A device for automatic stratified loading of discrete bodies in centrifuge tests

Abstract

This application proposes an automatic layered loading device for discrete materials in centrifuge testing. The device includes a centrifuge model comprising a model soil box. The testing apparatus further includes a loading device, an electrical control device, and a pull-out device. The loading device, a multi-layered box structure pre-loaded with bulk material for load simulation, is fixed to the loading area above the model soil box. The pull-out device is installed on the side of the loading device, and the two are elastically connected sequentially at the same layer level. Initially, the electrical control device connects the various layers of the loading device in series. During the simulation experiment, the devices are released sequentially to simulate layered load. This testing apparatus achieves discrete material loading without stopping the geotextile centrifuge while ensuring the stability of the fixed loading device. The loading device can be adjusted and designed at any time according to the single loading amount, the number of loading stages, and other working conditions to simulate the load conditions of discrete materials in actual engineering as closely as possible.

Description

Technical Field

[0001] This application belongs to the field of geotechnical centrifuge technology, specifically relating to an automatic layered loading device for discrete bodies in centrifuge testing. Background Technology

[0002] In geotechnical engineering, centrifuge testing can simulate the effects of a gravitational field using a centrifugal field, mimicking the high stress experienced by soil in actual engineering projects. This overcomes the shortcomings of ordinary indoor geotechnical tests and is currently a commonly used and effective simulation method. Simulation of surface loads is one of the most common engineering simulation quantities in testing, frequently encountered in composite foundation preloading and the impact of surface loads on tunnels, foundation pits, and pile foundation substructures. For multiple loading operations, current methods often employ multiple-stop loading or uniformly distributed loads using jacks. Stop loading can cause stress changes and soil rebound; while uniformly distributed loads using jacks cannot adequately account for the mutual friction between the loaded particles and the contact between the loaded material and the ground surface. Achieving continuous, layered loading under high-speed centrifuge rotation still presents challenges.

[0003] Currently, the prior publicly disclosed patented technology solutions for loading devices in centrifuge model tests are as follows:

[0004] Chinese utility model patent CN205003147U discloses a loading system for applying vertical loads based on a geotextile centrifuge. The system consists of a bearing support erected on the side plate of the model box, a loading mechanism placed on the bearing support, and a controller for controlling the loading mechanism. The controller controls the extension of the loading rod to achieve precise control of the output force.

[0005] Chinese utility model patent CN213068497U discloses a geotextile centrifuge composite foundation rigid loading test system, including a model box, a weighted liquid storage tank, a rigid caisson, a monitoring system, and a geotextile centrifuge. The rigid caisson is placed on the composite foundation, and the loading is controlled by the weighted liquid storage tank fixed on the centrifuge arm, which controls the addition rate and flow rate of the heavy liquid through an electric regulating valve.

[0006] In summary, while existing technologies, primarily employing concentrated force loading with jacks or large-area uniform loading, can simulate layered, multi-stage loading, they cannot meet the requirements for discrete body loading simulation. Furthermore, they cannot accurately characterize the natural contact between the loading body and the surface soil, making it difficult to obtain the true impact of the loading body on underground soil and rock structures. Therefore, a loading device suitable for automatically implementing layered discrete body loading under the high-speed rotation of a centrifuge is needed to accurately simulate and analyze the impact of discrete body loading on underground soil and rock structures. Summary of the Invention

[0007] The core of this application is an automatic layered loading device for discrete bodies in centrifuge testing. The purpose is to provide a multi-level layered loading device for discrete bodies in high-speed rotating centrifuge testing without stopping the machine. It can be used for related tests on the impact of surcharge on underground rock and soil structures such as tunnels, foundation pits, pile foundations, and composite foundations.

[0008] The technical solution of this application is as follows:

[0009] An automatic layered loading device for discrete bodies in centrifuge testing, applied to the simulation of surcharge conditions above underground structures in geotechnical engineering, includes a centrifuge model, which includes a model soil box 10, characterized in that:

[0010] The innovative part is a multi-layered design, which includes a loading device, an electrical control device, and a pull-out device. The loading device is a loading device that is fixed on the non-supported area (i.e., the slack loading area) above the model soil box 10. It is a multi-layered box structure pre-loaded with bulk materials for slack loading simulation. The pull-out device is installed on the side of the loading device, and the two are elastically connected sequentially at the same layer. In the initial state, the electrical control device is used to connect the box structures of each layer of the loading device in series. During the simulation experiment, they are released sequentially to realize the simulation of tiered slack loading.

[0011] The model soil box 10 is equipped with a partition 11 and a partition support 9; the unsupported side of the model soil box 10 is the area for placing the model test material and installing the loading device.

[0012] The loading device includes a fixed connecting plate 3, a loading box 4, and a pull-out sliding plate 5. The fixed connecting plate 3 is used to fix adjacent loading boxes together by three rows of hexagonal bolts. The loading box 4 has N layers from bottom to top, presenting a clear stepped shape, and contains discrete stacked materials. The pull-out sliding plate 5 has N layers from bottom to top, and is a sliding metal plate set at the bottom of each loading box.

[0013] The electronic control device includes a motor 1, a movable pin 2, and a control box 14. The pin 2 is a rotating shaft, and the output shaft of the motor 1 is coaxial with the pin 2. The control box 14 integrates a pulse generator and a microcontroller. The microcontroller has a control algorithm written on it. By receiving and parsing the pulse signal from the pulse generator, it manipulates the motor 1 to achieve precise control of the movable pin 2 to move upward.

[0014] The pull-out device includes a spring 6, a vertical partition 7, and a pin 8. The spring 6 connects the pull-out slide plate 5 to the vertical partition 7. The vertical partition 7 is fixed on one side of the pull-out slide plate 5 in the direction of sliding out and is located above the support area of ​​the model soil box 10. It has holes for the spring 6 to pass through. The pin 8 is located on the outside of the vertical partition 7 and is used to fix the spring 6 passing through the vertical partition 7. When the movable pin 2 disengages from the opening of the pull-out slide plate 5, the pull-out slide plate 5, which is pulled taut by the spring 6, is quickly pulled out. The bulk material in this layer of the loading box will fall to realize the load simulation of the centrifuge test. As the movable pin 2 gradually rises, the pull-out slide plate 5 is pulled out from bottom to top in sequence to realize the simulation of staged load.

[0015] Furthermore, the loading box 4 needs to have a hole below the movable pin 2, and similarly, the corresponding position of the pull-out slide plate 5 also needs to have a hole 13 so that the movable pin 2 can pass through.

[0016] Furthermore, grooves are made on both sides of the pull-out slide plate 5, and ball bearings 12 are installed to reduce friction so that the slide plate 5 can slide out quickly under the pull of the taut spring 6.

[0017] During installation, the movable pin 2 passes through the thick wall of the loading box 4 and the pull-out slide plate 5 at its bottom from top to bottom. During the test, under the control algorithm, the movable pin 2 moves layer by layer from bottom to top, and the pull-out slide plate 5 from bottom to top is hung on the inner wall of the vertical partition 7 one by one through the spring pin 8.

[0018] Compared with the prior art, this application has the following beneficial effects:

[0019] The device proposed in this application achieves discrete material loading without stopping the geotextile centrifuge while ensuring the stability of the loading device. The loading device can be adjusted and designed at any time according to the working conditions such as the single loading amount and the number of loading stages, so as to simulate the stacking conditions of discrete materials in actual engineering as much as possible. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the operation of the device in this application.

[0021] Figure 2 This is a schematic diagram of the device structure of this application.

[0022] Figure 3 This is an exploded view of the device structure in this application.

[0023] Figure 4 This is a detailed structural diagram of the pull-out slide plate in the device of this application.

[0024] Figure 5 This is a flowchart of the device operation process of this application.

[0025] Figure label:

[0026] 1-Motor, 2-Modible latch, 14-Control box

[0027] 3-Fixed connecting plate and bolts, 4-Filling box,

[0028] 5-Pull-out slide, 12-Ball bearing, 13-Pin hole,

[0029] 6-Pull-out spring, 7-Vertical partition, 8-Spring pin,

[0030] 9-Difference support, 10-Model soil box, 11-Difference. Detailed Implementation

[0031] The technical solutions provided in this application will be further described below with reference to specific embodiments and accompanying drawings. The advantages and features of this application will become clearer from the following description.

[0032] This application discloses an automatic layered loading device for discrete materials in centrifuge testing, applied to the simulation of surcharge conditions above underground structures in geotechnical engineering. The device includes a centrifuge model comprising a model soil box. The testing apparatus further includes a loading device, an electrical control device, and a pulling device. It simulates the surcharge conditions within the model soil box during centrifuge testing, achieving staged surcharge loading and simulating the interaction between the granular materials during the accumulation process. A schematic diagram of the device's operation is shown below. Figure 1 As shown.

[0033] like Figure 1 As shown, the centrifuge model includes a model soil box 10, and a partition 11 and a partition support 9 are provided inside the model soil box 10; the unsupported side of the model soil box 10 is the area for placing the model test material and installing the loading device.

[0034] like Figure 2 , Figure 3 As shown, the electrical control device includes a motor 1, a movable pin 2, and a control box 14; the upper end of the movable pin 2 extends into the motor 1 for fixation, and the other end passes through the holes of the loading box 4 and the pull-out slide plate 5 in sequence, fixing the pull-out slide plate 5 and the loading box 4 in the same vertical position.

[0035] like Figure 2 , Figure 3 As shown, the loading device includes a fixed connecting plate 3, a loading box 4, and a pull-out sliding plate 5, which are fixed above the non-supported area of ​​the model soil box 10. The specific fixing position is based on the loading area in the test design scheme.

[0036] like Figure 2 , Figure 3As shown, the pull-out device includes a spring 6, a vertical partition 7, and a pin 8. The spring 6 connects the pull-out slide 5 to the vertical partition 7. The vertical partition 7 is fixed on one side of the pull-out slide 5 in the sliding direction and is located above the support area of ​​the model soil box 10, and has holes for the spring 6 to pass through. The pin 8 passes through the vertical partition 7 to fix the spring 6. As an example and not a limitation, the vertical partition 7 is fixed to the model soil box 10 by the inner partition support 9 of the soil box.

[0037] like Figure 4 As shown, the feeding device has multiple slots on both sides of the pull-out slide plate 5, and ball bearings 12 are installed in the slots to reduce friction when the slide plate is pulled out. At the same time, lubricant needs to be applied to both sides and the ball bearings before use to reduce friction.

[0038] In this application, during centrifuge testing, the innovative part of the invention is connected to the centrifuge model box structure through fixed brackets, guide rails, etc., to maintain the stability of the device. The motor 1 is controlled by the control box 14, and the control box 14 is connected to the centrifuge control room and managed by the centrifuge control room, which is used for the layered multi-stage loading of discrete stack carriers.

[0039] Specifically, each layer of the loading box 4 in the loading device is connected by a fixed connecting plate 3. At the same time, a pull-out slide plate 5 is installed, and the movable pin 2 in the electronic control device passes through all the loading boxes 4 and the pull-out slide plate 5 in sequence. The length, width, height and number of layers of the loading box 4 can be adjusted according to the loading requirements of the test. The embodiment shown in the figure is designed with four layers. One end of the spring 6 of the pull-out device is fixed to the pull-out slide plate 5 by hooking it through a hole at one end, and the other end passes through the corresponding hole on the vertical partition 7 and is fixed by a pin 8. The vertical partition 7 is fixed on one side of the pull-out slide plate 5 in the direction of sliding out. The distance between the two is determined by tightening the spring 6. The vertical partition 7 has a circular hole to allow the spring 6 to pass horizontally after being tightened. The pin 8 is used to fix the spring 6 that passes through the vertical partition 7.

[0040] The motor 1 is started through the control box 14, and initialization settings are performed, including setting the rising speed, distance, direction, and loading level of the pin 2, and calibrating the initial position of the pin.

[0041] When loading begins, the computer in the centrifuge control room clicks the command to start loading. The pulse generator sends a signal, and the control algorithm receives the pulse signal from the pulse generator, analyzes the received pulse signal, determines the number and direction of the pulses, and then, based on the analyzed pulse signal, the number of pulses indicates the number of steps that motor 1 should rotate, the pulse frequency is the number of steps per unit time, and the pulse direction indicates the direction of rotation. Based on the analyzed signal, the microcontroller's control algorithm calculates the rotation angle and rotation speed of motor 1 (the rotation speed is controlled by the pulse frequency), and calculates the moving distance of pin 2, that is, the linear displacement of pin 2 is equal to the rotation angle multiplied by the pin pitch (the pin pitch refers to the linear displacement corresponding to one complete rotation of the stepper motor). The mechanical mechanism converts the rotational motion of motor 1 into linear movement, ultimately realizing the upward control of pin 2. When pin 2 disengages from the opening of the pull-out slide 5, the pull-out slide 5, which is tensioned by spring 6, is quickly pulled out, and the bulk material in this layer of the loading box will fall to realize the stacking simulation of the centrifuge test. At the same time, the current state of pin 2 is updated, and the loading of this stage is completed.

[0042] The centrifuge continues to rotate, enters the starting point of the next layer, and begins the next stage of loading;

[0043] Execute the above loop process multiple times;

[0044] Motor 1 controls pin 2 to move upward to a set position, causing the discrete body to fall into the soil box below. In each cycle, the control algorithm continuously receives pulse signals, controls the movement of the stepper motor and pin, and updates the system status.

[0045] As the movable pin 2 gradually rises, the pull-out slide 5 is pulled out horizontally to the right from bottom to top (see the embodiment diagram), thus simulating the staged loading.

[0046] During installation, the movable pin 2 passes through the thick wall of the loading box 4 and the pull-out slide plate 5 at its bottom from top to bottom. During the test, under the control algorithm, the movable pin 2 moves layer by layer from bottom to top, and the pull-out slide plate 5 from bottom to top is hung on the inner wall of the vertical partition 7 one by one through the spring pin 8.

[0047] This device is used as a loading device for geotechnical centrifuge model tests. It is suitable for simulating large-area loading conditions of discrete materials such as ore and sand in reality. The device can fully consider the interaction characteristics during the discrete material accumulation process and the interaction characteristics with the surface soil.

[0048] The above description is merely a description of preferred embodiments of this application and is not intended to limit the scope of this application in any way. Any changes or modifications made by those skilled in the art based on the above-disclosed technical content should be considered as equivalent and valid embodiments and fall within the scope of protection of the technical solution of this application.

Claims

1. An automatic layered loading device for discrete bodies in centrifuge testing, applied to the simulation of surcharge conditions above underground structures in geotechnical engineering, comprising a centrifuge model, the centrifuge model including a model soil box (10), characterized in that: The test apparatus also includes a loading device, an electrical control device, and a pull-out device. The loading device is a loading device that is fixed in the non-supported area above the model soil box (10), i.e., the slack loading area. It is a multi-layer box structure pre-loaded with bulk materials for slack loading simulation. The pull-out device is installed on the side of the loading device, and the two are elastically connected sequentially with the same number of layers. During installation, the electrical control device is used to connect the box structures of each layer of the loading device in series. During the test simulation, it is released sequentially to realize the simulation of graded slack loading. The loading device includes a fixed connecting plate (3), a loading box (4), and a pull-out sliding plate (5); the fixed connecting plate (3) fixes the adjacent loading boxes; the loading box (4) includes N layers from bottom to top, presenting a clear stepped shape, and contains discrete stacked materials; the pull-out sliding plate (5) includes N layers from bottom to top, and is a sliding metal plate set at the bottom of each loading box; The electrical control device includes a motor (1), a movable pin (2), and a control box (14). The movable pin (2) is a rotating shaft, and the output shaft of the motor (1) is coaxial with the movable pin (2). The control box (14) integrates a pulse generator and a microcontroller. The microcontroller has a control algorithm written on it. By inputting command signals and analyzing the pulse signals of the pulse generator, the motor (1) is manipulated to achieve precise control of the upward movement of the movable pin (2). During installation, the movable pin (2) passes through the thick wall of the loading box (4) and the bottom pull-out slide plate (5) from top to bottom. During the test simulation, the movable pin (2) moves from bottom to top layer by layer under the control algorithm. The pull-out slide plate (5) from bottom to top is hung on the inner wall of the vertical partition (7) one by one through the spring pin (8). The pull-out device includes a spring (6), a vertical partition (7), and a spring pin (8); the spring (6) is used to connect the pull-out slide (5) and the vertical partition (7); the vertical partition (7) is fixed on one side of the pull-out slide (5) in the direction of sliding out and is located above the support area of ​​the model soil box (10), and has holes for the spring (6) to pass through; the spring pin (8) is set on the outside of the vertical partition (7) and is used to fix the spring (6) passing through the vertical partition (7); When the movable pin (2) disengages from the hole (13) of the pull-out slide plate (5), the pull-out slide plate (5) which is pulled by the spring (6) is quickly pulled out, and the bulk material in the loading box of this layer will fall to realize the stacking simulation of the centrifuge test. As the movable pin (2) gradually rises, the pull-out slide plate (5) is pulled out from bottom to top in sequence to realize the simulation of graded stacking.

2. The apparatus as described in claim 1, characterized in that: The loading box (4) has a hole below the movable pin (2), and similarly, the corresponding position of the pull-out slide (5) also has a hole (13); the movable pin (2) passes through the thick wall of the loading box (4) and the hole of the pull-out slide (5) at its bottom from top to bottom.

3. The apparatus as described in claim 1, characterized in that: The two sides of the pull-out slide plate (5) are slotted and ball bearings (12) are installed to reduce friction so that the pull-out slide plate (5) can slide out quickly under the pull of the taut spring (6).

4. The apparatus as claimed in claim 1, characterized in that: The control process of the experimental apparatus is as follows: Start the motor (1) through the control box (14) and perform initialization settings; When loading begins, the computer in the centrifuge control room clicks the command to start loading. The pulse generator sends a signal, and the control algorithm receives the pulse signal from the pulse generator and analyzes the received pulse signal to determine the number and direction of the pulse. Based on the analyzed pulse signal, the number of pulses indicates the number of steps the motor (1) should rotate, the pulse frequency is the number of steps per unit time, and the direction of the pulse indicates the direction of rotation. Based on the analyzed signal, the control algorithm of the microcontroller calculates the rotation angle and rotation speed of the motor (1) and calculates the moving distance of the movable pin (2), converting the rotational motion of the motor (1) into linear movement, and realizing the upward control of the movable pin (2). When the movable pin (2) disengages from the opening of the pull-out slide (5), the pull-out slide (5) pulled by the spring (6) is quickly pulled out, and the bulk material in the loading box of this layer will fall to realize the stacking simulation of the centrifuge test. At the same time, the current state of the movable pin (2) is updated, and the loading of this stage is completed. The centrifuge continues to rotate, enters the starting point of the next layer, and begins the next stage of loading; Execute the above loop process multiple times; The motor (1) controls the movable pin (2) to move upward to the set position and cause the discrete body to fall into the soil box below. In each cycle, the control algorithm part continuously receives pulse signals, controls the movement of the stepper motor and the pin, and updates the system state. As the movable pin (2) gradually rises, the sliding plate (5) is pulled out horizontally to the right from bottom to top, realizing the simulation of graded stacking.

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