Apparatus for measuring natural and submerged angle of repose of coarse-grained soils based on tilt positioning technology and method of use

Abstract

The application discloses a coarse-grained soil natural and underwater repose angle measuring device based on a tilt positioning technology, which comprises a slope accumulation system, a water storage and drainage system, a pile releasing system and a repose angle measuring system, wherein the water storage and drainage system comprises a water storage tank, the slope accumulation system, the pile releasing system and the repose angle measuring system are fixed in the water storage tank, the pile releasing system is arranged at the tail end of the slope accumulation system, the slope accumulation system is provided with a vertical lifting surface, the pile releasing system is provided with a horizontal baffle, the height of the horizontal baffle is not lower than the height of the vertical lifting surface, the repose angle measuring system is arranged above the slope accumulation system, the repose angle measuring system is provided with a vertical buckle type sliding groove and a protractor, the left side of the vertical buckle type sliding groove is flush with the front end surface of the vertical lifting surface, and the lower end of the protractor is higher than the upper surface of the vertical lifting surface.

Description

Technical Field

[0001] This invention relates to the field of angle of repose measurement devices, and particularly to a device for measuring the angle of repose of coarse-grained soil in its natural and underwater states based on tilt positioning technology. Background Technology

[0002] Natural coarse-grained soils are characterized by large porosity, high permeability, and wide gradation. The particles comprising these soils include smaller sand and clay particles, as well as larger gravel and pebbles, exhibiting various morphologies such as rounded, angular, and sub-angular. They are widely found in nature, concentrated in landslides of Quaternary and modern loose deposits. In geotechnical engineering, these coarse-grained soils are used in rockfill dams, landslide slopes, and highway slopes, but they can also cause geological hazards such as bank collapses, landslides, and debris flows, significantly impacting social production and development. The angle of repose, as an important indicator of the stability of granular materials, is crucial for the accurate measurement of the angle of repose in coarse-grained soils, playing a vital role in studying the basic properties of loose deposits, transportation, and safe use.

[0003] The angle of repose generally refers to the natural slope formed when an object falls freely from a certain height and accumulates, ultimately under static or dynamic stable conditions. It is a macroscopic characteristic index reflecting the flowability and friction of particles within a soil mass. Currently, the measurement of the angle of repose mainly focuses on fine-grained soils. Therefore, traditional methods for measuring the angle of repose primarily include the injection method and the discharge method. However, these methods have varying degrees of limitations: the injection method is limited by the inaccuracy caused by the impact force of the falling material, while the discharge method is limited by the limitations of particle size measurement and the inconvenience of underwater angle of repose measurement. Furthermore, in existing methods for measuring the angle of repose of coarse-grained soils, due to the size effect, excessive soil is required when using the natural accumulation method and the discharge method to determine the angle of repose of large-particle soils. This results in excessive weight and the need for large-volume water tanks for underwater measurement of the angle of repose of coarse-grained soils. Moreover, in the underwater measurement of the angle of repose of granular soils, the refraction of water often leads to a series of problems such as inconvenience and inaccuracy in measurement. Therefore, there is an urgent need for a testing instrument that uses less material, provides more accurate measurements, and is applicable to both natural and underwater angles of repose measurements.

[0004] For example, CN103308001B discloses a device and method for measuring the underwater angle of repose of sediment based on optical imaging, which is complex in structure and high in cost; CN104315962B discloses a method for measuring the underwater angle of repose of sediment, which uses a funnel method to accumulate soil particles; this method is suitable for measuring the angle of repose of some smaller particles, but the soil is prone to peak-shaving during the descent through the funnel, which affects the accuracy of the accumulation stage. Furthermore, this method requires indirect calculation to obtain the angle of repose, which is not intuitive, and the accuracy of the angle of repose measurement is low; CN Patent 111998757B discloses a device and method for measuring the underwater angle of repose of cohesive soil. The device is constructed underwater by simultaneously stacking and raising the soil. When measuring the angle of repose of soil with larger particles, the test device needs to be made in a large volume and has a complex structure. It also needs to consider the integrity and integration of the water storage system, the stacking system and the measurement system. In the measurement stage of the angle of repose, it is necessary to perform inverse trigonometric function calculations after reading the value to obtain the angle of repose. During the reading calculation process, errors in calculation and reading can easily occur, resulting in low accuracy of the measured angle of repose. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device and method for measuring the natural and underwater angle of repose of coarse-grained soil based on tilt positioning technology, so as to realize the accurate measurement and direct reading of the angle of repose of coarse-grained soil, while ensuring the scientific nature and standardization of the test and the accuracy of the test data. The device is functionally integrated, simple in structure, and easy to carry.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a coarse-grained soil natural and underwater angle of repose measuring device based on inclined positioning technology, including a slope accumulation system and a water storage and drainage system, and further including an accumulation release system and an angle of repose measuring system. The water storage and drainage system includes a water storage tank. The slope accumulation system is fixed inside the water storage tank. The accumulation release system and the angle of repose measuring system are both fixed on the left and right side walls inside the water storage tank. The accumulation release system is located at the tail end of the slope accumulation system. The slope accumulation system is provided with a lower buffer surface and a vertical lifting surface. The accumulation release system is provided with a horizontal baffle. The height of the horizontal baffle is not lower than the height of the vertical lifting surface. The angle of repose measuring system is located above the slope accumulation system. The angle of repose measuring system is provided with a vertical snap-fit ​​sliding groove, a rotating positioning plate and a protractor. The left side of the vertical snap-fit ​​sliding groove is flush with the front end face of the vertical lifting surface. The lower end of the protractor is higher than the upper plane of the vertical lifting surface. The rotating positioning plate is located above the lower buffer surface and its length is 0.8 to 1.5 times the length of the lower buffer surface.

[0007] In a preferred embodiment, the slope stacking system includes an upper stacking surface, which is fixed inside the water storage tank and set at an angle of 40° to 65° with the horizontal plane. A lower buffer surface is rigidly fixed to the lower end of the upper stacking surface, and the lower buffer surface is set at an angle of 8° to 15° with the horizontal plane. A vertical lifting surface is rigidly fixed to the tail end of the lower buffer surface. The two sides of the upper stacking surface, the lower buffer surface, and the vertical lifting surface are all in contact with the left and right side walls inside the water storage tank. Sealing material is provided at the joints between the upper stacking surface, the lower buffer surface, the vertical lifting surface, and the water storage tank.

[0008] In a preferred embodiment, the upper stacking surface, the lower buffer surface, and the vertical lifting surface are made of stainless steel plates or tempered glass.

[0009] In a preferred embodiment, the sealing material is silicone sealant.

[0010] In a preferred embodiment, the accumulation and release system includes a set of horizontal sliding grooves fixed on the left and right side walls inside the water storage tank. Horizontal sliding pins are installed in the horizontal sliding grooves, and the other end of each horizontal sliding pin is detachably installed on a horizontal baffle. A set of baffle connecting rods is also installed on both sides of the horizontal baffle. A push-pull rod is rigidly fixed in the middle of the set of baffle connecting rods. Vertical sliding pins are detachably installed at both ends of the push-pull rods, and the other end of each vertical sliding pin is installed in a vertical sliding groove. The vertical sliding grooves are fixed in groups on the left and right side walls inside the water storage tank.

[0011] In a preferred embodiment, the angle of repose measuring system includes a set of vertical snap-fit ​​sliding grooves fixed on the left and right side walls inside the water storage tank. A snap-fit ​​sliding pin is installed in each vertical snap-fit ​​sliding groove. The other end of the snap-fit ​​sliding pin is detachably mounted on a vertical adjusting rod. A vertical displacement plate is fixed to the lower end of the vertical adjusting rod. A rotating positioning plate is mounted on the lower end of the vertical displacement plate using a damping hinge. A protractor is fixed to the lower end of the vertical displacement plate. A rotating pointer is fixed to the tail end of the rotating positioning plate. The protractor and the rotating pointer are fixed using a damping hinge, and their centers coincide with the center of the damping hinge.

[0012] In a preferred embodiment, the protractor is semi-circular, with the vertical center line of the semi-circle serving as the zero point. Bidirectional readings are provided on both sides of the zero point, and the measurement accuracy is 0.1 degrees. The protractor is made of a transparent plastic plate.

[0013] In a preferred embodiment, the width of the rotating positioning plate 36 is 0.25 to 0.5 times the width of the water storage tank 41, and the thickness is 2 to 5 mm, and it is made of plastic.

[0014] In a preferred embodiment, the water storage and drainage system further includes a water storage and drainage pipe, which is rigidly fixed to the lower end of the water storage tank. A flow control valve is also installed on the water storage and drainage pipe. The water storage tank is a sealed hexahedron made of tempered glass.

[0015] The method of using the coarse-grained soil natural and underwater angle of repose measurement equipment based on tilt positioning technology as described above includes the following steps: Step 1: First, install the coarse-grained soil natural and underwater angle of repose measuring equipment based on tilt positioning technology and adjust it to be level using a level. Also, ensure that the inside of the water storage tank is dry and that the upper accumulation surface and the lower buffer surface are flat and clean. Step 2: Move the horizontal baffle downwards until the distance between it and the vertical lifting surface reaches ten times the maximum particle size of the soil being tested, thus maintaining the size effect; Step 3: Use a shovel to place coarse soil on top of the upper pile surface, allowing the coarse soil to roll in a loose state, so that the coarse soil will accumulate at the lower buffer surface. Repeat the above process until the lower buffer surface is full. Then, place the shovel at a relatively close height from the top of the pile and let it fall freely, allowing the stones to fall at a low speed to avoid peak elimination caused by excessive initial velocity. Then, observe that the pile is basically stable, and the stones at the top roll along the slope of the pile, and the height of the stones no longer increases. Stop dumping stones at this time. This is the first pile state. Step 4: Move the vertical adjustment rod to move the vertical displacement plate to the vicinity of the accumulation angle of the lower buffer surface. Then, observe through the transparent tempered glass plate in front of the water tank to reduce errors. Gently push the end of the rotating positioning plate to make it gradually approach and finally fit with the slope formed by the accumulation. The rotating positioning plate drives the rotating pointer to rotate together and indicate the angle on the protractor. The tester directly reads the degree on the protractor to obtain the data value of the angle of repose. Step 5: Continue adding coarse soil and stone until the space between the horizontal baffle and the vertical lifting surface is filled, and the pile is observed to be basically stable. When the top stone rolls along the slope of the pile and the height of the stone no longer increases, stop adding stone and carry out the second pile. Then repeat step 4 and measure the angle of repose of the second pile. Step 6: By slowly moving the push-pull rod upward, the horizontal baffle slowly moves backward, allowing the coarse particle accumulation on the lower buffer surface to fall from the vertical lifting surface until the accumulation finally stabilizes. At this point, the accumulation is in a critical state of limit equilibrium. Then repeat step 4, measure the angle of repose of the third accumulation, and take the average of the above three sets of angles of repose. Step 7: When measuring the underwater angle of repose of the coarse-grained soil, the natural resting state of Step 6 must be maintained. Water is slowly introduced into the water storage tank through the water storage and drainage pipe and flow control valve, and the water level inside is slowly raised to allow air bubbles to slowly escape, so that the soil gradually reaches a saturated state. After the soil is completely submerged, it is left to stand for 60-120 minutes to further fill the pores in the coarse-grained soil with water. Then, Step 4 is repeated using the above method to measure the angle of repose and the underwater angle of repose of the coarse-grained soil is determined.

[0016] The device and method for measuring the natural and underwater angles of repose of coarse-grained soil based on tilt positioning technology provided by this invention have the following beneficial effects: 1. This invention is ingeniously designed and practical, and its method is scientific and standardized, enabling accurate measurement and direct reading of the angle of repose of coarse-grained soil, while ensuring the scientific nature and standardization of the experiment, as well as the accuracy of the test data; 2. This invention has a simple and reliable structure, highly integrated functions, is easy to carry, and offers a variety of measurement methods; 3. This invention is low in cost, uses conventional materials, requires little test soil, has wide applicability, and has high promotional value; 4. This invention is inexpensive, the materials required for this structure are common and can be reused; 5. In the slope accumulation system of the present invention, the accumulation structure formed by the upper accumulation surface, the lower buffer surface and the vertical lifting surface, due to the setting of the angle between the plate and the horizontal line of the ground, is more conducive to the accumulation of coarse-grained soil on the slope. Compared with traditional methods, less soil is used, and the accumulation is formed quickly, thus optimizing the accumulation process. 6. In the stacking and release system of the present invention, a horizontal baffle is set up, which can reduce the impact force when the soil slides, thereby allowing the soil to quickly reach the critical state of limit equilibrium. By using the baffle structure in conjunction with the slope stacking system, three readings can be taken, and the soil can be more easily kept stable in the critical state of limit equilibrium, thereby ensuring the accuracy of the angle of repose. 7. In the angle of repose measurement system of the present invention, the measurement system is set inside the box. When the slope accumulation is submerged in water, the measuring device is also in a submerged state, so that the reading can be accurately taken. Moreover, the reading method of using a rotating pointer and a protractor is adopted. Compared with the existing angle of repose measurement devices, it avoids the very cumbersome inverse trigonometric function calculations and directly reads the reading, thereby increasing the accuracy of the test results. 8. The water storage and drainage system of the present invention is equipped with a flow control valve, which can adjust the rate of water level rise, thereby facilitating the full immersion of coarse-grained soil and the discharge of gas between particles, increasing the standardization and accuracy of the test operation; at the same time, the integrated design of natural and underwater rest measurement is adopted, and there is no need to carry a water tank during field tests, which improves the convenience of operation, thus making the device more functional and more practical. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a front view of the present invention; Figure 3 This is a schematic diagram of the stacking and release system; Figure 4 This is a schematic diagram of the repose angle measurement system; Figure 5 A schematic diagram of the assembly of a protractor, a rotary pointer, and a damped hinge; Figure 6 This is a schematic diagram of the protractor. Figure 7 This is a schematic diagram of a rotating pointer. Figure 8 This is a schematic diagram of the first stacking step of the present invention; Figure 9 This is a schematic diagram of the second stacking process of the present invention; Figure 10 This is a schematic diagram of the natural state after the third accumulation and release according to the present invention; Figure 11 This is an underwater schematic diagram after the third accumulation and release of the present invention; In the diagram: 1. Slope stacking system; 2. Stacking release system; 3. Angle of repose measurement system; 4. Storage and drainage system; 11. Upper stacking surface; 12. Lower buffer surface; 13. Vertical lifting surface; 14. Sealing material; 21. Horizontal sliding groove; 22. Horizontal sliding pin; 23. Horizontal baffle; 24. Baffle connecting rod; 25. Push-pull rod; 26. Vertical sliding pin; 27. Vertical sliding groove; 31. Vertical snap-fit ​​sliding groove; 32. Snap-fit ​​sliding pin; 33. Vertical adjusting rod; 34. Vertical displacement plate; 35. Damped hinge; 36. Rotary positioning plate; 37. Protractor; 38. Rotary pointer; 41. Water storage tank; 42. Storage and drainage pipe; 43. Flow control valve. Detailed Implementation

[0018] like Figures 1-11As shown, the device and method for measuring the natural and underwater angle of repose of coarse-grained soil based on inclined positioning technology include a slope accumulation system 1 and a water storage and drainage system 4, as well as an accumulation release system 2 and an angle of repose measurement system 3. The water storage and drainage system 4 includes a water storage tank 41. The slope accumulation system 1 is fixed inside the water storage tank 41. The accumulation release system 2 and the angle of repose measurement system 3 are both fixed on the left and right side walls inside the water storage tank 41. The accumulation release system 2 is located at the tail end of the slope accumulation system 1. The slope accumulation system 1 is provided with a lower buffer surface 12 and a vertical lifting surface 13. The stacking and releasing system 2 is equipped with a horizontal baffle 23, the height of which is not lower than the height of the vertical lifting surface 13. The angle of repose measuring system 3 is set above the slope stacking system 1. The angle of repose measuring system 3 is equipped with a vertical snap-fit ​​sliding groove 31, a rotating positioning plate 36, and a protractor 37. The left side of the vertical snap-fit ​​sliding groove 31 is flush with the front end of the vertical lifting surface 13. The lower end of the protractor 37 is higher than the upper plane of the vertical lifting surface 13. The rotating positioning plate 36 is set above the lower buffer surface 12, and its length is 0.8 to 1.5 times the length of the lower buffer surface 12.

[0019] In this embodiment, the ramp stacking system 1 includes an upper stacking surface 11, which is fixed inside the water storage tank 41 and set at an angle of 40° to 65° with the horizontal plane. A lower buffer surface 12 is rigidly and flatly fixed at the lower end of the upper stacking surface 11, and the lower buffer surface 12 is at an angle of 8° to 15° with the horizontal plane. A vertical lifting surface 13 is rigidly and flatly fixed at the tail end of the lower buffer surface 12. The two sides of the upper stacking surface 11, the lower buffer surface 12, and the vertical lifting surface 13 are all in contact with the left and right side walls inside the water storage tank 41. Sealing material 14 is provided at the joints of the upper stacking surface 11, the lower buffer surface 12, the vertical lifting surface 13, and the water storage tank 41. The upper stacking surface 11, the lower buffer surface 12, and the vertical lifting surface 13 are made of stainless steel plates or tempered glass. The sealing material 14 is glass glue. The stacking and releasing system 2 includes a set of horizontal sliding grooves 21 fixed on the left and right side walls inside the water storage tank 41. A horizontal sliding pin 22 is installed in the horizontal sliding groove 21. The other end of the horizontal sliding pin 22 is detachably installed on the horizontal baffle 23. A set of baffle connecting rods 24 are also installed on both sides of the horizontal baffle 23. A push-pull rod 25 is rigidly fixed in the middle of the set of baffle connecting rods 24. Vertical sliding pins 26 are detachably installed at both ends of the push-pull rod 25. The other end of the vertical sliding pin 26 is installed in the vertical sliding groove 27. The vertical sliding grooves 27 are fixed in groups on the left and right side walls inside the water storage tank 41. The angle of repose measuring system 3 includes a set of vertical snap-fit ​​sliding grooves 31 fixed on the left and right side walls inside the water storage tank 41. Snap-fit ​​sliding pins 32 are installed in the vertical snap-fit ​​sliding grooves 31. The other end of the snap-fit ​​sliding pins 32 is detachably installed on a vertical adjusting rod 33. A vertical displacement plate 34 is fixed to the lower end of the vertical adjusting rod 33. A rotating positioning plate 36 is installed at the lower end of the vertical displacement plate 34 using a damped hinge 35. A protractor 37 is fixedly installed at the lower end of the vertical displacement plate 34. A rotary pointer 38 is fixedly installed at the tail end of the protractor 37. The protractor 37 and the rotary pointer 38 are fixed by a damped hinge 35, and the center of the pointer coincides with the center of the damped hinge 35. The protractor 37 is semi-circular, and the vertical center line of the semi-circle is the zero position of the protractor. The scale is set on both sides of the zero position for bidirectional reading, and the measurement accuracy is 0.1 degrees. The protractor 37 is made of transparent plastic plate. The width of the rotating positioning plate 36 is 0.25 to 0.5 times the width of the water storage tank 41, and the thickness is 2 to 5 mm. It is made of plastic plate. The water storage and drainage system 4 also includes a water storage and drainage pipe 42, which is rigidly fixed to the lower end of the water storage tank 41. A flow control valve 43 is also installed on the water storage and drainage pipe 42. The water storage tank 41 is a sealed hexahedron made of tempered glass.

[0020] In practical use: The method of using the coarse-grained soil natural and underwater angle of repose measurement equipment based on tilt positioning technology as described in any one of the embodiments includes the following steps: Step 1: First, install the coarse-grained soil natural and underwater angle of repose measuring equipment based on tilt positioning technology and adjust it to be level using a level. Also, ensure that the inside of the water storage tank 41 is dry and that the upper accumulation surface 11 and the lower buffer surface 12 are flat and clean. Step 2: By moving the push-pull rod 25 downward, the horizontal baffle 23 is moved to a position where the distance between it and the vertical lifting surface 13 reaches ten times the maximum particle size of the tested soil, thus maintaining the size effect; Step 3: Using a shovel, place coarse-grained soil on top of the upper pile surface 11, allowing it to roll freely in a loose state. This will cause the coarse-grained soil to accumulate at the lower buffer surface 12. Repeat this process until the lower buffer surface 12 is full. Then, place the shovel at a relatively close distance from the top of the pile and drop it freely, allowing the stones to fall at a low speed to avoid peak-shaving due to excessive initial velocity. Observe that the pile is basically stable, and the stones at the top roll along the slope of the pile, and the height of the stones no longer increases. Stop dumping stones at this point. This is the first pile-up state. Please refer to the appendix. Figure 8 ; Step 4: Move the vertical adjustment rod 33 to move the vertical displacement plate 34 to the vicinity of the accumulation angle of the lower buffer surface 12. Then, observe through the transparent tempered glass plate in front of the water tank 41 to reduce errors. Gently push the end of the rotating positioning plate 36 to make it gradually approach and finally fit with the slope formed by the accumulation. The rotating positioning plate 36 drives the rotating pointer 38 to rotate together and indicate the angle on the protractor 37. The tester directly reads the degree on the protractor 37 to obtain the rest angle data value. Step 5: Continue adding coarse-grained soil and stones until the space between the horizontal baffle 23 and the vertical lifting surface 13 is filled, and the pile is observed to be basically stable. Stop adding stones when the top stones begin to roll along the slope of the pile and the stone height no longer increases. Then, perform a second pile-up. Repeat Step 4, and measure the angle of repose for the second pile-up. (See Appendix for details.) Figure 9 ; Step 6: By slowly moving the push-pull rod 25 upwards, the horizontal baffle 23 slowly moves backwards, allowing the coarse particle accumulation on the lower buffer surface 12 to fall from the vertical lifting surface 13 until the accumulation finally stabilizes. At this point, the accumulation is in a critical state of limit equilibrium. Then, repeat step 4 and measure the angle of repose of the third accumulation. Please refer to the appendix. Figure 10 And take the average value of the above three sets of angles of repose; Step 7: When measuring the underwater angle of repose of the coarse-grained soil, maintain the natural resting state from Step 6. Slowly introduce water into the storage tank 41 through the drainage pipe 42 and flow control valve 43, allowing the water level to rise slowly and air bubbles to escape gradually, thus saturating the soil until it is completely submerged. Let it stand for 60-120 minutes to further fill the pores in the coarse-grained soil with water. Then, repeat Step 4 using the same angle of repose measurement method to determine the underwater angle of repose of the coarse-grained soil. Please refer to the appendix. Figure 11 .

[0021] In the preferred embodiment, the slope accumulation system 1 includes an upper accumulation surface 11, which is fixed inside the water storage tank 41 and set at an angle of 40° to 65° with the horizontal plane. A lower buffer surface 12 is rigidly and flatly fixed at the lower end of the upper accumulation surface 11, with an angle of 8° to 15° with the horizontal plane. A vertical lifting surface 13 is rigidly and flatly fixed at the tail end of the lower buffer surface 12. The two sides of the upper accumulation surface 11, the lower buffer surface 12, and the vertical lifting surface 13 are all in contact with the left and right side walls inside the water storage tank 41. Sealing material 14 is provided at the joints of the upper accumulation surface 11, the lower buffer surface 12, the vertical lifting surface 13, and the water storage tank 41. The above arrangement is more conducive to the accumulation of coarse-grained soil on the slope, and compared with traditional methods, less soil is used, and the accumulation is formed quickly, thus optimizing the accumulation process.

[0022] In the preferred embodiment, the upper stacking surface 11, the lower buffer surface 12, and the vertical lifting surface 13 are made of stainless steel or tempered glass; the sealing material 14 is glass glue; the protractor 37 is made of transparent plastic sheet; the rotating positioning plate 36 is made of plastic sheet; and the water storage tank 41 is a sealed hexahedron made of tempered glass. The above configuration ensures the strength and sealing of the test equipment, the smooth stacking process, and facilitates reading.

[0023] In a preferred embodiment, the accumulation and release system 2 includes a set of horizontal sliding grooves 21 fixed on the left and right side walls inside the water storage tank 41. A horizontal sliding pin 22 is installed in the horizontal sliding groove 21. The other end of the horizontal sliding pin 22 is detachably installed on a horizontal baffle 23. A set of baffle connecting rods 24 are also installed on both sides of the horizontal baffle 23. A push-pull rod 25 is rigidly fixed in the middle of the set of baffle connecting rods 24. Vertical sliding pins 26 are detachably installed at both ends of the push-pull rod 25. The other end of the vertical sliding pin 26 is installed in a vertical sliding groove 27. The vertical sliding grooves 27 are fixed in groups on the left and right side walls inside the water storage tank 41. The above configuration reduces the impact force when the soil slides, thereby allowing the soil to quickly reach the critical state of limit equilibrium. By using the baffle structure in conjunction with the slope accumulation system, three readings can be taken, and the soil can be more easily stabilized in the critical state of limit equilibrium, further ensuring the accuracy of the angle of repose.

[0024] In a preferred embodiment, the angle of repose measurement system 3 includes a set of vertical snap-fit ​​sliding grooves 31 fixed on the left and right side walls inside the water storage tank 41. A snap-fit ​​sliding pin 32 is installed in each vertical snap-fit ​​sliding groove 31. The other end of the snap-fit ​​sliding pin 32 is detachably mounted on a vertical adjusting rod 33. A vertical displacement plate 34 is fixed to the lower end of the vertical adjusting rod 33. A rotating positioning plate 36 is mounted on the lower end of the vertical displacement plate 34 using a damped hinge 35. A protractor 37 is fixed to the lower end of the vertical displacement plate 34. A rotating pointer 38 is fixed to the tail end of the rotating positioning plate 36. The protractor 37 and the rotating pointer 38 are fixed using a damped hinge 35, and their centers coincide with the center of the damped hinge 35. This configuration allows for accurate direct readings, avoiding the previously cumbersome inverse trigonometric function calculations and further ensuring the accuracy of the test results.

[0025] In a preferred embodiment, the water storage and drainage system 4 further includes a water storage and drainage pipe 42, which is rigidly fixed to the lower end of the water storage tank 41. A flow control valve 43 is also installed on the water storage and drainage pipe 42. The flow control valve can regulate the rate of water level rise, thereby facilitating the full immersion of coarse-grained soil and the expulsion of gas between particles, increasing the standardization and accuracy of the test operation. At the same time, the integrated design of natural and underwater rest measurement eliminates the need to carry a water tank during field tests, improving the convenience of operation. This makes the device more functional and more practical.

[0026] In the preferred embodiment, both the accumulation release system 2 and the angle of repose measuring system 3 are fixed to the left and right side walls inside the water storage tank 41. The accumulation release system 2 is located at the tail end of the slope accumulation system 1. The slope accumulation system 1 is provided with a lower buffer surface 12 and a vertical lifting surface 13. The accumulation release system 2 is provided with a horizontal baffle 23, the height of which is not lower than the height of the vertical lifting surface 13. The angle of repose measuring system 3 is located above the slope accumulation system 1 and is provided with a vertical snap-fit ​​mechanism. The sliding groove 31, the rotating positioning plate 36, and the protractor 37 are arranged such that the left side of the vertical snap-fit ​​sliding groove 31 is flush with the front end of the vertical lifting surface 13, the lower end of the protractor 37 is higher than the upper plane of the vertical lifting surface 13, and the rotating positioning plate 36 is set above the lower buffer surface 12 with a length of 0.8 to 1.5 times that of the lower buffer surface 12. The above settings further ensure the scientific and standardized nature of the experiment, conform to the actual state, and the measurement is not disturbed. At the same time, the standard is unified, ensuring that the reading is the actual angle of repose value. The following set of experimental data illustrates the actual experimental effects of this invention in detail. The experiments used coarse-grained crushed stone soil from Yiling District, Yichang City, and gravelly soil from a tributary of the Yangtze River as test materials. The experimental data obtained using both the present invention and the traditional disc packing method are shown in Table 1. Table 1 Comparison of the two types of methods for measuring the angle of repose

[0027] Note: 60~40mm and 40~20mm are the particle sizes of soil particles.

[0028] The experimental data from the comparative cases above show that the angles measured using the existing disc stacking method for the two types of test soils are generally smaller than those measured using the method of this invention, with errors typically between 1 and 2°. This is because during operation, since the disc is above ground level, when the soil is about to reach its limit equilibrium, newly added soil can cause the originally stable accumulation to fall out of the accumulation range. This introduces errors during the accumulation phase, resulting in a smaller measured angle of repose. When using the disc stacking method, the underwater angle of repose changes less compared to the natural angle of repose. This is because the lack of a water level control device causes uneven water flow, and the operation steps do not consider settling time, leading to insufficient saturation of the soil and resulting in this type of experimental error. Finally, the disc stacking method requires reading the scale on the disc rod, performing inverse trigonometric functions, and rounding the calculated value. This introduces multiple errors during the reading and calculation stages, leading to inaccuracies in the calculated angle of repose.

[0029] Based on the analysis of the above experimental results, the beneficial effects and advantages of the present invention have been further demonstrated: 1. In terms of angle measurement, it fits snugly against the slope surface for direct reading; 2. Regarding the measurement of the underwater angle of repose, the rate of water level rise in the water storage tank 41 was taken into account, and the immersion time of the accumulation body was ensured in the specific implementation steps. 3. In terms of soil material accumulation, sloping accumulation combined with horizontal baffles 23 is adopted, which makes the accumulated soil more stable in the critical state of limit equilibrium and ensures the accuracy of the accumulation stage. 4. In terms of the experimental operation process, compared with the existing disc stacking method, this invention saves more soil and is simpler and faster to operate.

Claims

1. A device for measuring the natural and underwater angle of repose of coarse-grained soil based on inclined positioning technology, comprising a slope accumulation system (1) and a water storage and drainage system (4), characterized in that: It also includes a stacking release system (2) and a repose angle measurement system (3). The water storage and drainage system (4) includes a water storage tank (41). The slope stacking system (1) is fixed inside the water storage tank (41). The stacking release system (2) and the repose angle measurement system (3) are both fixed on the left and right side walls inside the water storage tank (41). The stacking release system (2) is set at the tail end of the slope stacking system (1). The slope stacking system (1) is provided with a lower buffer surface (12) and a vertical lifting surface (13). The stacking release system (2) is provided with a horizontal baffle (23). 3) The height is not lower than the height of the vertical lifting surface (13). The angle of repose measuring system (3) is set above the slope accumulation system (1). The angle of repose measuring system (3) is equipped with a vertical snap-fit ​​sliding groove (31), a rotating positioning plate (36) and a protractor (37). The left side of the vertical snap-fit ​​sliding groove (31) is flush with the front end of the vertical lifting surface (13). The lower end of the protractor (37) is higher than the upper plane of the vertical lifting surface (13). The rotating positioning plate (36) is set above the lower buffer surface (12) and its length is 0.8~1 times the length of the lower buffer surface (12).5 times; the slope stacking system (1) includes an upper stacking surface (11), which is fixed inside the water storage tank (41) and set at an angle of 40°~65° with the horizontal plane. The lower end of the upper stacking surface (11) is rigidly connected to a lower buffer surface (12), which is at an angle of 8°~15° with the horizontal plane. The tail end of the lower buffer surface (12) is rigidly connected to a vertical lifting surface (13). The two sides of the upper stacking surface (11), the lower buffer surface (12), and the vertical lifting surface (13) are all attached to the left and right walls inside the water storage tank (41). The system comprises an upper stacking surface (11), a lower buffer surface (12), a vertical lifting surface (13), and a water storage tank (41), with sealing material (14) at each joint; the stacking release system (2) includes a set of horizontal sliding grooves (21) fixed on the left and right side walls inside the water storage tank (41), with horizontal sliding pins (22) installed in the horizontal sliding grooves (21), the other end of which is detachably installed on a horizontal baffle (23), and a set of baffle connecting rods (24) installed on both sides of the horizontal baffle (23). (24) A push-pull rod (25) is rigidly fixed in the middle. Vertical sliding pins (26) are detachably installed at both ends of the push-pull rod (25). The other end of the vertical sliding pin (26) is installed in the vertical sliding groove (27). The vertical sliding groove (27) is fixed in groups on the left and right side walls inside the water storage tank (41). The angle of repose measuring system (3) includes a set of vertical snap-fit ​​sliding grooves (31) fixed on the left and right side walls inside the water storage tank (41). Snap-fit ​​sliding pins (32) are installed in the vertical snap-fit ​​sliding grooves (31). The other end of component 32) is detachably mounted on the vertical adjustment rod (33). A vertical displacement plate (34) is fixed to the lower end of the vertical adjustment rod (33). A rotating positioning plate (36) is mounted on the lower end of the vertical displacement plate (34) using a damped hinge (35). A protractor (37) is fixedly mounted on the lower end of the vertical displacement plate (34). A rotating pointer (38) is fixedly mounted on the tail end of the rotating positioning plate (36). The protractor (37) and the rotating pointer (38) are fixed using a damped hinge (35), and their centers coincide with the center of the damped hinge (35).

2. The device for measuring the natural and underwater angle of repose of coarse-grained soil based on tilt positioning technology according to claim 1, characterized in that: The upper stacking surface (11), lower buffer surface (12) and vertical lifting surface (13) are made of stainless steel plate or tempered glass.

3. The device for measuring the natural and underwater angle of repose of coarse-grained soil based on tilt positioning technology according to claim 1, characterized in that: The sealing material (14) is glass glue.

4. The device for measuring the natural and underwater angle of repose of coarse-grained soil based on tilt positioning technology according to claim 1, characterized in that: The protractor (37) is semi-circular, with the vertical center line and the horizontal line at both ends of the semi-circle set as the zero position of the protractor (37). Bidirectional readings are set on both the inner and outer sides in the horizontal and vertical directions. The measurement accuracy is 0.1 degrees. The protractor (37) is made of transparent plastic plate.

5. The device for measuring the natural and underwater angle of repose of coarse-grained soil based on tilt positioning technology according to claim 1, characterized in that: The width of the rotating positioning plate (36) is 0.25 to 0.5 times the width of the water storage tank (41), and the thickness is 2 to 5 mm. It is made of plastic.

6. The device for measuring the natural and underwater angle of repose of coarse-grained soil based on tilt positioning technology according to claim 1, characterized in that: The water storage and drainage system (4) also includes a water storage and drainage pipe (42), which is rigidly fixed to the lower end of the water storage tank (41). A flow control valve (43) is also installed on the water storage and drainage pipe (42). The water storage tank (41) is a sealed hexahedron made of tempered glass.

7. A method for using a coarse-grained soil natural and underwater angle of repose measurement device based on tilt positioning technology, characterized in that: It includes the following steps: Step 1: First, install the coarse soil natural and underwater angle of repose measuring equipment based on tilt positioning technology and adjust the level using a level. Also, ensure that the inside of the water storage tank (41) is dry and that the upper accumulation surface (11) and the lower buffer surface (12) are flat and clean. Step 2: By moving the push-pull rod (25) downward, the horizontal baffle (23) is moved to a position where the distance between it and the vertical lifting surface (13) reaches ten times the maximum particle size of the tested soil, thus maintaining the size effect; Step 3: Use a shovel to place coarse soil on top of the upper pile surface (11), so that the coarse soil is in a loose rolling state, so that the coarse soil forms a pile at the lower buffer surface (12). Repeat the above process until the lower buffer surface (12) is filled. Place the shovel at a height close to the top of the pile and let it fall freely, so that the stones fall at a small speed to avoid the peak disappearance phenomenon caused by the initial velocity of the fall being too large. Then observe that the pile is basically stable, and the stones at the top roll along the slope of the pile, and the height of the stones no longer increases. Stop dumping the stones. This is the first pile state. Step 4: Move the vertical adjustment rod (33) to move the vertical displacement plate (34) to the vicinity of the stacking angle of the lower buffer surface (12). Then, observe through the transparent tempered glass plate in front of the water tank (41) to reduce the error. Gently push the end of the rotating positioning plate (36) to make it gradually approach and finally fit with the slope formed by the stack. The rotating positioning plate (36) drives the rotating pointer (38) to rotate together and indicates the angle on the protractor (37). The tester directly reads the degree on the protractor (37) to obtain the rest angle data value. Step 5: Continue adding coarse soil and stone until the space between the horizontal baffle (23) and the vertical lifting surface (13) is filled, and the pile is observed to be basically stable. When the top stone rolls along the slope of the pile and the height of the stone no longer increases, stop adding stone and carry out the second pile. Then repeat step 4 and measure the angle of repose of the second pile. Step 6: By slowly moving the push-pull rod (25) upward, the horizontal baffle (23) is slowly moved backward, allowing the coarse particle accumulation on the lower buffer surface (12) to fall from the vertical lifting surface (13) until the accumulation finally stabilizes. At this time, the accumulation is in the critical state of limit equilibrium. Then repeat step 4, measure the angle of repose of the third accumulation, and take the average value of the above three sets of angles of repose. Step 7: When measuring the underwater angle of repose of the coarse-grained soil, the natural repose state of step 6 must be maintained. Water is slowly introduced into the water storage tank (41) through the water storage and drainage pipe (42) and the flow control valve (43), and the water level inside is slowly raised to allow the air bubbles to slowly escape, so that the soil gradually reaches saturation. After the soil is completely submerged, it is left to stand for 60 to 120 minutes to allow the pores in the coarse-grained soil to be filled with water. Then, step 4 is repeated using the above-mentioned angle of repose measurement method to determine the underwater angle of repose of the coarse-grained soil.

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