Hoop type pile foundation uplift bearing capacity test device

Abstract

The invention discloses a hoop type pile foundation uplift bearing capacity test device, which is used for applying an uplift load to a pile foundation, and comprises a counter-force support assembly arranged on the ground and used for providing a test counter-force; the loading assembly is arranged on the counter-force supporting assembly and used for generating upward pulling force; the hoop is detachably fastened on the side wall of the pile foundation; and the flexible force transmission assembly is respectively connected with the loading assembly and the hoop. According to the invention, hoop force transmission is adopted to replace traditional steel bar force transmission, steel bar welding and threaded sleeve connection are avoided, material waste is reduced, and detection cost is reduced; the hoop is fastened through the high-strength bolt and is matched with the rubber cushion layer to increase friction force, so that the connection is reliable, test distortion caused by insufficient anchoring force is avoided, and the accuracy of a detection result is improved; the device is simple in structure and free of field welding operation, potential safety hazards are eliminated, meanwhile, damage to pile foundation steel bars is avoided, and safety and structural durability in the test process are improved.

Description

Technical Field

[0001] This invention relates to the field of foundation pile testing technology in building engineering, specifically a clamp-type pile foundation pull-out bearing capacity testing device. Background Technology

[0002] With the continuous development and utilization of urban underground space, large-scale underground projects such as underground parking garages and subway stations are increasing. As the main anti-buoyancy component, the requirements for testing the uplift bearing capacity of pile foundations are becoming increasingly stringent. According to the "Technical Specification for Testing of Building Foundation Piles" JGJ106-2014, pile foundations subjected to uplift forces must undergo single-pile vertical uplift bearing capacity testing to ensure project safety.

[0003] Existing pull-out test devices mostly use the steel reinforcement transfer method, that is, connecting the main reinforcement of the pile foundation to the top beam by welding or threaded sleeves, which has the following problems:

[0004] 1. The steel bars are used in large quantities, resulting in high costs. They are also easily damaged after repeated use and are difficult to reuse.

[0005] 2. On-site welding operations are inefficient, difficult to control in terms of quality, pose safety hazards, and require specialized equipment and personnel;

[0006] 3. Insufficient anchorage force between steel bars and concrete may lead to premature termination of the test, affecting the accuracy of the test results;

[0007] 4. It causes irreversible damage to the reinforcing steel in the pile foundation, affecting the structural durability.

[0008] Therefore, there is an urgent need for an efficient, safe, and reusable testing device for the pull-out bearing capacity of pile foundations to address the shortcomings of existing technologies. Summary of the Invention

[0009] The purpose of this invention is to overcome or at least partially solve the above-mentioned problems by proposing a clamp-type pile foundation pull-out bearing capacity testing device.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a clamp-type pile foundation pull-out bearing capacity testing device, used to apply pull-out loads to pile foundations, comprising:

[0011] The reaction support assembly, installed on the ground, is used to provide the test reaction force;

[0012] The loading component, set on the reaction support component, is used to generate an upward pulling force;

[0013] Clamps are detachably fastened to the sidewalls of the pile foundation;

[0014] The flexible force transmission component is connected to the loading component and the clamp respectively;

[0015] The upward pull-out force generated by the loading component is transmitted to the clamp through the flexible force transmission component, and then the static friction between the clamp and the side wall of the pile foundation applies a pull-out load to the pile foundation.

[0016] Preferably, the reaction support assembly includes piers spaced apart on both sides of the pile foundation, and a bottom beam erected on the piers.

[0017] Preferably, the loading component includes a jack disposed on the lower bottom beam and an upper top beam disposed on the top of the jack; the jack lifts the upper top beam upward to generate an upward pulling force.

[0018] Preferably, the upper top beam is a composite steel structure welded from I-beams and steel plates.

[0019] Preferably, the flexible force transmission component includes a steel wire rope and shackles at both ends thereon, the two ends of the steel wire rope being connected to clamps, and the middle part being tightly attached to the upper top beam.

[0020] Preferably, the clamp includes two semi-circular ring-shaped clamps, with lifting lugs at both ends of the top of the clamps, and the two clamps are connected and fixed to the side wall of the pile foundation by fasteners.

[0021] Preferably, the fastener is a high-strength bolt.

[0022] Preferably, the inner wall of the clamp is provided with a rubber pad layer.

[0023] Preferably, the upper top beam is provided with a limiting structure for restricting the movement of the wire rope.

[0024] Preferably, the wire rope is connected to the lifting lug of the clamp via a shackle.

[0025] Compared with existing technologies, this invention provides a clamp-type pile foundation pull-out bearing capacity testing device. It uses clamps to transmit force instead of traditional steel reinforcement, avoiding steel welding and threaded sleeve connections, reducing material waste and lowering testing costs. The clamps are secured with high-strength bolts, and a rubber pad increases friction, ensuring reliable connection and preventing test distortion caused by insufficient anchorage force, thus improving the accuracy of test results. Components such as the clamps, wire ropes, shackles, top beam, and bottom beam are all reusable, generating no waste and reducing long-term operating costs. It also eliminates the need for on-site welding, removing safety hazards and preventing damage to the pile foundation reinforcement, thereby improving the safety of the testing process and the structural durability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the clamp-type pile foundation pull-out bearing capacity testing device of the present invention;

[0027] Figure 2 This is a three-dimensional structural diagram of the clamp of the present invention.

[0028] In the diagram: 1. Pile foundation; 2. Rubber pad; 3. Hoop; 4. Lifting lug; 5. Shackle; 6. Wire rope; 7. Support; 8. Lower bottom beam; 9. Jack; 10. Upper top beam; 11. Steel plate. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this description, those skilled in the art can make creative modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

[0031] This invention provides a clamp-type pile foundation pull-out bearing capacity testing device, which solves the technical problems in the prior art. The overall concept is as follows:

[0032] Example 1:

[0033] Please see Figures 1-2 This invention provides a clamp-type pile foundation pull-out bearing capacity testing device, which transmits pull-out force through the friction between the clamp and the pile foundation, replacing the traditional steel reinforcement force transmission. The specific technical solution is as follows:

[0034] The core components and structures include:

[0035] Pile Foundation 1: The test object is a cast-in-place concrete pile or a precast pile.

[0036] Rubber pad 2: It is attached to the inside of the clamp 3 to increase the friction between the clamp and the pile foundation, while protecting the surface of the pile foundation.

[0037] Clamp 3: Made of 10mm thick steel plate, with a height of 500mm. The inner diameter can be adapted to pile foundations of different diameters such as 500mm, 600mm, 800mm, and 1000mm. The clamp is provided with high-strength bolt holes. By tightening with high-strength bolts, the clamp can be tightly fitted to the pile foundation to form a reliable friction force transmission interface.

[0038] Lifting lug 4: Steel lifting lug, welded and fixed to the clamp, used to connect the shackle.

[0039] Shackle 5: High-strength shackle, connecting the lifting lug to the wire rope and transmitting tension.

[0040] Steel wire rope 6: Model 6×37+1, nominal tensile strength 1700MPa, diameter 39mm, safety factor not less than 5, used to transfer the tension of the top beam to the clamp.

[0041] Pier 7: A reinforced concrete structure that acts as a reaction support, diverting the load transmitted from the bottom beam to the foundation.

[0042] Bottom beam 8: Made of double 40B I-beams welded together, used to support the jacks and transmit downward pressure.

[0043] Top beam 10: It is made of double 40B I-beams welded together and wrapped with a 10mm thick steel plate 11 to enhance the structural strength. The top beam is equipped with a limiting structure (such as a U-shaped groove) to fix the wire rope and ensure uniform stress.

[0044] Steel plate 11: 10mm thick steel plate, wrapped around the outside of the top beam, and welded with the I-beam to form a composite beam, improving the bending and shear resistance of the top beam.

[0045] Its detailed connection methods are well-known technologies in this field. The following mainly introduces the working principle and process, and the specific work is as follows:

[0046] Preparation: Select a clamp 3 with an appropriate inner diameter according to the diameter of the test pile foundation 1. Check the integrity of the clamp, rubber pad, wire rope, shackle and other components to ensure that there is no damage, corrosion or performance degradation. Treat the surface of the test section of the pile foundation 1, remove laitance and debris, and ensure that the surface is flat and firm. Pour or place reinforced concrete supports 7 to ensure that their strength and stability meet the test load requirements. The supports are symmetrically arranged on both sides of the pile foundation.

[0047] Device Installation: Evenly adhere the rubber pad 2 to the inside of the clamp 3, and place the clamp on the test section of the pile foundation 1. Secure it with high-strength bolts through the high-strength bolt holes on the clamp, ensuring a tight fit between the clamp and the pile foundation and preventing displacement of the rubber pad. Connect the shackle 5 to the lifting lug 4 on the clamp 3, then fix one end of the wire rope 6 to the shackle and embed the other end into the limiting structure of the upper beam 10. Adjust the length of the wire rope to ensure uniform stress on each wire rope. Place the lower beam 8 on the support 7, adjust its level, and symmetrically place the jacks 9 at their predetermined positions on the lower beam. Place the upper beam 10 on the jacks 9, adjust its position to ensure the wire ropes are taut and the force direction is parallel to the pile foundation axis. Install the oil pump loading device, load measuring device, and displacement measuring device, connect the wiring, and perform debugging to ensure normal operation of the equipment.

[0048] Test Operation: In accordance with the requirements of the "Technical Specification for Testing of Building Foundation Piles" JGJ106-2014, a graded loading method was adopted. The oil pump was started to drive the jack 9 to load in stages. After each stage of loading, the pressure was stabilized for a specified time, and the data was recorded in real time through the load measuring device and the displacement measuring device. During the loading process, the connection status of each component was closely observed, with a focus on checking the tightness of the clamps, the stress on the wire rope, and the working stability of the jack. If any abnormality was found, loading was stopped immediately and the problem was investigated. When the pile foundation reached its ultimate failure or the predetermined load value was reached, loading was stopped, and the unloading process was carried out according to the specification. After the test, the displacement measuring device, load measuring device, upper beam, jack, lower beam, wire rope, shackles, and clamps were removed in sequence. The site was cleaned and the equipment was maintained.

[0049] The above description of the embodiments is provided to facilitate understanding and use of the present invention by those skilled in the art. It is obvious to those skilled in the art that various modifications can be made to the embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A clamp-type pile foundation pull-out bearing capacity testing device, used to apply pull-out load to a pile foundation (1), characterized in that, include: The reaction support assembly, installed on the ground, is used to provide the test reaction force; The loading component, set on the reaction support component, is used to generate an upward pulling force; The clamp (3) is detachably fastened to the side wall of the pile foundation (1); The flexible force transmission component is connected to the loading component and the clamp (3) respectively; The upward pull force generated by the loading component is transmitted to the clamp (3) through the flexible force transmission component, and then the static friction between the clamp (3) and the side wall of the pile foundation (1) applies a pull-out load to the pile foundation (1).

2. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 1, characterized in that: The reaction support assembly includes piers (7) spaced apart on both sides of the pile foundation (1), and a bottom beam (8) erected on the piers (7).

3. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 2, characterized in that: The loading assembly includes a jack (9) mounted on the lower bottom beam (8) and an upper top beam (10) mounted on the top of the jack (9); the jack (9) lifts the upper top beam (10) upward to generate an upward pulling force.

4. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 3, characterized in that: The top beam (10) is a composite steel structure welded from I-beams and steel plates (11).

5. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 3, characterized in that: The flexible force transmission component includes a steel wire rope (6) and shackles (5) at both ends thereon. The two ends of the steel wire rope (6) are connected to the clamps (3), and the middle part is fastened to the upper top beam (10).

6. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 5, characterized in that: The clamp (3) includes two semi-circular ring-shaped clamps, and the top ends of the clamps are provided with lifting lugs (4). The two clamps are connected and fixed to the side wall of the pile foundation (1) by fasteners.

7. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 6, characterized in that: The fastener is a high-strength bolt.

8. A clamp-type pile foundation pull-out bearing capacity testing device according to claims 1-7, characterized in that: The inner wall of the clamp (3) is provided with a rubber pad layer (2).

9. The clamp-type pile foundation pull-out bearing capacity testing device according to claim 5, characterized in that: The upper top beam (10) is provided with a limiting structure for restricting the movement of the wire rope (6).

10. A test device for pull-out bearing capacity of a clamp-type pile foundation according to claim 6, characterized in that: The wire rope (6) is connected to the lug (4) of the clamp (3) via a shackle (5).

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