A kind of field detection device for soil shear strength parameter containing root system

Abstract

This invention provides a field testing device for root soil shear strength parameters, comprising a frame with mounting holes; a shearing ring for soil sampling and loading, adapted to pass through the mounting holes so that the shearing ring is assembled onto the frame; a pressure assembly detachably connected to the frame and positioned above the mounting holes to apply pressure to the shearing ring from a first direction; and a shearing force assembly detachably connected to the frame and configured to apply pressure to the shearing ring from a second direction, wherein the first direction is perpendicular to the second direction, the first direction is axially aligned with the shearing ring, and the second direction is axially aligned with the shearing surface of the shearing ring. This invention, by detachably connecting the shearing ring, pressure assembly, and shearing force assembly to the frame, enables vertical pressurization and horizontal shearing assembly of soil samples. The frame design is small in size and lightweight, facilitating disassembly, transport, and field assembly.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering equipment technology, and in particular to a field testing device for soil shear strength parameters containing root system components. Background Technology

[0002] In geotechnical experiments, shear strength parameters are of great significance for the deformation analysis of slope soil materials, and direct shear tests are the most efficient means of obtaining these parameters. In natural soil, root systems have a significant amplifying effect on the shear strength of the soil; therefore, plants are often used as ecological materials for slope protection, and the study of the shear strength of root-soil composites remains a persistent research hotspot.

[0003] Due to limitations in the portability of existing testing instruments, this type of research typically employs a process of collecting root soil samples in the field followed by indoor remodeling and shearing. Most existing shearing instruments utilize bulky rigid foundations, employing counterweights or hydraulic loading, and applying force via electric motors, making them power-dependent and unsuitable for field installation and use. The current research process makes it difficult to measure the shear strength of undisturbed soil samples; transportation disturbances and indoor remodeling affect the soil sample structure and root-soil contact, resulting in test results that are insufficient to reflect the actual soil-fixing capacity of the root system. Summary of the Invention

[0004] This invention provides a field testing device for soil shear strength parameters containing root system parameters, which solves the shortcomings of existing technology where the measuring devices are bulky and cannot be quickly measured in the field.

[0005] This invention provides a field testing device for soil shear strength parameters containing root system components, comprising:

[0006] The frame is equipped with mounting holes;

[0007] A shearing ring cutter is used to load soil samples, and the shearing ring cutter is detachably inserted into the mounting hole;

[0008] A pressure assembly, detachably connected to the frame and positioned above the mounting hole, applies pressure to the soil sample within the shearing ring from a first direction;

[0009] A shearing force assembly is detachably connected to the frame and configured to apply pressure to the shearing ring cutter from a second direction, wherein the first direction is perpendicular to the second direction, the first direction is arranged along the axial direction of the shearing ring cutter, and the second direction is arranged along the shearing surface direction of the shearing ring cutter.

[0010] According to the present invention, a field testing device for soil shear strength parameters containing roots is provided. The frame includes a first plate, a second plate, and a third plate arranged sequentially at intervals. The first plate, the second plate, and the third plate are connected by a fourth plate. A first space is formed between the first plate and the second plate, and a second space is formed between the second plate and the third plate.

[0011] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, the second plate is provided with a mounting hole, and the shearing ring cutter is partially inserted through the mounting hole; the first plate is provided with a first connecting hole, and the pressure component is inserted through the first connecting hole from the first direction; the fourth plate is provided with a second connecting hole, and the shearing force component is inserted through the second connecting hole from the second direction; a container is provided on the third plate, and the bottom of the shearing ring cutter is disposed in the container.

[0012] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, the mounting hole is equal to the outer diameter of the shear ring cutter; and / or

[0013] The inner diameter of the container is equal to the outer diameter of the shearing ring.

[0014] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, the shear cutter includes a first cutter, a second cutter, and a third cutter, wherein the first cutter, the second cutter, and the third cutter are connected to each other.

[0015] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, the shear force component includes a second lead screw, a tension / compression sensor, and a third pressure transmission plate connected to each other. The tension / compression sensor is disposed between the second lead screw and the third pressure transmission plate. A second insertion tube is connected to the end of the second lead screw away from the tension / compression sensor. The tension / compression sensor is detachably connected to the second lead screw.

[0016] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, a cavity is provided on the second lead screw, and a protrusion is provided on the tensile and compressive sensor. The protrusion is adapted to enter the cavity to connect the second lead screw to the tensile and compressive sensor.

[0017] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, the third pressure plate is provided with an arc-shaped recess, which matches the outer wall of the shearing ring blade.

[0018] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, the pressure assembly includes a first lead screw and a first pressure plate, a second pressure plate, and an elastic element fixedly connected to each other. The elastic element is located between the first pressure plate and the second pressure plate. One end of the first lead screw is connected to the first pressure plate, and the other end of the first lead screw is connected to a first insertion tube, which is perpendicular to the first lead screw.

[0019] According to the field testing device for soil shear strength parameters containing roots provided by the present invention, a nut is provided on the first lead screw to limit the deformation of the compression spring.

[0020] The present invention provides the following technical effects.

[0021] 1. This invention enables vertical pressurization and horizontal shearing assembly of soil samples by detachably connecting the shearing ring cutter, pressure component, and shearing force component to the frame. The frame of this design is small in size and light in weight, making it easy to disassemble, carry, and assemble in the field.

[0022] 2. The shearing ring cutter of the present invention consists of three ring cutters joined together, and the soil sample has two reserved shearing surfaces, which can realize the collection and shearing of undisturbed root-bearing soil.

[0023] 3. The pressure component of the present invention can apply pressure vertically and can be operated by hand in the field, avoiding the shortcomings of traditional devices such as weights and hydraulic systems that are inconvenient to carry and rely on electricity and fuel. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of a strain-controlled direct shear apparatus in the prior art.

[0026] Figure 2 This is a schematic diagram of the overall structure of the present invention.

[0027] Figure 3 This is a schematic diagram of the framework of the present invention.

[0028] Figure 4 This is a schematic diagram of the shearing ring blade of the present invention.

[0029] Figure 5 This is a schematic diagram of the pressure component of the present invention.

[0030] Figure 6 This is a schematic diagram of the shear force component of the present invention.

[0031] Figure label:

[0032] Frame 1, First plate 11, First connecting hole 111, Second plate 12, Mounting hole 121, Third plate 13, Container 131, Fourth plate 14, Second connecting hole 141, Shearing ring blade 2, First ring blade 21, Second ring blade 22, Third ring blade 23, Pressure assembly 3, First lead screw 31, Nut 311, First pressure transmission plate 32, Second pressure transmission plate 33, Elastic element 34, First insertion tube 35, Shearing force assembly 4, Second lead screw 41, Cavity 411, Tension / compression sensor 42, Protrusion 421, Third pressure transmission plate 43, Second insertion tube 44, Arc-shaped concave surface 431, Rotating lever 5. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] In geotechnical experiments, shear strength parameters are crucial for analyzing the deformation of slope soil materials, and the direct shear test is the most efficient method for obtaining these parameters. Root systems in natural soils have a significant amplifying effect on the soil's shear strength; therefore, plants are often used as ecological materials for slope protection. Research on the shear strength of root-soil composites has been a persistent research focus, and the direct shear test, as a primary method for studying the strength of root-soil composites, has also received considerable attention. The direct shear test apparatus is a direct shear apparatus based on Mohr's Coulomb's law. A typical direct shear apparatus should have the following structure:

[0035] 1. Specimen loading and constraint frame

[0036] 2. Clipboard

[0037] 3. Vertical pressure loading device

[0038] 4. Shear force application device

[0039] 5. Shear displacement and shear force measuring device

[0040] like Figure 1 As shown, taking the strain-controlled direct shear apparatus developed by Harvard University in 1932 as an example, its typical assembly is as follows:

[0041] 1. The loading and constraint frame 1, in accordance with the requirements of rigid constraints, shall be able to withstand the maximum vertical and perpendicular internal forces during shearing without deformation, satisfy the absolute constraints of the shear box 2, ensure the vertical stability of the vertical loading device 3, and satisfy the absolute constraints of the shear force application device and the shear displacement / shear force measurement system.

[0042] 2. The shear box consists of an upper box 21 with equal diameter (D) and height (H) and no bottom, and a lower box 22 with a bottom, joined together to form a rigid soil-carrying container with a specific volume. Its characteristic is that the upper and lower boxes 21 and 22 are smoothly joined, forming a reserved shear surface, such as... Figure 1 .

[0043] 3. During measurement, the shear box 2 is fully constrained by the sample loading and constraint frame 1. A soil sample of equal shape and volume is pushed into the shear box 2. A certain vertical pressure is applied to the top surface of the shear box 21. Then, the horizontal constraint of the upper box 21 is removed. The shear force application device 4 is used to apply a horizontal load to the upper box 21, so that the soil sample produces a uniform shear displacement on the reserved shear surface. During the shearing process, the shear force and shear displacement are measured by the shear force and shear displacement measurement device 5 until the shear force changes abruptly and shear failure occurs.

[0044] In some embodiments, the upper box is constrained and a horizontal force is applied to the lower box. The principle is the same as described above and they are similar designs.

[0045] After the experiment, the shear strength was calculated based on the maximum shear force and the shear surface area. The shear strength indexes cohesion c and friction angle φ were calculated using Mohr's Coulomb law.

[0046] The following is combined Figures 2-6 This invention describes a field testing device for soil shear strength parameters containing roots.

[0047] This invention provides a field testing device for soil shear strength parameters containing root system components, including a frame 1, a shearing ring 2, a pressure component 3, and a shear force component 4. The frame 1 supports the shearing ring 2, the pressure component 3, and the shear force component 4. By assembling the shearing ring 2, the pressure component 3, and the shear force component 4 onto the frame 1, the resulting rapid testing device is easy to assemble and disassemble, convenient to carry, and enables rapid testing of soil shear force in different environments.

[0048] It should be understood that the shearing ring 2 can be a circular ring, a rectangular ring, etc. In this application, the shearing ring 2 is a circular ring. This is so that soil can be taken in the field using a soil drill, and then immediately sheared using the device designed in this invention. Therefore, the shearing ring 2 is designed to be circular to work with the soil drill. It has two functions: first, it can be loaded onto the drill bit of the soil drill to take out natural soil samples; second, it can be loaded into the device designed in this invention to perform shearing tests. Therefore, the shearing ring 2 is generally circular; a square shape is inconvenient for sampling.

[0049] Specifically, the frame 1 is provided with a mounting hole 121. The shearing ring cutter 2 is used for soil sampling and loading. The shearing ring cutter 2 is adapted to pass through the mounting hole 121 so that it is assembled into the frame 1. It should be understood that when soil testing is required, the shearing ring cutter 2 is assembled into the mounting hole 121, and when testing is not required, the shearing ring cutter 2 can be freely placed without the mounting hole 121. The pressure assembly 3 is detachably connected to the frame 1 and is disposed above the mounting hole 121 to apply pressure to the shearing ring cutter 2 from a first direction. The shearing force assembly 4 is detachably connected to the frame 1 and configured to apply pressure to the shearing ring cutter 2 from a second direction, wherein the first direction is perpendicular to the second direction.

[0050] In actual testing, the first direction refers to the axial direction of the shearing ring 2, and the second direction refers to the transverse direction of the shearing ring 2, that is, the shearing surface direction of the shearing ring 2.

[0051] In one embodiment, the frame 1 is E-shaped, meaning that when viewed from the front, the frame 1 has an E-shaped structure. This design facilitates the installation of the pressure assembly 3, the shearing ring blade 2, and the shearing force assembly 4. The frame 1 includes a first plate 11, a second plate 12, and a third plate 13. The first plate 11, the second plate 12, and the third plate 13 are connected by a fourth plate 14 and spaced apart from each other. A first space is formed between the first plate 11 and the second plate 12, and a second space is formed between the second plate 12 and the third plate 13.

[0052] Mounting hole 121 is located on the second plate 121.

[0053] During installation, the pressure assembly 3 is mounted on the first plate 11, the shearing ring blade 2 is mounted on the second plate 12, and the shearing force assembly 4 is mounted on the fourth plate 14. Correspondingly, the pressure assembly 3 is partially located in the first space, and the shearing force assembly 4 is partially located in the second space. This design makes the overall structure more compact and rational.

[0054] In one embodiment, to constrain the position of the shearing ring 2, the mounting hole is equal to the outer diameter of the shearing ring 2; and / or the inner diameter of the container 131 is equal to the outer diameter of the shearing ring 2. Thus, when the shearing ring 2 is installed in the mounting hole, the mounting hole can constrain the position of the shearing ring 2, limiting its lateral movement. It should be understood that the container 131 is a cup-shaped container, and when the shearing ring 2 is inserted into the container 131, the container 131 constrains the shearing ring 2, preventing it from moving arbitrarily.

[0055] In one embodiment, the shearing ring cutter 2 includes a first ring cutter 21, a second ring cutter 22, and a third ring cutter 23. The first ring cutter 21, the second ring cutter 22, and the third ring cutter 23 are connected to each other and are identically configured. It should be understood that the so-called identical configuration means that the inner diameter D0, the outer diameter D1, and the height h of the three ring cutters are all equal. All three can be simultaneously inserted into a soil sampling drill to extract a soil sample containing roots with a diameter of D0 and a height of 3h. The soil sample is allowed to be loaded from top to bottom into the second space through the mounting hole 121 and placed in the container 131. The shearing ring cutter 2 is spliced ​​together from the first ring cutter 21, the second ring cutter 22, and the third ring cutter 23, which are divided into three equal parts, and two reserved shearing surfaces are left at the splicing points.

[0056] In one embodiment, the pressure assembly 3 includes a first lead screw 31 and a first pressure transmitting plate 32, a second pressure transmitting plate 33, and an elastic element 34 fixedly connected to each other. Here, the elastic element 34 is a spring. A first connecting hole 111 is provided on the first plate 11, and the first lead screw 31 is threaded to the first connecting hole 111. The elastic element 34 is located between the first pressure transmitting plate 32 and the second pressure transmitting plate 33. One end of the first lead screw 31 is connected to the first pressure transmitting plate 32, and the other end of the first lead screw 31 is connected to a first insertion tube 35, which is perpendicular to the first lead screw 31. The first pressure transmitting plate 32, the elastic element 34, and the second pressure transmitting plate 33 are welded into a whole. The first insertion tube 35 is welded to the first lead screw 31. The first insertion tube 35 is a rigid circular tube with an inner diameter of d0 and an outer diameter of d1, used to insert a rotating lever 5. The outer diameter of the rotating lever 5 is slightly smaller than d1. A nut 311 is provided on the first lead screw 31. By rotating the nut, the nut moves on the first lead screw 31 to limit the deformation of the compression spring.

[0057] In one embodiment, the shear force assembly 4 includes a second lead screw 41, a tension / compression sensor 42, and a third pressure transmission plate 43 interconnected with each other. A second connecting hole 141 is provided on the fourth plate 14, and the second lead screw 41 is threadedly connected to the second connecting hole 141. The tension / compression sensor 42 is disposed between the second lead screw 41 and the third pressure transmission plate 43. A second insertion tube 44 is connected to the end of the second lead screw 41 away from the tension / compression sensor 42. The tension / compression sensor 42 and the second lead screw 41 are detachably connected. The second lead screw 41 and the second insertion tube 44 are welded together. The second insertion tube 44 is a rigid circular tube with an inner diameter of d0 and an outer diameter of d1, used to insert the rotating lever 5.

[0058] Furthermore, the second lead screw 41 is provided with a cavity 411, and the tension / compression sensor 42 is provided with a protrusion 421. The protrusion 421 is adapted to enter the cavity 411 to connect the second lead screw and the tension / compression sensor 42. When the second lead screw 41 rotates, the tension / compression sensor 42 is displaced to the right, thereby causing the third pressure plate 43 to contact the outer wall surface of the shearing ring 2.

[0059] It should be understood that the third pressure plate 43 is provided with an arc-shaped recess 431, which matches the outer wall of the shearing ring blade 2. That is, the radius of curvature of the arc-shaped recess 431 is equal to that of the outer wall of the shearing ring blade 2. This results in more contact surface between the third pressure plate 43 and the shearing ring blade 2, and more accurate detection.

[0060] To facilitate manual operation, this device also includes accessories such as screw wrenches, levers, or handwheels that match the other components mentioned above.

[0061] The specific usage process of this device is as follows:

[0062] Step 1: The shearing ring cutter 2 in the above assembly structure is assembled inside the soil sampling drill bit to complete the on-site collection of the original root-containing soil with a diameter of D0 and a height of 3h, and there are two reserved shearing surfaces at the three-part splicing point of the shearing ring cutter 2.

[0063] Step 2: After being loaded with soil, the shearing ring cutter 2 is carefully loaded from top to bottom into the cup-shaped container 131131 in the lower space through the mounting hole 121 of the second plate of the frame, so as to avoid human damage.

[0064] Step 3: Place the first pressure transmission plate 311, elastic element 34 and second pressure transmission plate 33 of pressure assembly 3 on the upper surface of the soil-carrying ring cutter through the mounting hole 121, rotate the first lead screw 31 through the first connecting hole 111, and simultaneously install the nut 312 and keep it in a loose state so that the lower end of the first lead screw 31 just contacts the upper surface of the first pressure transmission plate 311.

[0065] Step 4: Insert the lever into the top cylinder of the first lead screw 31, manually rotate it to compress the spring by 1 / 4, generating a 50kPa normal pressure acting on the soil sample. Then, use a wrench to tighten the nut 311 in the opposite direction so that it is close to the bottom surface of the first plate 11, ensuring that the compression of the spring remains unchanged.

[0066] Step 5: Install the shear force assembly 4 through the second connecting hole 141 on the fourth plate 14 of the E-type frame 1. Insert the tension and compression sensor 42 and the third pressure transmission plate 43 into the front end of the second lead screw 41. Use a lever to pass through the second insertion tube 44 and rotate the second lead screw 41 until the third pressure transmission plate 43 just contacts the middle of the soil-carrying ring cutter. At this time, the pressure reading of the tension and compression sensor 42 is set to zero.

[0067] Step 6: Manually rotate the lever at a constant speed to make the shearing force component 4 spiral forward. The middle of the shearing ring cutter 2 will be displaced to the right, and the soil sample will be sheared and deformed from the two reserved shearing surfaces until the pressure reading of the tension and compression sensor 42 changes abruptly, and the soil sample shearing is completed.

[0068] Step 7: Repeat the above steps to collect soil samples. In Step 4, set pressure gradients of 100 kPa, 150 kPa, and 200 kPa respectively to conduct shear tests on the undisturbed soil samples. Record the shear force and shear displacement at shear failure. The shear strength parameters of the undisturbed soil samples are calculated according to Mohr's Coulomb law, using the following formula:

[0069] The shear strength τ is:

[0070]

[0071] The shear area S is:

[0072]

[0073] In the formula: F is the shear force, D0 is the soil sample diameter, and x is the shear displacement.

[0074] The present invention has the following advantages:

[0075] 1. This invention enables vertical pressurization and horizontal shearing assembly of soil samples by detachably connecting the shearing ring cutter, pressure component, and shearing force component to the frame. The frame of this design is small in size and light in weight, making it easy to disassemble, carry, and assemble in the field.

[0076] 2. The shearing ring cutter of the present invention consists of three ring cutters joined together, and the soil sample has two reserved shearing surfaces, which can realize the collection and shearing of undisturbed root-bearing soil.

[0077] 3. The pressure component of the present invention can apply pressure vertically and can be operated by hand in the field, avoiding the shortcomings of traditional devices such as weights and hydraulic systems that are inconvenient to carry and rely on electricity and fuel.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A field testing device for soil shear strength parameters containing root system components, characterized in that, include: The frame is equipped with mounting holes; A shearing ring cutter is used to load soil samples, and the shearing ring cutter is detachably inserted into the mounting hole; A pressure assembly, detachably connected to the frame and positioned above the mounting hole, applies pressure to the soil sample within the shearing ring from a first direction; A shearing force assembly is detachably connected to the frame and configured to apply pressure to the shearing ring cutter from a second direction, wherein the first direction is perpendicular to the second direction, the first direction is arranged along the axial direction of the shearing ring cutter, and the second direction is arranged along the shearing surface direction of the shearing ring cutter; The frame includes a first plate, a second plate, and a third plate arranged sequentially at intervals. The first plate, the second plate, and the third plate are connected by a fourth plate to make the frame E-shaped. A first space is formed between the first plate and the second plate. The pressure component is mounted on the first plate and partially located in the first space. A second space is formed between the second plate and the third plate. The shear force component is mounted on the fourth plate and partially located in the second space. The second plate has the mounting hole, through which the shearing ring blade passes; the first plate has the first connecting hole, through which the pressure component passes from the first direction; the fourth plate has the second connecting hole, through which the shearing force component passes from the second direction; the third plate has a container, with the bottom of the shearing ring blade disposed in the container; The shear force assembly includes a second lead screw, a tension / compression sensor, and a third pressure transmission plate that are interconnected with each other. The tension / compression sensor is disposed between the second lead screw and the third pressure transmission plate. A second insertion tube is connected to the end of the second lead screw away from the tension / compression sensor. The tension / compression sensor is detachably connected to the second lead screw.

2. The field testing device for soil shear strength parameters containing roots according to claim 1, characterized in that, The mounting hole is equal to the outer diameter of the shearing ring cutter; and / or The inner diameter of the container is equal to the outer diameter of the shearing ring.

3. The field testing device for soil shear strength parameters containing roots according to any one of claims 1 to 2, characterized in that, The shearing ring cutter includes a first ring cutter, a second ring cutter, and a third ring cutter, which are connected to each other.

4. The field testing device for soil shear strength parameters containing roots according to claim 1, characterized in that, The second lead screw has a cavity, and the tension / compression sensor has a protrusion that is adapted to enter the cavity to connect the second lead screw to the tension / compression sensor.

5. The field testing device for soil shear strength parameters containing roots according to claim 4, characterized in that, The third pressure plate is provided with an arc-shaped recess, which matches the outer wall of the shearing ring blade.

6. The field testing device for soil shear strength parameters containing roots according to any one of claims 1 to 2, characterized in that, The pressure assembly includes a first lead screw and a first pressure transmitting plate, a second pressure transmitting plate, and an elastic element that are fixedly connected to each other. The elastic element is located between the first pressure transmitting plate and the second pressure transmitting plate. One end of the first lead screw is connected to the first pressure transmitting plate, and the other end of the first lead screw is connected to a first insertion tube, which is perpendicular to the first lead screw.

7. The field testing device for soil shear strength parameters containing roots according to claim 6, characterized in that, A nut is provided on the first lead screw to limit the deformation of the elastic element.

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