New and old pile foundation load self-adaptive regulation and control device based on pre-pressing spring and hydraulic compensation

Abstract

The invention relates to the technical field of pile foundation construction, and particularly discloses a new and old pile foundation load self-adaptive regulation and control device based on a pre-pressing spring and hydraulic compensation, which comprises a pre-pressing spring unit arranged between the top of a new pile and a bearing platform and used for storing and releasing elastic potential energy to guide the new pile to sink and providing initial supporting force; the hydraulic buffer damping unit is connected with the pre-pressing spring unit in series, is internally provided with viscous fluid and a fluid channel with controllable on-off, and is used for adjusting the sinking rate of the new pile and limiting the damping force to be increased sharply when the rate is suddenly changed; the hydraulic load compensation unit is arranged in the new pile body and is used for applying active compensation supporting force to the new pile body so as to dynamically compensate the bearing capacity loss; and the elastic supporting unit is arranged between the bearing platform and the top of the old pile. By means of the structure, guiding of the new pile settlement process and buffering of stress of the old pile are achieved, and therefore vertical load distribution can be balanced and stabilized in a self-adaptive mode in a common stress system of the new pile foundation and the old pile foundation.

Description

Technical Field

[0001] This invention relates to the field of pile foundation construction technology, and in particular to an adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation. Background Technology

[0002] In the reinforcement, expansion, or adjacent new construction of existing buildings, it is often necessary to add new piles next to the existing foundation system so that the new piles and the existing piles share the load from the superstructure. This type of new and old pile foundation system has been widely used in engineering practice, aiming to reduce the stress on the old piles and improve overall safety by sharing the load with the new piles. However, after the new piles are constructed, the surrounding soil is still in the consolidation development stage, which often leads to significant settlement of the new piles in the early stages of service; while the old piles, due to long-term service, have basically stabilized their settlement and have limited capacity for further deformation. At this time, if the initial settlement of the new piles is rapid or the settlement is large, the relative displacement between the new piles and the superstructure increases rapidly, causing the new piles to fail to play their load-bearing role in time. Instead, the superstructure load is concentrated and transferred to the old piles through the pile cap or distribution components, causing the old piles to bear additional loads beyond their design state, and even leading to overload risks, additional settlement, and structural safety hazards.

[0003] To address the aforementioned issues, existing technologies have attempted to incorporate load-adjusting devices between the pile top and the pile cap, such as the "Pile-Soil Load Adjuster for Composite Pile Foundations" disclosed in Chinese Patent Publication No. CN110777858B. This adjuster, by pre-setting the deformation angle of the angled plate, provides a controllable and stable deformation curve under compression, thereby adjusting the load-sharing ratio between the pile and the soil, thus improving the calculation accuracy of composite pile foundation design. However, such adjusters are essentially passive devices based on fixed deformation characteristics; their deformation behavior is preset during installation and cannot be dynamically adjusted according to the settlement development of the pile foundation during actual service.

[0004] In practical engineering, foundation conditions are complex and variable, and the settlement process of new piles exhibits significant uncertainty. Relying solely on regulators with preset deformation curves is insufficient to continuously and effectively adapt to real-time changes in new pile settlement throughout the structure's service life, especially failing to provide timely load compensation when new pile settlement is too rapid or abrupt. Furthermore, if a rigid connection is used between the new pile and the pile cap, the initial settlement of the new pile will quickly translate into additional loads on the old pile; while a simple flexible connection may prevent the long-term bearing capacity of the new pile from being fully utilized. Therefore, how to achieve real-time monitoring, dynamic compensation, and adaptive balance of loads during the settlement development of new piles, while simultaneously controlling initial settlement and ensuring later bearing stability, remains a key technical challenge for systems where new and old piles share the same load. Summary of the Invention

[0005] The purpose of this invention is to provide an adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation, in order to solve the above-mentioned technical problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: an adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation, comprising: a preloaded spring unit, disposed between the top of the new pile and the pile cap, for storing and releasing elastic potential energy to guide the sinking of the new pile and provide initial support force to the pile cap; a hydraulic buffer damping unit, connected in series with the preloaded spring unit, for adjusting the sinking rate of the new pile, wherein the unit has a viscous fluid and a controllable flow channel to limit the surge in damping force when the settlement rate changes abruptly; a hydraulic load compensation unit, built into the pile body of the new pile, for applying active compensating support force to the pile body of the new pile to dynamically compensate for the bearing capacity loss caused by the settlement of the new pile; and an elastic support unit, disposed between the pile cap and the top of the old pile, for providing flexible support for the old pile and buffering load changes.

[0007] Optionally, the preloaded spring unit includes an elastic element and an adjustment mechanism for adjusting its initial compression. The lower end of the elastic element is connected to a fixed plate via a column, and the upper end is connected to a support platform.

[0008] Optionally, the elastic element is a high-strength helical spring or a disc spring assembly.

[0009] Optionally, the hydraulic buffer damping unit includes a cylinder, a piston, and a viscous fluid filled in the cylinder; the piston divides the interior of the cylinder into upper and lower chambers; the cylinder or piston is provided with a main damping channel and an auxiliary bypass channel, and the opening and closing of the auxiliary bypass channel is controlled by a valve-controlled switch.

[0010] Optionally, the opening and closing of the valve-controlled switch is affected by the preload of the structural limiting spring and the fluid pressure. When the fluid pressure is lower than the preload, the valve-controlled switch is closed, and the viscous fluid flows only through the main damping channel. When the fluid pressure is higher than the preload, the valve-controlled switch is opened, activating the auxiliary bypass channel.

[0011] Optionally, the fixed plate is provided with an outlet hole for accommodating viscous fluid flowing out due to piston movement.

[0012] Optionally, the hydraulic load compensation unit includes an upper loading section and a lower loading section arranged opposite to each other. The upper loading section and the lower loading section, under hydraulic drive, respectively push the upper structure of the pile body upward and press the lower structure of the pile body downward. The hydraulic load compensation unit is connected to an external hydraulic pump station and control system through hydraulic pipelines.

[0013] Optionally, the control system instructs the hydraulic load compensation unit to operate based on the new pile settlement and / or preload spring unit support force attenuation signals fed back by the monitoring system.

[0014] Optionally, the elastic support unit is composed of a rubber pad or a low-stiffness spring.

[0015] Optionally, the hydraulic load compensation unit can be used as a self-balancing loading system to conduct vertical static load tests on the new piles after the new pile construction is completed and before the pile cap is installed.

[0016] Compared with the prior art, the present invention discloses at least the following beneficial effects: This invention establishes an integrated and synergistic load control system by installing a preloaded spring unit and a hydraulic buffer damping unit connected in series between the top of the new pile and the pile cap, and embedding a hydraulic load compensation unit inside the new pile body. Simultaneously, an elastic support unit is installed between the pile cap and the top of the old pile. This structure allows the elastic potential energy released by the preloaded spring unit to be actively guided to gradually sink the new pile during its initial service phase, thereby accelerating the settlement of the new pile and promoting its rapid stabilization. During the settlement process, the hydraulic buffer damping unit adaptively adjusts the sinking rate, avoiding load impacts caused by rapid, instantaneous settlement. Meanwhile, the built-in hydraulic load compensation unit dynamically applies compensating support force based on monitoring signals, promptly compensating for the bearing capacity reduction caused by the settlement of the new pile, ensuring that the new pile continuously shares the upper load throughout the entire settlement development stage. The elastic support unit located at the top of the old pile effectively buffers load fluctuations transmitted to the old pile due to changes in the bearing capacity of the new pile, transforming the stress on the old pile from abrupt to gradual. Thus, the device achieves an organic combination of active guidance, active compensation and rate control in the settlement process of new piles, thereby significantly improving the real-time balance and stability of load distribution between new and old pile foundations, reducing the additional stress and overload risk of old piles, and enhancing the safety and reliability of the overall foundation system during long-term service. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation provided in an embodiment of the present invention. Reference numerals in the attached diagram: 1. Preload spring unit; 2. Outlet orifice; 3. Piston; 4. Main damping channel; 5. Cylinder body; 6. Hydraulic buffer damping unit; 7. Hydraulic load compensation unit; 8. Column; 9. Fixing plate; 10. Structural limit spring; 11. Valve-controlled switch; 12. Auxiliary bypass channel; 13. Viscous fluid; 14. New pile; 15. Old pile; 16. Elastic support unit; 17. Foundation. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention aims to propose an adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation. This device addresses the problem in systems where new and old piles share a load. In the early stages of service, the new piles experience rapid settlement and their deformation capacity is inconsistent with that of the old piles, making it difficult for the new piles to promptly and stably bear their share of the vertical load. This leads to a concentrated transfer of the superstructure load to the old piles, causing additional stress or even overloading risks. The device accelerates the settlement of the new piles and helps them reach a stable state as quickly as possible. Simultaneously, it dynamically compensates for the bearing capacity of the new piles during settlement and adjusts the stress level of the old piles accordingly, achieving real-time balance and stable distribution of the vertical load between the new and old piles throughout the entire service life.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Reference Figure 1 As shown, this embodiment provides an adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation. This device is applied to a system where new and old pile foundations share a common load, specifically positioned between the new pile 14 and the pile cap 17, and works in conjunction with the old pile 15. It mainly consists of a preloaded spring unit 1, a hydraulic buffer damping unit 6, a hydraulic load compensation unit 7, and an elastic support unit 16 positioned between the pile cap 17 and the old pile 15. These units work together to achieve real-time, adaptive control of the vertical load of the superstructure during the transfer between the new and old piles.

[0023] In one specific embodiment, the preloaded spring unit 1 is disposed between the top of the new pile 14 and the pile cap 17. Its structure includes an elastic element (e.g., a high-strength helical spring or disc spring assembly) and an adjustment mechanism (not shown) for adjusting and fixing its initial compression. During installation, a predetermined initial compression is applied to the elastic element via the adjustment mechanism, placing it in an energy-storing state. The lower end of the preloaded spring unit 1 is fixedly connected to the lower fixing plate 9 via a column 8, while the upper end is connected to the pile cap 17 or its distribution components. Its function is to: in the early stages of structural service, by releasing the pre-stored elastic potential energy, apply a continuous vertical force to the new pile 14, guiding the new pile 14 to gradually and gently sink, promoting soil compaction around the pile, and thus allowing the new pile to reach a stable bearing state as quickly as possible; simultaneously, the preloaded spring unit 1 provides initial support force upwards to the pile cap 17, enabling the new pile 14 to share part of the upper structure load in the early stages of settlement development, preventing the load from being entirely borne by the old pile 15.

[0024] In one specific embodiment, the hydraulic damping unit 6 is connected in series with the preload spring unit 1, and is located below the preload spring unit 1. The hydraulic damping unit 6 mainly includes a cylinder 5, a piston 3, and viscous fluid 13 filled within the cylinder 5. The piston 3 divides the interior of the cylinder 5 into upper and lower chambers. A main damping channel 4 and an auxiliary bypass channel 12 are provided on the wall of the cylinder 5 or on the piston 3. The main damping channel 4 has a smaller equivalent flow cross-section, allowing the viscous fluid 13 to pass through in a restricted manner when the piston 3 moves slowly, thereby generating a stable damping force related to the movement speed. The auxiliary bypass channel 12 has a larger equivalent flow cross-section, and its opening and closing is controlled by a valve-controlled switch 11.

[0025] The opening and closing of the valve-controlled switch 11 is affected by the preload of the structural limiting spring 10 and the fluid pressure: when the piston 3 moves at a low speed, the fluid pressure is insufficient to overcome the preload of the structural limiting spring 10, the valve-controlled switch 11 is closed, and the fluid flows only through the main damping channel 4; when the new pile 14 sinks at a large instantaneous speed, the piston 3 moves faster, causing the fluid pressure to increase sharply. When the pressure is sufficient to overcome the preload of the structural limiting spring 10, the valve-controlled switch 11 is pushed open, the auxiliary bypass channel 12 is activated, and a large amount of fluid can pass through quickly, thereby limiting the excessive increase of the internal pressure difference of the damping unit.

[0026] The fixed plate 9 has an outlet hole 2 to accommodate the viscous fluid 13 flowing out due to the movement of the piston 3. The function of the hydraulic buffer damping unit 6 is to adjust the sinking rate of the new pile 14: to provide smooth damping during normal slow settlement and control the settlement development; and to avoid itself becoming nearly rigid by opening the auxiliary bypass channel 12 during instantaneous rapid settlement, thereby ensuring the continuity and controllability of the settlement process and preventing sudden load impact.

[0027] In one specific embodiment, the hydraulic load compensation unit 7 is built into the middle of the pile body of the new pile 14. Its specific structure can refer to existing self-balancing loading devices, including an upper loading section and a lower loading section arranged opposite to each other. Under hydraulic drive, the upper loading section pushes upwards and the lower loading section presses downwards into the pile body, respectively. The hydraulic load compensation unit 7 is connected to an external hydraulic pump station and control system (not shown in the figure) via hydraulic pipelines.

[0028] The hydraulic load compensation unit 7 has a dual function: First, during the stage when the new pile 14 is completed but the superstructure such as the pile cap 17 has not yet been installed, hydraulic pressure can be applied to the unit to form a self-balancing loading system inside the pile body, thereby conducting on-site testing of the vertical bearing capacity of the new pile 14 and providing a basis for design. Second, during the service stage of the structure, when the monitoring system (such as displacement sensors and pressure sensors) detects that the new pile 14 has settled and the supporting force of the preloaded spring unit 1 has weakened, the control system can instruct the hydraulic load compensation unit 7 to act again, providing hydraulic pressure to the upward loading section, so that it applies an upward compensating supporting force to the upper part of the pile body, thereby dynamically compensating for the bearing capacity loss caused by the settlement of the new pile 14 and ensuring that the new pile 14 can continuously share the load throughout the entire settlement process.

[0029] In one specific embodiment, the elastic support unit 16 is disposed between the pile cap 17 and the top of the existing pile 15. This unit may be made of a rubber pad, a low-stiffness spring, or other elastic material. Its function is to provide flexible support for the existing pile 15, so that when the load transmitted to the pile cap 17 is redistributed due to changes in the bearing capacity of the new pile 14, the force on the existing pile 15 can change gradually, from abrupt change to gradual change, thereby effectively buffering the instantaneous overload impact and improving the safety of the existing foundation system.

[0030] The working process of the device of the present invention is as follows: During the construction phase, after the new pile 14 is completed, a vertical static load test can be conducted using the built-in hydraulic load compensation unit 7 to evaluate its initial bearing capacity. After the test, the unit remains in its original position. Upon entering the service phase, the preloaded spring unit 1 guides the new pile 14 to begin sinking and initially bearing load with its pre-stored elastic energy. The hydraulic buffer damping unit 6 smoothly adjusts the sinking rate of the new pile 14. As the new pile 14 settles, the preloaded spring unit 1 gradually elongates, and its supporting force decreases. At this time, the hydraulic load compensation unit 7 is activated under the command of the control system to provide active compensation support force, so that the load-sharing capacity of the new pile 14 can be maintained. During this process, the auxiliary bypass channel 12 of the hydraulic buffer damping unit 6 can be opened when the settlement rate changes abruptly to prevent a surge in damping force. At the same time, the elastic support unit 16 buffers the load changes on the old pile 15. Finally, as the soil around the new pile 14 is consolidated and the bearing capacity of the pile itself is stably established, each control unit gradually transitions to a stable stress state, and the system achieves a long-term balanced distribution of loads between the new and old pile foundations.

[0031] After the new pile 14 is constructed, the surrounding soil is not yet fully consolidated, and it will inevitably undergo an initial settlement process. If it is allowed to settle naturally, a large relative displacement may occur between the new pile 14 and the superstructure, causing the load-bearing capacity of the new pile 14 to be delayed, which in turn causes the load to be excessively concentrated on the old pile 15, resulting in additional stress or even overload risk. This device actively guides the sinking process of the new pile 14 through the preloaded spring unit 1—that is, it uses the pre-stored elastic potential energy to proactively "bring out" the expected settlement of the new pile 14 in advance, thereby accelerating its settlement development and prompting it to reach a stable load-bearing state as soon as possible, rather than passively waiting for its natural settlement. While guiding the sinking, the preloaded spring unit 1 also provides initial support force for the new pile 14, enabling it to share part of the load in the early stage of settlement.

[0032] Through the synergistic mechanism of passive guidance, active compensation and rate regulation, this device can transform the sudden settlement that may occur in the new pile 14 into a continuous and controllable development process, and realize the adaptive balance and stable distribution of vertical load in the joint force system of the new and old pile foundations.

[0033] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0034] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A new and old pile foundation load adaptive control device based on preloaded springs and hydraulic compensation, characterized in that, include: A preloaded spring unit (1) is set between the top of the new pile (14) and the pile cap (17) to store and release elastic potential energy to guide the new pile (14) to sink and provide initial support force for the pile cap (17); The hydraulic buffer damping unit (6) is connected in series with the preloaded spring unit (1) to adjust the sinking rate of the new pile (14). It is equipped with viscous fluid (13) and a controllable fluid channel to limit the surge of damping force when the settlement rate changes abruptly. The hydraulic load compensation unit (7) is built into the pile body of the new pile (14) and is used to apply active compensation support force to the pile body of the new pile (14) to dynamically compensate for the loss of bearing capacity caused by the settlement of the new pile (14). The elastic support unit (16) is set between the pile cap (17) and the top of the old pile (15) to provide flexible support for the old pile (15) and buffer load changes.

2. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 1, characterized in that, The preload spring unit (1) includes an elastic element and an adjustment mechanism for adjusting its initial compression. The lower end of the elastic element is connected to the fixed plate (9) through the column (8), and the upper end is connected to the support platform (17).

3. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 2, characterized in that, The elastic element is a high-strength helical spring or a disc spring assembly.

4. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 2, characterized in that, The hydraulic buffer damping unit (6) includes a cylinder (5), a piston (3), and a viscous fluid (13) filled in the cylinder (5); the piston (3) divides the interior of the cylinder (5) into upper and lower chambers; the cylinder (5) or the piston (3) is provided with a main damping channel (4) and an auxiliary bypass channel (12), and the opening and closing of the auxiliary bypass channel (12) is controlled by a valve control switch (11).

5. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 4, characterized in that, The opening and closing of the valve-controlled switch (11) is affected by the pre-pressure of the structural limiting spring (10) and the fluid pressure. When the fluid pressure is lower than the pre-pressure, the valve-controlled switch (11) is closed, and the viscous fluid (13) flows only through the main damping channel (4). When the fluid pressure is higher than the pre-pressure, the valve-controlled switch (11) is opened, activating the auxiliary bypass channel (12).

6. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 4, characterized in that, The fixed plate (9) has an outlet hole (2) for accommodating the viscous fluid (13) flowing out due to the movement of the piston (3).

7. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 1, characterized in that, The hydraulic load compensation unit (7) includes an upper loading section and a lower loading section arranged opposite to each other. The upper loading section and the lower loading section push the upper structure of the pile body upward and press the lower structure of the pile body downward respectively under hydraulic drive. The hydraulic load compensation unit (7) is connected to an external hydraulic pump station and control system through hydraulic pipelines.

8. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 7, characterized in that, The control system commands the hydraulic load compensation unit (7) to operate based on the settlement of the new pile (14) and / or the attenuation signal of the support force of the preload spring unit (1) fed back by the monitoring system.

9. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 1, characterized in that, The elastic support unit (16) is composed of a rubber pad or a low-stiffness spring.

10. The adaptive load control device for new and old pile foundations based on preloaded springs and hydraulic compensation according to claim 1, characterized in that, The hydraulic load compensation unit (7) can be used as a self-balancing loading system to conduct vertical static load tests on the new pile (14) after the new pile (14) is constructed and before the pile cap (17) is installed.

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