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

Abstract

The application discloses a horizontal loading test system applied to a geotechnical centrifuge and a control method thereof, and relates to the technical field of geotechnical centrifuges. The system comprises a model box, a supporting mechanism and a horizontal loading mechanism; the supporting mechanism is slidingly installed on the top of the model box; the horizontal loading mechanism is installed in the model box and is connected with the supporting mechanism through a screw rod; by adjusting the position of the loading mechanism in the model box, the horizontal loading test system can realize high-precision and multi-mode control under a high-g value environment.

Description

Technical Field

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

[0002] In geotechnical engineering, the stress level of soil and rock masses is closely related to their engineering properties. Due to the nonlinearity and complexity of soil and rock materials, conventional 1g small-scale model tests are insufficient to reproduce the physical characteristics of the prototype. Geotechnical centrifuge model tests, which generate a hypergravity field using a centrifuge, ensure that the stress state of the scaled-down model remains consistent with the prototype, and have become an important tool for studying complex geotechnical engineering problems. Furthermore, marine engineering structures such as cross-sea passages and offshore wind power foundations are often subjected to horizontal loads such as wind, waves, and ocean currents; their stability types and failure mechanisms often need to be simulated through centrifuge tests.

[0003] Currently, the following technical bottlenecks exist in centrifuge loading devices both domestically and internationally: 1. The loading force of electrically driven loading devices is relatively small. For example, the electric loading equipment of Nanjing Hydraulic Research Institute has a maximum loading force of 3kN, which is difficult to meet the requirements of large load and high precision test. 2. Hydraulic drive devices can provide larger loads, but their response speed is slow and their control accuracy is low; 3. Most existing loading devices do not have the function of freely switching between displacement control and force control modes, making it difficult to meet the requirements of complex loading paths; 4. Existing research mostly focuses on the problem of horizontal unidirectional static loading, and lacks the ability to realize horizontal cyclic loading in centrifuges; 5. Under high g-value centrifugal acceleration, the stability and accuracy of the loading device and sensing components are difficult to guarantee.

[0004] Therefore, there is an urgent need to develop a horizontal loading test system that can achieve high precision and multi-mode control in high-g environments. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies in the existing technology by providing a horizontal loading test system for geotextile centrifuges.

[0006] Another object of the present invention is to provide a control method for the above-described system.

[0007] The technical solution adopted to achieve the purpose of this invention is: A horizontal loading test system for a geotextile centrifuge includes a model box, a support mechanism, and a horizontal loading mechanism; the support mechanism is slidably mounted on the top of the model box, and the horizontal loading mechanism is located inside the model box and connected to the support mechanism; the horizontal loading mechanism's position within the model box is adjustable in the lateral, longitudinal, and vertical directions. The horizontal loading mechanism includes a mounting frame, a servo motor, a reducer, a ball screw, a loading assembly, and guide rails. The servo motor is mounted outside the mounting frame and is connected to the ball screw via the reducer. The guide rails, mounted on the mounting frame, are symmetrically arranged on both sides of the ball screw. The front end of each guide rail is connected to the loading assembly, which is located outside the mounting frame. A nut on the ball screw is connected to the loading assembly. A displacement sensor is fixedly mounted on the mounting frame to sense the longitudinal horizontal displacement of the loading assembly.

[0008] In the above technical solution, a force sensor is installed at the front end of the loading component and a connection hole is opened. The connection hole is connected to the scale model through a connecting accessory.

[0009] In the above technical solution, multiple oblong holes are provided on the support mechanism. The top of the screw passes through the oblong holes and is fixed by a fastener. The screw is suspended on the support mechanism by an adjustable support base, thereby suspending the horizontal loading mechanism at the bottom of the screw on the support mechanism. By adjusting the length of the screw extending out of the oblong holes, the vertical height of the horizontal loading mechanism in the model box can be adjusted. By adjusting the different positions of the screw in the oblong holes, the lateral position of the horizontal loading mechanism in the model box can be adjusted.

[0010] In the above technical solution, two lifting handles are installed on the top of the support mechanism, which can be used to easily lift the horizontal loading mechanism.

[0011] In the above technical solution, the horizontal loading test system also includes an electrical control mechanism, which includes a remote control terminal, a programmable controller, a data acquisition module, a remote monitoring module, and an energy supply module.

[0012] In the above technical solution, the remote control terminal is connected to the program controller via a remote monitoring module. The input end of the program controller is connected to the data acquisition module, and the output end of the program controller is connected to the servo motor. The data acquisition module acquires data from the displacement sensor or the force sensor and transmits it to the program controller. The program controller controls the action of the servo motor to achieve control of monotonic / cyclic loading mode, and can switch freely through programming. The energy supply module is connected to the remote control terminal, 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.

[0013] In the above technical solution, the program controller adopts PID closed-loop control.

[0014] Another aspect of the present invention includes a control method for the horizontal loading test system, comprising the following steps: Step 1: Place the horizontal loading test system inside the geotechnical centrifuge. The front end of the loading component is connected to the scale model via connecting accessories. Start the centrifuge until the set acceleration is reached. Step 2: Set the loading path and select displacement control or force control mode through the remote control terminal driver controller; Step 3: The program controller drives the servo motor to apply a horizontal monotonic or cyclic load to the scaled model according to the set loading path. Step 4: The displacement or force data is collected in real time through the data acquisition module and fed back to the program controller for closed-loop adjustment; Step 5: After loading is complete, switch to displacement control mode and retract the loading component.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention connects the support mechanism and the horizontal loading mechanism with a screw, and sets the screw in the waist-shaped hole to realize the vertical and horizontal position adjustment of the horizontal loading mechanism in the model box. At the same time, the support mechanism drives the horizontal loading mechanism to move longitudinally in the model box, thereby simulating experiments at different positions in the model box. 2. This invention can work stably under a high geotechnical centrifuge acceleration of up to 170g, with a maximum loading force of 5kN, a control accuracy of 5N, a maximum displacement stroke of 50mm, a displacement accuracy of 0.1mm, a cyclic loading frequency of 1Hz, and a cyclic amplitude of 10mm, meeting the loading requirements of most marine engineering long-term service conditions. 3. It adopts servo motor drive, which has fast response, high control precision, and supports free switching between displacement control and force control; 4. The electrical control mechanism adopts a modular design, and the loading structure is adjustable to adapt to different model sizes, shapes, and loading positions; 5. It has remote automatic control and real-time data acquisition and transmission functions to realize unmanned and intelligent testing. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the horizontal loading test system of the present invention.

[0017] Figure 2 This is a partial structural schematic diagram of the present invention.

[0018] Figure 3 This is a partial structural schematic diagram of the present invention.

[0019] Figure 4 This is a schematic diagram of the electrical control mechanism.

[0020] Among them, 1-model box; 2-slide rail; 3-support mechanism; 4-screw; 5-waist-shaped hole; 6-adjustable support base; 7-horizontal loading mechanism; 8-servo motor; 9-reducer; 10-ball screw; 11-fixed screw; 12-loading component; 13-guide rail; 14-displacement sensor; 15-remote control terminal; 16-drive cabinet; 17-optical transceiver; 18-fiber optic ring; 19-program controller; 20-mounting frame. Detailed Implementation

[0021] 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.

[0022] Example 1 like Figures 1-3 As shown, a horizontal loading test system for a geotextile centrifuge includes a model box 1, a support mechanism 3, a horizontal loading mechanism 7, and an electrical control mechanism. The support mechanism 3 is slidably mounted on the top of the model box 1, and the horizontal loading mechanism 7 is installed inside the model box 1 and connected to the support mechanism 3 via a screw 4. The horizontal loading mechanism 7 is adjustable in its horizontal, longitudinal, and vertical positions within the model box 1. Preferably, a slide rail 2 is provided on the top of the model box, and the support mechanism 3 is mounted on the slide rail 2 and fixed with bolts.

[0023] The horizontal loading mechanism 7 includes a mounting frame 20, a servo motor 8, a reducer 9, a ball screw, a loading assembly 12, and guide rails 13. The servo motor 8 is mounted on the rear exterior of the mounting frame 20 and is connected to the ball screw via the reducer 9. Guide rails 13 are symmetrically arranged on both sides of the ball screw 10 and mounted on the mounting frame 20. The front end of each guide rail 13 is connected to the loading assembly 12, which is located on the front exterior of the mounting frame 20. A nut on the ball screw 10 is connected to the loading assembly 12. The ball screw 10 converts the rotational motion of the servo motor 8 into linear motion, pushing the loading assembly 12 to move forward or backward longitudinally along the guide rails 13, thus applying a horizontal monotonic load or a horizontal cyclic load. A displacement sensor 14 is fixedly installed inside the mounting frame 20 to sense the longitudinal horizontal displacement of the loading assembly 12. Preferably, the bottom of the mounting frame 20 is installed inside the model box 1 by a fixing screw 11, and the fixing screw 11 maintains the stability of the loading horizontal plane during operation.

[0024] Furthermore, a force sensor is installed at the front end of the loading component 12 and a connection hole is opened. The connection hole is connected to the scale model through a connection accessory. The connection accessory can be adapted to different scale models. When the geotextile centrifuge is rotating, the force sensor collects the force applied to the scale model by the loading component 12 during the horizontal movement along the longitudinal direction of the model box 1.

[0025] Furthermore, multiple horizontally arranged oblong holes 5 are provided on the support mechanism 3. The upper part of each screw 4 passes through an oblong hole 5 and is fixed by a fastener (preferably a nut). The screw 4 is suspended on the support mechanism 3 by an adjustable support base 6, thereby suspending the horizontal loading mechanism 7 at the bottom of the screw 4 on the support mechanism 3. By adjusting the length of the screw 4 extending out of the oblong hole 5, the vertical height of the horizontal loading mechanism 7 in the model box 1 can be adjusted. By adjusting the screw 4 at different positions in the oblong hole 5 (the oblong hole 5 has a certain length, so the screw 4 can be placed at different positions in the oblong hole 5 and fixed by a nut), the horizontal position of the horizontal loading mechanism 7 in the model box 1 can be adjusted.

[0026] Furthermore, two handles are installed on the top of the support mechanism 3, which make it easy to lift the horizontal loading mechanism 7.

[0027] The electrical control mechanism includes a remote control terminal 15, a programmable controller 19, a data acquisition module, a remote monitoring module, and an energy supply module.

[0028] The remote control terminal 15 is connected to the program controller 19 via a remote monitoring module. The input terminal of the program controller 19 is connected to the data acquisition module, and the output terminal of the program controller 19 is connected to the servo motor 8. The data acquisition module acquires data from the displacement sensor 14 or force data from the force sensor and transmits it to the program controller 19. The program controller 19 controls the action of the servo motor 8 to achieve control of monotonic / cyclic loading mode, and can freely switch between them through programming.

[0029] The energy supply module is connected to the remote control terminal 15, the program controller 19, 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.

[0030] Specifically, the programmable controller 19 has motion control functions, employing closed-loop position feedback and closed-loop force feedback to achieve control in monotonic / cyclic loading modes, and allowing free switching through programming. The programmable controller 19 uses PID closed-loop control, controlling the servo motor 8 through displacement sensor 14, integrating speed feedforward, hysteresis feedforward, and acceleration feedforward to eliminate linearity errors and phase lag, achieving precise control of the servo motor 8's motion trajectory; this is the position control mode of the programmable controller 19. The outer loop collects real-time loading force signals through a force sensor, dynamically adjusting the inner loop position target based on force deviation to ensure force accuracy in monotonic / cyclic loading modes; this is the force control mode of the programmable controller 19.

[0031] The data acquisition module is used to acquire data from the force sensor and the displacement sensor 14. The force sensor has a maximum range of 5kN and an accuracy of 5N. The displacement sensor 14 has a maximum displacement stroke of 50mm, an accuracy of 0.1mm, a cyclic loading frequency of 1Hz, and a cyclic amplitude of ±10mm.

[0032] Preferably, the electrical control principle is as follows: Figure 4 As shown, the remote control terminal 15 issues a working instruction to the program controller 19. The working instruction is transmitted in the form of an electrical signal through the drive cabinet 16 and the optical transceiver 17 of the remote monitoring module, and then through the optical fiber ring 18 at the upper and lower connection points to the program controller 19. The program controller 19 sends a loading instruction to the servo motor 8, determines the loading mode as either displacement control mode (collecting displacement data from the displacement sensor) or force control mode (collecting force data from the force sensor), and determines the monotonic loading mode or the cyclic loading mode.

[0033] Example 2 This embodiment provides a control method for the horizontal loading test system described in Embodiment 1, including the following steps: Step 1: Place the horizontal loading test system inside the geotechnical centrifuge. The front end of the loading component 12 is connected to the scale model through the connecting accessories. Start the centrifuge until the set acceleration is reached (up to 170g). Step 2: Use the remote control terminal 15 to drive the controller 19, set the loading path, and select the displacement control or force control mode. Step 3: The program controller 19 drives the servo motor 8. The servo motor 8 adjusts the speed based on the internal decoder and drives the ball screw 10 to move through the reducer 9. The ball screw 10 converts its own rotational motion into the forward and backward motion of the loading component 12, thereby applying a horizontal monotonic or cyclic load to the scaled model. Step 4: The displacement or force data is collected in real time through the data acquisition module and fed back to the program controller 19 for closed-loop regulation; Step 5: After loading is complete, switch to displacement control mode and retract loading component 12.

[0034] 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 horizontal loading test system for geotextile centrifuges, characterized in that, It includes a model box, a support mechanism, and a horizontal loading mechanism; the support mechanism is slidably mounted on the top of the model box, and the horizontal loading mechanism is located inside the model box and connected to the support mechanism; the horizontal loading mechanism is adjustable in its horizontal, vertical, and longitudinal positions within the model box. The horizontal loading mechanism includes a mounting frame, a servo motor, a reducer, a ball screw, a loading assembly, and guide rails. The servo motor is mounted outside the mounting frame and is connected to the ball screw via the reducer. The guide rails are symmetrically arranged on both sides of the ball screw and mounted on the mounting frame. The front end of the guide rail is connected to the loading assembly, which is located outside the mounting frame. The nut on the ball screw is connected to the loading assembly. A displacement sensor is fixedly mounted on the mounting frame to sense the longitudinal horizontal displacement of the loading assembly. The loading component has a force sensor installed at the front end and a connection hole is provided. The connection hole is connected to the scale model through a connecting accessory. The horizontal loading mechanism is connected to the support mechanism via a screw.

2. The horizontal loading test system according to claim 1, characterized in that, The support mechanism has multiple oblong holes, through which the top of the screw passes and is fixed by a fastener.

3. The horizontal loading test system according to claim 1, characterized in that, Two handles are installed on the top of the support mechanism.

4. The horizontal loading test system according to claim 1, characterized in that, The horizontal loading test system also includes an electrical control mechanism, which comprises a remote control terminal, a programmable controller, a data acquisition module, a remote monitoring module, and an energy supply module.

5. The horizontal loading test system according to claim 4, characterized in that, The remote control terminal is connected to the program controller via a remote monitoring module. The input end of the program controller is connected to the data acquisition module, and the output end of the program controller is connected to the servo motor. The data acquisition module acquires data from the displacement sensor or the force sensor and transmits it to the program controller. The program controller controls the movement of the servo motor to achieve monotonic / cyclic loading mode control, and can switch freely through programming. The energy supply module is connected to the remote control terminal, the program controller, the data acquisition module, and the remote monitoring module, respectively.

6. The horizontal loading test system according to claim 4, characterized in that, The programmable controller uses PID closed-loop control.

7. The horizontal loading test system according to claim 1, characterized in that, The bottom of the mounting frame is installed inside the model box by fixing screws, and the fixing screws maintain the stability of the loading horizontal plane during operation.

8. The control method for the horizontal loading test system as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Place the horizontal loading test system inside the geotechnical centrifuge. The front end of the loading component is connected to the scale model. Start the centrifuge until the set acceleration is reached. Step 2: Set the loading path and select displacement control or force control mode through the remote control terminal driver controller; Step 3: The program controller drives the servo motor to apply a horizontal monotonic or cyclic load to the scaled model according to the set loading path. Step 4: The displacement or force data is collected in real time through the data acquisition module and fed back to the program controller for closed-loop adjustment; Step 5: After loading is complete, switch to displacement control mode and retract the loading component.

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