Saturated sand sample preparation and pore seepage observation device and use method thereof

Abstract

The invention provides a saturated sand sample preparation device for seepage observation and a use method thereof.The saturated sand sample preparation device comprises a support, the support is connected with a support mechanism in a lifting mode through a lifting driving mechanism, a sand storage device is placed on the support mechanism, and a sand dispersing mechanism with the constant falling distance is connected to the lower portion of the support mechanism; the sand dispersing mechanism comprises a screen and a laser range finder used for measuring sand, the support mechanism further comprises a support controller used for controlling the lifting driving mechanism to ascend and descend, the laser range finder is in electric signal connection with the support controller, and a model box is placed below the sand storage device. The laser range finder and the support controller used for controlling the support mechanism to ascend and descend form a feedback adjusting mechanism, in the sand scattering process, the distance between the bottom of a screen of the sand scattering mechanism and the sand accumulation surface in the model box can be automatically adjusted, and therefore precise and automatic constant control over the sand compactness is achieved.

Description

Technical Field

[0001] This invention relates to the field of geotechnical model experiment technology, and in particular to a saturated sand sample preparation device and its usage method that can be used for seepage observation. Background Technology

[0002] Under the influence of seepage, sandy soil foundations often exhibit seepage deformation. This deformation typically occurs when the seepage direction is not aligned with the direction of the soil's own weight. Once the seepage reaches the critical hydraulic gradient, soil particles lose effective stress due to the seepage force. Under seepage, this can lead to soil erosion, where particles are suspended and carried away by the water flow, or piping, where fine particles flow out of the soil's pores. Currently, conventional permeameters are relatively small, making it difficult to conduct model tests on the permeability of coarse-grained soils. Furthermore, conventional permeameters can only measure the soil's permeability coefficient and cannot effectively simulate soil seepage failure or observe the entire process from seepage development to failure.

[0003] Currently, seepage observation is commonly conducted using model boxes containing saturated sand. In geotechnical model tests, the sand rain method is a frequently used foundation preparation method for saturated sand foundations. Sand stored in a sand reservoir is dispersed into the model box via multiple layers of dispersers with different pore sizes. During this process, the density of the prepared sand sample can be adjusted by changing the pore size of the dispersers and the drop height of the sand. Then, fluid is slowly injected from the bottom of the model box until the fluid level exceeds the sand surface, thus obtaining a saturated sand sample. However, during the sand spreading process, as the sand accumulates and rises within the model box, the actual drop height of the sand decreases, leading to density differences in the sample along its height, interfering with the uniformity of seepage. Furthermore, traditional model boxes rely on sensors to obtain data, lacking intuitive and effective means of visually observing the seepage path. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device for preparing saturated sand samples and observing pore seepage, which can solve the problem of uneven sample density caused by changes in drop height and the problem of traditional model boxes lacking means to visualize seepage paths.

[0005] Therefore, the present invention adopts the following technical solution: A device for preparing saturated sand samples and observing pore seepage includes a support frame. A support mechanism is vertically connected to the support frame via a lifting drive mechanism. A sand storage container is placed on the support mechanism. A sand dispersion mechanism with a constant drop distance is connected below the support mechanism. The sand dispersion mechanism includes a sieve and a laser rangefinder for measuring the sand. The support mechanism also includes a support controller for controlling the lifting drive mechanism. The laser rangefinder and the support controller are electrically connected. A model box is placed below the sand storage container. The model box has at least one transparent side panel for observation. A grid dot matrix is ​​drawn on the transparent side panel. A seepage and observation mechanism is arranged on one side of the model box. The seepage and observation mechanism includes a liquid seepage unit and an image acquisition and analysis unit. The liquid seepage unit injects a colorless fluid to saturate the sand sample and a dyeing fluid for observing the seepage path into the model box. The image acquisition and analysis unit photographs the transparent side panel and analyzes the seepage path of the dyeing fluid in the pores of the saturated sand in conjunction with the grid dot matrix.

[0006] Based on the above technical solutions, the present invention may also employ the following further technical solutions, or combine these further technical solutions: The support structure consists of four columns and cross support rods for reinforcing adjacent columns.

[0007] The sand storage device includes four side plates, a bottom plate, and a misaligned plate. The bottom of two opposite side plates is provided with a first groove and a second groove, respectively. The bottom plate is inserted into the first groove and can slide within the first groove. The misaligned plate is inserted into the second groove and can slide within the second groove. The bottom plate and the misaligned plate are provided with a plurality of holes.

[0008] A first scale is provided on one of the side plates of the sand reservoir.

[0009] The bracket includes four columns, and the support mechanism includes two first supports and two second supports. The first supports and the second supports are respectively sleeved and connected to one of the columns. The lifting drive mechanism includes a rack, a gear, and a support motor. Each column is equipped with a rack. A gear is rotatably connected in each of the first and second supports. The gear meshes with the rack. A support drive shaft is connected between the first and second supports. The support drive shaft is connected to the gear axle through a coupling. The support motor is fixed to one side of the first support. The motor shaft of the support motor is poweredly connected to the gear axle in the first support. The support motor is electrically connected to the support controller.

[0010] The first support and the second support are respectively provided with support beams for placing the sand storage device on opposite sides. The end of the support beam is provided with a placement groove for connecting the elastic support leg. The upper end of the elastic support leg is rotatably connected to a roller. The roller abuts against the misalignment plate. The roller can press the elastic support leg downward under the gravity of the sand storage device and partially place it into the placement groove.

[0011] The sand dispersion mechanism also includes a support frame and a shielding curtain. The screen is connected to the lower part of the support mechanism through the support frame. The laser rangefinder is connected to the lower surface of the lowest screen. The shielding curtain is connected to the four sides of the screen and the model box through hooks. An elastic rope is also connected between the screen and the model box through the hooks. The elastic rope is used to support the shielding curtain.

[0012] A second scale is provided on one side of the model box wall, a pore water pressure gauge is provided on the inner surface of the side wall of the model box, and several distributed earth pressure cells are provided on the bottom surface of the model box.

[0013] The side wall of the model box is provided with several injection / drainage holes. The liquid seepage unit of the seepage and observation mechanism includes a storage tank, a main water pipe, and several branch water pipes. The main water pipe is connected to the storage tank, and the branch water pipes are connected to the main water pipe through a liquid pump. The branch water pipes are connected to the injection / drainage holes. Each branch water pipe is connected to two valves. Each branch water pipe is also connected to a dye pool structure and a hydraulic gauge. The dye pool structure and the hydraulic gauge are located between the two valves. The image acquisition and analysis unit of the seepage and observation mechanism includes a data acquisition and processing center and a camera.

[0014] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing saturated sand samples and using a pore seepage observation device, which can solve the problem of uneven sample density caused by changes in drop height and the problem of traditional model boxes lacking means to visualize seepage paths.

[0015] Therefore, the present invention adopts the following technical solution: A method for preparing saturated sand samples and using a pore seepage observation device includes the following steps: Step 1: Install the base plate and the misalignment plate into the first and second grooves at the bottom of the sand storage container, respectively, and adjust the misalignment plate so that the holes on it are completely misaligned with the holes on the base plate. Fill the sand storage container with sand, and lift the sand storage container filled with sand using a crane and place it on the support mechanism. Step 2: Before starting the sand spreading, set and determine the initial distance between the screen and the sand storage container and the model box, adjust the direction of the laser rangefinder to align it with the model box, and install a shielding curtain between the screen and the model box. Step 3: Use rollers to push the misalignment plate to slide, so that the holes on the misalignment plate are aligned with the holes on the bottom plate. The sand flowing out of the sand storage container is dispersed by the screen and scattered into the model box. Step 4: During the sand spreading process, the laser rangefinder measures the distance from the bottom of the screen to the surface of the sand accumulation inside the model box in real time and transmits the distance signal to the support controller. The support controller controls the support motor according to the distance signal to drive the support mechanism to move along the column, thereby automatically adjusting the height of the screen so that the distance from the bottom of the screen to the surface of the sand accumulation inside the model box remains constant. Step 5: Observe the second scale. When the sand accumulation surface in the model box reaches the preset height, use the roller to push the misalignment plate back to its original position, so that the holes on the misalignment plate are completely misaligned with the holes on the bottom plate again, and the sand no longer flows out of the sand storage container. The sand spreading is over. Step 6: Open the valve and start the liquid pump to inject the colorless fluid in the storage tank into the sand sample in the model box through the main water pipe and branch water pipe in sequence until the sample is completely saturated. Step 7: Add dye to the dye pool structure, restart the liquid pump, and inject the dyeing fluid mixed with dye into the saturated sand sample. At the same time, turn on the camera and the data acquisition and processing center. The data acquisition and processing center receives and processes the images continuously captured by the camera on the transparent side plate, and analyzes the seepage path of the dyeing fluid in the pores of the saturated sand sample by combining the grid dot matrix.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: The laser rangefinder provided by the present invention forms a feedback adjustment mechanism with the support controller used to control the lifting and lowering of the support mechanism. During the sand scattering process, the distance between the bottom of the screen of the sand dispersion mechanism and the sand accumulation surface in the model box can be automatically adjusted, thereby realizing precise and automatic constant control of the sand density; The present invention, by setting up a seepage and observation mechanism including a liquid seepage unit and an image acquisition and analysis unit, combined with the transparent side plate and the grid dot matrix on its surface, realizes the visualization observation of the fluid seepage path in the pores of saturated sand as well as image capture and analysis. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Figure 2 This is a front view of the connection structure of the bracket, support mechanism and lifting drive mechanism of the present invention.

[0019] Figure 3 This is a side view of the connection structure of the bracket, sand reservoir, support mechanism and lifting drive mechanism of the present invention.

[0020] Figure 4This is a cross-sectional structural diagram of the sand storage device of the present invention.

[0021] Figure 5 This is a schematic diagram showing the connection between the model box and the liquid seepage unit of the present invention.

[0022] Figure 6 This is a schematic diagram of the base plate and its holes of the present invention.

[0023] Figure 7 This is a schematic diagram of the misalignment plate and its holes according to the present invention.

[0024] Figure 8 This is a schematic diagram of the interlaced holes in the base plate and the misaligned plate of the present invention.

[0025] Figure 9 This is a schematic diagram showing the alignment of the holes in the base plate and the misalignment plate of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote elements with the same or similar functions throughout. However, it should be understood that the drawings are for illustrative purposes only and should not be construed as limiting the present invention. To better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size. It is understandable for those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present invention.

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0028] This invention provides a device for preparing saturated sand samples and observing pore flow, comprising a support 1, a support mechanism 3 connected to the support 1 via a lifting drive mechanism 7, a sand storage container 2 placed on the support mechanism 3, and a sand dispersion mechanism 4 with a constant drop distance connected below the support mechanism 3. The sand dispersion mechanism 4 includes a sieve 42 and a laser rangefinder 43 for measuring sand. The support mechanism 3 also includes a support controller 36 for controlling the lifting of the lifting drive mechanism 7. The laser rangefinder 43 and the support controller 36 are electrically connected. Below the sand storage container 2... A model box 5 is placed therein. The model box 5 has at least one transparent side plate 51 for observation. A grid dot matrix 57 is drawn on the transparent side plate 51. A seepage and observation mechanism 6 is arranged on one side of the model box 5. The seepage and observation mechanism 6 includes a liquid seepage unit and an image acquisition and analysis unit. The liquid seepage unit is used to inject colorless fluid to saturate the sand sample and dyeing fluid for observing the seepage path into the model box 5. The image acquisition and analysis unit is used to photograph the transparent side plate 51 and analyze the seepage path of the dyeing fluid in the pores of the saturated sand in combination with the grid dot matrix 57.

[0029] The laser rangefinder 43 is used to measure the distance from the bottom of the screen 42 to the surface of the sand accumulation inside the model box 5 (i.e., the sand drop distance).

[0030] The support controller 36 receives the distance signal from the laser rangefinder 43 and sends a command to the lifting drive mechanism 7 to drive the support mechanism 3 to move up and down along the support 1 to ensure that the sand drop distance is constant.

[0031] The grid 57 is a grid drawn on the side plate of the model box 5. Combined with the dyed fluid marked with color, it is used to locate the seepage path of the dyed fluid in the sand pores inside the model box 5.

[0032] The support frame 1 consists of four columns 10 and cross support rods 11 for reinforcing two adjacent columns 10.

[0033] The sand storage device 2 includes four side plates 21, a bottom plate 22, and a misaligned plate 23. The bottom of the two opposite side plates 21 is respectively provided with a first groove 25 and a second groove 26. The bottom plate 22 is inserted into the first groove 25 and can slide within the first groove 25. The misaligned plate 23 is inserted into the second groove 26 and can slide within the second groove 26. The bottom plate 22 and the misaligned plate 23 are respectively provided with a number of holes 27.

[0034] In this embodiment, the side plate of the sand storage device 2 can be made of transparent materials such as fiberglass or plastic. One of the side plates 21 of the sand storage device 2 is equipped with a first scale 24, which can be used to observe the remaining height of sand in the sand storage device 2 in real time.

[0035] The support frame 1 includes four columns 10. The support mechanism 3 includes two first supports 31 and two second supports 32. The first supports 31 and the second supports 32 are respectively connected to one of the columns 10. The lifting drive mechanism 7 includes a rack 71, a gear 72, and a support motor 73. Each column 10 is equipped with a rack 71. A gear 72 is rotatably connected in the first support 31 and the second support 32. The gear 72 meshes with the rack 71. A support drive shaft 38 is connected between the first support 31 and the second support 32. The support drive shaft 38 is connected to the axle of the gear 72 through a coupling. The support motor 73 is fixed to one side of the first support 31. The motor shaft of the support motor 73 is poweredly connected to the axle of the gear 72 in the first support 31. The support motor 73 is electrically connected to the support controller 36.

[0036] The first support 31 and the second support 32 are respectively provided with support beams 37 for placing sand storage 2 on opposite sides. The end of the support beam 37 is provided with a placement groove for connecting the elastic support leg 34. The upper end of the elastic support leg 34 is rotatably connected with a roller 35. The roller 35 abuts against the misalignment plate 23. The roller 35 can press the elastic support leg 34 downward under the gravity of the sand storage 2 and partially place it into the placement groove.

[0037] In this embodiment, the roller 35 can be driven by a motor, which is more precise than manual adjustment. The outer layer of the roller 35 is covered with a rubber tire to increase the friction between it and the misaligned plate 23 in contact with it. The misaligned plate 23 can be pushed out or pulled into the second groove 26 by relying on the friction force.

[0038] The holes in the base plate 22 and the misalignment plate 23 can be fully aligned or partially misaligned in order to control the outflow rate of sand in the sand reservoir 2.

[0039] The sand dispersion mechanism 4 also includes a support 41 and a shielding curtain 44. The screen 42 is connected to the bottom of the support mechanism 3 through the support 41. The laser rangefinder 43 is connected to the lower surface of the bottom screen 42. The shielding curtain 44 is connected to the four sides of the screen 42 and the model box 5 through hooks 46. The screen 42 and the model box 5 are also connected by an elastic rope 45 through the hooks 46. The elastic rope 45 is used to support the shielding curtain 44.

[0040] like Figure 1 As shown, two layers of screens 42 are connected to the support 41.

[0041] In this embodiment, the support 41 can be a telescopic support, which makes it easy to adjust its length so that two layers of screens 42 can be installed according to the design height.

[0042] The sieve 42 has circular or square holes of a certain diameter, which disperse the sand flowing out from the bottom of the sand storage container 2, thereby improving the uniformity and compactness of the sand sample prepared in the model box 5 placed below.

[0043] The shielding curtain 44 is made of a transparent film. The shielding curtain 44 is used to form a relatively closed space between the screen 42 and the model box 5 to prevent the fine sand sprinkled from the screen 42 from drifting outward. At the same time, the operator can observe the entire sand-sprinkling process in real time through the shielding curtain 44.

[0044] The side panels and bottom plate of the model box can be made of transparent or opaque materials such as plexiglass, stainless steel, aluminum alloy, or plastic. The transparent side panel 51 is made of transparent materials such as glass or plastic. A second scale 53 is provided on one side of the model box 5 wall for reading the height of the sand surface inside the model box 5. A pore water pressure gauge 54 is provided on the inner surface of the side wall of the model box 5 for measuring the pore water pressure acting on the side panel of the model box 5. Several distributed earth pressure cells 55 are provided on the bottom surface inside the model box 5 for measuring the pressure acting on the bottom plate of the model box 5.

[0045] like Figure 1 As shown, the bottom of the model box 5 is also connected to an omnidirectional roller 58 and a fixed roller 59, which are used to support the model box 5 and facilitate the movement of the model box 5. The omnidirectional roller 58 can rotate freely in a plane of 360 degrees while rolling, while the fixed roller 59 can only roll and cannot rotate.

[0046] The side wall of the model box 5 is provided with several injection / drainage holes 56. The liquid seepage unit of the seepage and observation mechanism 6 includes a liquid storage tank 61, a main water pipe 67, and several branch water pipes 68. The main water pipe 67 is connected to the liquid storage tank 61. The branch water pipes 68 are connected to the main water pipe 67 through a liquid pump 62. The branch water pipes 68 are connected to the injection / drainage holes 56. Each branch water pipe 68 is connected to two valves 66. Each branch water pipe 68 is also connected to a dye pool structure 63 and a hydraulic gauge 65. The dye pool structure 63 and the hydraulic gauge 65 are located between the two valves 66. The image acquisition and analysis unit of the seepage and observation mechanism 6 includes a data acquisition and processing center 69 and a camera 610.

[0047] The liquid pump 62 is used to pump the fluid in the liquid storage tank 61 into the branch water pipe 68 through the main water pipe 67.

[0048] like Figure 5 As shown, the dye pool structure 63 is provided with a feeding port 64, which facilitates the addition of dyeing agent into the dye pool structure 63.

[0049] The dye tank structure 63 can be a drum-type dye tank, which is equipped with a stirring propeller inside to fully mix the dyeing agent and the fluid.

[0050] Hydraulic gauge 65 is used to measure the fluid pressure in each branch water pipe 68.

[0051] The camera 610 is mounted in front of the model box 2 to take photos and videos of the grid dot matrix 57 on the side plate of the model box 2 and record the seepage of the dyed fluid in the pores of the sand. The data acquisition and processing center 69 is used to receive and process the information captured by the camera 610 and analyze the seepage path of the dyed fluid in the pores of the sand in combination with the grid dot matrix 57.

[0052] The present invention provides a method for preparing saturated sand samples and using a pore seepage observation device, comprising the following steps: Step 1: Install the base plate 22 and the misalignment plate 23 into the first groove 25 and the second groove 26 at the bottom of the sand storage container 2, respectively, and adjust the misalignment plate 23 so that the hole 27 on it is completely misaligned with the hole 27 on the base plate 22. Fill the sand storage container 2 with sand, and lift the sand storage container 2 filled with sand with a crane and place it on the support mechanism 3. Step 2: Before starting the sand spreading, set and determine the initial distance between the screen 42 and the sand storage container 2 and the model box 5, adjust the direction of the laser rangefinder 43 to align it with the model box 5, and install the shielding curtain 44 between the screen 42 and the model box 5. Step 3: Use roller 35 to push the misalignment plate 23 to slide, so that the hole 27 on the misalignment plate 23 is aligned with the hole 27 on the bottom plate 22. The sand flowing out of the sand storage container 2 is dispersed by the screen 42 and falls into the model box 5. Step 4: During the sand spreading process, the laser rangefinder 43 measures the distance from the bottom of the screen 42 to the surface of the sand accumulation inside the model box 5 in real time, and transmits the distance signal to the support controller 36. The support controller 36 controls the support motor 73 according to the distance signal to drive the support mechanism 3 to move along the column 10, thereby automatically adjusting the height of the screen 42 so that the distance from the bottom of the screen 42 to the surface of the sand accumulation inside the model box 5 remains constant. Step 5: Observe the second scale 53. When the sand accumulation surface in the model box 5 reaches the preset height, use the roller 35 to push the misalignment plate 23 to reset, so that the hole 27 on the misalignment plate 23 is completely misaligned with the hole 27 on the bottom plate 22 again, and the sand no longer flows out of the sand storage container 2. The sand spreading is over. Step 6: Open valve 66 and start liquid pump 62 to inject the colorless fluid in storage tank 61 into the sand sample in model box 5 through main water pipe 67 and branch water pipe 68 until the sample is completely saturated. Step 7: Add dye to the dye pool structure 63, restart the liquid pump 62, and inject the dyeing fluid after mixing the dye into the saturated sand sample. At the same time, turn on the camera 610 and the data acquisition and processing center 69. The data acquisition and processing center 69 receives and processes the images continuously captured by the camera 610 on the transparent side plate 51, and analyzes the seepage path of the dyeing fluid in the pores of the saturated sand sample by combining the grid dot matrix 57.

[0053] Based on the description and accompanying drawings of this invention, those skilled in the art can easily manufacture or use the saturated sand sample preparation device and its method for use in seepage observation, and can achieve the positive effects described in this invention.

[0054] It should be noted that the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. The terms "installed," "set," "equipped with," "connected," "linked," and "sleeve" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral construction; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two mechanisms, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] In the description of this invention, it should be understood that the terms "one end," "the other end," "outer side," "inner side," "horizontal," "end," "length," "outer end," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the mechanism or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. The terms "first" and "second" are also used only for the sake of brevity in description and do not indicate or imply relative importance.

[0056] Furthermore, in practicing the claims of this invention, those skilled in the art can understand and influence variations to the disclosed embodiments through a study of the drawings, the disclosure, and the appended claims. Additionally, in the claims and description, words such as "comprising" and "containing" do not exclude other elements or steps, and non-plural nouns do not exclude their plural forms.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes and modifications made in accordance with the present invention are covered by the scope of the claims of the present invention, and will not be listed here.

Claims

1. A device for preparing saturated sand samples and observing pore flow, characterized in that, The system includes a support frame (1), on which a support mechanism (3) is vertically connected via a lifting drive mechanism (7). A sand storage container (2) is placed on the support mechanism (3). A sand dispersion mechanism (4) with a constant drop distance is connected below the support mechanism (3). The sand dispersion mechanism (4) includes a screen (42) and a laser rangefinder (43) for measuring sand. The support mechanism (3) also includes a support controller (36) for controlling the lifting drive mechanism (7). The laser rangefinder (43) and the support controller (36) are electrically connected. A mold is placed below the sand storage container (2). Model box (5), the model box (5) has at least one transparent side plate (51) for observation, the transparent side plate (51) is drawn with grid dot matrix (57), a seepage and observation mechanism (6) is arranged on one side of the model box (5), the seepage and observation mechanism (6) includes a liquid seepage unit and an image acquisition and analysis unit, the liquid seepage unit is used to inject colorless fluid to saturate the sand sample and dyeing fluid for observing the seepage path into the model box (5), the image acquisition and analysis unit is used to photograph the transparent side plate (51) and analyze the seepage path of the dyeing fluid in the pores of saturated sand in combination with the grid dot matrix (57).

2. The device for preparing saturated sand samples and observing pore flow as described in claim 1, characterized in that, The support (1) consists of four columns (10) and cross support rods (11) for reinforcing two adjacent columns (10).

3. The device for preparing saturated sand samples and observing pore flow as described in claim 1, characterized in that, The sand storage device (2) includes four side plates (21), a bottom plate (22), and a misaligned plate (23). The bottom of the two opposite side plates (21) is provided with a first groove (25) and a second groove (26), respectively. The bottom plate (22) is inserted into the first groove (25) and can slide in the first groove (25). The misaligned plate (23) is inserted into the second groove (26) and can slide in the second groove (26). The bottom plate (22) and the misaligned plate (23) are respectively provided with a plurality of holes (27).

4. The saturated sand sample preparation and pore seepage observation device as described in claim 3, characterized in that, A first scale (24) is provided on one of the side plates (21) of the sand reservoir (2).

5. The device for preparing saturated sand samples and observing pore flow as described in claim 3, characterized in that, The bracket (1) includes four columns (10), the support mechanism (3) includes two first supports (31) and two second supports (32), the first supports (31) and the second supports (32) are respectively sleeved and connected to one of the columns (10), the lifting drive mechanism (7) includes a rack (71), a gear (72) and a support motor (73), each column (10) is equipped with a rack (71), and the first supports (31) and the second supports (32) are respectively rotatably connected to a gear (73). 72), the gear (72) meshes with the rack (71), a support drive shaft (38) is connected between the first support (31) and the second support (32), the support drive shaft (38) is connected to the gear (72) axle by a coupling, the support motor (73) is fixed on one side of the first support (31), the motor shaft of the support motor (73) is poweredly connected to the gear (72) axle in the first support (31), and the support motor (73) is electrically connected to the support controller (36).

6. The device for preparing saturated sand samples and observing pore flow as described in claim 5, characterized in that, The first support (31) and the second support (32) are respectively provided with support beams (37) for placing the sand storage container (2) on opposite sides. The end of the support beam (37) is provided with a placement groove for connecting the elastic support leg (34). The upper end of the elastic support leg (34) is rotatably connected with a roller (35). The roller (35) abuts against the misalignment plate (23). The roller (35) can press the elastic support leg (34) downward under the gravity of the sand storage container (2) and partially place it into the placement groove.

7. The device for preparing saturated sand samples and observing pore flow as described in claim 5, characterized in that, The sand dispersion mechanism (4) also includes a support (41) and a shielding curtain (44). The screen (42) is connected to the bottom of the support mechanism (3) through the support (41). The laser rangefinder (43) is connected to the lower surface of the bottom screen (42). The shielding curtain (44) is connected to the four sides of the screen (42) and the model box (5) through hooks (46). An elastic rope (45) is also connected between the screen (42) and the model box (5) through the hooks (46). The elastic rope (45) is used to support the shielding curtain (44).

8. The device for preparing saturated sand samples and observing pore flow as described in claim 1, characterized in that, The model box (5) has a second scale (53) on one side of the box wall, a pore water pressure gauge (54) on the inner surface of the side wall of the model box (5), and a number of distributed earth pressure cells (55) on the bottom surface of the model box (5).

9. The device for preparing saturated sand samples and observing pore flow as described in claim 1, characterized in that, The side wall of the model box (5) is provided with several injection / drainage holes (56). The liquid seepage unit of the seepage and observation mechanism (6) includes a storage tank (61), a main water pipe (67), and several branch water pipes (68). The main water pipe (67) is connected to the storage tank (61). The branch water pipes (68) are connected to the main water pipe (67) through a liquid pump (62). The branch water pipes (68) are connected to the injection / drainage holes (56). Each branch water pipe (68) is connected to two valves (66). Each branch water pipe (68) is also connected to a dye pool structure (63) and a hydraulic gauge (65). The dye pool structure (63) and the hydraulic gauge (65) are located between the two valves (66). The image acquisition and analysis unit of the seepage and observation mechanism (6) includes a data acquisition and processing center (69) and a camera (610).

10. A method for preparing saturated sand samples and using a pore flow observation device, characterized in that, Includes the following steps: Step 1: Install the base plate (22) and the misalignment plate (23) into the first groove (25) and the second groove (26) at the bottom of the sand storage container (2), respectively, and adjust the misalignment plate (23) so that the hole (27) on it is completely misaligned with the hole (27) on the base plate (22). Fill the sand storage container (2) with sand, and lift the sand storage container (2) filled with sand by a crane and place it on the support mechanism (3). Step 2: Before starting the sand spreading, set and determine the initial distance between the screen (42) and the sand storage container (2) and the model box (5), adjust the direction of the laser rangefinder (43) to align it with the model box (5), and install a shielding curtain (44) between the screen (42) and the model box (5). Step 3: Use the roller (35) to push the misalignment plate (23) to slide, so that the hole (27) on the misalignment plate (23) is aligned with the hole (27) on the bottom plate (22). The sand flowing out of the sand storage container (2) is dispersed by the screen (42) and falls into the model box (5). Step 4: During the sand spreading process, the laser rangefinder (43) measures the distance from the bottom of the screen (42) to the surface of the sand accumulation inside the model box (5) in real time, and transmits the distance signal to the support controller (36). The support controller (36) controls the support motor (33) according to the distance signal to drive the support mechanism (3) to move along the column (10), thereby automatically adjusting the height of the screen (42) so that the distance from the bottom of the screen (42) to the surface of the sand accumulation inside the model box (5) remains constant. Step 5: Observe the second scale (53). When the sand accumulation surface in the model box (5) reaches the preset height, use the roller (35) to push the misalignment plate (23) back to its original position, so that the hole (27) on the misalignment plate (23) and the hole (27) on the bottom plate (22) are completely misaligned again, and the sand no longer flows out of the sand storage container (2). The sand spreading is over. Step 6: Open valve (66) and start liquid pump (62) to inject the colorless fluid in storage tank (61) into the sand sample in model box (5) through main water pipe (67) and branch water pipe (68) until the sample is completely saturated. Step 7: Add dye to the dye pool structure (63), start the liquid pump (62) again, and inject the dyeing fluid after mixing the dye into the saturated sand sample. At the same time, turn on the camera (610) and the data acquisition and processing center (69). The data acquisition and processing center (69) receives and processes the images continuously captured by the camera (610) on the transparent side plate (51), and analyzes the seepage path of the dyeing fluid in the pores of the saturated sand sample by combining the grid dot matrix (57).

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