Electromagnetic ejection type rapid load method pile foundation horizontal bearing capacity detection device and method

Abstract

The invention particularly relates to a device and method for detecting the horizontal bearing capacity of a pile foundation through an electromagnetic ejection type speed load method, and the device comprises an electromagnetic ejection device which is transversely and fixedly arranged on the foundation and comprises two electromagnetic guide rails which are parallel to each other and extend horizontally; the armature is embedded in the electromagnetic guide rail in a sliding manner; the pulse power supply and the control switch are electrically connected with the electromagnetic guide rail; the bearing device comprises a bearing box of which the bottom is rigidly connected with the armature through an insulating connecting rod; the impact head is arranged at the front end of the bearing box; the detection balance weight is detachably placed in the bearing box; the buffer device is arranged on the impacted side of the to-be-detected pile foundation; the signal detection system is arranged on the pile foundation to be detected; the resetting device comprises a winch and a steel cable for connecting the bearing device and the winch; and the control system is in signal connection with the pulse power supply and the reset device. The method has the advantages that the efficiency and the cost are obviously optimized; the safety and the field adaptability are outstanding; the data quality is high; and the information dimensions are rich.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation detection, and in particular to a device and method for detecting the horizontal bearing capacity of a pile foundation using an electromagnetic ejection rapid loading method. Background Art

[0002] Pile foundation is a common foundation form in high-rise buildings, ports, bridges and other projects. Whether its horizontal bearing capacity meets the design requirements is related to the stability and safety of the structure under horizontal loads. Therefore, the horizontal bearing capacity testing of pile foundation is an important part of ensuring the quality and performance of pile foundation construction in civil engineering.

[0003] Currently, the primary methods for testing the horizontal bearing capacity of pile foundations are horizontal static load tests and rapid load tests. The horizontal static load test applies graded static loads to the pile and measures the displacement of the pile top to create a load-displacement curve. This is the most direct and reliable method for evaluating the bearing capacity of a pile foundation. However, this method requires bulky testing equipment, is costly, and time-consuming.

[0004] The rapid load horizontal test is a new detection method that is widely used abroad. It usually involves rapidly burning special gunpowder in the cylinder of the device. The high-pressure gas generated pushes the heavy object outward with a large acceleration, causing it to collide with the pile foundation. Its advantages are short test time and high efficiency, but the special gunpowder used is an explosive and is subject to supervision by relevant departments. At the same time, its combustion will produce polluting toxic gases, polluting the environment.

[0005] The applicant proposed an electromagnetic ejection rapid loading method pile foundation vertical bearing capacity detection device and method, but the device and method can only be used to detect the vertical pile foundation bearing capacity, which cannot solve the technical problem of using the rapid loading method to detect the horizontal bearing capacity of the pile foundation in the present invention.

[0006] Therefore, it is urgent to design a device and method for horizontal rapid loading method that can replace the use of gunpowder explosion as power in the existing technology, and provide a stable, environmentally friendly and safe device and method for rapid loading method pile foundation horizontal bearing capacity detection. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity detection device and method, which uses an electromagnetic catapult device instead of gunpowder to provide a power source for the counterweight, avoids pollutants produced by gunpowder combustion and explosion in conventional rapid loading method tests, reduces carbon emissions, and improves the safety and efficiency of the test.

[0008] In order to achieve the above-mentioned purpose, an electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity detection device is designed, comprising: an electromagnetic catapult device fixedly arranged laterally on the foundation, comprising: two electromagnetic guide rails parallel to each other and extending horizontally; an armature slidably embedded in the electromagnetic guide rails; a pulse power supply and a control switch electrically connected to the electromagnetic guide rails; a bearing device, connected to the armature and sliding horizontally along the electromagnetic guide rails, comprising: a bearing box with a bottom rigidly connected to the armature through an insulating connecting rod; an impact head arranged at the front end of the bearing box; a detection counterweight detachably placed in the bearing box; a buffer device arranged on the impacted side of the pile foundation to be detected; a signal detection system, arranged on the pile foundation to be detected, for real-time collection of horizontal force, displacement and acceleration time-history curves under the action of impact load; a reset device, comprising a power device fixedly arranged on the ground and a steel cable connecting the bearing device and the power device; a control system, connected to the pulse power supply and the reset device signal, for synchronously controlling the start, stop and reset actions of the electromagnetic catapult.

[0009] Preferably, the present invention further comprises: a groove is provided on the top of the electromagnetic guide rail, the carrying box is embedded in the groove via a bottom pulley to achieve low-friction horizontal sliding, and the electromagnetic guide rail serves as a horizontal guide and reaction force component.

[0010] Preferably, the present invention further comprises: a through slot conforming to the electromagnetic guide rail is provided on the armature, so that the center line of the horizontal impact load and the axis of the pile foundation to be tested are in the same horizontal plane.

[0011] Preferably, the present invention further comprises: the impact head is coaxially arranged with the center line of the buffer device, a force sensor and an acceleration sensor are provided in the buffer device, and the displacement sensor is arranged on the foundation and parallel to the impact direction.

[0012] Preferably, the present invention further comprises: the detection counterweight is fixed to the carrying box by a wooden wedge or a fastener, so as to form a fixed connection between the carrying box and the detection counterweight during the acceleration and impact process.

[0013] Preferably, the present invention further includes: the pulse power supply forms an adjustable pulse width of 100ms-800ms by adjusting the output current to match the detection requirements of different design level bearing capacities.

[0014] The present invention also provides a method for detecting the horizontal bearing capacity of a pile foundation using an electromagnetic catapult-type rapid loading method implemented using the device, comprising the following steps: step a, fixing the electromagnetic guide rail horizontally on the foundation and leveling and calibrating it; step b, installing the bearing box on the electromagnetic guide rail through a pulley, and connecting the armature and the pulse power supply; step c, assembling the detection counterweight and adjusting the output current of the pulse power supply according to the designed horizontal bearing capacity of the pile foundation to be detected; step d, installing a buffer device and a signal detection system, and completing system debugging; step e, starting the control system, closing the control switch, so that the armature pushes the bearing box to accelerate in the horizontal direction under the action of the electromagnetic force; step f, the impact head hits the buffer device, and the signal detection system collects the force-displacement-acceleration time history curve in real time; step g, after the impact is completed, the reset device pulls the bearing box back to the initial position; step h, analyzing the horizontal bearing capacity of the pile foundation, the bending moment distribution of the pile body, and the lateral resistance of the soil based on the collected time history curve.

[0015] Preferably, the present invention further comprises: in step e, the combined force of the electromagnetic thrust and the counterweight inertia acts for a time period of 100 ms-800 ms, so as to place the pile foundation land system in a quasi-static response range.

[0016] Compared with the prior art, the present invention has the following advantages: 1. Significantly Improved Efficiency and Cost: The rapid loading method utilizes millisecond-level (100-800ms) transient horizontal loads (such as hydraulic shock) for testing. Single-point testing takes only minutes to half an hour, representing a tenfold improvement in efficiency compared to the multi-day cycle of traditional horizontal static load tests. Furthermore, the electromagnetic ejection method enables lightweight equipment (eliminating the need for hundreds of tons of reaction loads or complex anchoring systems) and a high degree of automation, significantly reducing equipment transportation, installation, and labor costs (overall costs can be reduced by over 50%). This method is particularly suitable for projects with tight deadlines or large-scale pile foundation testing.

[0017] 2. Outstanding safety and site adaptability: The instantaneous loading method completely avoids the safety risks associated with traditional methods, such as reaction platform instability and collapse caused by long-term loading. It is particularly suitable for hazardous sites such as soft soil, high water levels, or deep foundation pits. Horizontal loads can easily cause eccentric stress on the pile body. The electromagnetic catapult rapid loading method's guide device ensures precise load transfer and reduces the risk of lateral deviation.

[0018] 3. High Data Quality and Rich Information: Compared to the high-strain dynamic measurement method, the rapid loading method's longer loading duration makes the dynamic response of the pile foundation soil closer to quasi-static, allowing direct acquisition of highly accurate horizontal load-displacement curves (PY curves), with displacement measurement errors controlled to within 0.1mm. Combining sensor data with signal fitting techniques (such as the unloading point method) not only reliably assesses horizontal bearing capacity (corrected error <10%), but also analyzes pile bending moment distribution, lateral soil resistance classification, plastic hinge location, and soil damping characteristics, providing a multi-dimensional and in-depth basis for lateral force resistance design and safety assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a front view of the device of the present invention; Figure 2 It is a top view of the carrier box; In the figure: 1 buffer device, 2 electromagnetic guide rail, 3 impact head, 4 insulating connecting rod, 5 armature, 6 bearing box, 7 control switch, 8 pulse power supply, 9 signal detection system, 10 reset device, 11 detection counterweight, 12 pile foundation. DETAILED DESCRIPTION

[0020] In order to make the purpose, principle and structure of the present invention clearer, the following is further elaborated with reference to the drawings and specific embodiments. The described embodiments are only part of the present invention and not all of it. Any exemplary embodiment is only for explanation and does not constitute a limitation on the application or use of the present invention. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work all fall within the scope of protection of the present invention. Unless otherwise specified, the relative arrangement, expression and numerical values ​​of the components and steps in the examples do not limit the scope of the present invention; the dimensions of the components in the drawings are not drawn according to the actual scale. Known technologies, methods and equipment are deemed to be part of this specification when necessary. The specific numerical values ​​in all examples are exemplary and not restrictive.

[0021] In response to the shortcomings of existing pile foundation horizontal bearing capacity detection methods, the present invention proposes a new pile foundation horizontal bearing capacity detection method that uses an electromagnetic catapult device instead of gunpowder, avoiding pollution caused by gunpowder combustion and explosion, reducing carbon emissions, and improving test safety and efficiency.

[0022] See also Figure 1 、 2 The present invention discloses an electromagnetic ejection type rapid loading method pile foundation horizontal bearing capacity detection device and method, the device is composed of an electromagnetic ejection device, a bearing device, a detection counterweight 11, a buffer device 1, a signal detection system 9, a control system and a reset device 10.

[0023] The electromagnetic catapult device comprises: electromagnetic rails 2, an armature 5, a generator, a pulse power supply 8, and a control switch 7. The electromagnetic rails 2 consist of two horizontally parallel tracks. When energized, they generate a strong magnetic field, providing guidance and positioning for the armature 5 and the load-carrying device, which slide in contact with them. The armature 5 has a transverse groove or recessed structure shaped like the electromagnetic rails 2 in its center. The armature 5 slides into the groove of the electromagnetic rails 2. When energized, the armature 5 forms a closed circuit with the electromagnetic rails 2. Electromagnetic force propels the load-carrying box 6 within the load-carrying device through the upwardly angled insulating connecting rod 4. This not only transmits force from the armature 5 to the load-carrying device but also prevents any conflict between the armature 5's transmission structure and the electromagnetic rails 2. The generator provides a stable voltage for the pulse power supply 8, which can store, release, and regulate energy, releasing large amounts of energy in a short period of time to generate a strong electromagnetic force. The control switch 7 is connected to the control system. When closed, the pulse power supply 8 instantly discharges, creating a strong magnetic field between the electromagnetic rails 2 and pushing the load-carrying box 6 forward.

[0024] The load-bearing device consists of a load-bearing box 6, an impact head 3, and an insulating connecting rod 4. The load-bearing box 6 has a cavity inside. The load-bearing box 6 is inserted into the top groove of the electromagnetic guide rail 2 via a pulley at the bottom, and the insulating connecting rod 4 rolls in engagement. The insulating connecting rod 4 bypasses the electromagnetic guide rail 2 or passes through the gap between the parallel tracks of the electromagnetic guide rail 2. The insulating connecting rod 4 connects the load-bearing box 6 and the armature 5. The impact head 3 is rigidly mounted at the front end of the load-bearing box 6 to transmit the transient impact load directly to the pile foundation 12 to be tested. This reduces the contact area between the load-bearing box and the pile foundation 12 to be tested, thereby increasing the pressure while maintaining the mass of the load-bearing device. The load-bearing box 6 and the electromagnetic guide rail 2, as well as the insulating connecting rod 4 and the armature 5, are all insulated.

[0025] The detection counterweight 11 is evenly placed in the carrying box 6. It is an object with a certain mass. There is no relative displacement between the detection counterweight 11 and the carrying box 6 during the movement process. The gap between the detection counterweight 11 and the carrying box 6 is filled with wooden wedges or connecting parts.

[0026] The buffer device 1 is arranged on the impact side of the pile foundation 12 (or the side close to the impact head 3), and is set close to the pile foundation 12. The material can be rubber or elastomer. The force and acceleration sensors are set in the buffer device 1, and the elasticity is used to buffer the dynamic load, prolong the contact time, and protect the pile foundation 12 and the bearing box 6.

[0027] The signal detection system 9 collects the time-history curves of force, displacement, and acceleration transmitted to the pile foundation 12 through the buffer device 1. After the electromagnetic catapult is activated, the detection counterweight 11 accelerates forward. The collection starts at the moment the impact head 3 contacts the buffer device 1 and stops until the impact head 3 is rebounded and separated from the buffer device 1. The signal detection system 9 then outputs three time-history curves within the action time period t for analyzing the quality and horizontal bearing capacity of the pile foundation 12.

[0028] The control system is used to synchronously control the start and stop of the electromagnetic catapult and the reset device 10. The control system is electrically connected to the electromagnetic catapult and the reset device 10. The reset device 10 consists of a power device and a steel cable; the power device can be a winch installed on the ground. The two ends of the steel cable are connected to the rear end of the carrier box 6 and the winch, respectively, to pull the carrier box 6 back to its initial position after it is ejected.

[0029] During on-site inspection, the device can be disassembled and assembled on site: first fix the electromagnetic guide rail 2 and verify the stability; then install the signal detection system 9 on the pile foundation 12; install the carrying box 6 through the groove of the electromagnetic guide rail 2 and level it; install the armature 5, control switch 7, pulse power supply 8 and generator, and verify the performance; install the reset device 10; the buffer device 1 is close to the pile foundation 12; assemble and test the counterweight 11 and fill the gap with wooden wedges. The height of the counterweight shall not exceed 1 / 3 of the height of the inner cavity of the carrying box 6 to ensure the low center of gravity and stable movement of the carrying device; finally, install the control system.

[0030] At the beginning of the test, the control system closes the control switch 7, and the pulse power supply 8, the electromagnetic guide rail 2 and the armature 5 form a closed loop. The electromagnetic guide rail 2 is energized to generate a strong magnetic field. The armature 5 is subjected to the Ampere force to generate a driving force for displacement. The driving force on the armature 5 is transmitted to the bearing box 6 through the insulating connecting rod 4, causing the two to accelerate together; when the impact head 3 contacts the buffer device 1, the signal detection system 9 starts to collect force, displacement and acceleration signals; after the impact head 3 rebounds and separates from the buffer device 1, the signal detection system 9 stops collecting and outputs the force, displacement and acceleration time history curve within time t for analyzing the horizontal bearing capacity and integrity of the pile foundation 12.

[0031] Based on the above device, the present invention provides a method for detecting the horizontal bearing capacity of a pile foundation using a rapid loading method, the steps of which are as follows: 1. Determine the installation position of the electromagnetic guide rail 2 and test the bearing capacity and stability of the foundation; 2. Electromagnetic guide rail 2, detection counterweight 11, carrying box 6, reset device 10, etc. enter the site; 3. Install the electromagnetic guide rail 2, armature 5, pulse power supply 8, generator, reset device 10, signal detection system 9 and control system, and level the electromagnetic guide rail 2; 4. Debug the control system to ensure the reliability of the start-stop electromagnetic ejection device and the reset device 10; 5. Push the carrying box 6 to the preset position through the groove of the electromagnetic guide rail 2 and connect it to the armature 5 through the insulating connecting rod 4; 6. Assemble the test weight 11 according to the designed bearing capacity of the pile foundation 12 and set the current of the pulse power supply 8 to ensure that the test weight 11 is tightly connected to the bearing box 6 without displacement; 7. Debug the signal detection system 9 to ensure normal acquisition and output of three time history curves; 8. Close control switch 7. The test weight 11, under the action of electromagnetic force, acts on the buffer device 1 through the impact head 3. The signal detection system 9 collects data. After the rebound, the data collection stops and three time history curves within the time period t are output. If the result is unsatisfactory, the reset device 10 pulls the carrying box 6 and the test weight 11 back to the initial position and restarts until the result is qualified. 9. Analyze the integrity and horizontal bearing capacity of pile foundation 12 based on the three time history curves obtained, and issue a test report.

[0032] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent replacement or change made by any technician familiar with the technical field within the technical scope disclosed by the present invention based on the technical solution and novel concept of the present invention should be covered by the scope of protection of the present invention.

Claims

1. An electromagnetic ejection type rapid loading method pile foundation horizontal bearing capacity detection device, characterized in that: include: The electromagnetic catapult device is fixedly arranged on the foundation in a horizontal direction, and includes: Two electromagnetic guide rails (2) extending parallel to each other and horizontally; an armature (5) slidably embedded in the electromagnetic guide rails (2); a pulse power supply (8) and a control switch (7) electrically connected to the electromagnetic guide rails (2); A bearing device is connected to the armature (5) and slides horizontally along the electromagnetic guide rail (2), comprising: a bearing box (6) whose bottom is rigidly connected to the armature (5) via an insulating connecting rod (4); an impact head (3) arranged at the front end of the bearing box (6); a detection counterweight (11) detachably placed in the bearing box (6); and a buffer device (1) arranged on the impacted side of the pile foundation (12) to be detected; A signal detection system (9) is provided on the pile foundation (12) to be detected and is used for real-time acquisition of horizontal force, displacement and acceleration time curves under the action of impact load; a reset device (10) comprises a power device fixedly provided on the ground and a steel cable connecting the bearing device and the power device; a control system is connected to the pulse power supply (8) and the reset device (10) signal and is used for synchronously controlling the start, stop and reset actions of the electromagnetic catapult.

2. The electromagnetic ejection rapid loading method pile foundation horizontal bearing capacity detection device according to claim 1, characterized in that: A groove is provided on the top of the electromagnetic guide rail (2), and the carrying box (6) is embedded in the groove via a bottom pulley to achieve low-friction horizontal sliding. The electromagnetic guide rail (2) also serves as a horizontal guide and reaction force component.

3. The electromagnetic ejection type rapid loading method pile foundation horizontal bearing capacity detection device according to claim 1, characterized in that: The armature (5) is provided with a through groove that is shaped like the electromagnetic guide rail (2), so that the center line of the horizontal impact load and the axis of the pile foundation (12) to be tested are in the same horizontal plane.

4. The electromagnetic ejection rapid loading method pile foundation horizontal bearing capacity detection device according to claim 1, characterized in that: The impact head (3) is coaxially arranged with the center line of the buffer device (1), and a force sensor and an acceleration sensor are provided in the buffer device (1), and the displacement sensor is arranged on the foundation and parallel to the impact direction.

5. The electromagnetic ejection rapid loading method pile foundation horizontal bearing capacity detection device according to claim 1, characterized in that: The detection counterweight (11) is fixed to the carrying box (6) by means of a wooden wedge or a fastener, thereby forming a fixed connection between the carrying box (6) and the detection counterweight (11) during acceleration and impact.

6. The electromagnetic ejection type rapid loading method pile foundation horizontal bearing capacity detection device according to claim 1, characterized in that: The pulse power supply (8) forms an adjustable pulse width of 100ms-800ms by adjusting the output current to match the detection requirements of different design level load-bearing capacities.

7. A method for detecting the horizontal bearing capacity of a pile foundation using an electromagnetic ejection rapid loading method implemented by the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step a, fixing the electromagnetic guide rail (2) horizontally on the foundation, and leveling and calibrating it; Step b, installing the carrying box (6) on the electromagnetic guide rail (2) through a pulley, and connecting the armature (5) and the pulse power supply (8); Step c, if the designed horizontal bearing capacity of the pile foundation (12) is to be tested, assemble the test counterweight (11) and adjust the output current of the pulse power supply (8); Step d, installing the buffer device (1) and the signal detection system (9), and completing system debugging; Step e: starting the control system and closing the control switch (7) so that the armature (5) pushes the carrying box (6) to accelerate in the horizontal direction under the action of the electromagnetic force; Step f, the impact head (3) impacts the buffer device (1), and the signal detection system (9) collects the force-displacement-acceleration time history curve in real time; Step g: After the impact is completed, the reset device (10) pulls the carrying box (6) back to the initial position; Step h: Analyze the horizontal bearing capacity of the pile foundation (12), the bending moment distribution of the pile body, and the lateral resistance of the soil based on the collected time history curve.

8. A method for detecting the horizontal bearing capacity of a pile foundation using an electromagnetic ejection rapid loading method according to claim 7, characterized in that: In step e, the combined force of the electromagnetic thrust and the counterweight inertia acts for a period of 100 ms–800 ms, which is used to keep the pile foundation-ground system in a quasi-static response range.

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