A vertical cyclic loading test system applied to a geotechnical centrifuge and a control method thereof

Abstract

The application discloses a vertical cyclic loading test system applied to a geotechnical centrifuge and a control method, which comprises a model box, a counterforce mechanism, a vertical loading mechanism and an electrical control mechanism, the counterforce mechanism is fixed on the top of the model box, the vertical loading mechanism is vertically installed on the counterforce mechanism, and the vertical and horizontal position of the vertical loading mechanism on the counterforce mechanism is adjustable, the application can stably work under a high centrifugal acceleration of 160g, the maximum loading force reaches 400kN, the control precision is 0.2kN, the maximum displacement stroke is 160mm, the displacement precision is 0.1mm, the cyclic loading frequency is 1Hz, and the cyclic amplitude is ±30mm, so that the simulation requirement of most high bearing capacity working conditions of marine engineering, pile foundation engineering and the like can be met.

Description

Technical Field

[0001] This invention relates to the field of geotechnical centrifuge model testing technology, and in particular to a vertical cyclic loading test system and control method for geotechnical centrifuges. Background Technology

[0002] Geotechnical centrifuge model testing is an important tool for studying geotechnical engineering problems. High-speed centrifugal rotation generates a hypergravity field, ensuring that the stress state of the scaled-down model remains consistent with the prototype. In fields such as marine engineering, underground structures, and pile foundation engineering, structures often need to withstand large vertical loads, such as offshore wind turbine tube foundations, caisson and immersed tube structures, and large-diameter pile foundations.

[0003] Currently, centrifuge vertical loading devices mostly employ hydraulic or electric drive to apply loads. Electric drive devices are simple in structure and offer high control precision, but their loading capacity is limited, typically not exceeding 12kN, making it difficult to simulate high-volume load conditions. While hydraulic drives can provide larger loads, they also have many limitations: (1) The hydraulic system has poor stability under high g-value acceleration and is easily affected by centrifugal force; (2) The control accuracy is low, making it difficult to achieve high-precision displacement control or force control; (3) The hydraulic pipeline layout is complex and there is a risk of leakage; (4) The loading device currently in use does not have the function of freely switching between displacement control and force control.

[0004] (6) The existing vertical loading device used in matching geotextile centrifuges is difficult to realize the cyclic loading function.

[0005] Therefore, there is an urgent need for a vertical loading test system that can achieve high precision and multi-mode control in high-g environments. Summary of the Invention

[0006] The purpose of this invention is to address the technical deficiencies in existing technologies, such as insufficient loading capacity, low control precision, and poor system stability, by providing a vertical cyclic loading test system for geotextile centrifuges.

[0007] Another object of the present invention is to provide a control method for the above-described system.

[0008] The technical solution adopted to achieve the purpose of this invention is: A vertical cyclic loading test system for a geotextile centrifuge includes a model box, a reaction mechanism, a vertical loading mechanism, and an electrical control mechanism. The reaction mechanism is fixedly mounted on the top of the model box. The vertical loading mechanism is vertically mounted on the reaction mechanism, and its vertical and horizontal positions on the reaction mechanism are adjustable. The vertical loading mechanism includes a servo hydraulic power source, a hydraulic servo valve, a displacement sensor, a loading assembly, a hydraulic cylinder, and a force sensor. The servo hydraulic power source is installed in the centrifuge basement and connected to the hydraulic cylinder via a centrifuge rotary joint. The hydraulic servo valve is connected to the servo hydraulic power source, installed on the centrifuge rotating arm, and connected to the hydraulic cylinder. The displacement sensor is installed at the top of the hydraulic cylinder, the loading assembly is installed at the drive end of the hydraulic cylinder, and the force sensor is installed at the bottom of the loading assembly.

[0009] In the above technical solution, the top of the reaction mechanism is provided with a uniformly distributed array of screw holes, and the vertical loading mechanism is vertically installed on the reaction mechanism through the threaded holes in the screw hole array.

[0010] In the above technical solution, the displacement sensor is a built-in magnetostrictive displacement sensor.

[0011] In the above technical solution, the electrical control mechanism includes a remote control module, an energy supply module, a programmable controller, a data acquisition module, and a remote monitoring module.

[0012] In the above technical solution, the remote control module communicates with the program controller through the remote monitoring module. The input end of the program controller is communicated with the data acquisition module, and the output end of the program controller is connected to the hydraulic cylinder. The data acquisition module collects data from the displacement sensor or the force sensor and transmits it to the program controller. The program controller controls the action of the hydraulic cylinder to realize the control of monotonic / cyclic loading mode, and can freely switch between them through programming.

[0013] The energy supply module is connected to the remote control module, the program controller, the data acquisition module, and the remote monitoring module, respectively, and realizes the supply of weak current and strong current through the signal loop and the power loop.

[0014] Another aspect of the present invention includes a control method for the vertical cyclic loading test system, comprising the following steps: Step 1: The vertical cyclic loading test system is placed inside a centrifuge, and the centrifuge is started until the set acceleration is reached; Step 2: Set the loading path and select displacement control mode or force control mode through the remote control module driver controller; Step 3: Drive the hydraulic servo valve through the program controller to control the hydraulic oil flow and direction of the hydraulic cylinder; Step 4: The hydraulic cylinder applies a monotonic / cyclic vertical load according to the set loading path; Step 5: Collect displacement and force data in real time and feed them back to the program controller for closed-loop regulation; Step 6: After loading is complete, the hydraulic cylinder returns to its initial position.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention can work stably under a high centrifugal acceleration of 160g, with a maximum loading force of 400kN, a control accuracy of 0.2kN, a maximum displacement stroke of 160mm, a displacement accuracy of 0.1mm, a cyclic loading frequency of 1Hz, and a cyclic amplitude of ±30mm. It can meet the simulation requirements of most marine engineering, pile foundation engineering and other high bearing capacity working conditions.

[0016] 2. The hydraulic cylinder drive, combined with the hydraulic servo valve installed in the center of the centrifuge arm, can effectively overcome the impact of high g-value environments on the hydraulic system.

[0017] 3. It has the function of switching between displacement control mode and force control mode, and supports precise control of complex loading paths.

[0018] 4. Modular design: Multi-point loading can be achieved through the screw hole array on the reaction mechanism to adapt to different test requirements.

[0019] 5. It has remote control and real-time data acquisition functions to realize intelligent testing and precise data analysis. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the vertical cyclic loading test system of the present invention.

[0021] Figure 2 This is a partial structural diagram of a vertical cyclic loading test system.

[0022] Figure 3 This is a partial structural diagram of a vertical cyclic loading test system.

[0023] Figure 4 This is an electrical control schematic diagram.

[0024] Among them, 1-model box; 2-reaction mechanism; 3-vertical loading mechanism; 4-displacement sensor; 5-loading component; 6-hydraulic cylinder; 7-force sensor; 8-hydraulic servo valve; 9-remote control module; 10-drive cabinet; 11-optical transceiver; 12-fiber optic ring; 13-servo oil source; 14-program controller; 15-screw hole array. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] Example 1 A vertical cyclic loading test system for a geotextile centrifuge includes a model box 1, a reaction mechanism 2, a vertical loading mechanism 3, and an electrical control mechanism. The reaction mechanism 2 is fixedly mounted on the top of the model box 1, and the top of the reaction mechanism 2 is provided with a uniformly distributed array of screw holes 15 to adapt to the loading requirements at different positions. The vertical loading mechanism 3 is vertically mounted on the reaction mechanism 2 through the threaded holes in the screw hole array 15. The vertical loading mechanism 3 can be installed on different threaded holes in the screw hole array 15, thereby realizing the adjustment of the loading position. The vertical loading mechanism 3 includes a servo oil source 13, a hydraulic servo valve 8, a displacement sensor 4, a loading assembly 5, a hydraulic cylinder 6, and a force sensor 7. The servo oil source 13 is installed in the centrifuge basement and connected to the hydraulic cylinder 6 through the centrifuge rotary joint, providing hydraulic power to the hydraulic cylinder 6. The hydraulic servo valve 8 is connected to the servo oil source 13 through a high-pressure hose. The hydraulic servo valve 8 is installed at the center of the centrifuge arm and connected to the hydraulic cylinder 6 to adjust the hydraulic flow and direction of the hydraulic cylinder 6 to eliminate the impact of high g-value acceleration. The displacement sensor 4 is fixedly installed on the top of the hydraulic cylinder 6. The loading assembly 5 is installed on the drive end of the hydraulic cylinder 6. The force sensor 7 is fixedly installed on the bottom end of the loading assembly 5. Preferably, the oil circuit system is equipped with a safety valve and a pressure sensor 7 to ensure safe operation of the system. The displacement sensor 4 is a magnetostrictive displacement sensor 4.

[0027] The electrical control mechanism includes a remote control module 9, an energy supply module, a programmable controller 14, a data acquisition module, and a remote monitoring module; The remote control module 9 is connected to the program controller 14 via the remote monitoring module. The input end of the program controller 14 is connected to the data acquisition module, and the output end of the program controller 14 is connected to the hydraulic cylinder 6. The data acquisition module acquires data from the displacement sensor 4 or the force sensor 7 and transmits it to the program controller 14. The program controller 14 controls the action of the hydraulic cylinder 6 to achieve control of monotonic / cyclic loading mode, and can switch freely through programming. The energy supply module is connected to the remote control module 9, the program controller 14, the data acquisition module, and the remote monitoring module, respectively, and realizes the supply of weak current and strong current through the signal loop and the power loop.

[0028] Preferably, the program controller 14 transmits data and communicates with the remote control module 9 via Ethernet and fiber optic ring 12, and synchronously switches between displacement control and force control modes. Specifically, the displacement sensor 4 and hydraulic cylinder 6 integrate velocity feedforward, hysteresis feedforward and acceleration feedforward to eliminate linear errors and phase lag, thereby realizing the displacement control mode; the force sensor 7 collects real-time loading force signals and dynamically adjusts the inner loop position target based on the force deviation to ensure the force value accuracy in monotonic / cyclic loading mode, thereby realizing the switching of the force control mode.

[0029] Preferably, the electrical control principle is as follows: Figure 4 As shown, the remote control module 9 sends a work command to the program controller 14. The work command is transmitted in the form of an electrical signal through the drive cabinet 10 of the remote monitoring module, the optical transceiver 11, and the optical fiber ring 12 at the upper and lower connection points to the program controller 14. The program controller 14 sends a loading command to the hydraulic cylinder 6, determines the loading mode as either displacement control mode or force control mode, and determines monotonic loading and cyclic loading modes.

[0030] Example 2 This embodiment provides a control method for the vertical cyclic loading test system described in Embodiment 1, including the following steps: Step 1: The vertical cyclic loading test system is placed inside a centrifuge, and the centrifuge is started until the set acceleration (up to 160g) is reached. Step 2: Set the loading path and select displacement control mode or force control mode through the remote control module 9 and driver controller 14. Step 3: Drive the hydraulic servo valve 8 through the program controller 14 to control the hydraulic oil flow and direction of the hydraulic cylinder 6; Step 4: Hydraulic cylinder 6 applies a monotonic / cyclic vertical load according to the set loading path; Step 5: Real-time acquisition of displacement and force data, and feedback to program controller 14 for closed-loop regulation; Step 6: After loading is complete, hydraulic cylinder 6 returns to its initial position.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A vertical cyclic loading test system for geotextile centrifuges, characterized in that, It includes a model box, a reaction mechanism, a vertical loading mechanism, and an electrical control mechanism. The reaction mechanism is fixedly mounted on the top of the model box. The vertical loading mechanism is vertically mounted on the reaction mechanism, and its vertical and horizontal positions on the reaction mechanism are adjustable.

2. The vertical cyclic loading test system according to claim 1, characterized in that, The vertical loading mechanism includes a servo hydraulic power source, a hydraulic servo valve, a displacement sensor, a loading assembly, a hydraulic cylinder, and a force sensor. The servo hydraulic power source is installed in the centrifuge basement and connected to the hydraulic cylinder via a centrifuge rotary joint. The hydraulic servo valve is connected to the servo hydraulic power source, installed on the centrifuge rotating arm, and connected to the hydraulic cylinder. The displacement sensor is installed at the top of the hydraulic cylinder, the loading assembly is installed at the drive end of the hydraulic cylinder, and the force sensor is installed at the bottom of the loading assembly.

3. The vertical cyclic loading test system according to claim 1, characterized in that, The reaction mechanism has a uniformly distributed array of screw holes at its top, and the vertical loading mechanism is vertically mounted on the reaction mechanism through the threaded holes in the screw hole array.

4. The vertical cyclic loading test system according to claim 2, characterized in that, The displacement sensor is a built-in magnetostrictive displacement sensor.

5. The vertical cyclic loading test system according to claim 1, characterized in that, The electrical control mechanism includes a remote control module, an energy supply module, a programmable controller, a data acquisition module, and a remote monitoring module.

6. The vertical cyclic loading test system according to claim 1, characterized in that, The remote control module communicates with the program controller via the remote monitoring module. The input terminal of the program controller is connected to the data acquisition module, and the output terminal of the program controller is connected to the hydraulic cylinder. The data acquisition module collects data from the displacement sensor or the force sensor and transmits it to the program controller. The program controller controls the movement of the hydraulic cylinder to achieve monotonic / cyclic loading mode control, and can freely switch between them through programming. The energy supply module is connected to the remote control module, the program controller, the data acquisition module, and the remote monitoring module respectively, and realizes the supply of low-voltage and high-voltage electricity through the signal loop and the power loop.

7. The control method for the vertical cyclic loading test system as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: The vertical cyclic loading test system is placed inside a centrifuge, and the centrifuge is started until the set acceleration is reached; Step 2: Set the loading path and select displacement control mode or force control mode through the remote control module driver controller; Step 3: Drive the hydraulic servo valve through the program controller to control the hydraulic oil flow and direction of the hydraulic cylinder; Step 4: The hydraulic cylinder applies a monotonic / cyclic vertical load according to the set loading path; Step 5: Collect displacement and force data in real time and feed them back to the program controller for closed-loop regulation; Step 6: After loading is complete, the hydraulic cylinder returns to its initial position.

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