CN111337221A - Tower type multifunctional automatic soil body accelerating device for geotechnical centrifugal test - Google Patents

Abstract

The invention relates to a tower-type multifunctional automatic soil acceleration device for geotechnical centrifugation test, comprising: a bottom plate arranged on a basket of a centrifuge; a model box arranged on the bottom plate for simulating fluid-structure interaction; The acceleration device includes an acceleration channel, a baffle, and a multi-function motor. The acceleration channel is vertically arranged and the lower end communicates with the top of the model box. The baffle is rotatably arranged in the acceleration channel for initially carrying soil samples. The motor screw controls the opening and closing of the baffle; the image acquisition device includes a high-speed camera and a light source, and the high-speed camera is arranged on the base plate through the camera frame. Compared with the prior art, the present invention can not only restore the high-speed characteristics of large deformation soil flow geological disasters, but also have different acceleration levels, which is beneficial to study the impact of impact speed on the disaster-causing mechanism, and can be accelerated without external loads. It makes full use of the supergravity centrifugal field created by the centrifuge, so it is economical and easy to operate.

Description

A tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test

technical field

The invention relates to the field of engineering geology, in particular to a tower-type multifunctional automatic soil acceleration device used for a geotechnical centrifugal test.

Background technique

In recent years, geological disasters such as debris flows, debris flows, high-speed and long-distance landslides have occurred frequently, causing serious casualties and economic losses. A notable feature of such large-deformation soil flow disasters is the ultra-high movement speed. For example, the major landslide in Guangming New District, Shenzhen in 2015, the maximum speed exceeded 20m/s; the average movement speed of Qingchuan Donghekou high-speed remote landslide exceeded 25m/s. The ultra-high movement speed carries huge impact energy, so the destructive force is extremely large, causing a large number of engineering structures on the movement path to be washed away. The theory and technology of its control has always been a major problem in the world. The physical model test based on conventional gravity is the main method to study such geological disasters, but there are two problems: First, the scaled model under the condition of 1g gravity is difficult to reproduce the high-speed characteristics of large deformation soil flow or is difficult to realize ; Second, conventional gravity model tests are difficult to effectively reflect the deformation characteristics of geotechnical materials related to stress. The centrifugal model test can not only restore the spatial dimension of the prototype through the virtual high-power gravity field, but also provide a stress field similar to the prototype, thus effectively solving the above two problems. But the centrifugal test has not been effectively used in this aspect, one of the important reasons is the lack of soil acceleration device to restore the high-speed characteristics of large deformation soil flow geological disasters.

The difficulty with this type of device is:

(1) At present, most of the model boxes that can be carried by centrifuges in service around the world are small. In a small space, the acceleration stroke of soil is very limited, so it is difficult to obtain different levels of soil movement speed, that is, poor functionality;

(2) When the centrifuge is running, the soil is subjected to a huge centrifugal force. When accelerating the soil, the additional load must meet several conditions: First, the loading speed must be fast enough and automatically controlled. When the baffle is opened, the load is instantaneous. Second, after the acceleration is completed, the additional load must be released in time; third, the magnitude of the additional load must be at least at the same level as the centrifugal force. Most of the loading methods that meet the requirements of the above three conditions are relatively expensive, that is, the economy is insufficient;

(3) In a high-gravity environment, the requirements for the safety of the additional devices on the centrifuge basket will also increase significantly. Therefore, the fixation of the additional devices is very important, that is, how to meet the safety requirements;

(4) Under the super-gravity environment, the pressure of the soil on the baffle in the initial state is dozens of times higher than that under 1 g of gravity. Under the huge pressure, how to fix the baffle to keep its locked state is a major technical problem, and How to quickly open the baffle to prevent the baffle opening speed from affecting the soil movement is another major technical problem;

(5) In the fully enclosed test environment, how to realize remote automatic operation of soil acceleration process is also a technical problem.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test in order to overcome the above-mentioned defect of the prior art that it is difficult to restore the high-speed characteristics of large deformation soil flow geological disasters.

The object of the present invention can be realized through the following technical solutions:

A tower-type multifunctional automatic soil acceleration device for geotechnical centrifugation test, comprising a bottom plate arranged on a basket of a centrifuge, and further comprising:

a model box, disposed on the base plate, for simulating fluid-structure interaction;

The acceleration device includes an acceleration channel, a baffle, and a multi-function motor. The acceleration channel is vertically arranged and the lower end communicates with the top of the model box. The baffle is rotatably arranged in the acceleration channel for initially carrying soil. In the same way, the motor screw of the multi-function motor controls the opening and closing of the baffle;

The image acquisition device includes a high-speed camera and a light source, and the high-speed camera is arranged on the base plate through a camera frame.

Preferably, a plurality of the baffles are provided, and the plurality of baffles are arranged up and down in the acceleration channel at a certain distance in sequence.

Preferably, the multifunctional motor is fixed on one side of the acceleration channel through a motor carrying device, and a plurality of carrying platforms with different heights are arranged on the motor carrying device.

Preferably, the acceleration channel is provided with an opening on the lower side of the baffle position for the motor screw rod of the electric multi-function motor to pass through, and a feeding port is provided on the upper side of the baffle position.

Preferably, the contact portion of the motor lead screw and the baffle is flat.

Preferably, the high-speed camera is fixed on the camera frame by a camera fixing device, and the camera fixing device includes a casing that completely wraps the high-speed camera.

Preferably, the camera frame includes channel steel arranged in a vertical direction and a horizontal direction.

Preferably, the light source is a spherical or planar light source.

Preferably, the model box is provided with a transparent surface, and the model box is provided with a sliding surface and an engineering structure.

Preferably, the acceleration device is fixed on the bottom plate through a vertical column, and a diagonal brace is provided between the vertical column and the bottom plate.

Compared with the prior art, the present invention can be used to obtain soil bodies with different flow velocities, used to simulate the impact-induced disaster process under the high-speed flow of large-deformed soil bodies, and provides a theoretical basis for the research and development of disaster prevention technologies for such geological disasters. The following advantages:

1. Economy: The present invention makes full use of the hypergravity field created by the centrifuge, and achieves the acceleration effect by changing the acceleration stroke of the soil body, avoiding the use of additional loads, and effectively controlling the cost of the device;

2. Simplicity: all the devices involved in the present invention are assembled by sub-components, which is convenient for disassembly and transportation;

3. Multi-function: The invention independently designs a multi-function motor and a motor carrying device, and controls the baffles at different heights through different combinations to obtain different soil acceleration effects;

4. Fully automatic: The present invention controls the state of the baffle through the motor screw, the motor can be controlled remotely, and one key can control the opening of the baffle and feeding, and then complete the acceleration, so as to restore the high-speed characteristics of large deformation soil flow disasters;

5. Fast opening speed: in the present invention, the baffle completely relies on centrifugal force when opening, and does not require any auxiliary measures, because under the supergravity environment, the baffle is subject to huge gravitational force, and the baffle is turned over quickly at the moment of opening, and the opening speed can reach 1g gravity dozens of times lower.

Description of drawings

Fig. 1 is the left side schematic diagram of the overall structure of the device of the present invention;

Fig. 2 is the right side schematic diagram of the overall structure of the device of the present invention;

3 is a schematic diagram of a multifunctional motor in the present invention;

4 is a schematic diagram of a motor carrying device in the present invention;

5 is a schematic front view of an acceleration channel in the present invention;

Fig. 6 is the backside schematic diagram of the acceleration channel in the present invention;

7 is a schematic diagram of baffle control in the present invention;

FIG. 8 is a schematic diagram of the multi-functional motor and the motor carrying device in the present invention, wherein (a) to (d) are the combination modes when controlling the No. 1 to No. 4 baffles, respectively;

FIG. 9 is a disassembled view of the feeding port in the present invention.

Notes on the figure:

1. Bottom plate; 2. Model box; 3. Slip surface; 4. Engineering structure; 5. Transparent surface; 6. Light source fixing device; 7. Light source; 8. Camera stand; 9. Camera fixing device; 10. High-speed camera; 11A, No. 1 bezel; 11B, No. 2 bezel; 11C, No. 3 bezel; 11D, No. 4 bezel; 12, opening; 13, column; 14, diagonal support column; 15, column fixing device; 16, Fixing device for diagonal struts; 17. First fixing strip; 18. Second fixing strip; 19. Acceleration channel; 20. Motor carrying device; 21. Multi-function motor; 22. Motor host; 23. Motor screw; Distal connecting plate; 25, proximal connecting plate; 26, rotating shaft; 27, first bearing platform; 28, second bearing platform; 29, third bearing platform; 30, feeding port.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

As shown in Figures 1 and 2, the present application proposes a tower-type multifunctional automatic soil acceleration device for geotechnical centrifugation tests, comprising a bottom plate 1 arranged on the centrifuge basket, on the one hand, used to fix the upper acceleration device, On the other hand, it is used to expand the size of the basket of the centrifuge; the model box 2 is arranged on the bottom plate 1 and includes a transparent surface 5 made of plexiglass to observe the flow state of the large deformation soil. The model box 2 mainly carries the load. The sliding surface 3 and the engineering structure 4 are used to simulate the interaction between fluid and structure; the acceleration device includes the acceleration channel 19, the baffles (11A-11D), and the multi-function motor 21. The acceleration channel 19 is vertically arranged and the lower end extends into the model box 2. A certain distance inside is used to constrain soil samples and install baffles. The baffles are rotatably arranged in the acceleration channel 19 to initially carry the soil samples. There are multiple baffles, and multiple baffles are in the acceleration channel 19. The top and bottom are arranged at a certain distance in sequence, and the motor screw 23 of the multi-function motor 21 controls the opening and closing state of the baffle; the image acquisition device includes a high-speed camera 10 and a light source 7, and the high-speed camera 10 is used to capture the large deformation soil in the model box 2. During the disaster process caused by the flow impact, the high-speed camera 10 is arranged on the base plate 1 through the camera frame 8 , and the light source 7 is used to fill light for the high-speed camera 10 .

The bottom plate 1 can be made of high-strength aluminum plate, which can reduce its weight and avoid the difficulty in installation of the device due to its heavy weight. The bottom plate 1 is mainly used to fix the upper acceleration device. The fixing method adopts high-strength bolts to anchor the upper device to the aluminum plate. This method ensures the flexibility of the device and facilitates disassembly and assembly. The size of the bottom plate 1 can be selected according to the size of the centrifuge basket used in practice. If the size of the basket is insufficient, the size of the bottom plate 1 can be increased to expand the size of the centrifuge basket, increase the camera object distance, and reduce the impact on the camera. The requirements of the lens can also avoid the small focal length caused by improper lens selection, such as the distortion of the image captured by the fisheye lens, which affects the analysis of the results.

Model box 2 should be selected as long as possible to ensure that the soil has enough movement space, so that some dynamic characteristics such as particle sorting can be fully displayed; big. One side of the model box 2 adopts a transparent surface 5 made of transparent plexiglass, which is convenient for observing the flow state of the soil body with large deformation. The model box 2 is provided with a sliding surface 3 and an engineering structure 4, and the sliding surface 3 is fixed at the bottom of the model box 2 to avoid shaking; the engineering structure 4 can be made of particulate concrete to study the impact of the structure in large deformation soil flow under the action of the destruction mechanism.

As shown in FIG. 3 , the multifunctional motor 21 includes a motor host 22 , a motor screw 23 and several connecting wires. The upper and lower sides of the motor main body 22 are respectively provided with motor connection plates, the far end connection plate 24 is farther from the motor main body 22 , and the proximal connection plate 25 is closer to the motor main body 22 . The contact part between the head of the cylindrical motor screw 23 and the baffle is appropriately flattened to a flat surface to ensure that it can closely fit with the baffle. The main motor 22 can be connected to the transfer system of the centrifuge through wires, and then the operation of the motor can be controlled in the control room. In order to ensure economy and simplicity, the motor should be easily disassembled. Therefore, the motor carrying device 20 is used to assist in fixing the motor, so that the baffles at different positions can be controlled by the same motor.

The multi-function motor 21 is fixed on one side of the acceleration channel 19 by the motor carrying device 20 . As shown in FIG. 4 , the motor carrying device 20 is made of steel to ensure sufficient strength. The motor carrying device 20 is provided with several carrying platforms with different heights for fixing the multifunctional motor 21 . The bottom of the motor carrying device 20 is the first carrying platform 27, which is arranged on the top of the model box 2; the first carrying platform 27 is provided with two second carrying platforms 28 separated by a certain distance. There are two third bearing platforms 29 therebetween, and a gap for the motor host 22 to pass through is arranged in the middle of the third bearing platforms 29 . The combination of the carrying platform and the motor connecting plate can control the baffles at different heights.

As shown in Figures 5 and 6, the acceleration device is designed to be safe, economical, multi-functional, and fully automatic. It makes full use of the hypergravity centrifugal field created by the centrifuge as the acceleration load to change the movement of the soil in the centrifugal field. , so that the soil gets different velocities. The movement path of the soil is controlled by the acceleration channel 19, so that it is always consistent with the direction of the maximum centrifugal force to obtain the best acceleration effect. The baffle is connected to the side surface of the acceleration channel 19 through the rotating shaft 26 to ensure that the baffle can rotate freely around the rotating shaft 26 . The front of the acceleration channel 19 is provided with an opening 12 of a suitable size on the lower side of the baffle position, so that the motor screw 23 can freely enter and exit, thereby controlling the baffle state. The back of the acceleration channel 19 is provided with a feeding port 30 on the upper side of the baffle position, which is convenient for filling. The height of the acceleration channel 19 can be determined according to the actual configuration of the centrifuge, and the installation position of the baffle can also be independently selected according to the needs of the experimental design.

As shown in Fig. 7, when the baffle is in the initial state, the baffle is closed through the feeding port 30 and then the motor screw 23 is extended. The motor screw 23 passes through the opening 12, so that the baffle is just pressed against the head of the motor screw 23, overlapping The amount should be greater than 10mm. The remote control motor host 22 works to shrink the motor screw 23, thereby controlling the opening of the baffle. The baffle is used in conjunction with the multi-function motor 21 and is installed at different heights to obtain different speeds after releasing the soil samples.

As shown in FIG. 8 , (a) the distal end connecting plate 24 and the first bearing platform 27 are fixed with high-strength bolts, which is the first configuration to control the No. 1 baffle 11A; (b) The functional motor 21, the proximal connecting plate 25 is fixed on the first bearing platform 27 to control the No. 2 baffle 11B; in (c), the multi-functional motor 21 is removed, and the distal connecting plate 24 is fixed on the No. 2 higher position. Three bearing platforms 29, the proximal connecting plate 25 is fixed to the second bearing platform 28 at a lower position, and can control the No. 3 baffle 11C; in (d) the proximal connecting plate 25 and the second bearing platform 28 at a higher position Connected, the distal connecting plate 24 is connected with the lower third bearing platform 29, which can control the No. 4 baffle 11D.

The image acquisition device mainly relies on the high-speed camera 10 to capture the evolution process of the flow behavior of the soil with large deformation. In order to prevent the high-speed camera 10 and the lens interface from falling off in a high-gravity environment, the camera fixing device 9 is specially designed, and a high-strength polymer material is used to process a shell according to the shape of the high-speed camera 10 to completely wrap the high-speed camera 10. The integrity of the high-speed camera 10 is strengthened, and each part is closely attached to the camera fixing device 9 to ensure that each part of the high-speed camera 10 is evenly stressed.

The camera frame 8 is made of channel steel, the vertical part is directly anchored on the bottom plate 1, and the horizontal part is connected with the vertical part by high-strength bolts, so it can be adjusted freely to ensure the proper height and position of the camera. The fixing device 9 of the high-speed camera 10 is fixed on the horizontal channel steel by bolts, and the position can be adjusted horizontally to ensure the proper horizontal position of the camera. The optimum shooting angle can be obtained by adjusting the camera frame 8 .

The light source 7 should preferably be a spherical or planar light source 7 to ensure good scattering of the light source 7 and avoid excessive concentration of light, which affects the image quality. The light source 7 is anchored to the base plate 1 through the light source fixing device 6 .

The acceleration device is fixed on the bottom plate 1 through the upright column 13, and a diagonal brace 14 is arranged between the upright column 13 and the bottom plate 1 to improve the integrity of the device and ensure the safety of the test process. The acceleration channel 19 is connected with the upright column 13 through the first fixing strip 17 . The bottom of the motor carrying device 20 is fixed to the top of the model box 2 , the side is fixed to the upright column 13 through the second fixing bars 18 , and the components are connected by high-strength bolts. The bottoms of the upright column 13 and the diagonal brace 14 are respectively connected to the bottom plate 1 through the upright column fixing device 15 and the diagonal brace column fixing device 16 , and the connecting components are high-strength bolts.

As shown in FIG. 9 , the filling port includes a groove and a cover sheet opened on the surface of the acceleration channel 19 . The size of the groove is subject to the convenience of packing. The size of the cover sheet is matched with the groove to ensure the smoothness of the inner and outer walls of the acceleration channel 19 .

The use flow of the device of the present invention is as follows:

(1) Place the bottom plate 1 on the centrifuge basket and fix it firmly, and then fix the model box 2 on the bottom plate 1. Note that the position of the model box 2 should be marked in advance to avoid the upper structure being difficult due to the dislocation of the model box 2. assemble;

(2) Determine the angle of the sliding surface 3 and fix it well to ensure that the side surface of the sliding surface 3 is closely attached to the inner wall of the model box 2 to prevent the soil sample from leaking during the sliding process, which will make it difficult to obtain the soil body in the later image processing process. The real speed information of the movement; determine the type, size, placement position, etc. of the engineering structure 4, and then fix it firmly;

(3) Fix the baffle plate firmly with the acceleration channel 19 first, and then fix the first fixing strip 17 for fixing the acceleration channel 19 on the acceleration channel 19 according to the reserved bolt holes, and screw all the bolts in place to ensure the firmness between the two. connect;

(4) In order to avoid difficulty in installing the second fixing bar 18 for fixing the motor carrying device 20 after the acceleration channel 19 is installed, before installing the upright column 13, first install the second fixing bar 18 on the upright column 13 through the reserved bolt holes , to ensure a firm connection between the two;

(5) In order to improve the simplicity of the device, all components are completed by bolt splicing. Therefore, in order to avoid too many bolt holes and it is difficult to precisely control the hole positions, some of the holes are processed in advance, and the other part of the bolt holes are installed and spliced according to the actual situation. The position needs to be processed again, so next, the spliced column 13 and the acceleration channel 19 should be assembled, the bolt hole position should be determined, and the two should be fixed firmly;

(6) Determine the installation position of the column 13, make a mark, then install the diagonal brace 14, and mark the bolt hole position of the fixed end of the diagonal brace 14, and then process the bolt hole position on site, and connect the vertical column 13 to the oblique brace. The support column 14 is fixed on the bottom plate 1, and the bolts are all screwed in place;

(7) Close the baffle, determine the position of the motor carrying device 20 according to the position of the baffle and the length of the motor screw 23, make a mark, and then place the motor carrying device 20 in the predetermined position, first bolt the bottom with the model The box 2 is firmly fixed, and the bolt holes of the second fixing strip 18 on the side of the installation are processed again. After the processing is completed, all the bolts are screwed in place to ensure the integrity of the device. So far, the acceleration device is assembled;

(8) Close the No. 1 shutter 11A, install the multi-function motor 21 at the predetermined position in the way of controlling the No. 1 shutter 11A, check the fit between the No. 1 shutter 11A and the motor screw 23, and confirm that there is no After the problem, sort out the wires, connect the wires to the transfer system that comes with the centrifuge, and transfer the motor control end to the centrifuge control room;

(9) Debug the operation of the acceleration device and make necessary improvements;

(10) Install the camera frame 8, the high-speed camera 10 and the light source 7, and repeat debugging until the optimal shooting angle and brightness are obtained;

(11) Open the feeding port 30 corresponding to the No. 1 baffle 11A, fill the soil sample prepared in advance into the acceleration channel 19 according to the falling sand method, and compact it in layers until the compactness of the experimental design is reached, and then close the feeding port 30;

(12) Check the test environment, after confirming that there is no safety problem, start the centrifuge to start the test. After the test is over, change the position of the multi-function motor 21, and control the baffle at the corresponding position according to the above steps, and then simulate the flow of different flow speeds. Large deformation soil flow geological disasters.

The device has the characteristics of multi-function, automatic and high safety. It can not only restore the high-speed characteristics of large-deformed soil flow geological disasters, but also have different acceleration levels, which is beneficial to study the impact of impact speed on the disaster-causing mechanism. The device does not use external loads for acceleration, and makes full use of the hypergravity centrifugal field created by the centrifuge, so it is economical and easy to operate.

Claims (10)

1. a tower type multifunctional automatic soil acceleration device for geotechnical centrifugal test, comprises the bottom plate that is arranged on the centrifuge basket, is characterized in that, also comprises: a model box, disposed on the base plate, for simulating fluid-structure interaction; The acceleration device includes an acceleration channel, a baffle, and a multi-function motor. The acceleration channel is vertically arranged and the lower end communicates with the top of the model box. The baffle is rotatably arranged in the acceleration channel for initially carrying soil. In the same way, the motor screw of the multi-function motor controls the opening and closing of the baffle; The image acquisition device includes a high-speed camera and a light source, and the high-speed camera is arranged on the base plate through a camera frame. 2. a kind of tower type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1, is characterized in that, described baffle plate is provided with multiple, and multiple baffle plates are in order up and down in acceleration channel Set a certain distance apart. 3. a kind of tower type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 2, is characterized in that, described multifunctional motor is fixed on one side of acceleration channel by motor carrying device, described The motor carrying device is provided with several carrying platforms with different heights. 4. a kind of tower type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1, is characterized in that, described acceleration channel is provided with electric multifunctional motor on the lower side of baffle position The opening through which the motor screw rod passes has a feeding port on the upper side of the baffle position. 5 . The tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1 , wherein the contact part between the motor screw and the baffle is a plane. 6 . 6. A tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1, wherein the high-speed camera is fixed on a camera frame by a camera fixing device, and the camera fixing device Includes a case that completely encloses the high-speed camera. 7 . The tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1 , wherein the camera frame comprises channel steel arranged in a vertical direction and a horizontal direction. 8 . 8 . The tower-type multifunctional automatic soil acceleration device for geotechnical centrifugation test according to claim 1 , wherein the light source is a spherical or planar light source. 9 . 9 . The tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1 , wherein the model box is provided with a transparent surface, and the model box is provided with a sliding surface. 10 . and engineering structures. 10. The tower-type multifunctional automatic soil acceleration device for geotechnical centrifugal test according to claim 1, characterized in that, the acceleration device is fixed on the bottom plate through a column, and the distance between the column and the bottom plate is There are diagonal struts in the room.

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