An in-situ testing device and method for shear strength index of simulated lunar soil

Abstract

The present invention provides an in-situ testing device and method for the shear strength index of simulated lunar soil, which relates to lunar soil detection equipment. The device includes: a loading platform; a crossbeam; a static penetration probe; a dense cylinder group, including a plurality of layered dense cylinders that are detachably connected in sequence along the vertical direction, each layered dense cylinder being used to hold simulated lunar soil of different densities; and a driving assembly that drives the crossbeam to move vertically and drives the static penetration probe to move, so that the static penetration probe is inserted into one of the layered dense cylinders. The beneficial effects of the present invention are as follows: by using a plurality of layered dense cylinders to hold simulated lunar soil of different densities, real in-situ undisturbed lunar soil is simulated, static penetration tests are performed on simulated lunar soils of different densities, a physical model between the shear strength index and resistance of the simulated lunar soil is established, and the shear strength index of the simulated lunar soil is measured, thereby reducing the test process, improving test efficiency, and reducing test costs during lunar exploration.

Description

Technical Field

[0001] The present invention relates to the technical field of lunar soil detection equipment, and in particular to an in-situ testing device and method for the shear strength index of simulated lunar soil. Background Art

[0002] The shear strength of lunar soil, including its internal friction angle and cohesion, reflects its maximum ability to resist shear failure and is a key mechanical property of lunar soil. Therefore, measuring the shear strength of lunar soil is a crucial aspect of lunar exploration.

[0003] The shear strength of lunar soil generally needs to be measured through indoor testing, but collecting lunar soil samples and transporting them back to Earth for testing is extremely difficult and costly. Furthermore, the drilling, sampling, and transportation of the test samples disturb the original structure of the lunar soil and release in situ stress, leading to certain errors in the test results. The testing process also consumes a certain amount of manpower and time. Therefore, in situ testing is necessary to characterize and test the shear strength of lunar soil. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides an in-situ testing device and method for the shear strength index of simulated lunar soil.

[0005] An embodiment of the present invention provides an in-situ testing device for the shear strength index of simulated lunar soil, comprising:

[0006] Loading gantry;

[0007] a crossbeam, which is vertically slidably mounted on the loading platform;

[0008] a static penetration probe rod, which is installed on the beam;

[0009] A dense cylinder group is located below the static penetration probe rod, and the dense cylinder group includes a plurality of layered dense cylinders, each of which is detachably connected in sequence along the vertical direction, and each of which is used to hold simulated lunar soil of different densities;

[0010] And a driving assembly, which includes a motor and a transmission mechanism connected to the motor, wherein the transmission mechanism is connected to the crossbeam to drive the crossbeam to move vertically and drive the static sounding probe to move, so that the static sounding probe is inserted into one of the layered dense cylinders.

[0011] Furthermore, the layered dense tube is a flange tube with connecting flanges at both ends, and the connecting flanges of two adjacent layered dense tubes are affixed and detachably connected by fasteners.

[0012] Furthermore, the transmission mechanism includes a chain mechanism, a worm gear mechanism and a screw mechanism, the motor is connected to the chain mechanism, the chain mechanism is connected to the worm gear mechanism, the worm gear mechanism is connected to the screw mechanism, and the screw mechanism is connected to the beam to drive the beam to move vertically.

[0013] Furthermore, the number of the driving assemblies is set to two, and the two driving assemblies are respectively connected to the two ends of the beam.

[0014] Furthermore, it also includes a controller, which is connected to the motor.

[0015] Furthermore, the number of the static penetration probe rods is set to be multiple, and the multiple static penetration probe rods are connected in sequence, and a static penetration probe head is provided at the lower end of the lowest static penetration probe rod.

[0016] Furthermore, it also includes a measuring head, which is connected to the static penetration probe and is used to convert the detection signal of the static penetration probe into cone tip resistance and side friction resistance.

[0017] Furthermore, the static penetration probe rod is vertically arranged at the midpoint of the beam.

[0018] Furthermore, a bearing platform is provided on the loading platform, and the layered dense cylinder is supported on the bearing platform.

[0019] An embodiment of the present invention further provides an in-situ testing method for the shear strength index of simulated lunar soil, using the above-mentioned in-situ testing device for the shear strength index of simulated lunar soil, and comprising the following steps:

[0020] S1. Prepare simulated lunar soil samples of different densities;

[0021] S2. Test the shear strength of simulated lunar soils of different densities through direct shear tests;

[0022] S3. Establish a physical model between the density and shear strength of the simulated lunar soil through regression method;

[0023] S4. Place the simulated lunar soil samples of each density into a set of dense cylinders;

[0024] S5. Drive the crossbeam downwardly by the drive assembly to penetrate the static penetration probe into the simulated lunar soil, and measure the resistance of the static penetration probe;

[0025] S6. Establishing a physical model simulating the relationship between the density of lunar soil and the resistance of the static penetration probe by using a regression method;

[0026] S7. Using the two physical models obtained in steps S3 and S6, a physical model is established between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe to measure the shear strength index of the simulated lunar soil.

[0027] The beneficial effects brought about by the technical solution provided by the embodiments of the present invention are: an in-situ testing device for the shear strength index of simulated lunar soil of the present invention uses multiple layered dense cylinders to hold simulated lunar soil of different densities to simulate real in-situ undisturbed lunar soil, and performs static penetration tests on simulated lunar soil of different densities to obtain the values ​​of the cone tip resistance and side friction resistance of the simulated lunar soil at different densities, and obtains the shear strength index of the simulated lunar soil through in-situ testing, and establishes a physical model between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe rod to measure the shear strength index of the simulated lunar soil. During the lunar exploration process, the test process is reduced, which can greatly improve the test efficiency and reduce the test cost, providing convenience for lunar exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of an in-situ testing device for the shear strength index of simulated lunar soil according to the present invention;

[0029] Figure 2 It is a schematic diagram of multiple layered dense cylinders;

[0030] Figure 3 It is a schematic diagram of the chain mechanism.

[0031] In the figure: 1. Controller; 2. Upper layer dense cylinder; 3. Lower layer dense cylinder; 4. Fasteners; 5. Loading stand; 6. Motor; 7. Sprocket; 8. Chain; 9. Screw mechanism; 10. Crossbeam; 11. Static sounding rod; 12. Threaded sleeve; 13. Static sounding probe; 14. Cable; 15. Measuring head. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the present invention more apparent, embodiments of the present invention will be further described below with reference to the accompanying drawings. The following describes a preferred embodiment of the present invention among multiple possible embodiments, which is intended to provide a basic understanding of the present invention but is not intended to identify the key or decisive elements of the present invention or to limit the scope of protection.

[0033] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0034] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0035] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in the subsequent drawings. At the same time, it should be understood that for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual scale.

[0036] It should be noted that, unless otherwise specified or limited, the terms "mounted" and "connected" should be understood broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0037] Please refer to Figure 1 An embodiment of the present invention provides an in-situ testing device for the shear strength index of simulated lunar soil, which mainly includes a loading platform 5, a beam 10, a static penetration probe rod 11, multiple dense cylinder groups and a drive assembly.

[0038] The loading platform 5 is a rectangular frame, and the interior of the loading platform 5 is a static penetration test space. The crossbeam 10 is mounted on the loading platform 5 so as to be vertically slidable. Here, the ends of the crossbeam 10 are slidably connected to the two sides of the two loading platforms 5, so that the crossbeam 10 can only slide in the vertical direction.

[0039] The static penetration probe rod 11 is installed on the crossbeam 10. The static penetration probe rod 11 is generally vertically arranged at the midpoint of the crossbeam 10. The vertical movement of the crossbeam 10 will drive the vertical movement of the static penetration probe rod 11. In some embodiments, the number of the static penetration probe rods 11 can be set to multiple, and the multiple static penetration probe rods 11 are threadedly connected in sequence through threaded sleeves 12. The lower end of the lowest static penetration probe rod 11 is provided with a static penetration probe 13. In this way, the overall length of the static penetration probe rod 11 can be extended, and the movement stroke of the crossbeam 10 can be reduced.

[0040] In some embodiments, the in-situ testing device for the shear strength index of the simulated lunar soil also includes a measuring head 15, which is connected to the static penetration probe 13 through a cable 14. The measuring head 15 is used to convert the detection signal of the static penetration probe 13 into cone tip resistance and side friction resistance.

[0041] Combine Figure 2As shown, the dense cylinder group is located below the static penetration probe rod 11. The dense cylinder group includes a plurality of layered dense cylinders, each of which is detachably connected in sequence along the vertical direction. Each of the layered dense cylinders is used to hold simulated lunar soil of different densities. The number of the layered dense cylinders can be flexibly set according to actual test needs. For example, in this embodiment, the number of the layered dense cylinders is set to two, namely, the upper layered dense cylinder 2 and the lower layered dense cylinder 3. It is understandable that the number of the layered dense cylinders can also be set to more, such as 7.

[0042] The layered compact tubes are generally constructed of tubes of the same diameter, with the ends of adjacent layered compact tubes completely aligned and detachably connected. In this embodiment, the layered compact tubes are flanged tubes with connecting flanges at both ends. The connecting flanges of two adjacent layered compact tubes are aligned and detachably connected via fasteners 4. Bolt holes are provided in the connecting flanges, and the fasteners 4 are bolts that pass through the bolt holes in the connecting flanges of the two adjacent layered compact tubes, thereby connecting the two layered compact tubes.

[0043] The driving assembly includes a motor 6 and a transmission mechanism connected to the motor 6. The transmission mechanism is connected to the crossbeam 10 to drive the crossbeam 10 to move vertically and drive the static penetration probe 11 to move, so that the static penetration probe 11 is inserted into one of the layered dense cylinders.

[0044] Specifically, such as Figure 1 and 3 As shown, the transmission mechanism includes a chain 8 mechanism, a worm gear mechanism and a screw mechanism 9. The motor 6 is connected to the chain 8 mechanism, the chain 8 mechanism is connected to the worm gear mechanism, the worm gear mechanism is connected to the screw mechanism 9, and the screw mechanism 9 is connected to the beam 10 to drive the beam 10 to move vertically. The chain 8 mechanism includes two sprockets 7 and a chain 8, the chain 8 is mounted on the two sprockets 7, the worm gear mechanism includes a worm wheel and a worm that mesh with each other, the screw mechanism 9 includes a screw and a slider, the slider is mounted on the screw, the motor 6 is connected to one sprocket 7, the other sprocket 7 is connected to the worm wheel, the screw is vertically arranged, the worm is connected to the screw, and the slider is connected to the beam 10. In this way, the motor 6 drives one sprocket 7 to rotate, driving the other sprocket 7 to rotate, so that the worm wheel and the worm are driven to drive the screw to rotate, thereby driving the slider to drive the beam 10 to move vertically.

[0045] In order to make the crossbeam 10 move vertically more smoothly, the number of the driving assemblies is set to two, and the two driving assemblies are respectively connected to the two ends of the crossbeam 10.

[0046] Furthermore, considering the need to accurately control the displacement of the motor 6 driving the vertical movement of the beam 10 , the in-situ testing device for the shear strength index of the simulated lunar soil also includes a controller 1 , which is connected to the motor 6 .

[0047] In some embodiments, the loading platform 5 is provided with a bearing platform on which the layered dense cylinder is supported. The layered dense cylinder is placed on the bearing platform, and the bearing platform provides a reaction force to the simulated lunar soil in the layered dense cylinder, without the need for an additional reaction force mechanism.

[0048] In addition, an embodiment of the present invention further provides an in-situ testing method for the shear strength index of simulated lunar soil, using the above-mentioned in-situ testing device for the shear strength index of simulated lunar soil, and comprising the following steps:

[0049] S1. Prepare simulated lunar soil samples of different densities.

[0050] S2. Test the shear strength index of simulated lunar soil with different densities through direct shear test.

[0051] Specifically, a mass of m3 of simulated lunar soil is poured into the shear box and vibrated to a density of Dr1. A direct shear apparatus is then used to shear the simulated lunar soil in the shear box until shear failure occurs. The shear strength indexes of the simulated lunar soil, cohesion c1 and internal friction angle, are calculated using the formula

[0052] S3. Establish a physical model simulating the relationship between lunar soil density and shear strength indicators through regression method.

[0053] S4. Place the simulated lunar soil samples of each density into a group of dense cylinders.

[0054] The measurement method of layer density is:

[0055] During the compaction process of the simulated lunar soil, the density of the simulated lunar soil in the compaction barrels is uneven due to gravity and external forces. To obtain the actual density of the simulated lunar soil in each layer of the compaction barrels, the layered density of the simulated lunar soil is measured. Taking two layers of compaction barrels as an example, the method for measuring the density of the simulated lunar soil in each layer of the compaction barrels is explained:

[0056] Tightly connect the upper layer dense barrel and the lower layer dense barrel;

[0057] Pour the simulated lunar soil of corresponding mass at different densities into two-layer compaction barrels, and compact them by vibration until the upper surface of the simulated lunar soil is flush with the upper edge of the upper layer compaction barrel 2;

[0058] Remove the screws connecting the two layered dense barrels, use an iron sheet to move the upper layered dense barrel 2 and the simulated lunar soil inside it along the lower edge of the barrel onto an electronic scale, and weigh the mass of the iron sheet, the upper layered dense barrel 2, and the simulated lunar soil inside as m1; pour out the simulated lunar soil in the barrel, and weigh the mass of the iron sheet and the upper layered dense barrel 2 as m2. The density is calculated as follows:

[0059]

[0060] Where: ρ dmax is the maximum dry density of simulated lunar soil, ρ dmin To simulate the minimum dry density of lunar soil, V is the volume of the upper layered dense barrel 2. These three parameters are all known values ​​that can be obtained through calculation.

[0061] S5. Drive the crossbeam 10 downward through the driving assembly, penetrate the static penetration probe 13 at the lower end of the static penetration probe rod 11 into the simulated lunar soil, and measure the resistance of the static penetration probe rod 11.

[0062] S6. Establish a physical model simulating the relationship between the density of the lunar soil and the resistance of the static penetration probe 11 through a regression method.

[0063] A mass of simulated lunar soil (m4) was poured into the compaction cylinder and vibrated to a density of Dr1. The static penetration test then began. The test results showed the cone tip resistance value (qc1) at a density of Dr1.

[0064] Here, the upper layered dense barrel 2 and the lower layered dense barrel 3 are first filled with simulated lunar soil and vibrated to a density of Dr1. Then the density of the two layered dense barrels is measured layer by layer. After the density measurement is completed, the simulated lunar soil is poured out from the simulated lunar soil samples in the two layered dense barrels. Then, the layered dense barrels are refilled with the same mass of simulated lunar soil and vibrated to a density of Dr1. Then, a static penetration test is carried out. During the static penetration test, the density of the simulated lunar soil in the upper layered dense barrel 2 and the lower layered dense barrel 3 is obtained by the previous layered measurement.

[0065] S7. Using the two physical models obtained in steps S3 and S6, a physical model is established between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe to measure the shear strength index of the simulated lunar soil.

[0066] When the density is Dr1, the shear strength index of the simulated lunar soil with a cone tip resistance of qc1 is c1 and In the relationship corresponding to the shear strength index, each density Dr value corresponds to a set of shear strength indexes c and In the corresponding relationship with the penetration resistance, each density Dr value corresponds to a cone tip resistance value qc. Taking the density Dr as the intermediate value, the penetration resistance is corresponded to the shear strength index, that is, each cone tip resistance value qc will have a set of shear strength indexes c and The value of corresponds to it, and through this method, a physical model of penetration resistance and shear strength index is established.

[0067] It should be noted that the direct shear test can be used to obtain the shear strength indexes of the simulated lunar soil at a certain density, namely, the cohesion c and the internal friction angle. However, direct shear testing is an indoor test and cannot obtain the relevant mechanical properties of undisturbed soil in situ. Therefore, a static penetration test was conducted within the in-situ test to determine the penetration resistance of the simulated lunar soil at the same density. A physical model was established by linking the shear strength index of the simulated lunar soil with its density through direct shear testing. A physical model was then established by linking the penetration resistance of the simulated lunar soil with its density through static penetration testing. Finally, the shear strength index of the simulated lunar soil was linked to the penetration resistance through its density, resulting in a physical model of the penetration resistance and shear strength index of the simulated lunar soil.

[0068] In this document, directional terms such as front, back, top, and bottom are defined based on the positions of components in the accompanying drawings and relative to each other, and are intended for clarity and convenience in describing the technical solution. It should be understood that these terms are relative and may vary depending on usage and placement. The use of these directional terms should not limit the scope of protection claimed in this application.

[0069] The above embodiments and features of the embodiments may be combined with each other unless they conflict. The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An in-situ testing method for the shear strength index of simulated lunar soil, characterized by: The test was conducted using an in-situ testing device for the shear strength index of simulated lunar soil, the testing device comprising: Loading gantry; a crossbeam, which is vertically slidably mounted on the loading platform; a static penetration probe rod, which is installed on the beam; A dense cylinder group is located below the static penetration probe rod, and the dense cylinder group includes two layered dense cylinders, which are detachably connected in sequence along the vertical direction; and a drive assembly comprising a motor and a transmission mechanism connected to the motor, wherein the transmission mechanism is connected to the crossbeam to drive the crossbeam to move vertically and drive the static penetration probe to move, so that the static penetration probe is inserted into one of the layered dense cylinders; The test method comprises the following steps: S1. Prepare simulated lunar soil samples of different densities; S2. Test the shear strength of simulated lunar soils of different densities through direct shear tests; S3. Establish a physical model between the density and shear strength of the simulated lunar soil through regression method; S4. placing the simulated lunar soil samples of each density into a group of the dense cylinders; S5. Drive the crossbeam downwardly by the drive assembly to penetrate the static penetration probe into the simulated lunar soil, and measure the resistance of the static penetration probe; S6. Establishing a physical model simulating the relationship between the density of lunar soil and the resistance of the static penetration probe by using a regression method; S7. Using the two physical models obtained in steps S3 and S6, a physical model is established between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe to measure the shear strength index of the simulated lunar soil; During the test, the upper and lower layered dense cylinders were first filled with simulated lunar soil and vibrated to a density of Dr1. The densities of the two layered dense cylinders were then measured layer by layer. After the density measurements were completed, the simulated lunar soil samples in the two layered dense cylinders were poured out. The two layered dense cylinders were then refilled with the same mass of simulated lunar soil and vibrated to a density of Dr1. The static penetration test was then carried out. During the static penetration test, the density of the simulated lunar soil in the upper and lower layered dense cylinders was obtained from the previous layered measurement. The measurement method of layer density is: Tightly connect the upper layer dense cylinder and the lower layer dense cylinder; Pour the corresponding masses of simulated lunar soil at different densities into two layers of layered compaction cylinders and compact them by vibration until the upper surface of the simulated lunar soil is flush with the upper edge of the upper layer of the layered compaction cylinder. Remove the screws at the connection between the two layered dense cylinders, use an iron sheet to move the upper layered dense cylinder along the lower edge of the cylinder, and transfer the upper layered dense cylinder and the simulated lunar soil inside the cylinder to an electronic scale. Weigh the mass of the iron sheet, the upper layered dense cylinder, and the simulated lunar soil inside the cylinder as m1; pour out the simulated lunar soil in the cylinder, and weigh the mass of the iron sheet and the upper layered dense cylinder as m2. The density is calculated as follows: ， Where: ρ dmax is the maximum dry density of the simulated lunar soil, ρ dmin To simulate the minimum dry density of lunar soil, V is the volume of the upper layer of dense cylinder.

2. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1, characterized in that: The layered dense tube is a flange tube with connecting flanges at both ends. The connecting flanges of two adjacent layered dense tubes are fitted together and detachably connected by screws.

3. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1, characterized in that: The transmission mechanism includes a chain mechanism, a worm gear mechanism and a screw mechanism. The motor is connected to the chain mechanism, the chain mechanism is connected to the worm gear mechanism, the worm gear mechanism is connected to the screw mechanism, and the screw mechanism is connected to the beam to drive the beam to move vertically.

4. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1 or 3, characterized in that: The number of the driving assemblies is set to two, and the two driving assemblies are respectively connected to the two ends of the beam.

5. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1, characterized in that: The testing device further includes a controller connected to the motor.

6. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1, characterized in that: The number of the static penetration probe rods is set to be multiple, and the multiple static penetration probe rods are connected in sequence, and a static penetration probe head is provided at the lower end of the lowest static penetration probe rod.

7. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 6, characterized in that: The testing device further comprises a measuring head connected to the static penetration probe, and the measuring head is used to convert the detection signal of the static penetration probe into cone tip resistance and side friction resistance.

8. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1, characterized in that: The static penetration probe rod is vertically arranged at the midpoint of the beam.

9. The in-situ testing method for the shear strength index of simulated lunar soil according to claim 1, characterized in that: A bearing platform is provided on the loading platform, and the dense cylinder group is supported on the bearing platform.

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