Electromagnetic catapult type rapid loading method pile foundation horizontal bearing capacity detection device and method

Abstract

The application is specifically an electromagnetic ejection type speed load method pile foundation horizontal bearing capacity detection device and method, which comprises: an electromagnetic ejection device fixedly arranged on the ground in the transverse direction, comprising: two electromagnetic rails parallel to each other and horizontally extending; an armature slidingly embedded in the electromagnetic rails; a pulse power supply and a control switch electrically connected with the electromagnetic rails; a bearing device comprising a bearing box rigidly connected with the armature through an insulating connecting rod at the bottom; an impact head arranged at the front end of the bearing box; a detection weight detachably placed in the bearing box; a buffer device arranged at the impact side of the pile foundation to be detected; a signal detection system arranged on the pile foundation to be detected; a reset device comprising a winch and a steel cable connecting the bearing device and the winch; and a control system signal connected with the pulse power supply and the reset device. The application has the advantages of: significant optimization of efficiency and cost; outstanding safety and site adaptability; high data quality and rich information dimension.

Description

Technical Field

[0001] This invention relates to the field of pile foundation testing technology, specifically to an electromagnetic catapult-type rapid loading method for testing the horizontal bearing capacity of pile foundations. Background Technology

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

[0003] Currently, the main methods for testing the horizontal bearing capacity of pile foundations are the horizontal static load test and the rapid load test. The horizontal static load test is the most direct and reliable method, which involves applying static loads to the pile in stages and measuring the displacement at the pile top to plot a load-displacement curve to evaluate the bearing capacity of the pile foundation. However, this method requires large testing equipment, is expensive, and is time-consuming.

[0004] The rapid load test is a relatively new testing method widely used abroad. It typically involves rapidly burning a special explosive in a cylinder of a device. The resulting high-pressure gas propels a heavy object outward with great acceleration, causing it to collide with the pile foundation. Its advantages are short test time and high efficiency. However, the special explosive used is an explosive and is subject to regulation by relevant departments. In addition, the combustion of the explosive produces polluting and toxic gases, polluting the environment.

[0005] The applicant has proposed an electromagnetic catapult-type rapid loading method for detecting the vertical bearing capacity of pile foundations. However, this device and method can only be used to detect the vertical bearing capacity of pile foundations, and it cannot solve the technical problem of using the rapid loading method to detect the horizontal bearing capacity of pile foundations in this invention.

[0006] Therefore, there is an urgent need to design a horizontal rapid load method device and method that can replace the existing technology that uses gunpowder explosion as a power source, and to provide a stable, environmentally friendly, and safe device and method for testing the horizontal bearing capacity of pile foundations using the rapid load method. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electromagnetic catapult-type rapid load method for testing the horizontal bearing capacity of pile foundations. This invention utilizes an electromagnetic catapult device to replace gunpowder as the power source for counterweight, avoiding pollutants generated by gunpowder combustion and explosion in conventional rapid load method tests, reducing carbon emissions, and improving the safety and efficiency of the test.

[0008] To achieve the above objectives, an electromagnetic catapult-type rapid load method pile foundation horizontal bearing capacity testing device is designed, comprising: an electromagnetic catapult device horizontally fixed on the foundation, including: two parallel and horizontally extending electromagnetic rails; an armature slidably embedded in the electromagnetic rails; a pulse power supply and a control switch electrically connected to the electromagnetic rails; a bearing device connected to the armature and sliding horizontally along the electromagnetic rails, including: a bearing box rigidly connected to the armature at its bottom via an insulating connecting rod; an impact head located at the front end of the bearing box; a detection counterweight detachably placed inside the bearing box; a buffer device located on the impact side of the pile foundation to be tested; a signal detection system located on the pile foundation to be tested, used to collect the time history curves of horizontal force, displacement, and acceleration under impact load in real time; a reset device, including a power device fixed on the ground and a steel cable connecting the bearing device and the power device; and a control system connected to the pulse power supply and the reset device, used to synchronously control the start, stop, and reset actions of the electromagnetic catapult.

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

[0010] Preferably, the present invention further includes: the armature is provided with a through groove that conforms to the electromagnetic guide rail, 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 includes: the impact head and the center line of the buffer device are coaxially arranged, and the buffer device is provided with a force sensor and an acceleration sensor, and the displacement sensor is arranged on the foundation and parallel to the impact direction.

[0012] Preferably, the present invention further includes: the detection counterweight is fixed to the bearing box by wooden wedges or fasteners, forming a fixed connection between the bearing box and the detection counterweight during acceleration and impact.

[0013] Preferably, the present invention further includes: the pulse power supply adjusting the output current to form an adjustable pulse width of 100ms-800ms in milliseconds to match the testing requirements of different design load-bearing capacities.

[0014] This invention also provides a method for detecting the horizontal bearing capacity of pile foundations using the electromagnetic catapult-type rapid loading method implemented by the aforementioned 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 via pulleys and connecting the armature to the pulse power supply; Step c, assembling the detection counterweight and adjusting the output current of the pulse power supply according to the design horizontal bearing capacity of the pile foundation to be tested; Step d, installing the buffer device and 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 horizontally under the action of electromagnetic force; Step f, the impact head impacts 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 pile bending moment distribution, and the lateral resistance of the soil based on the collected time history curve.

[0015] Preferably, the present invention further includes: in step e, the combined force of the electromagnetic thrust and the counterweight inertia acts for 100ms–800ms, so that the pile foundation soil system is in the quasi-static response range.

[0016] Compared with the prior art, the advantages of this invention are: 1. Significantly Optimized Efficiency and Cost: The rapid load method conducts tests using transient horizontal loads (such as hydraulic impact) at the millisecond level (100-800ms). Single-point testing takes only a few minutes to half an hour, which is more than ten times more efficient than the several days required for traditional horizontal static load tests. Simultaneously, the electromagnetic catapult method makes the equipment lightweight (eliminating the need for hundreds of tons of reaction force or complex anchoring systems) and highly automated, significantly reducing equipment transportation, installation costs, and labor input (overall costs can be reduced by more than 50%). It is particularly suitable for projects with tight schedules or large-scale pile foundation testing projects.

[0017] 2. Excellent safety and site adaptability: The instantaneous loading method completely avoids the safety risks of reaction platform instability and collapse caused by long-term loading in traditional methods, making it particularly suitable for dangerous sites such as soft soil, high water levels, or deep foundation pits. Horizontal loads can easily cause eccentric stress on the pile body; the guiding device of the electromagnetic catapult-type rapid loading method ensures accurate load transfer and reduces the risk of lateral deviation.

[0018] 3. High-quality data and rich information dimensions: Compared with the high-strain dynamic measurement method, the longer load application time of the rapid load method makes the soil dynamic response of the pile foundation closer to the quasi-static state, and can directly obtain high-precision horizontal load-displacement curves (PY curves), with displacement measurement errors controlled within 0.1mm. Combined with sensor data and signal fitting techniques (such as the unloading point method), it can not only reliably assess the horizontal bearing capacity (corrected error <10%), but also analyze the pile bending moment distribution, lateral soil resistance classification, plastic hinge location, and soil damping characteristics, providing multi-dimensional and in-depth evidence for lateral force design and safety assessment. Attached Figure Description

[0019] Figure 1 This is a front view of the device of the present invention; Figure 2 This is a top view of the carrier box; In the diagram: 1. Buffer device, 2. Electromagnetic 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 Implementation

[0020] To make the objectives, principles, and structure of this invention clearer, the following description, in conjunction with the accompanying drawings and specific embodiments, provides further details. The described embodiments are only part of, and not all of, this invention. Any exemplary embodiment is for illustrative purposes only and does not constitute a limitation on the application or use of this invention. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort all fall within the protection scope of this invention. Unless otherwise stated, the relative arrangement, expression, and numerical values ​​of components and steps in the examples do not limit the scope of this invention; the dimensions of the components in the drawings are not drawn to scale. Known technologies, methods, and devices are considered integral parts of this specification when necessary. All specific numerical values ​​in the examples are exemplary and not restrictive.

[0021] This invention addresses the shortcomings of existing methods for testing the horizontal bearing capacity of pile foundations by proposing a novel method that uses an electromagnetic catapult to replace gunpowder. This method avoids pollution caused by gunpowder combustion and explosion, reduces carbon emissions, and improves the safety and efficiency of the test.

[0022] See Figure 1 , 2 This invention discloses an electromagnetic catapult-type fast-load method for detecting the horizontal bearing capacity of pile foundations. The device consists of an electromagnetic catapult 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 includes: 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 arranged, parallel tracks. When energized, the electromagnetic rails 2 generate a strong magnetic field, guiding and limiting the armature 5 and the supporting device, which slide and engage with the electromagnetic rails 2. The armature 5 has a transverse slot or groove structure in its middle that conforms to the shape of the electromagnetic rails 2. The armature 5 slides into the slot of the electromagnetic rails 2, forming a closed loop with the electromagnetic rails 2 when energized. Under the action of electromagnetic force, the armature 5 pushes the supporting box 6 within the supporting device via an inclined, upward-facing insulating connecting rod 4. This achieves the transmission of force from the armature 5 to the supporting device while avoiding limiting conflicts between the armature 5's transmission structure and the electromagnetic rails 2. The generator provides a stable voltage to the pulse power supply 8, which can store, release, and regulate current, releasing a large amount of electrical energy in a short time to generate a strong electromagnetic force. The control switch 7 is connected to the control system. When closed, the pulse power supply 8 discharges instantaneously, and the strong current forms a strong magnetic field between the electromagnetic rails 2, propelling the supporting box 6 forward.

[0024] The bearing device consists of a bearing box 6, an impact head 3, and an insulating connecting rod 4. The bearing box 6 has an internal cavity. The bearing box 6 is embedded in the top groove of the electromagnetic guide rail 2 via a bottom pulley and rolls in contact with it. 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 bearing box 6 and the armature 5 respectively. The impact head 3 is rigidly installed at the front end of the bearing box 6 and is used to directly transfer the transient impact load to the pile foundation 12 to be tested. This reduces the contact area between the bearing device and the pile foundation 12 to be tested without changing the mass of the bearing device, thereby increasing the pressure. The bearing box 6 and the electromagnetic guide rail 2, and the insulating connecting rod 4 and the armature 5 are all insulated connections.

[0025] The detection counterweight 11 is evenly placed inside the bearing box 6. It is an object with a certain mass. During the movement, there is no relative displacement between it and the bearing box 6. The gap between the detection counterweight 11 and the bearing box 6 is filled with wooden wedges or connectors.

[0026] The buffer device 1 is located 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. Force and acceleration sensors are set inside the buffer device 1 to use elastic buffering to buffer dynamic loads, extend contact time, and protect the pile foundation 12 and the bearing box 6.

[0027] The signal detection system 9 collects the force, displacement, and acceleration time history curves transmitted to the pile foundation 12 via the buffer device 1. After the electromagnetic catapult is started, the detection counterweight 11 accelerates forward. The acquisition begins the instant the impact head 3 contacts the buffer device 1 and continues until the impact head 3 is bounced off the buffer device 1 and the acquisition stops. Then, the signal detection system 9 outputs three time history curves within the action time period t, which are used to analyze the mass 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 both the electromagnetic catapult and the reset device 10. The reset device 10 consists of a power unit and a steel cable. The power unit can be a winch, which is installed on the ground. The two ends of the steel cable are connected to the tail of the carrier box 6 and the winch, respectively, and are used to pull the carrier box 6 back to its initial position after it is launched.

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

[0030] At the start of the test, the control system closes the control switch 7, and the pulse power supply 8, electromagnetic rail 2, and armature 5 form a closed loop. The electromagnetic rail 2 is energized to generate a strong magnetic field, and the armature 5 is subjected to the Ampere force to generate a displacement driving force. The driving force on the armature 5 is transmitted to the bearing box 6 through the insulating connecting rod 4, so that the two accelerate together. When the impact head 3 contacts the buffer device 1, the signal detection system 9 begins to collect force, displacement, and acceleration signals. After the impact head 3 rebounds and leaves the buffer device 1, the signal detection system 9 stops collecting and outputs the force, displacement, and acceleration time history curves within time t, which are used to analyze the horizontal bearing capacity and integrity of the pile foundation 12.

[0031] Based on the above-mentioned device, the present invention provides a method for detecting the horizontal bearing capacity of pile foundations using the rapid loading method, the steps of which are as follows: 1. Determine the installation position of electromagnetic rail 2 and test the bearing capacity and stability of the foundation; 2. Electromagnetic guide rail 2, detection counterweight 11, bearing box 6, reset device 10, etc., arrive on site; 3. Install electromagnetic rail 2, armature 5, pulse power supply 8, generator, reset device 10, signal detection system 9 and control system, and level electromagnetic rail 2; 4. Debug and adjust the control system to ensure the reliability of the start / stop electromagnetic catapult device and the reset device 10; 5. Push the carrier 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 and test the counterweight 11 according to the bearing capacity design of pile foundation 12 and set the pulse power supply 8 current to ensure that the test counterweight 11 is tightly connected to the bearing box 6 without displacement; 7. Debug the signal detection system 9 to ensure that it can properly acquire and output three time history curves; 8. Close the control switch 7. The detection counterweight 11 acts on the buffer device 1 through the impact head 3 under the action of electromagnetic force. The signal detection system 9 collects data. After rebounding and detaching, the data collection stops and the system outputs three time history curves within the time period t. If the result is not qualified, the reset device 10 pulls the bearing box 6 and the detection counterweight 11 back to the initial position and restarts until it 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 merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the invention, based on the technical solutions and novel concepts of the invention, should be covered within the scope of protection of the invention.

Claims

1. An electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity testing device, characterized in that, include: An electromagnetic catapult device, horizontally fixed to the foundation, includes: Two parallel and horizontally extending electromagnetic rails (2); an armature (5) slidably embedded in the electromagnetic rails (2); a pulse power supply (8) and a control switch (7) electrically connected to the electromagnetic rails (2); The bearing device, connected to the armature (5) and sliding horizontally along the electromagnetic rail (2), includes: a bearing box (6) whose bottom is rigidly connected to the armature (5) through an insulating connecting rod (4); an impact head (3) set at the front end of the bearing box (6); a detection counterweight (11) detachably placed inside the bearing box (6); and a buffer device (1) set on the impact side of the pile foundation (12) to be tested. The signal detection system (9) is set on the pile foundation (12) to be tested and is used to collect the time history curves of horizontal force, displacement and acceleration under impact load in real time; the reset device (10) includes a power equipment fixed on the ground and a steel cable connecting the bearing device and the power equipment; the control system is connected to the pulse power supply (8) and the reset device (10) to synchronously control the start, stop and reset actions of the electromagnetic catapult.

2. The electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity testing device as described in claim 1, characterized in that, The top of the electromagnetic rail (2) has a groove, and the bearing box (6) is embedded in the groove through the bottom pulley to achieve low-friction horizontal sliding. The electromagnetic rail (2) also serves as a horizontal guide and reaction component.

3. The electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity testing device as described in claim 1, characterized in that, The armature (5) is provided with a through groove that is similar in shape to the electromagnetic rail (2), so that the center line of the horizontal impact load is in the same horizontal plane as the axis of the pile foundation (12) to be tested.

4. The electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity testing device as described in claim 1, characterized in that, The impact head (3) and the buffer device (1) are coaxially arranged, and the buffer device (1) is equipped with a force sensor and an acceleration sensor. The displacement sensor is set on the foundation and parallel to the impact direction.

5. The electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity testing device as described in claim 1, characterized in that, The detection counterweight (11) is fixed to the bearing box (6) by wooden wedges or fasteners, forming a fixed connection between the bearing box (6) and the detection counterweight (11) during acceleration and impact.

6. The electromagnetic catapult-type rapid loading method pile foundation horizontal bearing capacity testing device as described in claim 1, characterized in that, The pulse power supply (8) generates an adjustable pulse width of 100ms-800ms by adjusting the output current to match the testing requirements of different design load levels.

7. A method for detecting the horizontal bearing capacity of pile foundations using the electromagnetic catapult-type rapid loading method implemented with any one of the devices described in claims 1-6, characterized in that, Includes the following steps: Step a: Fix the electromagnetic rail (2) horizontally on the foundation and level and calibrate it; Step b: Install the carrier box (6) onto the electromagnetic rail (2) via pulleys, and connect the armature (5) to the pulse power supply (8); Step c: Assemble the test counterweight (11) according to the bearing capacity design of the pile foundation (12) to be tested and adjust the output current of the pulse power supply (8); Step d: Install the buffer device (1) and signal detection system (9), and complete system debugging; Step e: Start the control system and close the control switch (7) so that the armature (5) pushes the carrier box (6) to accelerate in the horizontal direction under the action of electromagnetic force; Step f: Impact head (3) impact buffer device (1), signal detection system (9) real-time acquisition of force-displacement-acceleration time history curve; Step g: After the impact is completed, the reset device (10) pulls the bearing box (6) back to the initial position; Step h: Analyze the horizontal bearing capacity, pile bending moment distribution and soil lateral resistance of the pile foundation (12) based on the collected time history curves.

8. The method for testing the horizontal bearing capacity of pile foundations using the electromagnetic catapult-type rapid loading method as described in claim 7, characterized in that, In step e, the combined force of the electromagnetic thrust and the counterweight inertia acts for 100 ms–800 ms, so that the pile foundation soil system is in the quasi-static response range.

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