A new device for rapid determination of soil swelling rate of biological crust

Abstract

The utility model discloses a novel device of quick determination biological incrustation soil expansion rate belongs to soil measuring equipment field. The device includes support assembly, measurement subassembly, soil body fixed assembly, water supply assembly, the soil body fixed assembly includes with water supply assembly connection's water tank, is placed in the water tank bottom's water -permeable stone, and the water -permeable stone is placed the sample to be measured, and the sample to be measured is connected bolt fixed on the water tank lateral wall, the measurement subassembly includes with support assembly connection's metal fixed disc, takes scale thin metal wire, circular ring's light waterproof metal sheet, the metal wire top is connected on the metal fixed disc or water tank lateral wall, and the metal wire bottom is conical needle structure, and it passes through waterproof metal sheet vertical or horizontal and inserts the soil body, and waterproof metal sheet is attached with the soil body surface. The device works, and the metal wire is buried into the soil sample vertically / horizontally, and the soil sample is saturated, and its expansion promotes waterproof sheet vertical displacement lifting / horizontal displacement, and the expansion rate is calculated according to the position change of sheet.

Description

Technical Field

[0001] This utility model belongs to the field of soil measurement equipment, specifically relating to a novel device for rapidly determining the swelling rate of soil with biological crusts. Background Technology

[0002] Biocrusts are complex aggregates formed by cryptogams such as lichens and mosses, along with soil microorganisms, through mycelia, rhizoids, and secretions, cementing them with surface soil particles. Due to their widespread distribution across various climate zones globally and their deep involvement in soil formation, biocrusts play a crucial role in improving soil structure, influencing soil water infiltration and distribution, promoting soil nutrient cycling, and maintaining surface ecological balance, increasingly becoming a research hotspot in soil physics and agricultural irrigation. Soil swelling rate is one of the fundamental physicochemical properties of soil, reflecting its ability to expand in volume after absorbing water. Soil swelling after water absorption easily leads to soil instability and exacerbates soil erosion, making it a focus of engineering construction and soil and water conservation. As the "skin" of the soil, biocrusts also exhibit swelling characteristics. Because biocrusts are thin and have a complex composition, the swelling characteristics of a biocrust (approximately 2 cm thick) and the underlying soil differ significantly from ordinary soil. Therefore, traditional soil swelling rate testing devices have insufficient applicability in testing the swelling rate of biocrust soils.

[0003] Currently, the most commonly used methods for determining soil swelling rate are the direct metal rod method and the loaded swelling instrument method. The direct metal rod method is relatively traditional. A metal rod is inserted to a certain depth into an undisturbed soil sample or ring sample, and its initial position is marked. Within a specified time period, the position on the metal rod after the soil absorbs a certain amount of water and swells is recorded. The difference between two consecutive measurements represents the change in soil height during that time period, from which the swelling rate can be calculated. However, this method has several drawbacks. Firstly, the lack of graduations on the metal rod and the untimely marking of the rod lead to significant errors in measuring the change in height. Secondly, the commonly used large-diameter metal rods, inserted from top to bottom, carry surface biocrusts into the soil, significantly disturbing the original structure of the biocrusts. Furthermore, the insertion of the metal rod compacts the soil, altering its internal structure. Simultaneously, because the side of the metal rod not inserted into the soil is not fixed, the metal rod rises along with the overall soil structure during water absorption and swelling, affecting the accuracy of the obtained swelling rate. The overall experimental process is lengthy and complex, highly susceptible to human influence. Furthermore, the extremely thin biocrust makes its height changes before and after water absorption and swelling difficult to characterize on a large-diameter, unmarked metal rod, resulting in poor data reproducibility and repeatability. In contrast, a more widely applicable method is the load dilatation meter method. This involves immersing the soil sample in a ring sampler, monitoring the swelling deformation with a dial gauge, assessing the swelling pressure under stress conditions, and calculating the swelling amount of the undisturbed soil sample under no-load or stress conditions. However, this method, whether using manual data recording or automated data acquisition, involves a tedious loading process (generally requiring dozens of repetitions), significantly reducing experimental efficiency and easily leading to soil volume fluctuations, thus decreasing the accuracy of the obtained swelling rate. Moreover, the surface roughness of biocrusts (especially algal biocrusts) is significantly greater than that of non-bacterial soils. Since the loading panel is a monolithic panel, the surface of the biocrust experiences uneven stress during the overall pressure application, and the measured swelling rate does not adequately account for this uneven expansion across different areas.

[0004] In addition to the above-mentioned shortcomings, the two mainstream methods for measuring soil swelling rate have a common problem: regardless of whether the soil sample is abiotic or biotic, they can only measure the swelling rate in the vertical direction and cannot simultaneously measure the swelling rate in the horizontal direction, resulting in insufficient measurement area.

[0005] In summary, while the study of soil swelling rate in biocrusts is of great significance, existing measurement techniques have significant limitations. The direct measurement method using metal rods disrupts the structure of biocrusts and has limited applicability in characterizing the height change of thin-layered crusts before and after swelling. The load-based dilatometer method is limited by the uneven stress on the surface of the biocrust and changes in the internal soil structure after loading, making it difficult to accurately obtain the soil swelling rate. Neither method can accurately and rapidly measure the soil swelling rate of biocrusts without damaging the structural characteristics of the biocrust. Therefore, there is an urgent need to develop a new measuring device that can accurately and rapidly measure the swelling rate of biocrusts, and can be flexibly adjusted to meet the need to measure the horizontal lateral swelling rate of biocrusts and the underlying soil when soil conditions permit, in order to overcome current technological bottlenecks and promote further research. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a novel device for rapidly determining the swelling rate of biocrust soil. This device utilizes multiple thin metal wires with adjustable insertion depths into the biocrust and underlying soil, along with a thin, waterproof metal sheet that amplifies the variation in soil height. It rapidly measures the swelling of the biocrust soil in both vertical and horizontal directions, directly calculating the swelling rate of the biocrust and underlying soil within a target depth range. This invention is flexible and applicable, enabling rapid and accurate determination of the swelling rate characteristics of biocrust soil, providing reliable technical support for research on the water effects of biocrust in various regions and for the prevention and control of soil erosion.

[0007] The objective of this utility model is achieved through the following technical solution:

[0008] A novel device for rapidly determining the swelling rate of biocrust soil includes a metal support assembly, a measuring assembly, a soil fixation assembly, and a water replenishment assembly.

[0009] The metal support assembly includes a metal base (1), a height-adjustable metal column (2), and a metal rod (3) with adjustable direction and position. The metal base (1) has a certain mass to stabilize the entire support assembly; the metal column (2) is vertically fixed to the metal base (1), preferably by a threaded connection; the metal rod (3) is detachably fixed to the metal column (2). The metal rod (3) and the metal column (2) are preferably fixed by metal fasteners (4) and hand-tightened bolts (5). The total height of the metal base (1) and the metal column (2) is preferably 300 mm.

[0010] The measuring assembly includes a metal fixing plate (6), a graduated thin metal wire (9), and a thin, waterproof metal sheet (10). The metal fixing plate (6) and the metal rod (3) are an integral structure, with the metal fixing plate (6) fixedly connected to one end of the metal rod (3). The surface of the metal fixing plate (6) is evenly provided with threaded holes (8) from top to bottom for the top of the graduated thin metal wire (9) to pass through. The diameter of the threaded holes (8) is preferably 1 mm. A certain number of graduated thin metal wires (9) can be spirally connected to the threaded holes (8) according to the actual measurement requirements. The graduated thin metal wire (9) has a threaded top and a conical needle-like structure at the bottom, which is convenient for insertion into the soil. The total length is preferably 150 mm, and the diameter is preferably 1 mm. The top of the graduated thin metal wire (9) is spirally connected and fixed to the metal fixing plate (6) by a nut (7) of the same type. It can be assembled or disassembled as needed. The graduated thin metal wire (9) is not only vertically connected to the metal fixing plate (6) by a spiral, but can also be horizontally connected to the wall of the water tank (15) by a nut (7B) of the same type. The thin waterproof metal sheet (10) is annular, preferably with an inner diameter of 1.5 mm, an outer diameter of 3 mm, and a thickness of 0.5 mm, and is concentrically connected to the graduated thin metal wire (9) by a vertical connection. The graduated thin metal wire (9) passes through the inner ring (10) of the thin waterproof metal sheet and is inserted into the soil. The thin waterproof metal sheet (10) is in contact with the surface of the soil and moves along the graduated thin metal wire (9) as the soil expands.

[0011] The soil fixing assembly includes a large bolt (11), a large nut (12), a permeable stone (14), and a water trough (15). The water trough (15) is preferably a cylindrical stainless steel water trough with a diameter of 150 mm, a height of 75 mm, and a wall thickness of 2 mm. The permeable stone (14) is also preferably cylindrical and is placed at the center of the bottom of the water trough (15) to hold the sample to be tested. The permeable stone (14) has a diameter of 130 mm and a height of 5 mm. Experimental water can enter the test ring sample (13) through the permeable stone (14), and the permeable stone (14) can also prevent the soil at the bottom of the ring sample (13) from spilling out. The test ring sample (13) is located inside the water trough (15) and above the permeable stone (14). The wall of the water trough (15) is provided with threaded holes for the large bolt (11) to pass through. Preferably, four threaded holes are evenly arranged in the same horizontal direction. The preferred dimensions of the large bolt (11) are 70mm in length and approximately 5mm in diameter, with its center preferably 30mm from the top of the water tank (15). It spirals through the water tank (15) and abuts against the metal wall of the test ring sample (13), fixing the ring sample (13) around its perimeter on the same horizontal plane. The large nut (12) tightens the large bolt (11) to the wall of the water tank (15), ensuring that the test ring sample (13) does not shake. The test ring sample (13) is approximately the size of a commercially available 500cm ring sample. 3The ring cutter has a maximum diameter of 100 mm and a height of 63.7 mm. In actual testing, if the diameter of the ring cutter is smaller than the diameter of the ring cutter sample to be tested, the depth of the large bolt inserted into the water tank can be adjusted by screwing to fix the sample to be tested. The water tank (15), the permeable stone (14), and the ring cutter sample (13) to be tested should be kept as concentric as possible. The wall of the water tank (15) is also provided with a threaded hole for the top of the graduated fine metal wire (9) to pass through, as well as a mounting hole for installing a valve (16).

[0012] The water replenishment assembly includes a valve (16), a latex hose (17), and a filter screen (18). The valve (16) is preferably 40mm in total length and 10mm in inner diameter, and is spirally connected to the water tank (15). The spiral depth is preferably 5mm, which is sufficient to control the amount of water entering the tank for experimental purposes. The latex hose (17) is connected to the end of the valve and is detachable. The filter screen (18) is located at the tail end of the valve (16) spiraling into the water tank (15), and is snap-fitted to the valve (16). It is detachable for easy cleaning of debris. The mesh size of the filter screen (18) is preferably 0.01mm, which helps prevent the loss of soil particles from the sample being tested.

[0013] When this device is in operation, metal wires are vertically / horizontally embedded into the soil sample, and the sample is saturated with water. The expansion of the water pushes a waterproof sheet to rise vertically / horizontally. Multiple graduated thin metal wires simultaneously capture the rise height / horizontal extension length of the sheet, and the average value is used to calculate the expansion rate. This device can capture the heterogeneity of biological crust expansion, reducing the measurement error of the expansion rate.

[0014] This utility model has the following advantages and beneficial effects:

[0015] This utility model device has a simple and reasonable structure, small size, and is easy to assemble. It can quickly determine the expansion rate of biological crusts. The measurement process is simple and convenient to operate, the expansion rate characterization reading is accurate, and the measurement accuracy is high. It is more suitable for the fine and uneven expansion characteristics of biological crusts.

[0016] This invention's device causes minimal disturbance to the in-situ soil structure, and can meet the experimental requirements for accurately and rapidly measuring the swelling rate of biological crust soil without damaging the structural characteristics of biological crust.

[0017] When soil conditions permit, this invention's device can measure the horizontal lateral swelling rate of biological crusts and the underlying soil, thus broadening the scope of research on the swelling rate of biological crust soils. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the device of this utility model.

[0019] Figure 2 This is a structural diagram and a partial enlarged view of the device of this utility model.

[0020] In the diagram, 1-metal base, 2-metal column, 3-metal rod, 4-metal fastener, 5-hand-tightening bolt, 6-metal fixing plate, 7 (7A, 7B)-nut, 8-threaded hole, 9 (9A, 9B)-fine metal wire with graduations, 10-thin waterproof metal sheet, 11-large bolt, 12-large nut, 13-sample of the ring cutter to be tested, 14-permeable stone, 15-water tank; 16-valve, 17-latex hose, 18-filter screen. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0022] Example 1

[0023] A novel device for rapidly determining the swelling rate of biocrust soil consists of four parts: a metal support assembly, a measuring assembly, a soil fixing assembly, and a water supply assembly. Its structure is as follows: Figure 1 As shown. The metal support assembly includes a metal base 1, a metal column 2, a metal rod 3, a metal fastener 4, and a large hand-tightening bolt 5. The measuring assembly includes a metal fixing plate 6, threaded holes 8 on the metal fixing plate, graduated thin metal wires 9 (9A, 9B), nuts 7 (7A, 7B) of the same size for fixing the thin metal wires 9, and a thin waterproof metal sheet 10; the metal rod 3 and the metal fixing plate 6 are an integral structure, and the metal fixing plate 6 has threaded holes 8 for the graduated thin metal wires 9 to pass through. The soil fixing assembly includes a large bolt 11, a large nut 12, a permeable stone 14, and a water trough 15; the side wall of the water trough 15 has threaded holes for the large bolt 11 to pass through, threaded holes for the graduated thin metal wires 9B to pass through, and mounting holes for installing valves 16. The water replenishment assembly includes a valve 16, a latex hose 17, and a filter screen 18.

[0024] The assembly and specific measurement method of the device include the following steps:

[0025] (1) Prepare the test ring sample 13. The test ring sample 13 is a biological crust and its underlying soil obtained by the field undisturbed ring sampling method and naturally dried, ensuring that the internal structure of the soil sample is not damaged.

[0026] (2) Cut several pieces of laboratory filter paper with a diameter slightly larger than that of the sample to be tested into a ring cutter for later use;

[0027] (3) Attach filter paper to the bottom surface of the test ring sample 13 to ensure that the contact surface is flat to avoid gaps and that there is a margin at the edge;

[0028] (4) Place the permeable stone 14 at the center of the bottom of the water tank 15;

[0029] (5) Simultaneously tilt the test ring sample 13 and the water tank 15 slightly so that the bottom filter paper layer of the test ring sample 13 is in close contact with the surface of the permeable stone 14, and then restore it to a horizontal position.

[0030] (6) Screw the four large bolts 11 into the threaded holes on the side wall of the water tank 15 until they are evenly pressed against the side wall of the test ring sample 13 from four directions. Tighten the large nut 12 to ensure that the test ring sample 13 will not shake and that the soil at its bottom will not spill out.

[0031] (7) Screw the horizontally graduated thin metal wire 9B into the side wall of the water tank 15 to a shallow depth, ensuring that its end does not contact the test ring sample 13, and tighten the matching nut 7B of the graduated thin metal wire 9B to achieve that all parts of the water tank 15 are closed except for the water replenishment device and the top.

[0032] (8) Based on the diameter of the ring sample 13 to be tested and the experimental requirements, determine the number of graduated thin metal wires 9 required to measure the vertical expansion rate; Figure 1 For example, install nine graduated thin metal wires 9A, so that the needle-shaped ends of the wires are on the same horizontal plane, and the other end is neatly spiraled to the metal fixing plate 6 and fixed with nuts 7A of the same type;

[0033] (9) Place the nine thin waterproof metal sheets 10 into the corresponding positions of the nine graduated thin metal wires, ensuring that the sheets are laid flat;

[0034] (10) Screw the metal column 2 onto the metal base 1 of a certain mass;

[0035] (11) Adjust the metal rod 3 and the metal fixing plate 6 so that the nine graduated thin metal wires 9A and the nine thin waterproof metal sheets 10 are vertically inserted into the test ring sample 2cm (2cm is the thickness of the general biological crust). The above satisfies that the metal fixing plate 6 is concentrically perpendicular to the ring sample 13 and the nine thin waterproof metal sheets 10 are attached to the soil surface.

[0036] (12) Adjust the height of the metal column 2 and the direction and length of the metal rod 3. Fix the metal column 2 and the metal rod 3 with the metal fastener 4 and the hand-tightened bolt 5 to ensure that they can withstand the stress transmitted to the measuring component and the support component during the soil expansion process.

[0037] (13) Tighten the valve 16 into the water tank 15 with a screw thread. The valve is in the closed state. Snap the 0.01mm mesh filter 18 into one end of the valve 16 and screw it into the water tank 15. Connect the latex hose 17 to the other end of the valve 16 and turn on the test water.

[0038] (14) Record the initial height readings of the nine thin, waterproof metal sheets 10 on the graduated thin metal wire 9;

[0039] (15) Open valve 16 and inject test water into water tank 15 through water replenishment component;

[0040] (16) At specific intervals, record the real-time rising height of soil sample 13 by the change in height reading of thin waterproof metal sheet 10 on graduated thin metal wire 9 until the sample expansion ends; determine the expansion rate of soil sample 13 at each test time by measuring the values ​​at each test time.

[0041] In step (6) above, if it is necessary to test the horizontal expansion rate of the loose soil, carefully remove the metal outer wall of the ring cutter. Screw the four large bolts 11 into the side wall of the water tank 15 to a shallow depth to avoid contact with the loose soil sample. Tighten the large nut 12 to fix the large bolts 11 to the water tank 15. In step (7) above, after screwing the horizontally graduated thin metal wire 9B into the water tank 15, pass it through the matching thin waterproof metal sheet 10, insert it into the side of the soil to a fixed depth, and tighten the matching nut 7B of the graduated thin metal wire 9B to ensure that all other parts of the water tank 15 are sealed except for the water replenishment device and the top. The horizontally graduated thin metal wire 9B inserted into the soil can both measure the horizontal expansion rate of the soil and fix the soil. The thin waterproof metal sheet 10 is attached to the surface of the soil.

[0042] In step (16) above, if the soil sample is loose soil not wrapped by a ring cutter, the real-time rise height and horizontal diameter change of the soil sample need to be recorded at specific intervals until the sample expansion ends; the expansion rate of the sample at each test time is determined by the measured values ​​at each test time.

[0043] In step (16) above, the expansion rate of the sample at each test time is calculated as follows:

[0044]

[0045] In the above calculation method, V0 is the initial volume of the soil sample, V t Let be the real-time volume of the soil sample at test time t. The initial volume of the soil sample is:

[0046]

[0047] The real-time volume of the soil sample at test time t is divided into two cases: retaining the metal wall of the ring cutter and loose soil.

[0048]

[0049]

[0050] In the above calculation method, V0 is the initial volume of the soil sample, V tThis represents the real-time volume of the soil sample at test time t. r0 is the initial radius of the soil sample, which is also the inner diameter of the ring sampler; r t h is the real-time radius of the loose soil at test time t; h is the initial height of the soil sample. t h represents the real-time height of the soil sample. t With r t Calculate by taking the average.

[0051] This invention represents a breakthrough improvement in the testing process for the swelling rate of soil with biological crusts. During the test, the insertion of a graduated thin metal wire into the sample causes almost no disturbance to the surface of the biological crust, has minimal impact on the integrity of its internal structure, and minimally interferes with the accuracy of the measurement results. Because the graduated thin metal wire has minimal influence on the soil, the resistance to soil swelling is significantly reduced. Subtle changes in soil swelling are amplified by the displacement of the thin, waterproof metal sheet, resulting in more precise readings and thus more accurate measurements at various time points during the testing process.

[0052] In this invention, the adjustable height metal column, the adjustable direction and position metal rod, and the metal fixing plate with graduated fine metal wire have a wide range of applications and are suitable for ring cutter samples and loose soil samples of different specifications. Because the device of this invention is easy to assemble and disassemble, it also has broad application prospects in field experiments.

[0053] The above embodiments illustrate and describe the basic principles, main features, and advantages of this utility model. It should be noted that the above embodiments are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by this utility model.

Claims

1. A novel device for rapidly determining the swelling rate of biological crust soil, characterized in that: Includes metal support components, measurement components, soil stabilization components, and water replenishment components; The metal support assembly includes a metal base (1), a metal column (2), and a metal rod (3). The metal column (2) is vertically fixed on the metal base (1), and the metal rod (3) is fixed on the metal column (2) by a detachable connection. The measuring assembly includes a metal fixing plate (6), a graduated thin metal wire (9), and a thin waterproof metal sheet (10); the metal fixing plate (6) is fixedly connected to one end of the metal rod (3); the metal fixing plate (6) is provided with a threaded hole (8) for the top of the graduated thin metal wire (9) to pass through; the graduated thin metal wire (9) is threaded at the top and has a conical needle-like structure at the bottom, and the top of the graduated thin metal wire (9) is spirally connected to the metal fixing plate (6) through the threaded hole (8) on the metal fixing plate (6) and a nut (7); the thin waterproof metal sheet (10) is a ring-shaped structure that allows the bottom of the graduated thin metal wire (9) to pass through; The soil fixing assembly includes a large bolt (11), a large nut (12), a permeable stone (14), and a water trough (15); the permeable stone (14) is placed at the center of the bottom of the water trough (15) for placing the sample to be tested; the wall of the water trough (15) is provided with a threaded hole for the large bolt (11) to pass through, and the large nut (12) tightens and fixes the large bolt (11) to the wall of the water trough (15); the wall of the water trough (15) is provided with a mounting hole for installing a valve (16); The water replenishment component includes a valve (16), a latex hose (17), and a filter screen (18); the valve (16) is spirally connected to the water tank (15); the latex hose (17) is connected to the outer end of the valve, and the filter screen (18) is located at the inner end of the valve (16).

2. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The metal column (2) is fixed to the metal base (1) by a threaded connection.

3. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The metal rod (3) and the metal column (2) are fixed by metal fasteners (4) and hand-tightened bolts (5).

4. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The metal fixing disk (6) and the metal rod (3) are an integral structure.

5. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The diameter of the graduated fine metal wire (9) is 1 mm.

6. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 5, characterized in that: The inner diameter of the thin waterproof metal sheet (10) is 1.5 mm.

7. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The water tank (15) is a cylindrical stainless steel water tank.

8. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: Four threaded holes for large bolts (11) to pass through are evenly arranged in the same horizontal direction on the wall of the water tank (15).

9. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The wall of the water tank (15) is provided with a threaded hole for the top of a graduated fine metal wire (9) to pass through.

10. The novel device for rapidly determining the swelling rate of biological crust soil according to claim 1, characterized in that: The sample to be tested is a ring sample or a loose soil sample.

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