Sand rain method apparatus and method for producing sand layers of specific moisture content

Abstract

This invention belongs to the field of geotechnical testing technology and discloses a sand rain method device and preparation method for preparing sand layers with specific moisture content. This device aims to solve the problems of existing sand rain methods, such as the inability to simultaneously control the moisture content of the sand layer during sample preparation, poor uniformity of sand application, and difficulty in accurately maintaining the sand application drop distance. It mainly includes a support frame, a horizontally movable frame, and a water-storage sand box. The water-storage sand box integrates a sand-filling area and a water-storage area. The bottom of the sand-filling area has two counter-rotating grooved rollers to achieve uniform and vertical sand application. The bottom of the water-storage area has an adjustable nozzle that can spray water simultaneously during sand application. The device also includes a laser rangefinder for real-time monitoring and automatic adjustment of the distance between the sand outlet and the sand layer surface to maintain a constant sand application drop distance. This invention can efficiently and repeatedly prepare sandy soil layer models with controllable moisture content and uniform density, significantly improving the accuracy and reliability of sand rain method tests.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical testing technology, specifically relating to a sand rain method device and preparation method for preparing sand layers with specific moisture content. Background Technology

[0002] The sand-rain method is a method for preparing test soil samples by simulating the sedimentation process of sand particles under the action of natural forces such as wind and water. The mechanical properties of the samples prepared by this method are very close to those of natural sedimentary sandy soil foundations, and it is a commonly used model preparation method for sandy soil foundation tests.

[0003] However, existing sand rain methods still have several limitations, restricting the efficiency and quality of sample preparation. First, in terms of sand spreading methods, traditional funnel-type feeding devices suffer from low formation preparation efficiency, large spatial dispersion, high density, and poor repeatability. Single-roller sand discharge devices have a fixed discharge direction, easily leading to uneven sedimentary sand layer height. Conventional sand rain methods can only prepare dry or fully saturated sand samples, lacking the function of simultaneously and precisely controlling the moisture content during sand spreading and forming, and cannot directly prepare uniform sandy soil strata models with specific target moisture content. Existing patent CN116798303 B discloses a sandy soil preparation device and method for large-scale soil tank experiments; it includes an experimental tank, a sand rain unit, and a seepage unit. This invention uses a "step-by-step" process of spreading sand first and then adding water through bottom or top seepage, causing moisture in the sand layer to rely on capillary action or hydraulic gradient migration, making it difficult to accurately prepare uniform sand layers with specific moisture content under unsaturated conditions.

[0004] In addition, the determination of the drop distance from the sand outlet to the sedimentation surface often relies on visual estimation by the operator, making it difficult to maintain a precise and constant drop distance dynamically during the preparation process. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a sand rain method device and preparation method for preparing sand layers with specific moisture content. It aims to solve the problems of existing sand rain method devices being unable to simultaneously control the moisture content of the sand layer during sample preparation, having poor uniformity of sand spreading, and having difficulty in accurately maintaining the sand spreading drop distance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a sand-rain method device for preparing sand layers with a specific moisture content, comprising a support frame, on which a water-storing sand box movable in both vertical and horizontal directions is provided; the water-storing sand box contains a sand-filling area in the middle and water-storing areas on both sides of the sand-filling area; the two water-storing areas are connected by a connecting pipe to ensure that the water level and water pressure of the two water-storing areas are consistent; the bottom of the sand-filling area is open and connected to two grooved rollers, which rotate counterclockwise and clockwise towards the center of the opening respectively, causing the sand in the sand-filling area to be sprayed out from the center of the opening; the water-storing area is provided with an adjustable nozzle, which sprays water simultaneously during the sand-spraying process to prepare a sand layer with a specified moisture content.

[0007] As a further technical solution, a laser rangefinder is installed on the bottom outer side of the sand storage tank, which can measure the vertical distance from the sand inlet to the sand surface. The sand storage tank can then rise according to the measured distance to meet the set sand spreading height.

[0008] As a further technical solution, the laser rangefinders are distributed on both sides, with two on each side, and the vertical distance from the sand inlet to the sand surface is determined by the average value of the measurements.

[0009] As a further technical solution, the laser rangefinder can move along the rangefinder track and set an appropriate spacing according to the size of the prepared sand layer.

[0010] As a further technical solution, the adjustable nozzle can be uniformly tilted up and down to control the spray rate. Depending on the moisture content of the prepared sand layer, the nozzle type can be changed to an atomizing nozzle (suitable for low moisture content) or a fan-shaped nozzle (suitable for high moisture content).

[0011] As a further technical solution, the grooved roller has spiral grooves, and sand enters the grooves and is then scattered by the rotation of the roller. Different sand-spreading rates can be set by controlling the rotation speed of the grooved roller.

[0012] As a further technical solution, a shielding rubber strip is provided at the bottom opening edge of the sand-filling area to prevent sand from spilling out from both sides of the opening.

[0013] Secondly, based on the above-mentioned sand rain method device for preparing sand layers with specific moisture content, the present invention also provides a preparation method, as detailed below; Step 1: Establish the proportional relationship between the relative density of the formation and the sand drop distance, the horizontal moving speed of the water storage sand box, and the rotation speed of the grooved roller through indoor calibration experiments. At the same time, establish the proportional relationship between the moisture content of the formation and the set adjustable nozzle pressure and nozzle opening size. According to the design requirements of the target experimental formation, determine the specified sand drop distance, the horizontal moving speed of the water storage sand box, the rotation speed of the grooved roller, the nozzle pressure, and the nozzle size. Step 2: Adjust the horizontal moving frame on the support frame to the starting height, fill the sand filling area in the center of the sand storage box with dried sand, and inject sufficient water into the water storage areas on both sides through the water inlet. Use the connecting pipe to automatically balance the water level on both sides to ensure the stability of the center of gravity of the sand storage box and the consistency of the water pressure during the movement. Step 3: Move the horizontal frame to raise the sand storage tank to the designated height; drive the sand storage tank to make uniform reciprocating motion in the horizontal direction, and at the same time open the two counter-rotating grooved rollers at the bottom to make the sand fall vertically into the formation container in a curtain shape. At this time, the adjustable nozzles arranged on both sides of the sand outlet spray water synchronously, so that the sand particles are mixed with water in the air or when they reach the deposition surface, thus forming a uniform sand layer with a specific water content in one go.

[0014] This method involves the continuous horizontal reciprocating movement of a water-storage sand box, which allows sand layers with a specific moisture content to accumulate and stack one by one until a preset stratum height is reached. At this point, the controller automatically shuts off the power of the grooved roller and the water spraying system, and stops the frame movement, thus completing the preparation of a high-precision, highly consistent unsaturated homogeneous sand stratum model.

[0015] As a further technical solution, during the sample preparation process, a laser rangefinder (whose position can be adjusted on the rangefinder track) fixed to the bottom of the sand tank monitors the distance between the sand inlet and the already formed sand surface below in real time, and transmits the feedback data to the controller. Once it is found that the drop distance is less than the preset value due to the rise of the sand surface, the controller immediately drives the vertical moving motor to drive the entire horizontal moving frame to rise at a constant speed along the vertical guide rail and vertical rack, ensuring that the sand drop distance remains constant throughout the entire sample preparation process.

[0016] The beneficial effects of this invention are as follows: This device includes a sand storage tank, which integrates a sand filling area and a water storage area. The bottom of the sand filling area has two counter-rotating grooved rollers to ensure uniform and vertical sand drop. The bottom of the water storage area has adjustable nozzles that can dynamically spray water simultaneously during sand application. The integrated sand storage tank enables simultaneous sand application and spraying, utilizing adjustable nozzles to instantly coat the sand particles with water as they fall and settle, ensuring highly uniform and precisely controllable moisture content at both the macroscopic and microscopic levels in the sand model. The device employs dual counter-rotating rollers to ensure vertical and uniform sand output, and uses laser ranging to automatically adjust the drop distance in real time, fundamentally eliminating disturbance to the sand layer's density during water addition and achieving highly repeatable sand preparation for complex working conditions.

[0017] This invention can efficiently and repeatedly prepare sandy soil strata models with controllable moisture content and uniform density, significantly improving the accuracy and reliability of sand rain method tests.

[0018] The device is also equipped with a laser rangefinder, which is used to monitor and automatically adjust the distance between the sand outlet and the sand layer surface in real time to maintain a constant sand-spreading distance. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a bottom view of the horizontal moving frame and the water storage sand box in this invention; Figure 3 This is a top view of the water storage sand box in this invention; Figure 4 for Figure 3 Top view of section AA in the middle; Figure 5 for Figure 3 Front view of section AA; Figure 6 This is a bottom view of the water storage sand box in this invention; Figure 7 This is a schematic diagram of the grooved roller in the water storage sand box of the present invention; The components include: 1. Support frame; 2. Horizontal moving frame; 3. Sand storage tank; 4. Vertical guide rail; 5. Vertical rack; 6. Vertical moving motor; 7. Horizontal guide rail; 8. Horizontal rack; 9. Horizontal moving motor; 10. Sand filling area; 11. Water storage area; 12. Connecting pipe; 13. Connecting slider; 14. Grooved roller; 15. Shielding rubber belt; 16. Water inlet; 17. Adjustable nozzle; 18. Laser rangefinder; 19. Rangefinder track; 20. Spiral groove. Detailed Implementation

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves, and do not limit the structure. They are merely for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or component 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.

[0023] As described in the background section, the existing technology has shortcomings. In order to solve the above-mentioned technical problems, the present invention proposes a sand rain method device and method for preparing sand layers with specific moisture content. The device aims to solve the problems of existing sand rain method devices being unable to simultaneously control the moisture content of the sand layer during the sample preparation process, having poor sand spreading uniformity, and having difficulty in accurately maintaining the sand spreading drop distance.

[0024] In a typical embodiment of the present invention, such as Figure 1 , Figure 2 As shown, this embodiment provides a sand rain method device for preparing sand layers with specific moisture content, which includes a support frame 1, a horizontally movable frame 2 and a water storage sand box 3; A vertical guide rail 4 and a vertical rack 5 are provided on the support frame 1; the horizontal moving frame 2 is connected to the vertical guide rail 4 and the vertical rack 5 on the support frame 1, and is driven and controlled by the vertical moving motors 6 on both sides to realize the upward and downward movement of the horizontal moving frame 2 in the vertical direction. The water storage sand box 3 is connected to the horizontal guide rail 7 and horizontal rack 8 on the horizontal moving frame 2, and is driven and controlled by the left and right horizontal moving motors 9 to realize the reciprocating motion of the water storage sand box 3 in the horizontal direction. like Figure 3 As shown, the sand storage box 3 contains two parts: a sand-filling area 10 and a water-storage area 11. It can simultaneously spread sand and spray water during horizontal movement to prepare a uniform sandy soil layer with a specified moisture content. The sand storage box 3 includes a central sand-filling area 10 and two water-storage areas 11 on both sides. The water-storage areas 11 are located on both sides of the sand storage box 3 and are connected by a connecting pipe 12 to ensure that the water level and water pressure of the two water-storage areas are consistent. The bottom of the sand-filling area 10 is open and connected to two grooved rollers 14. The two grooved rollers 14 rotate counterclockwise and clockwise towards the center of the opening, respectively, causing the sand in the sand-filling area 10 to be spread out from the center of the opening. This sand-spreading method can ensure that the initial velocity of the sand is vertically downward and the amount of sand discharged is more uniform.

[0025] As a further technical solution, the support frame 1 is a steel structure with strong support capacity; the inner side of the frame is equipped with a vertical guide rail 4 and a vertical rack 5, the horizontal moving frame 2 is a steel structure, and a gear that meshes with the vertical rack 5 is provided on the horizontal moving frame 2. Driven by the vertical moving motor 6, the gear drives the horizontal moving frame 2 to rise and fall along the vertical guide rail 4 and the vertical rack 5, and the speed is stable and adjustable. As a further technical solution, the water-storage sand box 3 can be filled with sand and water. It is connected to the horizontal guide rail 7 via a connecting slider 13 and driven by a horizontal moving motor 9 to achieve horizontal reciprocating motion with stable and adjustable speed. Specifically, the connecting slider 13 is located at the four corners of the water-storage sand box 3. The horizontal moving motor 9 and the horizontal rack 8 are located below the horizontal moving frame 2, with the horizontal rack 8 facing away from the water-storage sand box 3. The water-storage sand box 3 is equipped with a gear that meshes with the horizontal rack 8. The horizontal moving motor 9 drives the gear to move along the horizontal rack 8, which can prevent excess sand from adhering to the rack during the filling and spreading process.

[0026] As a further technical solution, the grooved roller 14 has spiral grooves 20, and sand enters the grooves and is then scattered by the rotation of the roller. Different sand-spreading rates can be set by controlling the rotation speed of the grooved roller 14.

[0027] As a further technical solution, a shielding rubber strip 15 is provided at the bottom opening edge of the sand filling area 10 to prevent sand from spilling out from both sides of the opening.

[0028] Furthermore, the bottom of the water storage area 11 is provided with a water inlet 16 and an adjustable nozzle 17, so that water is sprayed simultaneously during the sand spreading process to prepare a sand layer with a specified moisture content; water can be added to the water storage area 11 through the water inlet 16. Furthermore, the adjustable nozzle 17 can be uniformly tilted up and down to control the water spray rate. Depending on the moisture content of the prepared sand layer, the nozzle type can be changed to an atomizing nozzle for low moisture content and a fan-shaped nozzle for high moisture content.

[0029] Furthermore, a laser rangefinder 18 is installed on the bottom outer side of the water-sand tank 3, which can measure the vertical distance from the sand inlet to the sand surface; thus, the water-sand tank 3 can rise and fall according to the measured distance to meet the set sand-spreading height; specifically, after the laser rangefinder 18 measures the height of the water-sand tank 3, it sends a signal to the control system. After the control system judges the height, it controls the vertical moving motor 6 to drive the horizontal moving frame 2 to move up and down.

[0030] Furthermore, the laser rangefinders 18 are distributed on both sides, two on each side, and the vertical distance from the sand inlet to the sand surface is determined by the average value of the measurements.

[0031] Furthermore, the laser rangefinder 18 can move on the rangefinder track 19, and the spacing can be set according to the size of the prepared sand layer.

[0032] The aforementioned device integrates a sand-filling area and a water-storage area within a sand tank. The sand-filling area has two counter-rotating grooved rollers at its bottom, ensuring uniform and vertical sand drop. The water-storage area has adjustable nozzles at its bottom, allowing for simultaneous dynamic water spraying during sand application. This integrated sand tank enables simultaneous sand application and spraying, utilizing adjustable nozzles to instantly encapsulate moisture as sand particles fall and settle, ensuring highly uniform and precisely controllable moisture content at both macroscopic and microscopic levels in the sand model. The device employs dual counter-rotating rollers to ensure vertical and uniform sand output, and utilizes laser ranging to automatically adjust the drop distance in real time, fundamentally eliminating disturbances to sand layer density during water addition and achieving highly repeatable sand preparation under complex conditions. This device can efficiently and repeatedly prepare sand strata models with controllable moisture content and uniform density, significantly improving the accuracy and reliability of sand rain testing.

[0033] Specifically, using the aforementioned sand rain method apparatus, this embodiment takes the preparation of a sand layer with a moisture content of 10% as an example to illustrate the specific preparation method, as follows: Step 1: The relative density of the formation was determined through indoor calibration experiments, relating it to the sand-spreading drop distance, the horizontal moving speed of the water-sand box 3, and the rotational speed of the grooved roller 14. Simultaneously, the ratio of the formation's 10% moisture content to the set adjustable nozzle pressure and nozzle opening size was calibrated. Based on the design requirements of the target experimental formation, the specified sand-spreading drop distance, the horizontal moving speed of the water-sand box 3, the rotational speed of the grooved roller 14, the nozzle pressure, and the nozzle size were determined.

[0034] Step 2: Adjust the horizontal moving frame 2 on the support frame 1 to the starting height, fill the sand filling area 10 in the center of the sand storage box 3 with dried sand, and inject sufficient water into the water storage areas 11 on both sides through the water inlet 16. Use the connecting pipe 12 to automatically balance the water level on both sides to ensure the stability of the center of gravity of the sand storage box 3 and the consistency of the water pressure during the movement.

[0035] Step 3: Measure the distance using a laser rangefinder 18, and lift the water storage sand box 3 to the specified height using a vertical moving motor 6 driving a horizontal moving frame 2; start a horizontal moving motor 9 to drive the water storage sand box 3 to reciprocate at a uniform speed along a horizontal guide rail 7, and simultaneously open the two counter-rotating grooved rollers 14 at the bottom (using the spiral grooves 20 on them) to make the sand fall vertically into the formation container in a curtain shape. At this time, the adjustable nozzles 17 arranged on both sides of the sand outlet spray water synchronously, so that the sand particles complete the water mixing instantly when falling in the air or reaching the deposition surface, thereby forming a uniform sand layer with a specific moisture content in one go.

[0036] Step 4: During the sample preparation process, a laser rangefinder 18 (whose position can be adjusted on the rangefinder track 19) fixed to the bottom of the sand storage tank 3 is used to monitor the distance between the sand inlet and the already formed sand surface below in real time, and the feedback data is transmitted to the controller. Once it is found that the drop distance is less than the preset value due to the rise of the sand surface, the controller immediately drives the vertical moving motor 6 to drive the entire horizontal moving frame 2 to rise at a constant speed along the vertical guide rail 4 and the vertical rack 5, ensuring that the sand drop distance remains constant throughout the entire sample preparation process.

[0037] Step 5: By continuously moving the water storage sand box 3 horizontally back and forth, the sand layers with a specific moisture content are accumulated and stacked layer by layer until the preset stratum height is reached. Then, the controller automatically shuts off the power and water spraying system of the grooved roller 14 and stops the frame movement, thus completing the preparation of a high-precision and highly consistent unsaturated uniform sand stratum model.

[0038] It should be further noted that when it is necessary to prepare sand layers with other moisture contents, this can be achieved simply by adjusting the size of the nozzle.

[0039] Finally, it should be noted that relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sand rain method apparatus for preparing sand layers with specific moisture content, characterized in that, The system includes a support frame on which a water-storing sand box capable of moving vertically and horizontally is mounted. The sand box contains a central sand-filling area and water-storing areas on either side of the sand-filling area. The two water-storing areas are connected by a connecting pipe to ensure consistent water level and pressure. The bottom of the sand-filling area is open, connected to two grooved rollers. The two rollers rotate counterclockwise and clockwise towards the center of the opening, respectively, causing sand to be sprayed out from the center of the opening. The water-storing area is equipped with an adjustable nozzle to simultaneously spray water during the sand-spraying process to prepare a sand layer with a specified moisture content.

2. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, A laser rangefinder is installed on the bottom of the outer side of the water storage sand tank, which can measure the vertical distance from the sand inlet to the sand surface.

3. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, The laser rangefinders are distributed on both sides, two on each side, and the vertical distance from the sand inlet to the sand surface is determined by the average value of the measurements.

4. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, The laser rangefinder can move along the rangefinder track and set an appropriate spacing according to the size of the prepared sand layer.

5. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, The adjustable nozzle can be uniformly tilted up and down to control the spray rate.

6. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, The groove of the grooved roller is a spiral groove. After the sand enters the spiral groove, it is scattered out under the action of the roller rotation.

7. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, Different sand-spreading rates can be set by controlling the rotation speed of the roller.

8. The sand rain method apparatus for preparing sand layers with specific moisture content as described in claim 1, characterized in that, The bottom opening edge of the sand-filling area is equipped with a shielding rubber strip to prevent sand from spilling out from both sides of the opening.

9. A method for preparing a sand layer with a specific moisture content using the apparatus according to any one of claims 1-8, characterized in that, as follows: Step 1: The ratio of relative compaction of the formation to sand drop distance, horizontal moving speed of water storage sand box and rotation speed of groove roller was prepared through indoor calibration experiments. At the same time, the ratio of formation moisture content to the set adjustable nozzle pressure and nozzle opening size was calibrated. Based on the design requirements of the target experimental stratum, determine the specified sand-spreading distance, horizontal moving speed of the water storage sand box, rotation speed of the grooved roller, nozzle pressure, and nozzle size. Step 2: Adjust the horizontal moving frame on the support frame to the starting height, fill the sand filling area in the center of the sand storage box with dried sand, and inject sufficient water into the water storage areas on both sides through the water inlet. Use the connecting pipe to automatically balance the water level on both sides to ensure the stability of the center of gravity of the sand storage box and the consistency of the water pressure during the movement. Step 3: The horizontal moving frame lifts the water storage sand box to the designated height, drives the water storage sand box to make uniform reciprocating motion in the horizontal direction, and at the same time, the two counter-rotating grooved rollers at the bottom start to rotate, so that the sand falls vertically into the formation container in a curtain shape. The adjustable nozzle sprays water synchronously, so that the sand particles are mixed with water in the air or when they reach the deposition surface, thus forming a uniform sand layer with a specific water content in one go.

10. The method for preparing a sand layer with a specific moisture content as described in claim 9, characterized in that, During the process of replicating the sample from the water-sand tank, a laser rangefinder fixed to the bottom of the water-sand tank is used to monitor the distance between the sand inlet and the already formed sand surface below in real time, and transmits the feedback data to the controller. Once it is found that the drop distance is less than the preset value due to the rise of the sand surface, the controller immediately drives the entire horizontal moving frame to rise at a constant speed to ensure that the sand drop distance remains constant throughout the entire sample preparation process.

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