Sandy soil preparation device and preparation method for large-scale soil trough experiments

Abstract

The embodiment of the present invention discloses a sandy soil preparation device and preparation method for large-scale soil trough experiments, comprising: an experimental trough, formed with a holding cavity for holding the experimental soil; a seepage unit, connected to the holding cavity, capable of seeping liquid into the experimental soil from the top of the holding cavity from top to bottom, or from the bottom of the holding cavity from bottom to top as a seepage direction, and the seepage direction is switchable; a sand rain unit, comprising a sand supply mechanism, and a dispersed sand spreading mechanism connected to the sand supply mechanism and capable of providing sand into the holding cavity, and the dispersed sand spreading mechanism realizes uniform supply of sand by reciprocating along the extension direction of the experimental trough. Through the above scheme, the problems of uneven material spreading, long time consumption, low efficiency, and difficult control of sand parameters in the preparation of sand in soil troughs in the prior art, especially in the preparation of sand in large soil troughs, are overcome.

Description

Technical Field

[0001] The embodiments of the present invention relate to the fields of soil mechanics, geotechnical engineering and marine engineering, and particularly to a device and method for preparing sandy soil for large-scale soil trough experiments. Background Art

[0002] Geotechnical model experiments are of great significance in revealing the mechanisms and laws of natural geological disasters and instability of engineering foundation structures. Large-scale geotechnical model experiments can break through the limitations of scale effects, simulate and reproduce real physical processes more realistically and accurately, and have irreplaceable value in the study of scientific issues related to geotechnical mechanics. However, large-scale geotechnical model experiments inevitably involve the preparation and recovery of large soil models, especially for sandy soils. How to accurately and efficiently prepare soil models that can reflect the conditions of the prototype project, ensure that the density, saturation, and uniformity of the soil model meet the experimental requirements, and at the same time, be able to quickly and efficiently complete the removal and recovery of the soil after the experiment is completed, and improve the efficiency of the use of experimental equipment, is one of the main technical difficulties in the design of sand model experiments.

[0003] Existing research indicates that the sand-drip method is an effective method for ensuring the uniformity of sand models when preparing them. Relative density is a key indicator of engineering mechanical properties such as the internal friction angle and foundation bearing capacity of saturated sand. It also reflects physical parameters such as the porosity and bulk density of sand. The drop distance, flow rate, and sand-discharge hole size when sand is added to the soil trough all affect the final relative density of the soil model. Relative density is positively correlated with drop distance and negatively correlated with sand-discharge hole size and flow rate. The principle is that when the drop distance is large, the impact of sand on the existing soil produces a vibratory rolling effect on the prepared soil, contributing to its densification. On the other hand, when the flow rate and sand-discharge hole size are large, the sand particles are locally piled up, causing the sand particles at the top of the pile to roll down, resulting in a relatively loose initial state.

[0004] For preparing sandy soils for large-scale soil trough experiments, a simple pouring method offers the advantage of time-saving preparation. However, the resulting soil has poor uniformity, and bubbles are easily trapped within the pores of the prepared sandy soil, making it difficult to meet experimental saturation requirements. While the sand-rain method allows for relatively precise control of the soil model's saturation and relative density, it suffers from low preparation efficiency and is generally suitable for preparing sandy soils in small soil troughs less than 1 meter wide and 5 meters long. Furthermore, when using the sand-rain method to lay wide soils, a small hopper requires the sand-rain to reciprocate simultaneously along the length and width of the trough, making control complex. A large hopper, however, would be too heavy, making it difficult to simultaneously achieve the desired consistency of the sand-rain and uniformity of the soil model. Furthermore, because the hopper itself needs to reciprocate directly above the prepared soil, preparing large-volume soil models requires repeatedly moving the hopper to the edge of the trough for filling, resulting in a time-consuming and inefficient preparation process. In addition, when the soil model was excavated after the experiment, the soil contained a lot of water and was generally dense, so the removal operation took a long time. Summary of the Invention

[0005] To this end, an embodiment of the present invention provides a sandy soil preparation device and preparation method for large-scale soil trough experiments to overcome the problems of uneven material laying, long time consumption, low efficiency, and difficult control of sand parameters in the preparation of sand in soil troughs in the prior art, especially in the preparation of sand in large soil troughs.

[0006] In order to achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] In one aspect of an embodiment of the present invention, a sandy soil preparation device for a large soil trough experiment is provided, comprising:

[0008] An experimental tank is formed with a receiving cavity for receiving the experimental soil;

[0009] a seepage unit, connected to the accommodating chamber, capable of seeping liquid into the test soil from the upper side of the accommodating chamber to the lower side, or from the lower side of the accommodating chamber to the upper side, and the seepage direction is switchable;

[0010] The sand rain unit includes a sand supply mechanism and a dispersed sand spreading mechanism connected to the sand supply mechanism and capable of providing sand and soil into the accommodating cavity. The dispersed sand spreading mechanism evenly provides sand and soil by reciprocating along the extension direction of the experimental tank.

[0011] As a preferred embodiment of the present invention, the seepage unit comprises at least a water supply tank group, a first seepage supply component and a second seepage supply component respectively connected to the water supply tank group; wherein,

[0012] The first seepage flow providing component is connected to the accommodating chamber from below, and the first seepage flow providing component at least includes a liquid level regulating structure connected to the accommodating chamber for controlling the seepage flow pressure;

[0013] The second seepage flow providing component is connected to the accommodating cavity from above;

[0014] The first seepage providing component and / or the second seepage providing component provides seepage liquid into the accommodating chamber.

[0015] As a preferred solution of the present invention, the first seepage flow providing component includes a clear water tank, and the liquid level regulating structure is connected to the clear water tank and the accommodating cavity; wherein,

[0016] The liquid level regulating structure includes a connecting well with a through cavity formed at least from top to bottom, the upper end of the connecting well is connected to the clean water tank through a water injection pump, and the lower end of the connecting well is connected to the lower end of the accommodating cavity through an equipotential pipe.

[0017] As a preferred solution of the present invention, a water level sensor is further provided in the communication well;

[0018] The accommodating cavity is separated by a water filtering layer, and the accommodating cavity located above the water filtering layer is used to accommodate experimental soil, and a supporting structure for supporting the water filtering layer is formed in the accommodating cavity located below the water filtering layer.

[0019] As a preferred solution of the present invention, the second seepage providing component includes a sedimentation tank, and a liquid supply pipe with one end connected to the sedimentation tank and the other end extending above the accommodating cavity, and the liquid supply pipe is also connected to a reflux pump.

[0020] As a preferred embodiment of the present invention, the support structure includes a plurality of columns extending from top to bottom, a main beam erected above the plurality of columns, and a secondary beam connected between the main beams, wherein the main beam and the secondary beam cooperate to form a bearing surface for supporting the water filtration layer;

[0021] The water filtering layer comprises a lattice plate and a water filtering plate arranged from bottom to top.

[0022] As a preferred embodiment of the present invention, the sand supply mechanism includes a conveyor belt having a transport plane and being arranged in a transportable manner, a drive motor for driving the conveyor belt to transmit, and a sand collecting plate located near one end of the conveyor belt near the transmission end, wherein the conveyor belt transmission can drive the sand on the conveyor belt to gather on the sand collecting plate;

[0023] The sand collecting plate is formed with an opening communicated with the sand dispersing mechanism.

[0024] As a preferred embodiment of the present invention, the sand dispersing mechanism includes a sand separation conveyor belt connected to the opening of the sand collecting plate, a sand separation plate reciprocatingly arranged on the conveying surface of the sand separation conveyor belt along the conveying direction of the sand separation conveyor belt, and a spreading structure located on one side of the sand separation conveyor belt;

[0025] The sand dividing plate blocks the sand and allows the sand to fall toward the side where the spreading structure is located, and the sand dividing plate can limit the falling position of the sand by moving;

[0026] The spreading structure includes a plurality of spreading hoppers arranged in sequence along the conveying direction of the sand separation conveyor belt.

[0027] As a preferred solution of the present invention, the sandy soil preparation device further includes a recovery unit, which includes at least a mud suction pump that can be located in the accommodating chamber, and a moving part for driving the mud suction pump to move in the accommodating chamber.

[0028] In another aspect of the embodiments of the present invention, a method for preparing sandy soil for a large soil trough experiment is provided, using the sandy soil preparation device described above. The sandy soil preparation method includes:

[0029] S101, using a sand-rain unit to evenly spread sand into the accommodating cavity;

[0030] S102, according to preset seepage parameters, seeping liquid into the accommodation cavity from bottom to top until the liquid overflows the surface of the sand;

[0031] S103, continuously extracting the liquid overflowed in step S102 until no obvious bubbles are generated on the surface of the overflowed liquid;

[0032] S104, adjusting the seepage direction, so that the seepage liquid flows from top to bottom to compact the sand;

[0033] or,

[0034] S201, seeping liquid into the accommodation chamber from bottom to top according to preset seepage parameters until the liquid reaches a preset water level in the accommodation chamber;

[0035] S202: While maintaining the seepage state in step S201, using a sand rain unit to lay sand into the accommodating cavity until the sand thickness reaches a preset value;

[0036] S203. Continue to maintain the seepage state from bottom to top until there is no obvious bubble escape from the sand surface.

[0037] The embodiments of the present invention have the following advantages:

[0038] 1. Sand models with higher density and saturation can be prepared: Based on the setting of a seepage unit with switchable seepage direction, the present invention can prepare a high-density sand model by first preparing dry sand, then saturating it through upward seepage, and finally performing secondary compaction through downward seepage, so that the sand model has higher density and saturation.

[0039] 2. A sand model with a lower density can be prepared: Furthermore, when preparing a low-density sand model, the effective weight of the sand particles can be further reduced based on the upward seepage force, and a model with a lower initial relative density can be prepared.

[0040] 3. Save time: The present invention's technical solution, through the reciprocating sand-raining unit, enables continuous feeding from a fixed position when preparing large soil troughs, eliminating the need to repeatedly withdraw the hopper for refilling. Furthermore, after the experiment, the seepage unit can be used to loosen the sand and soil for rapid extraction from the experimental soil trough. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0042] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0043] Figure 1 A schematic structural diagram of a sandy soil preparation device provided in an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of the partial structure of a test tank provided in an embodiment of the present invention;

[0045] Figure 3 A schematic structural diagram of a sand rain unit provided in an embodiment of the present invention;

[0046] Figure 4 A schematic structural diagram of a sand supply mechanism provided in an embodiment of the present invention;

[0047] Figure 5A schematic diagram of a first partial structure of a sand spreading mechanism provided by an embodiment of the present invention;

[0048] Figure 6 A schematic diagram of a second partial structure of the sand spreading mechanism provided by an embodiment of the present invention;

[0049] Figure 7 A schematic diagram of a third partial structure of the sand spreading mechanism provided in an embodiment of the present invention;

[0050] Figure 8 A schematic diagram of a fourth partial structure of the sand spreading mechanism provided in an embodiment of the present invention;

[0051] Figure 9 A circuit control schematic diagram of a sand and rain unit provided by an embodiment of the present invention;

[0052] Figure 10 A schematic structural diagram of a recovery unit provided in an embodiment of the present invention.

[0053] In the picture:

[0054] 1-Experimental trough; 2-Experimental soil;

[0055] 11-water filter layer; 12-support structure; 13-track;

[0056] 111- lattice plate; 112- water filter plate;

[0057] 121-column; 122-main beam; 123-secondary beam;

[0058] 31-Clear water tank; 32-Connecting well; 33-Water injection pump; 34-Isopotential pipe; 35-Water level sensor; 36-Sedimentation tank; 37-Liquid supply pipe; 38-Return pump; 39-Servo switch;

[0059] 41-sand supply mechanism; 42-sand dispersion mechanism;

[0060] 411- conveyor belt; 412- driving motor; 413- sand collecting plate; 414- opening; 415- sand supply end;

[0061] 421 - Sand-separating conveyor belt; 422 - Sand-separating plate; 423 - Spreading hopper; 424 - Working vehicle; 425 - Horizontal feeding motor; 426 - First support frame; 427 - Driving sprocket; 428 - First reversing contact block; 429 - Steel wire; 430 - Horizontal chain; 431 - First reversing lever; 432 - Horizontal guide rail; 433 - Horizontal travel motor; 434 - Second support frame; 435 - Horizontal slider; 436 - Driven sprocket; 437 - Second reversing contact block; 438 - Third reversing contact block; 439 - Reversing contact spring; 440 - Stepping contact spring; 441 - Stepping contact block; 442 - Second reversing lever; 443 - Reverse switch; 444 - Forward switch; 445 - Stepping switch; 446 - Magnet;

[0062] 51- Mud suction pump; 52- Sand suction pipe. DETAILED DESCRIPTION

[0063] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0064] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0065] like Figures 1-10 As shown, an embodiment of the present invention provides a sandy soil preparation device for large-scale soil trough experiments, specifically comprising an experimental trough 1, a seepage unit, a sand rain unit and a recovery unit.

[0066] Example 1: Seepage unit

[0067] like Figure 1 and Figure 2 As shown in Figure 1, the seepage unit is used to generate vertical upward or downward seepage in the soil model, and to achieve the levitation or compaction of soil particles through seepage force. The seepage unit can also be used to saturate existing dry sand. The seepage unit is arranged as follows: Figure 1 shown.

[0068] The water injection pump 33 pumps water from the clean water tank 31 into the connecting well 32. A water level sensor 35 is located on the inner wall of the connecting well 32. This sensor transmits a water level signal to a servo switch 39. This servo switch 39 controls the start and stop of the water injection pump 33, maintaining the water level in the connecting well 32 at the designed value.

[0069] A connecting well 32 is connected to the bottom of the test tank 1. The bottom of the test tank 1 is arranged, from bottom to top, with a support structure 12, a filter layer 11, and the test soil 2. Water enters the bottom space of the test tank 1 through the connecting well 32, then flows through the support structure 12 and filter layer 11 into the test soil 2, forming a uniform upward seepage flow within the test soil 2 and ultimately draining out of the upper surface of the test soil 2. The filter layer 11 has the property of blocking sand and allowing water to flow through.

[0070] The floating soil and water discharged from the upper surface of the experimental soil body 2 are pumped into the sedimentation tank 36 by the return pump 38. The sediment particles in the water are allowed to settle in the sedimentation tank 36. The clear water after settling is returned to the clear water tank 31 for recycling.

[0071] When vertical downward soil seepage is required, the return pump 38 and the clear water tank 31 can be reversed: the return pump 38 pumps the purified water in the sedimentation tank 36 into the experimental tank 1; the injection pump 33 lowers the water level in the connecting well 32 to be lower than the water level in the experimental tank 1.

[0072] In the above structure, the detailed arrangement of the support structure 12, the filter layer 11 and the experimental soil 2 is as follows: Figure 2 As shown, columns 121 are installed at the bottom of the test trough 1. Main beams 122 are installed between columns 121. Secondary beams 123 are installed between main beams 122. Main beams 122 and secondary beams 123 form a load-bearing surface, above which lattice panels 111 are laid. A filter layer 11 is laid above lattice panels 111. Permeable stone can be used, or other filter materials can be selected based on the sand particle size. The test soil 2 is laid above the filter layer 11.

[0073] Columns 121 are constructed of standard H-shaped steel with similar bending stiffness in the xy direction, while main beams 122 and secondary beams 123 are constructed of H-shaped or I-shaped steel. Columns 121, main beams 122, and secondary beams 123 are fastened at the joints to facilitate installation, disassembly, and reuse of the steel components. The deadweight of the experimental soil 2 acts as a uniformly distributed load, gradually concentrated through the lattice plates 111, secondary beams 123, and main beams 122, and ultimately transferred to columns 121. The height of the columns can be adjusted to control the thickness of the experimental soil 2 according to experimental needs.

[0074] Example 2, Sand Rain Unit

[0075] like Figure 3-Figure 9 As shown, the sand rain unit is used to evenly distribute sand into the experimental tank 1 to form an experimental soil body 2. Its specific subdivision structure mainly includes a sand supply mechanism 41 and a sand dispersion mechanism 42 (including a sand separation part and a spreading part).

[0076] The sand supply mechanism 41 is composed of a conveyor belt 411 for supplying sand, a longitudinal feeding motor (i.e., a driving motor 412) and a sand collecting plate 413. Figure 4As shown. A longitudinal feeding motor is mounted at one end of a conveyor belt 411, driving the conveyor belt 411 in the direction of the arrow in the figure. A sand collecting plate 413 is provided on the conveyor belt 411. The front end of the conveyor belt 411 is a sand supply end 415, where a stable and continuous supply of dry sand can be provided mechanically or manually. The sand collecting plate 413 is fixed to a sand separator and can move along the longitudinally extending track 13 of the sand separator. The sand collecting plate 413, on the side facing the direction of movement of the conveyor belt 411, is in close contact with the conveyor belt 411 and is provided with an opening 414 and an inclined surface, which collects dry sand from the conveyor belt 411 onto the sand collecting plate 413. A vertical baffle is provided on the side facing away from the direction of movement of the conveyor belt 411, which directs dry sand accumulated on the sand collecting plate 413 toward the sand separator. An opening 414 and an inclined surface are provided on one side of the sand separator, which transfers dry sand to the conveyor belt 411.

[0077] The sand separation part mainly consists of a track 13, a working vehicle 424, a sand separation conveyor belt 421, a sand separation plate 422 and other functional accessories installed on the working vehicle 424, such as Figure 5 As shown. Two longitudinally extending tracks 13 are arranged at the outer edges of the test tank 1, parallel to the conveyor belt 411. A work vehicle 424 is mounted on the tracks 13, and a longitudinal travel motor is installed within the work vehicle 424 to drive the work vehicle 424 along the longitudinally extending tracks 13. A sand separation conveyor belt 421 is mounted on the work vehicle 424. A sand separation plate 422 is mounted on the sand separation conveyor belt 421. Driven by a transverse feed motor 425, the sand separation conveyor belt 421 can move in the direction indicated by the arrow in the figure.

[0078] The arrangement of the sand dividing piece at the head end is as follows Figure 6 As shown. A first support frame 426 is provided on the work vehicle 424 to fix the sand collecting plate 413. A transverse feeding motor 425 is provided at the head end of the sand separation conveyor belt 421. A transverse guide rail 432, a first reversing lever 431, a transverse travel motor 433, a transverse chain 430, and a steel wire 429 are provided on one side of the head end of the work vehicle 424. Among them, the first reversing lever 431 is fixed to the side of the work vehicle 424 via an axis located at the center of the lever and can rotate around the axis; a steel wire 429 is connected to each end of the first reversing lever 431, and the other end of the steel wire 429 is connected to the two ends of the second reversing lever 442. A first reversing contact block 428 is fixed to each end of the first reversing lever 431. The transverse travel motor 433 can drive the driving sprocket 427 and the transverse chain 430.

[0079] The tail end of the sand dividing piece is arranged as follows Figure 7As shown. Among them, the transverse slider 435 is set on the transverse guide rail 432, on which a second support frame 434 is set, and the sand dividing plate 422 is fixed to the second support frame 434. The transverse slider 435 is fixed to the transverse chain 430 and can move along the transverse guide rail 432 under the drive of the transverse travel motor 433. The sand dividing plate 422 is provided with an open mouth and an inclined surface on the side facing the running direction of the sand dividing conveyor belt 421, so that the dry sand on the sand dividing conveyor belt 421 can be collected on the sand dividing plate 422; a vertical baffle is provided on the side facing away from the running direction of the sand dividing conveyor belt 421, so that the dry sand can be directed to the side of the spreading unit; an inclined surface and a vertical baffle are provided on one side of the spreading unit, so that the dry sand can be poured into the spreading unit (composed of a plurality of extended spreading hoppers 423).

[0080] The end side of the working vehicle 424 on the sand dividing piece is provided with a control mechanism and a control circuit of a longitudinal travel motor and a transverse travel motor 433. Figure 8 and Figure 9 As shown, the following is a further detailed description of its working status. It should be noted that, Figure 9 The longitudinal feeding motor in FIG. 1 corresponds to the driving motor 412 in other figures.

[0081] 1. Controlling the Reciprocating Motion of the Sand Dividing Plate 422 and the Horizontal Slider 435: A reversing contact spring 439 and a third reversing contact 438 are sequentially positioned on either side of the horizontal slider 435. A second reversing lever 442 is positioned on the same side as the end of the work carriage 424. Its structure and connection to the work carriage 424 are similar to those of the first reversing lever 431. Second reversing contacts 437 are positioned at both ends of the second reversing lever 442. A contact-type forward switch 444 and a reverse switch 443 are positioned behind each of the second reversing contacts 437. When the second reversing contact 437 makes contact with the corresponding forward switch 444 or reverse switch 443, the corresponding switch closes. Conversely, when the second reversing contact 437 loses contact with the switch, the switch opens. Magnets 446 are secured to the rear of each of the forward and reverse switches 444 and 443.

[0082] In the initial state, one of the second reversing contacts 437 is attracted to the reverse switch 443 by the magnet 446, and the reverse control circuit 2 is turned on, driving the transverse travel motor 433 to drive the active sprocket 427 (the active sprocket 427 further drives the driven sprocket 436 to realize the movement of the overall sprocket structure after the two are combined) and the transverse chain 430, so that the transverse slider 435 moves to the left. Figure 8When the transverse slider 435 moves along the transverse guide rail 432 to the right end of the work vehicle 424, the third reversing contact 438 first contacts the second reversing contact 437; then the reversing contact spring 439 is compressed. When the pressure of the reversing contact spring 439 is sufficient to push the second reversing lever 442, the second reversing lever 442 rotates to connect the second reversing contact 437 with the forward switch 444 and disconnect it from the reverse switch 443, thereby causing the transverse travel motor 433 to drive the transverse slider 435 to Figure 8 When the lateral slider 435 moves to the left end of the work vehicle 424, the reversing contact spring 439 pushes the first reversing lever 431 to rotate, and drives the second reversing lever 442 to rotate in the same manner through the steel wire 429, thereby reversing the on / off states of the forward switch 444 and the reverse switch 443, completing the next switching of the driving direction of the lateral travel motor 433.

[0083] II. Intermittent Stepping Control of the Work Carriage 424: A contact-type stepping switch 445 is located at the rear end of the work car 424. When the transverse slider 435 moves along the transverse guide rail 432, the stepping contact 441 first contacts the stepping switch 445, activating the longitudinal travel motor and driving the work car 424 along the track 13. As the transverse slider 435 continues to move toward the rear end of the work car 424, triggering the forward switch 444 and the reverse switch 443, and ultimately moving away from the rear end of the work car 424, the stepping contact spring 440 undergoes a process of compression followed by relaxation, ultimately causing the stepping contact 441 to disengage from the stepping switch 445, and the work car 424 stops moving along the track 13. When the transverse slider 435 returns to the rear end of the work car 424, the aforementioned motion is triggered again. The distance traveled by the work car 424 during each step can be adjusted by adjusting the speed of the longitudinal travel motor or the length of the stepping contact spring 440.

[0084] The spreading mechanism consists of several continuously arranged sand hoppers (i.e., spreading hoppers 423), which are fixed to the work vehicle 424 on the other side of the transverse slider 435 along the transverse direction of the test tank 1. The number of sand hoppers mounted can be selected based on the transverse dimensions of the soil to be prepared. The bottom of the sand hopper is equipped with a strip-shaped leak hole with a quantitatively adjustable width to adjust the sand flow rate.

[0085] Example 3, recovery unit

[0086] The recovery unit is used to recover the existing saturated sand and soil, thereby emptying the experimental tank 1. It mainly includes equipment such as a work vehicle 424, a sand suction pipe 52, and a mud suction pump 51. Figure 10 shown.

[0087] As shown in the figure, the working vehicle 424, track 13, transverse slider 435 and the like are arranged in the same manner as the sand rain unit (preferably, the recovery unit and the sand rain unit here can choose to use the same set of working vehicles 424, tracks 13, transverse slider 435 according to actual conditions, or use different sets of working vehicles 424, tracks 13, transverse slider 435. Those skilled in the art can make corresponding selections and settings according to actual conditions, and will not be elaborated here). The sand suction pipe 52 is fixed on the transverse slider 435, and the length of its drooping section is adjustable. The end of the sand suction pipe 52 is connected to the mud suction pump 51. The mud suction pump 51 is immersed in the experimental soil 2.

[0088] In the working state, driven by the longitudinal travel motor and the transverse travel motor 433, the sand suction pipe 52 drives the mud suction pump 51 to perform transverse reciprocating motion and longitudinal stepping motion inside the experimental tank 1, thereby pumping the saturated sand in the experimental tank 1 to the outside of the experimental tank 1 through the sand suction pipe 52.

[0089] Furthermore, based on the above structure, the specific operation process is as follows.

[0090] For the seepage unit, there are two typical operation modes:

[0091] The first operation mode: suitable for preparing sandy soil with high relative density

[0092] A. Install the support structure and filter layer at the bottom of the test tank according to the soil depth requirements;

[0093] B. Use the sand rain unit to prepare a dry sand bed of specified thickness;

[0094] C. Start the water injection pump to inject water into the connecting well and stabilize the water level to the designed value;

[0095] D. Turn on the reflux pump to drain the water overflowing from the soil surface out of the test tank;

[0096] E. Maintain the above working conditions until no obvious bubbles are observed escaping from the water surface.

[0097] F. Reverse the water injection pump and the return pump to form a vertical downward seepage flow in the test tank and perform secondary compaction on the saturated sand.

[0098] The technical solution of the present invention utilizes the first operating method described above. Compared to the prior art method of adding water first and then laying soil, this method utilizes upward seepage to promote saturation, enabling a method of directly laying dry soil in the test trough and then adding water. Conventional soil troughs, such as laying dry soil first and then adding water, can increase the relative density of the test soil but cannot guarantee the saturation of the sand. Furthermore, the present invention achieves further compaction of the sand through downward seepage.

[0099] The second operation mode: suitable for preparing sandy soil with low relative density

[0100] A. Install the support structure and filter layer at the bottom of the test tank according to the soil depth requirements;

[0101] B. Start the water injection pump and reflux pump, and stabilize the water level in the test tank to the designed value, forming a vertical upward seepage flow in the test tank;

[0102] C. Keep the water injection pump and reflux pump turned on, and use the sand rain unit to sprinkle sand into the test tank until the sand layer reaches the designed thickness;

[0103] D. When no obvious bubbles are observed escaping from the water surface, turn off the water injection pump and the return pump.

[0104] Based on the technical solution of the present invention, the above-mentioned second operation mode is adopted to provide an upward seepage environment during the sand spreading process (i.e., soil particles falling in water), thereby further reducing the falling speed of soil particles and obtaining a test soil with a relatively lower density.

[0105] For the sand and rain unit, the specific operation steps are as follows:

[0106] A. Install the sand-rain unit, where the conveyor belt length should match the longitudinal extent of the prepared soil, and the sand separation conveyor belt length should match the lateral extent of the soil;

[0107] B. Initial positioning of the sand supply mechanism and the sand spreading mechanism, with the work vehicle located at the tail end of the conveyor belt and the sand distribution plate located at the head end of the sand distribution conveyor belt;

[0108] C. Turn on the longitudinal feeding motor through the master switch (connect Figure 9 A terminal in the circuit diagram);

[0109] D. Continue to supply dry sand to the sand supply end until sand enters the sand collecting plate;

[0110] E. Connect via the master switch Figure 9 The B end in the circuit diagram starts the sand separation component;

[0111] F. The sand separation parts automatically perform the following actions in sequence:

[0112] a. The sand separation plate moves toward the rear end of the work vehicle, and the sand separation conveyor belt transports the sand to the rear end;

[0113] b. The sand dividing plate approaches the rear end of the working vehicle and is connected to the stepping switch, and the working vehicle enters the soil trough range in the longitudinal direction;

[0114] c. The sand dividing plate reaches the rear end of the work vehicle and triggers the forward switch and reverse switch, causing the sand dividing plate to move toward the front end of the work vehicle;

[0115] d. The stepping switch is disconnected and the work vehicle stops moving longitudinally;

[0116] e. The sand separation plate continues to move toward the front end of the work vehicle and guides the dry sand on the sand separation conveyor belt into the sand spreading funnel;

[0117] f. When the sand dividing plate reaches the front end of the working vehicle, the forward switch and reverse switch are triggered again, and the above ab cycle is repeated.

[0118] g. When the work vehicle reaches the edge of the soil trough, connect the main control switch Figure 9 At the C end of the circuit diagram, the longitudinal travel motor drives the work vehicle to move continuously in the opposite direction;

[0119] h. When the work car returns to the tail end of the sand supply conveyor belt, connect the main control switch Figure 9 At the B end in the circuit diagram, repeat the above fh cycle until the soil thickness reaches the design value and then stop the sand rain unit.

[0120] For the recovery unit, in order to better process and recover the mechanical energy of the experimental soil after the experiment, the recovery unit can be carried out simultaneously with the seepage unit. The specific operation steps are as follows:

[0121] A. Start the injection pump and reflux pump, and stabilize the water level in the test tank to the designed value, forming a vertical upward seepage flow in the test tank;

[0122] B. Keep the water injection pump and return pump turned on, and insert the mud suction pump into the test soil;

[0123] C. Turn on the mud suction pump, longitudinal travel motor and transverse travel motor to suck the sand and soil out of the test soil trough.

[0124] Based on the above technical solution, the present invention has the following beneficial effects:

[0125] (1) Sand models with higher density and saturation can be prepared: When preparing high-density sand models, the method of first preparing dry sand, then saturating it through upward seepage, and finally compacting it again through downward seepage can make the sand model have higher density and saturation.

[0126] (2) A sand model with a lower density can be prepared: When preparing a low-density sand model, the upward seepage force can further reduce the effective weight of the sand particles, and a model with a lower initial relative density can be prepared.

[0127] (3) Save working time: For large-volume soil trough preparation tasks, the sand rain unit can realize continuous feeding from a fixed position, eliminating the need to repeatedly withdraw the hopper for filling. After the experiment is completed, the seepage unit can be used to loosen the sand and soil so that it can be quickly withdrawn from the experimental soil trough.

[0128] (4) Strong engineering adaptability: Mechanical design is used to replace complex displacement control programs, and only simple motor start-stop and steering control circuits are needed to achieve the coordination between the horizontal reciprocating sand rain and the longitudinal stepping motion.

[0129] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A sandy soil preparation device for large-scale soil trough experiments, characterized in that: include: An experimental trough (1) is formed with a receiving cavity for receiving the experimental soil (2); A seepage unit is connected to the accommodating chamber and can seep liquid into the test soil (2) from the top of the accommodating chamber to the bottom, or from the bottom of the accommodating chamber to the top, and the seepage direction is switchable; A sand rain unit comprises a sand supply mechanism (41) and a dispersed sand spreading mechanism (42) connected to the sand supply mechanism (41) and capable of providing sand into the accommodating chamber, wherein the dispersed sand spreading mechanism (42) uniformly provides sand by reciprocating along the extension direction of the experimental tank (1); The seepage unit at least includes a water supply tank group, a first seepage supply component and a second seepage supply component respectively connected to the water supply tank group; wherein, The first seepage flow providing component is connected to the accommodating chamber from below, and the first seepage flow providing component at least includes a liquid level regulating structure connected to the accommodating chamber for controlling the seepage flow pressure; The second seepage flow providing component is connected to the accommodating cavity from above; The first seepage providing component and / or the second seepage providing component provide seepage liquid into the accommodating chamber; The first seepage flow providing component comprises a clear water tank (31), and the liquid level regulating structure is in communication with the clear water tank (31) and the accommodating cavity; wherein, The liquid level regulating structure comprises a communication well (32) having a through cavity formed at least from top to bottom, the upper end of the communication well (32) being connected to the clean water tank (31) via a water injection pump (33), and the lower end of the communication well (32) being connected to the lower end of the accommodating cavity via an isopotential pipe (34); A water level sensor (35) is also provided in the communication well (32); The accommodating cavity is separated by a water filtering layer (11), and the accommodating cavity located above the water filtering layer (11) is used to accommodate the experimental soil (2), and a support structure (12) for supporting the water filtering layer (11) is formed in the accommodating cavity located below the water filtering layer (11); The second seepage flow providing assembly comprises a sedimentation tank (36), and a liquid supply pipe (37) having one end connected to the sedimentation tank (36) and the other end extending above the accommodating cavity. The liquid supply pipe (37) is also connected to a reflux pump (38).

2. The sandy soil preparation device according to claim 1, characterized in that: The support structure (12) comprises a plurality of columns (121) extending from top to bottom, a main beam (122) erected above the plurality of columns (121), and a secondary beam (123) connected between the main beams (122), wherein the main beam (122) and the secondary beam (123) cooperate to form a bearing surface for bearing the water filter layer (11); The water filtering layer (11) comprises a lattice plate (111) and a water filtering plate (112) arranged from bottom to top.

3. The sandy soil preparation device according to claim 1, characterized in that: The sand supply mechanism (41) comprises a conveyor belt (411) formed with a transport plane and arranged in a transportable manner, a drive motor (412) for driving the conveyor belt (411) to perform transport, and a sand collecting plate (413) located near one end of the conveyor belt (411) near the transport terminal, wherein the conveyor belt (411) can drive the sand on the conveyor belt (411) to gather on the sand collecting plate (413); An opening (414) communicating with the sand dispersing mechanism (42) is formed on the sand collecting plate (413).

4. The sandy soil preparation device according to claim 3, characterized in that: The sand dispersing mechanism (42) comprises a sand separation conveyor belt (421) connected to the opening (414) of the sand collecting plate (413), a sand separation plate (422) arranged on the transmission surface of the sand separation conveyor belt (421) so as to be reciprocatingly movable along the transmission direction of the sand separation conveyor belt (421), and a spreading structure located on one side of the sand separation conveyor belt (421); The sand dividing plate (422) blocks the sand and causes the sand to fall toward the side where the spreading structure is located, and the sand dividing plate (422) can limit the falling position of the sand by moving; The spreading structure comprises a plurality of spreading hoppers (423) arranged in sequence along the conveying direction of the sand separation conveyor belt (421).

5. The sandy soil preparation device according to claim 1, characterized in that: The sandy soil preparation device further comprises a recovery unit, which comprises at least a mud suction pump (51) capable of being located in the accommodating cavity, and a moving part for driving the mud suction pump (51) to move in the accommodating cavity.

6. A method for preparing sandy soil for large-scale soil trough experiments, characterized in that: Using the sandy soil preparation device according to any one of claims 1 to 5, the sandy soil preparation method includes: S101, using a sand-rain unit to evenly spread sand into the accommodating cavity; S102, according to preset seepage parameters, seeping liquid into the accommodation cavity from bottom to top until the liquid overflows the surface of the sand; S103, continuously extracting the liquid overflowed in step S102 until no obvious bubbles are generated on the surface of the overflowed liquid; S104, adjusting the seepage direction, so that the seepage liquid flows from top to bottom to compact the sand; or, S201, seeping liquid into the accommodation chamber from bottom to top according to preset seepage parameters until the liquid reaches a preset water level in the accommodation chamber; S202: While maintaining the seepage state in step S201, using a sand rain unit to lay sand into the accommodating cavity until the sand thickness reaches a preset value; S203. Continue to maintain the seepage state from bottom to top until there is no obvious bubble escape from the sand surface.

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