CN111337221A

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

Info

Publication number: CN111337221A
Application number: CN202010111268.8A
Authority: CN
Inventors: 黄雨; 张贝
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2020-06-26

Abstract

The invention relates to a tower type multifunctional automatic soil body accelerating device for a geotechnical centrifugal test, which comprises: a bottom plate arranged on the centrifuge basket; a mold box disposed on the base plate for simulating fluid-structure interaction; the accelerating device comprises an accelerating channel, a baffle plate and a multifunctional motor, wherein the accelerating channel is vertically arranged, the lower end of the accelerating channel is communicated with the top of the model box, the baffle plate is rotatably arranged in the accelerating channel and used for initially bearing a soil sample, and a motor screw rod of the multifunctional motor controls the opening and closing of the baffle plate; the image acquisition device comprises a high-speed camera and a light source, wherein the high-speed camera is arranged on the bottom plate through a camera frame. Compared with the prior art, the invention not only can restore the high-speed characteristic of the flowing geological disaster of the large deformation soil body, but also has different acceleration levels, is beneficial to researching the influence of the impact speed on a disaster-causing mechanism, can accelerate without the help of external load, and fully utilizes the supergravity centrifugal field built by the centrifugal machine, thereby having good economy and simple and convenient operation.

Description

Tower type multifunctional automatic soil body accelerating 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 body accelerating device for a geotechnical centrifugal test.

Background

In recent years, geological disasters such as debris flow, debris flow and high-speed remote landslide frequently occur, and serious casualties and economic losses are caused. A remarkable characteristic of the large deformation soil mass flowing type disaster lies in the ultra-high movement speed, for example, the maximum speed of the major landslide in the Shenzhen Guangming new region in 2015 exceeds 20 m/s; the average movement speed of the high-speed remote landslide of the estuary of the Qingchuan east exceeds 25 m/s. The ultra-high movement speed carries huge impact energy, so that the destructive power is extremely large, and a large amount of engineering structures on the movement path are destroyed by washing. The prevention theory and the prevention technology are always a big problem all over the world. Conventional gravity-based physical model testing is currently the main means for studying such geological disasters, but has two problems: firstly, a reduced scale model under the condition of 1g gravity is difficult to reproduce the high-speed characteristic of the flowing of a large-deformation soil body or is difficult to realize; secondly, the deformation characteristics of the rock-soil material related to stress are difficult to effectively reflect by the conventional gravity model test. The centrifugal model test can not only restore the space dimensionality of the prototype through the virtual high-power gravity field, but also provide a stress field similar to the prototype, thereby effectively solving the two problems. But centrifugal testing is not currently being used effectively in this regard, one important reason being the lack of soil acceleration devices to restore the high speed characteristics of large deformation soil flow geological hazards.

The difficulties with such devices are:

(1) at present, most of model boxes which can be carried by centrifuges in service in the world are small, and in a narrow space, the acceleration stroke of soil is very limited, so that the difficulty in obtaining the movement speeds of the soil at different levels is high, namely the functionality is poor;

(2) when the centrifugal machine operates, the soil body is subjected to huge centrifugal force, and when the soil body is accelerated, the additional load must meet several conditions: firstly, the loading speed is high enough and needs to be automatically controlled, and the load is applied instantly when the baffle is opened; secondly, after acceleration is finished, the additional load can be timely relieved; thirdly, the magnitude of the additional load is at least at a level with the centrifugal force. The loading modes meeting the requirements of the three conditions are large in implementation cost, namely, the economy is insufficient;

(3) under the high gravity environment, the requirement on the safety of an additional device on a basket of the centrifuge is greatly increased, so that the fixation of the additional device is crucial, namely, how to meet the safety requirement;

(4) under the environment of supergravity, the pressure of the soil body to the baffle in the initial state is increased by dozens of times compared with the pressure of the soil body under the gravity of 1g, under the huge pressure, how to fix the baffle and keep the baffle in a locking state is a great technical problem, and how to quickly open the baffle and prevent the baffle from being opened too slowly to influence the movement of the soil body is another great technical problem;

(5) under the totally-enclosed test environment, how to realize remote automatic operation in the soil acceleration process is also a technical problem.

Disclosure of Invention

The invention aims to overcome the defect that the high-speed characteristic of the flowing geological disaster of the large-deformation soil body is difficult to restore in the prior art, and provides a tower type multifunctional automatic soil body accelerating device for a geotechnical centrifugal test.

The purpose of the invention can be realized by the following technical scheme:

the utility model provides a multi-functional automatic soil body accelerating device of tower for geotechnological centrifugal test, includes the bottom plate of setting on the centrifuge basket, still includes:

a mold box disposed on the base plate for simulating fluid-structure interactions;

the accelerating device comprises an accelerating channel, a baffle plate and a multifunctional motor, wherein the accelerating channel is vertically arranged, the lower end of the accelerating channel is communicated with the top of the model box, the baffle plate is rotatably arranged in the accelerating channel and used for initially bearing a soil sample, and a motor screw rod of the multifunctional motor controls the opening and closing of the baffle plate;

the image acquisition device comprises a high-speed camera and a light source, wherein the high-speed camera is arranged on the bottom plate through a camera frame.

Preferably, the baffle is provided with a plurality of, and a plurality of baffles are arranged at certain intervals in the accelerating channel from top to bottom in sequence.

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

Preferably, the accelerating channel is provided with an opening for passing a motor screw rod of the electric multifunctional motor at the lower side of the position of the baffle, and a feeding port is arranged at the upper side of the position of the baffle.

Preferably, the contact part of the motor screw rod and the baffle is a plane.

Preferably, the high-speed camera is fixed on the camera stand by a camera fixing device including a housing that completely encloses the high-speed camera.

Preferably, the camera frame includes channel steel disposed 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 a sliding surface and an engineering structure are arranged in the model box.

Preferably, the accelerating device is fixed on the bottom plate through an upright post, and an inclined strut is arranged between the upright post and the bottom plate.

Compared with the prior art, the method can be used for obtaining the soil bodies with different flowing speeds, is used for simulating the impact disaster-causing process of the large-deformation soil body under the high-speed flowing, provides a theoretical basis for researching and developing the disaster prevention technology of the geological disasters, and has the following advantages:

1. the economic efficiency is as follows: the invention fully utilizes the super-gravity field created by the centrifuge, achieves the acceleration effect by changing the acceleration stroke of the soil body, avoids using additional load and effectively controls the cost of the device;

2. simplicity: the device is assembled by sub-components, so that the device is convenient to disassemble and transport;

3. and (4) multiple functions: the multifunctional motor and the motor bearing device are independently designed, and baffles at different heights are controlled in different combination modes to obtain different soil body acceleration effects;

4. full-automatic: according to the invention, the state of the baffle is controlled through the motor lead screw, the motor can be controlled remotely, the baffle can be opened for feeding by one key, and then acceleration is completed, so that the high-speed characteristic of the large-deformation soil body flowing disaster is restored;

5. the door opening speed is high: the baffle plate of the invention completely depends on centrifugal force when being opened, and does not need any auxiliary measures, because under the environment of supergravity, the baffle plate is subjected to huge gravitation, the baffle plate can be quickly turned over at the moment of opening, and the opening speed can reach dozens of times under the gravity of 1 g.

Drawings

FIG. 1 is a schematic view of the left side of the overall structure of the apparatus of the present invention;

FIG. 2 is a right side schematic view of the overall structure of the apparatus of the present invention;

FIG. 3 is a schematic view of a multifunctional motor according to the present invention;

FIG. 4 is a schematic view of a motor carrying device according to the present invention;

FIG. 5 is a schematic front view of an acceleration channel according to the present invention;

FIG. 6 is a schematic rear view of an acceleration channel according to the present invention;

FIG. 7 is a schematic view of the damper control of the present invention;

FIG. 8 is a schematic view of the multifunctional motor and the motor carrying device in cooperation, wherein (a) to (d) are respectively combined for controlling No. 1 to No. 4 baffles;

fig. 9 is an exploded view of the feed opening of the present invention.

The figures are labeled as follows:

1. a base plate; 2. a model box; 3. a sliding surface; 4. an engineering structure; 5. a transparent surface; 6. a light source fixing device; 7. a light source; 8. a camera frame; 9. a camera fixture; 10. a high-speed camera; 11A, No. 1 baffle; no. 11B and No. 2 baffles; baffle No. 11C, 3; baffle No. 11D and No. 4; 12. an opening; 13. a column; 14. a diagonal bracing column; 15. a column fixing device; 16. a diagonal bracing column fixing device; 17. a first fixing strip; 18. a second fixing strip; 19. an acceleration channel; 20. a motor carrying device; 21. a multifunctional motor; 22. a motor host; 23. a motor lead screw; 24. a distal connection plate; 25. a proximal end connection plate; 26. a rotating shaft; 27. a first load-bearing platform; 28. a second load-bearing platform; 29. a third load-bearing platform; 30. a feeding port.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1 and 2, the present application provides a tower type multifunctional automated soil acceleration device for geotechnical centrifuge test, which comprises a bottom plate 1 arranged on a basket of a centrifuge, for fixing an upper acceleration device on one hand, and for enlarging the size of the basket of the centrifuge on the other hand; the model box 2 is arranged on the bottom plate 1, comprises a transparent surface 5 made of organic glass and is used for observing the flowing state of a large-deformation soil body, and a main bearing sliding surface 3 and an engineering structure 4 are arranged in the model box 2 and are used for simulating fluid-structure interaction; the accelerating device comprises an accelerating channel 19, baffle plates (11A-11D) and a multifunctional motor 21, wherein the accelerating channel 19 is vertically arranged, the lower end of the accelerating channel extends into the model box 2 for a certain distance to restrain a soil sample and install the baffle plates, the baffle plates are rotatably arranged in the accelerating channel 19 and are used for initially bearing the soil sample, a plurality of baffle plates are arranged in the accelerating channel 19 at certain intervals in sequence from top to bottom, and a motor screw 23 of the multifunctional motor 21 controls the opening and closing states of the baffle plates; the image acquisition device comprises a high-speed camera 10 and a light source 7, wherein the high-speed camera 10 is used for capturing the flowing impact disaster-causing process of the large-deformation soil body in the model box 2, the high-speed camera 10 is arranged on the bottom plate 1 through the camera frame 8, and the light source 7 is used for supplementing light for the high-speed camera 10.

The bottom plate 1 can be made of high-strength aluminum plates, so that the weight of the bottom plate can be reduced, and the difficulty in mounting the device due to too large weight can be avoided. The bottom plate 1 is mainly used for fixing the upper accelerating device, the upper accelerating device is anchored on an aluminum plate by adopting a high-strength bolt in a fixing mode, the flexibility of the device is guaranteed by the mode, and the device can be conveniently disassembled and assembled. The size of the bottom plate 1 can be selected according to the size of a centrifuge hanging basket used in practice, if the size of the hanging basket is not enough, the size of the bottom plate 1 can be increased, the size of the centrifuge hanging basket is enlarged, the object distance of a camera is increased, the requirement on a camera lens is reduced, the phenomenon that the focal length is small due to improper lens selection can be avoided, and the result analysis is influenced if the image captured by the fisheye lens is distorted.

The model box 2 is selected to have a larger length as much as possible, so that the soil body has enough movement space, and some dynamic characteristics such as particle sorting and the like can be fully expressed; the width is selected based on the fact that the flow state of the large-deformation soil body is not influenced, and the width is generally not too large. One side of the model box 2 adopts a transparent surface 5 made of transparent organic glass, so that the flowing state of the large-deformation soil body can be conveniently observed. A sliding surface 3 and an engineering structure 4 are arranged in the model box 2, 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 particle concrete and is used for researching a damage mechanism of the structure under the action of flow impact of a large deformation soil body.

As shown in fig. 3, the multifunctional motor 21 includes a motor main body 22, a motor lead screw 23 and a plurality of connecting wires. The upper side and the lower side of the motor host 22 are respectively provided with a motor connecting plate, the part far away from the motor host 22 is a far-end connecting plate 24, and the part near the motor host 22 is a near-end connecting plate 25. The contact part of the head of the cylindrical motor screw rod 23 and the baffle is properly flattened into a plane, so that the contact part can be tightly attached to the baffle. The motor main unit 22 can be connected with a switching system of the centrifuge through a lead, and then the operation of the motor can be controlled in a control room. In order to ensure economy and simplicity, the motor is convenient to disassemble, so that the motor bearing device 20 is adopted to assist in fixing the motor, and baffles at different positions can be controlled by the same motor.

A multifunctional motor 21 is fixed to one side of the acceleration channel 19 by a motor carrier 20. As shown in fig. 4, the motor carrier 20 is made of steel to ensure sufficient strength. The motor bearing device 20 is provided with a plurality of bearing platforms with different heights for fixing the multifunctional motor 21. The lowest part of the motor bearing device 20 is a first bearing platform 27 which is arranged at the top of the model box 2; two second bearing platforms 28 are arranged on the first bearing platform 27 at a certain distance, two third bearing platforms 29 are arranged between the two second bearing platforms 28, and a gap through which the motor main unit 22 can pass is arranged in the middle of the third bearing platforms 29. The bearing platform and the motor connecting plate are combined to control the baffles at different height positions.

As shown in fig. 5 and 6, the accelerating device takes safety, economy, multifunction and full automation as design targets, and fully utilizes the hypergravity centrifugal field built by the centrifugal machine as an accelerating load to change the movement stroke of the soil body in the centrifugal field, so that the soil body obtains different speeds. The movement path of the soil body is controlled through the acceleration channel 19, so that the movement path is always consistent with the direction of the maximum centrifugal force to obtain the optimal acceleration effect. The baffle is connected with the side surface of the accelerating channel 19 through a rotating shaft 26, and the baffle can freely rotate around the rotating shaft 26. The front surface of the accelerating channel 19 is provided with an opening 12 with proper size at the lower side of the baffle position, so that the motor screw rod 23 can freely go in and out, thereby controlling the baffle state. The back of the accelerating channel 19 is provided with a feeding port 30 at the upper side of the baffle position, so that the filling is convenient. The height of the accelerating channel 19 can be determined according to the configuration of the practically-adopted centrifugal machine, and the installation position of the baffle can be selected automatically according to the requirements of experimental design.

As shown in figure 7, in the initial state of the baffle, the baffle is closed through the feeding port 30, then the motor screw 23 is extended, the motor screw 23 passes through the opening 12, so that the baffle is just pressed at the head of the motor screw 23, and the overlapping amount is more than 10 mm. The remote control motor host 22 works to contract the motor lead screw 23, thereby controlling the opening of the baffle. The baffle plate is matched with the multifunctional motor 21 for use, is arranged at different heights, and can obtain different speeds after the soil sample is released.

As shown in fig. 8, (a) the middle distal connecting plate 24 and the first bearing platform 27 are fixed by high strength bolts, which is a first configuration for controlling the No. 1 baffle 11A; (b) the middle turning multifunctional motor 21 fixes the near-end connecting plate 25 on the first bearing platform 27 to control the No. 2 baffle 11B; (c) the multifunctional motor 21 is detached, the far-end connecting plate 24 is fixed on the third bearing platform 29 at a higher position, the near-end connecting plate 25 is fixed on the second bearing platform 28 at a lower position, and the No. 3 baffle 11C can be controlled; (d) the near-end connecting plate 25 is connected with a second bearing platform 28 which is higher, and the far-end connecting plate 24 is connected with a third bearing platform 29 which is lower, so that the No. 4 baffle 11D can be controlled.

The image acquisition device mainly depends on the high-speed camera 10 to capture the evolution process of the flowing state of the large-deformation soil body. In order to prevent the body and the lens interface of the high-speed camera 10 from falling off in a high-gravity environment, the camera fixing device 9 is specially made, a shell is processed by adopting a high-strength high polymer material according to the shape of the high-speed camera 10 to completely wrap the high-speed camera 10, so that the integrity of the camera is enhanced, all parts are tightly attached to the camera fixing device 9, and all parts of the high-speed camera 10 are ensured to be uniformly 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 through high-strength bolts, so that the camera can be freely adjusted, and the height position of the camera is ensured to be appropriate. The fixing device 9 of the high-speed camera 10 is fixed on the horizontal channel steel through bolts, the position can be adjusted horizontally, and the camera is guaranteed to be suitable in horizontal position. An optimum shooting angle can be obtained by adjusting the camera frame 8.

The light source 7 is preferably a spherical or planar light source 7, so that the light source 7 is ensured to have good scattering property, and the phenomenon that the image quality is influenced by over-concentration of light rays is avoided. The light source 7 is anchored to the base plate 1 by means of a light source fixture 6.

The accelerating device is fixed on the bottom plate 1 through the upright column 13, and the inclined supporting column 14 is arranged between the upright column 13 and the bottom plate 1, so that the integrity of the device is improved, and the safety of the test process is ensured. The acceleration channel 19 is connected to the upright 13 by means of a first fixing strip 17. The bottom of the motor bearing device 20 is fixed on the top of the model box 2, the side is fixed on the upright post 13 through the second fixing strip 18, and all the parts are connected through high-strength bolts. The bottoms of the upright column 13 and the diagonal brace 14 are respectively connected with the bottom plate 1 through an upright column fixing device 15 and a diagonal brace fixing device 16, and the connecting parts adopt high-strength bolts.

As shown in fig. 9, the filling opening includes a groove and a cover plate opened on the surface of the acceleration channel 19. The size of the groove is based on convenient filling. The size of the cover sealing sheet is matched with that of the groove, so that the flatness of the inner wall and the outer wall of the accelerating channel 19 is ensured.

The device of the invention has the following use flow:

(1) placing the bottom plate 1 on a centrifuge basket at a proper position for fixing firmly, then fixing the model box 2 on the bottom plate 1, paying attention to the fact that the placing position of the model box 2 is marked in advance, and avoiding the problem that the upper structure is difficult to assemble due to the dislocation of the model box 2;

(2) the angle of the sliding surface 3 is determined and fixed, so that the side surface of the sliding surface 3 is tightly attached to the inner wall of the model box 2, and the soil sample is prevented from leaking in the sliding process, so that the real speed information of the soil motion is difficult to obtain in the later image processing process; determining the type, size, placement position and the like of the engineering structure 4, and then fixing firmly;

(3) the baffle plate is firmly fixed with the accelerating channel 19, then a first fixing strip 17 for fixing the accelerating channel 19 is fixed on the accelerating channel 19 according to a reserved bolt hole, and the bolts are all screwed in place to ensure the firm connection between the baffle plate and the accelerating channel 19;

(4) in order to avoid the difficulty in mounting the second fixing strip 18 for fixing the motor bearing device 20 after the acceleration channel 19 is mounted, before the upright column 13 is mounted, the second fixing strip 18 is mounted on the upright column 13 through a reserved bolt hole, so that the second fixing strip and the upright column are firmly connected;

(5) in order to improve the simplicity of the device, all the components are spliced through bolts, so that in order to avoid the problem that the hole positions are difficult to control accurately due to too many bolt holes, one part of the hole positions are processed in advance, and the other part of the bolt holes are processed according to the requirements of actual positions during installation and splicing, so that next, the spliced upright post 13 and the acceleration channel 19 are assembled, the bolt hole positions are determined, and the bolt hole positions and the acceleration channel are fixed firmly during site construction;

(6) determining the installation position of the upright column 13, marking, installing the diagonal bracing column 14, marking the hole position of a bolt at the fixed end of the diagonal bracing column 14, then processing the hole position of the bolt in site construction, fixing the upright column 13 and the diagonal bracing column 14 on the bottom plate 1, and screwing the bolts in place;

(7) closing the baffle plate, determining the position of the motor bearing device 20 according to the position of the baffle plate and the length of the motor screw 23, marking, then placing the motor bearing device 20 at a preset position, firstly firmly fixing the bottom of the motor bearing device with the model box 2 by using bolts, then processing bolt hole positions of the second fixing strips 18 on the installation side surface, screwing all the bolts in place after processing is completed, ensuring the integrity of the device, and thus finishing the assembly of the accelerating device;

(8) closing the No. 1 baffle 11A, finishing the installation of the multifunctional motor 21 at a preset position according to a mode of controlling the No. 1 baffle 11A, checking the bonding condition between the No. 1 baffle 11A and the motor screw rod 23, combing a wire after confirming that no problem exists, connecting the wire into a switching system of the centrifuge, and transferring a motor control end into a centrifuge control chamber;

(9) debugging the running condition of the accelerating device and making necessary improvement;

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

(11) opening a feeding port 30 corresponding to the No. 1 baffle 11A, filling a soil sample prepared in advance into the accelerating channel 19 according to a shakeout method, compacting in layers until the compactness of the experimental design is reached, and then closing the feeding port 30;

(12) checking the test environment, starting the centrifugal machine to start the test after confirming that no safety problem exists, changing the position of the multifunctional motor 21 after the test is finished, controlling the baffle at the corresponding position according to the steps, and then simulating the large deformation soil body flowing geological disasters with different flowing speeds.

The device has the characteristics of multifunction and full automation, has higher safety, can restore the high-speed characteristic of the flowing geological disaster of the large-deformation soil body, also has different acceleration levels, is favorable for researching the influence of the impact speed on a disaster-causing mechanism, does not accelerate by means of external load, and fully utilizes the supergravity centrifugal field built by the centrifugal machine, thereby having the characteristics of good economy and simple and convenient operation.

Claims

1. The utility model provides a multi-functional automatic soil body accelerating device of tower for geotechnological centrifugal test, is including setting up the bottom plate on the centrifuge basket, its characterized in that still includes:

2. The tower type multifunctional automatic soil mass accelerating device for the geotechnical centrifugal test according to claim 1, wherein a plurality of baffles are arranged in the accelerating channel at certain intervals in sequence from top to bottom.

3. The tower type multifunctional automated soil mass accelerating device for geotechnical centrifugal test according to claim 2, wherein the multifunctional motor is fixed at one side of the accelerating channel through a motor bearing device, and a plurality of bearing platforms with different heights are arranged on the motor bearing device.

4. The tower type multifunctional automated soil mass accelerating device for geotechnical centrifugal test according to claim 1, wherein the accelerating channel is provided with an opening for passing a motor screw rod of the electric multifunctional motor at the lower side of the position of the baffle, and a feeding port at the upper side of the position of the baffle.

5. The tower type multifunctional automated soil mass accelerating device for geotechnical centrifugal test according to claim 1, wherein the contact part of the motor screw rod and the baffle is a plane.

6. The tower-type multifunctional automated soil mass accelerating device for geotechnical centrifuge test according to claim 1, wherein the high-speed camera is fixed on the camera frame through a camera fixing device, and the camera fixing device comprises a shell which completely wraps the high-speed camera.

7. The tower type multifunctional automated soil mass accelerating device for geotechnical centrifugal test according to claim 1, wherein the camera frame comprises channel steel which is arranged in vertical direction and horizontal direction.

8. The tower type multifunctional automated soil mass accelerating device for geotechnical centrifugal test according to claim 1, wherein the light source is spherical or planar.

9. The tower type multifunctional automatic soil mass accelerating device for the geotechnical centrifugal test according to claim 1, wherein a transparent surface is arranged on the model box, and a sliding surface and an engineering structure are arranged in the model box.

10. The tower type multifunctional automatic soil mass accelerating device for the geotechnical centrifugal test according to claim 1, wherein the accelerating device is fixed on the bottom plate through a stand column, and a diagonal bracing column is arranged between the stand column and the bottom plate.