or piezoelectric types, can be selected as needed to collect contact pressure data in real time and transmit it to the control system. This not only assesses the stress state of the device but also ensures compliance with constraint stress regulations.

[0032] Furthermore, the axial drive component 11 includes a hydraulic jack 110, an upper loading plate 111, and a lower loading plate 112. The output end of the hydraulic jack 110 is connected to the upper loading plate 111, and the fixed end is connected to the lower loading plate 112. Between adjacent axial drive members 11, the lower loading plate 112 of the upper axial drive member 11 and the upper loading plate 111 of the next axial drive member 11 are simultaneously connected to the two axial ends of a telescopic part 20.

[0033] Specifically, the hydraulic jack 110 has advantages such as large output force, controllable stroke, and smooth operation, providing sufficient and precise power for the expansion and contraction of the telescopic part 20. The hydraulic jack 110 can be of single-acting or double-acting type, and its piston rod extension stroke should be sufficient to meet the axial displacement required for the telescopic part 20 to switch from the contracted state to the expanded state. The upper loading plate 111 and the lower loading plate 112 are used to transmit axial driving force and can be made of plate-like structures with certain rigidity and strength, such as steel plates or other high-strength alloy materials.

[0034] Based on this, between adjacent axial drive members 11, the lower loading plate 112 of the upper axial drive member 11 and the upper loading plate 111 of the next axial drive member 11 are simultaneously connected to both ends of a telescopic part 20 in the axial direction. That is, the upper end (or the end closer to the lifting point 10) of a telescopic part 20 is connected to the lower loading plate 112 of the axial drive member 11 above it, while the lower end (or the end farther from the lifting point 10) of the telescopic part 20 is connected to the upper loading plate 111 of the axial drive member 11 below it. In this way, when the hydraulic jack 110 works, the axial force it generates can be transmitted to both ends of the telescopic part 20 through the loading plate, thereby driving the telescopic part 20 to expand or contract. This series connection method makes the entire device form a continuous force transmission chain in the axial direction, ensuring the coordination of the actions of each telescopic part 20.

[0035] Furthermore, the upper loading plate 111 is provided with a plurality of guide rods 113 extending along the axial direction of the pipe pile 4, and the lower loading plate 112 is provided with guide through holes corresponding to the guide rods 113 one by one. When the upper loading plate 111 moves axially under the action of the axial driving member 11, the cooperation between the guide rods 113 and the guide through holes can precisely guide it linearly, which can avoid tilting, deflection or lateral displacement that may occur during the movement of the upper loading plate 111, thereby ensuring that the axial driving force can be stably and uniformly transmitted to the telescopic part 20.

[0036] Furthermore, the telescopic part 20 includes a first transmission member 200, a second transmission member 201, an elastic constraint ring 202, and a plurality of inclined support rods 203: The elastic constraint ring 202 abuts against the inner wall of the pipe pile 4 in the expanded state, and a number of support rods 203 are evenly distributed along the circumference of the elastic constraint ring 202. One end of the support rod 203 is hinged to the elastic constraint ring 202, and the other end is divided into two groups, one group is hinged to the first transmission member 200, and the other group is hinged to the second transmission member 201. The outer circumferential surface of the elastic constraint ring 202 is fitted with several rolling bearings.

[0037] Specifically, the elastic constraint ring 202, as the constraint execution component that directly contacts the inner wall of the pipe pile 4, adopts a composite structure of high-strength rubber, fiber-reinforced composite material (FRP), or segmented metal ring and elastic connector. It possesses sufficient radial elastic deformation capacity, allowing it to tightly conform to the inner wall of the pipe pile 4 in an expanded state, adapting to the surface irregularities of the inner wall. The inclined support rods 203 are evenly distributed circumferentially along the elastic constraint ring 202. These rods can be made of high-strength alloy steel, with one end hinged to the elastic constraint ring 202 via a roller, and the other end divided into two groups, each hinged to the first and second transmission components 201 via rollers. The elastic constraint ring 202 can also be fitted with multiple sets of rolling bearings to achieve rolling contact with the inner wall of the pipe pile 4. During operation, the linear push-pull force output by the axial drive component 11 is transmitted to the inclined support rod 203 via the first and second transmission components 201. Since the support rod 203 is at a suitable angle to the axis of the pipe pile 4, the axial force is decomposed into radial component and axial component. The radial component directly pushes the elastic constraint ring 202 to form radial expansion. The circumferentially symmetrically distributed support rod 203 ensures that the elastic constraint ring 202 maintains good roundness during the expansion process, so that the circumferential constraint force is evenly distributed on the inner wall of the pipe pile 4.

[0038] Furthermore, both the first transmission component 200 and the second transmission component 201 include a transmission ring and several axial connecting rods. The transmission ring is fixedly connected to the adjacent axial driving component 11 via the axial connecting rods. The support rod 203 is hinged to the transmission ring, and the outer diameter of the transmission ring is smaller than the inner diameter of the elastic constraint ring 202 when it is in the contracted state. By replacing the axial connecting rods of different lengths, the distance between the two telescopic parts 20 can be adjusted to adapt to the construction requirements of different pipe pile lengths 4, or the constraint distance can be dynamically optimized according to the changes in working conditions during the pile driving process, ensuring the uniform distribution of circumferential constraint force and construction stability. Under this configuration, no structural modifications to the core transmission components are required; parameter adjustments can be completed simply by replacing standardized parts, significantly improving the versatility and ease of maintenance of the device.

[0039] Example 3 Embodiment 3 of this application proposes a second implementation method for the circumferential constraint device of the pipe pile (not shown). The driving mechanism 1 is the same as in Embodiment 2, consisting of an axial driving member 11. The telescopic part 20 is composed of a fixed conical ring, a movable conical ring, multiple sets of wedge blocks, and an elastic constraint ring 202. The fixed and movable conical rings are coaxially mounted conical components. The wedge blocks are evenly distributed circumferentially between the two conical rings. The upper and lower surfaces of the wedge blocks are precisely fitted with the conical surfaces of the fixed and movable conical rings, respectively, and their outer surfaces contact the inner wall of the elastic constraint ring 202. When the axial driving member 11 extends, the movable conical ring moves closer to the fixed conical ring. Under the squeezing action of the conical surface, the wedge blocks move radially outward, pushing the elastic constraint ring 202 to expand uniformly and press against the inner wall of the pipe pile 4. When the axial driving member 11 retracts, the movable conical ring moves away from the fixed conical ring, and the wedge blocks move radially inward under the contraction force of the elastic constraint ring 202, causing the elastic constraint ring 202 to return to its contracted state. With this setting, the self-locking property of the conical surface can maintain the constrained state when power is lost or power is interrupted, thus improving construction safety.

[0040] Example 4 Both Embodiments 2 and 3 require multiple axial drive components 11 to achieve synchronous constraint of each telescopic part 20, resulting in a bulky structure and poor synchronization. To further improve the effect of synchronous constraint, Embodiment 4 of this application proposes a third implementation method for the circumferential constraint device of the pipe pile. For details, please refer to... Figure 6 and Figure 7 The drive mechanism 1 includes a servo motor, and the telescopic part 20 includes a cylindrical base 204, a rotating rod 205, a nut 206, a transmission rod 207, and a slider 208.

[0041] The cylindrical base 204 has an internal cavity and at least four grooves circumferentially distributed in communication with the cavity. The rotating rod 205 passes through the cavity axially. The nut 206 is located in the cavity and is threadedly engaged with the rotating rod 205 and the nut 206. The two ends of the transmission rod 207 are hinged to the nut 206 and the slider 208, respectively. The slider 208 is slidably disposed in the groove. Several rollers are arranged in an array on the side of the slider 208 away from the rotating rod 205. The rotating rods 205 between adjacent telescopic parts 20 are coaxially connected by a coupling. The rotating rod 205 located at the first telescopic part 20 is connected to the output shaft of the servo motor by a coupling.

[0042] Specifically, the servo motor features fast response speed, high positioning accuracy, and stable torque output. It can precisely output torque and speed according to control signals, thereby achieving refined control of the circumferential constraint device of the pipe pile. Its working principle is based on a closed-loop control system, which monitors the motor position and speed in real time through feedback devices such as encoders and compares them with target values ​​for precise adjustment. The cylindrical base 204 has a cylindrical structure and can be made of metal or high-strength plastic. The interior of the cylindrical base 204 has an axially extending receiving cavity, where internal transmission components such as the rotating rod 205, nut 206, and transmission rod 207 are located. The sliding grooves are circumferentially distributed channels on the cylindrical base 204 that communicate with the receiving cavity, guiding the slider 208 to slide radially. The number of sliding grooves can be set to 4, 8, or more, evenly distributed on the circumference of the cylindrical base 204. The specific number can be predicted based on the contact area between the slider 208 and the inner wall of the pipe pile 4, the diameter of the pipe pile 4, and the geological conditions of the construction site; generally, 4 to 8 grooves are preferred. The rotating rod 205 passes axially through the receiving cavity, with both ends of the rotating rod 205 protruding from the ends of the cylindrical base 204 to connect to the rotating rods 205 of adjacent telescopic parts 20. The rotating rod 205 has a threaded section that engages with the nut 206, thereby converting the rotational motion provided by the servo motor into the axial linear motion of the nut 206. The nut 206 is threadedly engaged with the rotating rod 205. When the rotating rod 205 rotates, the nut 206 moves along the axial direction of the rotating rod 205. The transmission rod 207 converts the axial linear motion of the nut 206 into the radial sliding motion of the slider 208. Through the design of the inclination angle and length of the transmission rod 207, a specific conversion relationship between the axial displacement of the nut 206 and the radial displacement of the slider 208 can be achieved, thereby controlling the expansion or contraction of the telescopic part 20. The roller array (not shown) is distributed on the side of the slider 208 away from the rotating rod 205, that is, the side that contacts the inner wall of the pipe pile 4. Its function is to provide rolling contact when the telescopic part 20 expands and presses against the inner wall of the pipe pile 4, thereby reducing frictional resistance, protecting the inner wall of the pipe pile 4, and ensuring that the telescopic part 20 can apply the constraint force smoothly and evenly.

[0043] In this embodiment, the servo motor transmits power to the rotating rods 205 of each telescopic section 20 via a coupling, ensuring that the rotating rods 205 of multiple telescopic sections 20 can rotate synchronously and precisely. Inside each telescopic section 20, the threaded engagement between the rotating rod 205 and the nut 206 efficiently converts the rotational motion into the axial linear motion of the nut 206. Subsequently, the transmission rod 207 converts the axial motion of the nut 206 into the radial sliding of the slider 208. The slider 208 moves stably within the groove of the cylindrical base 204 and rolls against the inner wall of the pipe pile 4 with the help of its roller on the side opposite to the rotating rod 205, ultimately enabling the device to accurately apply and maintain the preset circumferential constraint stress, effectively avoiding the gap and hysteresis problems that may exist in Embodiment 2.

[0044] Furthermore, the cylindrical base 204 of the telescopic part 20 includes a base plate, an end plate, and at least four blocking posts. The blocking posts are arranged in a circular array around the central axis of the rotating rod 205, and both ends of the blocking posts are fixedly connected to the base plate and the end plate, respectively. The gap between adjacent blocking posts forms the sliding groove. The blocking posts are provided with guide bars perpendicular to the axis of the rotating rod 205, and the slider 208 is provided with guide grooves that cooperate with the guide bars.

[0045] Example 5 Corresponding to the aforementioned embodiments of the circumferential restraint device for pipe piles, this application also provides a construction method for the circumferential restraint device for pipe piles, such as... Figure 8 As shown, the specific steps include: First, step S1 is executed, in which the circumferential restraint device of the pipe pile is hoisted into the inner cavity of the pipe pile 4, the servo controller loads the preset circumferential restraint stress model, and connects the circumferential restraint device of the pipe pile to the pile driving equipment.

[0046] Specifically, the circumferential restraint device for the pipe pile is hoisted into the inner cavity of the pipe pile 4. Lifting equipment (such as tower cranes, truck cranes, etc.) can be used to place the entire circumferential restraint device into the internal space of the pipe pile 4. After the servo controller loads the circumferential restraint stress model, it precisely controls the action and output load of the drive mechanism 1 according to preset instructions and real-time feedback signals.

[0047] The specific implementation process of this circumferential constraint stress model is as follows: (1) Calculate the dynamic strain rate of the pile body from the impact force Based on the one-dimensional stress wave propagation theory, the impact force at the pile top will generate a transient stress wave in the pile body, and its strain rate can be calculated using the following formula:

[0048] in, Dynamic strain rate of the pile (unit: s) 1 ); The maximum impact force at the pile top (unit: N) can be estimated from the hammer impact height using the momentum conservation formula (Mh is the hammer core mass, g is the gravitational acceleration, and h is the hammer impact height):

[0049] A is the cross-sectional area of ​​the pile (unit: m). 2 E is the elastic modulus of the pile material (unit: Pa), which is 30~40 GPa for concrete piles and 206 GPa for steel pipe piles. The stress wave pulse rise time (unit: s) is 3~10ms for hydraulic impact hammers, which can be determined by hammer type calibration. For example, when the hammer bounces 1.5m high, the hammer core mass is 20t, and the pile cross-sectional area is 0.1256m²... 2 With an elastic modulus of 35 GPa and a pulse rise time of 5 ms, the calculated strain rate is approximately 1.27 s. 1 .

[0050] (2) Material strength correction under strain rate effect The mechanical properties of concrete and steel increase significantly with strain rate (dynamic strengthening effect), requiring correction of the strain rate to obtain dynamic strength. 2.1 Dynamic compressive strength of concrete (using the CEB-FIP model), the formula is as follows:

[0051] The dynamic compressive strength of concrete (unit: MPa); This refers to the static compressive strength of concrete (unit: MPa), such as 80 MPa for C80 concrete. Static strain rate (taken as 1×10⁻⁶) 6 s 1 ).

[0052] 2.2 Dynamic yield strength of steel, the formula is as follows:

[0053] Dynamic yield strength of steel (unit: MPa); This represents the static yield strength of the steel (unit: MPa), such as 355 MPa for Q355 steel.

[0054] For example, when the strain rate is 1.27 s 1 At that time, the dynamic strength correction factor of C80 concrete was approximately 1.18, and the dynamic compressive strength was 94.4 MPa.

[0055] 3. Calculate the maximum allowable axial compressive stress in the pile body. To avoid damage to the pile body, a target control stress needs to be set, as shown in the following formula:

[0056] For safety, a value of 1.2 to 1.5 is recommended, and it can be adjusted according to the construction risk level.

[0057] For example, with a dynamic strength of 94.4 MPa and a safety factor of 1.3, the target control stress is approximately 72.6 MPa. 4. Calculate the overload stress that the expansion joint 20 needs to bear. By comparing the actual maximum compressive stress of the pile with the target control stress, the overload stress that needs to be offset by the circumferential constraint is obtained, as shown in the following formula:

[0058] The actual maximum compressive stress in the pile (unit: MPa) is calculated directly from the impact force. = / A.

[0059] For example, when the impact force is 1600kN and the pile cross-sectional area is 0.1256m² 2 When the actual compressive stress is approximately 12.7 MPa, if the target control stress is 72.6 MPa, then the overload stress is 0 (i.e., no constraint is required); if the actual compressive stress exceeds the target control stress, then the constraint stress needs to be calculated.

[0060] 5. Inverse calculation of circumferential constraint stress based on a constrained concrete model Using the Mander-confined concrete model, a quantitative relationship between axial compressive strength and circumferential confinement stress is established, and the simplified formula is as follows:

[0061] The required circumferential constraint stress (unit: MPa); The constraint effect coefficient is 4.0~4.5 for the circular cross-section spiral hoop constraint. The elastic constraint ring 202 of this device can be taken from this range. For example, when the overload stress is 10 MPa and the constraint effect coefficient is 4.2, the required circumferential constraint stress is approximately 2.38 MPa.

[0062] 6. Converted into the output load of drive mechanism 1 The circumferential constraint stress is converted into the output load of the drive mechanism 1 (such as a hydraulic jack) through the mechanical transmission ratio of the device:

[0063] The inherent transmission ratio of the device (unit: m) 2 The angle of the support rod 203 and the area of ​​the elastic constraint ring 202 are determined by static analysis or calibration tests. The typical range for this device is 0.05~0.10m. 2 .

[0064] For example, when the circumferential constraint stress is 2.38 MPa and the transmission ratio is 0.08 m... 2 At that time, the jack needs to output an axial load of approximately 190 kN.

[0065] The above model can provide a basis for calculating the target load for the servo controller under different pile driving conditions.

[0066] Next, step S2 is executed to start the pile driving equipment for pile driving operations, while simultaneously monitoring the hammer bounce value of the pile driving equipment and the penetration depth per blow of the pipe pile 4.

[0067] The pipe pile 4 is impacted or vibrated by a pile driving device (e.g., hydraulic hammer, vibratory hammer, etc.) to gradually penetrate into the soil layer 5. A servo controller synchronously monitors the hammer impact height, a crucial parameter reflecting the energy transfer efficiency of the hammer impact and the impedance of the pipe pile 7-soil layer 5 system. This height can be acquired using a displacement sensor or accelerometer mounted on the pile hammer. Penetration per blow refers to the distance the pipe pile 4 penetrates into the soil layer 5 after each hammer blow. It reflects the penetration resistance of the pipe pile under the current soil layer 5 conditions and is measured using a displacement sensor mounted on the top of the pipe pile 4 or on the pile driving device.

[0068] Subsequently, step S3 is executed, where the servo controller determines whether the circumferential stress of the current pipe pile 4 has reached the preset monitoring threshold based on the current hammer bounce height, penetration depth per blow, and preset penetration efficiency coefficient.

[0069] The preset monitoring threshold can be determined using the energy-efficiency ratio threshold method, the penetration attenuation rate threshold method, and the comprehensive stiffness threshold method.

[0070] The energy-efficiency ratio threshold method is as follows: Define parameters: ,in This represents the penetration efficiency coefficient for that hammer strike. The energy conversion coefficient is related to the hammer shape.

[0071] Setting the baseline: During a normal pile driving process before entering the suspected hard layer (e.g., the last 10 blows), calculate the average penetration efficiency coefficient. and its standard deviation .

[0072] Trigger threshold: When calculated in real time Three consecutive hits below At times, or in a single strike Below When this occurs, the system automatically determines that the area has entered a high-stress zone and triggers an alarm.

[0073] The penetration attenuation rate threshold method is as follows: Define parameters: , which is the relative decay rate of two adjacent penetrations.

[0074] Trigger threshold: when If the penetration exceeds a certain set value (e.g., 50%) continuously, and the jump height is increasing or remaining high, then a sudden change in resistance is determined. For example, if the penetration of the previous shot was 10mm, and the penetration of the current shot drops sharply to below 5mm while the jump height remains unchanged or increases. If ), then it will be triggered.

[0075] The comprehensive stiffness threshold method is more accurate than the two methods mentioned above, as detailed below: Parameter definition: Utilizing the principle of high strain dynamic testing (PDA), the impact stiffness or dynamic resistance of the pile body is calculated in real time.

[0076] (Simplified dynamic drag estimation) in This represents the maximum force measured at the top of the pile. Let A be the maximum velocity at the top of the pile, A be the cross-sectional area of ​​the pile, and E be the elastic modulus.

[0077] Trigger threshold: When the calculated dynamic resistance RSPD suddenly increases to more than 1.5-2 times the previous average value, and the penetration decreases synchronously, it can be clearly determined that the region has entered the extremely high resistance zone.

[0078] Finally, in step S4, if the stress of the pipe pile 4 reaches the threshold, the circumferential constraint device of the pipe pile is first positioned in the stress zone of the pipe pile; then, based on the jump value of the previous hammer blow, the servo controller calculates the current required circumferential constraint stress value and the corresponding target load in combination with the hammer impact load and the circumferential constraint stress model; then, the drive mechanism 1 is controlled to output the target load, driving all the telescopic parts 20 to expand synchronously and press against the inner wall of the pipe pile 4; then, steps S2 to S3 are repeated until the pile driving depth meets the design requirements; if the stress of the pipe pile 4 does not reach the threshold, steps S2 to S3 are repeated, and the servo controller maintains the contracted state of the telescopic parts 20 until the pile driving depth meets the design requirements.

[0079] Furthermore, such as Figure 8 As shown, step S1 specifically includes the following sub-steps: S11. An installation hole is opened on the top side wall of the pipe pile 4, and the circumferential restraint device of the pipe pile is hoisted to the preset position inside the pipe pile 4 by the main lifting equipment; S12. The steel rope of the automatic lifting control device is passed through the installation hole and wound around the pulley block, and then connected to the lifting point 10 of the circumferential restraint device of the pipe pile; S13. The power line of the drive mechanism 1 is led out of the pipe pile 4 through the installation hole and connected to the servo controller; S14. The servo controller is connected to the control system of the pile driving equipment.

[0080] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A circumferential restraint device for pipe piles, characterized in that, Includes the drive mechanism and radial telescopic assembly; The drive mechanism is used to output a linear driving force along the axial direction of the pipe pile. Its output end is connected to a radial telescopic component, and the drive mechanism is provided with a lifting point. The radial telescopic assembly includes several telescopic parts arranged coaxially side by side. Each telescopic part has an expanded state that can press against the inner wall of the pipe pile and a contracted state that can detach from the inner wall of the pipe pile, and the telescopic part is in rolling contact with the inner wall of the pipe pile. When the drive mechanism drives the telescopic part away from the lifting point, the telescopic part switches to the expanded state; when the drive mechanism drives the telescopic part closer to the lifting point, the telescopic part switches to the retracted state.

2. The circumferential restraint device for pipe piles according to claim 1, characterized in that, The drive mechanism includes several axial drive components, and a telescopic part is provided between two adjacent axial drive components. The axial drive component at the first end is provided with the lifting point, and the axial drive component at the last end is provided with a conical base, and a pressure sensor is provided on the outer side of the conical base.

3. The circumferential restraint device for pipe piles according to claim 2, characterized in that, The axial drive component includes a hydraulic jack, an upper loading plate, and a lower loading plate. The output end of the hydraulic jack is connected to the upper loading plate, and the fixed end is connected to the lower loading plate. Between adjacent axial drive components, the lower loading plate of the previous axial drive component and the upper loading plate of the next axial drive component are simultaneously connected to both ends of a telescopic part.

4. The circumferential restraint device for pipe piles according to claim 3, characterized in that, The upper loading plate is provided with a number of guide rods extending along the axial direction of the pipe pile, and the lower loading plate is provided with guide through holes corresponding to the guide rods.

5. The circumferential restraint device for pipe piles according to claim 2, characterized in that, The telescopic part includes a first transmission component, a second transmission component, an elastic constraint ring, and several inclined support rods: The elastic constraint ring abuts against the inner wall of the pipe pile in the expanded state, and several support rods are evenly distributed along the circumference of the elastic constraint ring. One end of the support rod is hinged to the elastic constraint ring, and the other end is divided into two groups, one group is hinged to the first transmission component, and the other group is hinged to the second transmission component. The outer circumferential surface of the elastic constraint ring is fitted with several rolling bearings.

6. The circumferential restraint device for pipe piles according to claim 5, characterized in that, Both the first and second transmission components include a transmission ring and several axial connecting rods. The transmission ring is fixedly connected to an adjacent axial driving component through the axial connecting rods. The support rod is hinged to the transmission ring, and the outer diameter of the transmission ring is smaller than the inner diameter of the elastic constraint ring when it is in a contracted state.

7. The circumferential restraint device for pipe piles according to claim 1, characterized in that, The drive mechanism includes a servo motor; The telescopic part includes a cylindrical base, a rotating rod, a nut, a transmission rod, and a slider: The cylindrical base has an internal cavity and at least four grooves that communicate with the cavity in the circumferential direction. The rotating rod passes through the receiving cavity axially, the nut is located in the receiving cavity, and the rotating rod and the nut are threaded together. The two ends of the transmission rod are respectively hinged to the nut and the slider, and the slider is slidably disposed in the slide groove. The slider has several rollers arranged in an array on one side away from the rotating rod; The rotating rods between adjacent telescopic sections are coaxially connected by a coupling, and the rotating rod located at the first telescopic section is connected to the output shaft of the servo motor by a coupling.

8. The circumferential restraint device for pipe piles according to claim 7, characterized in that, The cylindrical base includes a base plate, an end plate, and at least four blocking columns. The blocking columns are arranged in a circular array around the central axis of the rotating rod, and the two ends of the blocking columns are fixedly connected to the base plate and the end plate, respectively. The gap between adjacent blocking posts forms the sliding groove. The blocking posts are provided with guide bars perpendicular to the axis of the rotating rod, and the slider is provided with guide grooves that cooperate with the guide bars.

9. A construction method for a circumferential restraint device for pipe piles according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Hoist the circumferential restraint device of the pipe pile into the inner cavity of the pipe pile, load the preset circumferential restraint stress model into the servo controller, and connect the circumferential restraint device of the pipe pile to the pile driving equipment. S2. Start the pile driving equipment to carry out pile driving operations, and simultaneously monitor the hammer bounce value of the pile driving equipment and the penetration depth of the pipe pile per blow. S3. The servo controller determines whether the circumferential stress of the current pipe pile has reached the preset monitoring threshold based on the current hammer bounce height, penetration depth per blow, and preset penetration efficiency coefficient. S4. If the stress of the pipe pile reaches the threshold, the circumferential restraint device of the pipe pile shall be positioned in the stress zone of the pipe pile first. Subsequently, based on the jump height value of the previous hammer blow, the servo controller calculates the current required circumferential constraint stress value and the corresponding target load, combined with the hammer impact load and circumferential constraint stress model. Then, it controls the drive mechanism to output the target load, driving all expansion parts to expand synchronously and press against the inner wall of the pipe pile. Then, steps S2 to S3 are repeated until the pile driving depth meets the design requirements. If the stress of the pipe pile does not reach the threshold, steps S2 to S3 are repeated. The servo controller maintains the contraction state of the telescopic part until the pile driving depth meets the design requirements.

10. The construction method of the circumferential restraint device for pipe piles according to claim 9, characterized in that, Step S1 specifically includes: S11. An installation hole is opened on the top side wall of the pipe pile, and the circumferential restraint device of the pipe pile is hoisted to the preset position inside the pipe pile cavity by the main lifting equipment. S12. The steel rope of the automatic lifting control device is threaded through the installation hole and wound around the pulley block, and then connected to the lifting point of the circumferential restraint device of the pipe pile. S13. Lead the power line of the drive mechanism out of the pipe pile through the mounting hole and connect it to the servo controller. S13. Establish a communication connection between the servo controller and the control system of the pile driving equipment.

Images