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

Abstract

The invention provides an in-situ test device and method for a shear strength index of simulated lunar soil, and relates to lunar soil detection equipment. A cross beam; a static sounding probe rod; the compacting cylinder group comprises a plurality of layered compacting cylinders which are detachably connected in sequence in the vertical direction, and the layered compacting cylinders are used for containing simulated lunar soil with different compacts; and the driving assembly drives the cross beam to vertically move and drives the static sounding probe rod to move, so that the static sounding probe rod is inserted into one of the layered compaction cylinders. The device has the beneficial effects that the simulated lunar soil with different compactness is contained in the plurality of layered compacting cylinders to simulate real in-situ undisturbed lunar soil, static sounding tests are performed on the simulated lunar soil with different compactness, and a physical model between the shear strength index and resistance of the simulated lunar soil is established to measure the shear strength index of the simulated lunar soil, so that the comprehensive performance of the simulated lunar soil is improved. In the moon exploration process, the test process is reduced, the test efficiency is improved, and the test cost is reduced.

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 shear strength index of simulated lunar soil. Background Art

[0002] The shear strength index of lunar soil includes internal friction angle and cohesion, which reflects the maximum ability of lunar soil to resist shear failure and is an important mechanical property of lunar soil. Therefore, measuring the shear strength index of lunar soil is an important part of lunar exploration.

[0003] The shear strength index of lunar soil generally needs to be measured through indoor tests, but collecting lunar soil samples and transporting them back to Earth for testing is very difficult and costly. In addition, during the drilling, sampling, and transportation of test samples, there are problems of disturbance to the original structure of the lunar soil and in-situ stress release. There will be certain errors in the test results, and the test process will also consume certain manpower and time costs. Therefore, it is necessary to characterize and test the shear strength index of lunar soil through in-situ testing. 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 rack;

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

[0008] A static penetration probe rod, which is installed on the crossbeam;

[0009] A compact cylinder group, located below the static penetration probe rod, comprising a plurality of layered compact cylinders, each of which is detachably connected in sequence along a vertical direction, and each of which is used to contain 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 rod to move, so that the static sounding probe rod 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 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 compacting cylinder is supported on the bearing platform.

[0019] The embodiment of the present invention further provides an in-situ testing method for the shear strength index of simulated lunar soil, using the 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 with different densities;

[0021] S2. Test the shear strength index of simulated lunar soil with different densities through direct shear test;

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

[0023] S4, placing each simulated lunar soil sample of a certain density into a group of dense cylinders;

[0024] S5, driving the crossbeam downward by the driving assembly, penetrating the static penetration probe into the simulated lunar soil, and measuring the resistance of the static penetration probe;

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

[0026] S7. Using the two physical models obtained in step S3 and step S6, a physical model between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe is established 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, which 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 soils 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 lunar exploration, the test process can be reduced, which can greatly improve the test efficiency and reduce the test cost, thereby providing convenience for lunar exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of an in-situ testing device for 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 probe rod; 12. threaded sleeve; 13. static sounding probe; 14. cable; 15. measuring head. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in conjunction with the accompanying drawings. The following is a preferred embodiment of the present invention, which is intended to provide a basic understanding of the present invention, but is not intended to confirm 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 as 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 as part of the specification.

[0035] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so 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 proportional relationship.

[0036] It should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to 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 stand 5, a beam 10, a static penetration probe rod 11, a plurality of dense cylinder groups and a driving 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 vertically slidably installed on the loading platform 5, and the two 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 contact probe rod 11 is installed on the crossbeam 10. The static contact probe rod 11 is generally vertically arranged at the midpoint of the crossbeam 10. The vertical movement of the crossbeam 10 will drive the static contact probe rod 11 to move vertically. In some embodiments, the number of the static contact probe rods 11 can be set to multiple, and the multiple static contact probe rods 11 are threadedly connected in sequence through threaded sleeves 12, and a static contact probe head 13 is provided at the lower end of the lowest static contact probe rod 11. In this way, the overall length of the static contact 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 simulated lunar soil also includes a measuring head 15, which is connected to the static penetration probe 13 via a cable 14, and 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] Combination Figure 2As shown, the dense cylinder group is located below the static penetration probe rod 11, 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. The number of the layered dense cylinders can be flexibly set according to the actual test needs. For example, in this embodiment, the number of 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 be set to more, such as 7.

[0042] The layered dense tube generally selects a tube body with the same diameter, and the ends of adjacent layered dense tubes are completely fitted and detachably connected. In this embodiment, 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 fitted and detachably connected through fasteners 4. Bolt holes are provided on the connecting flanges, and the fasteners 4 are bolts. The fasteners 4 pass through the bolt holes on the connecting flanges of the two adjacent layered dense tubes, thereby connecting the two layered dense tubes.

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

[0044] Specifically, 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 cross beam 10 to drive the cross beam 10 to move vertically. The chain 8 mechanism includes two sprockets 7 and a chain 8, the chain 8 is sleeved 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 sleeved on the screw, the motor 6 is connected to one of the sprockets 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 cross beam 10, so that the motor 6 drives one of the sprockets 7 to rotate and drives 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 cross beam 10 to move vertically.

[0045] In order to make the cross beam 10 move vertically more smoothly, the number of the driving components is set to two, and the two driving components are respectively connected to the two ends of the cross beam 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 simulated lunar soil also includes a controller 1 , which is connected to the motor 6 .

[0047] In some embodiments, a bearing platform is provided on the loading platform 5, and the layered dense cylinder is supported on the bearing platform. 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, and no additional reaction force mechanism is required.

[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, the simulated lunar soil with a mass of m3 is poured into the shear box, vibrated and compacted until the density reaches Dr1, and the simulated lunar soil in the shear box is sheared using a direct shear instrument until the simulated lunar soil is sheared. The shear strength index of the simulated lunar soil, cohesion c1 and internal friction angle, are calculated by 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 each simulated lunar soil sample of different density into a group of dense cylinders.

[0054] The measurement method of layer density

[0055] In the process of simulating the compaction of lunar soil, due to the effects of gravity and external forces, the density of the simulated lunar soil in the compaction barrel group is unevenly distributed. In order to obtain the true density of the simulated lunar soil in each layer of the compaction barrel, the layered density of the simulated lunar soil is measured. Taking two layers of compaction barrels as an example, the measurement method of the density of the simulated lunar soil in each layer of the compaction barrel group is explained:

[0056] The upper layer dense barrel and the lower layer dense barrel are tightly connected;

[0057] Pour the simulated lunar soil of corresponding mass under different densities into the two-layer compaction barrel, and make the upper surface of the simulated lunar soil just flush with the upper edge of the upper layer compaction barrel 2 by vibration compaction method;

[0058] Remove the screws at the connection of the two layered dense barrels, use an iron sheet to transfer the upper layered dense barrel 2 and the simulated lunar soil in the barrel to an electronic scale along the lower edge of the upper layered dense barrel 2, and weigh the mass of the iron sheet, the upper layered dense barrel 2 and the simulated lunar soil in the barrel as m1; pour out the simulated lunar soil in the barrel, weigh the mass of the iron sheet and the upper layered dense barrel 2 as m2, and the calculation formula for density is as follows:

[0059]

[0060] Where: 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, and 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. A physical model simulating the compactness of lunar soil and the resistance of the static penetration probe 11 is established by regression method.

[0063] The simulated lunar soil with a mass of m4 was poured into the compaction cylinder group and compacted by vibration until the density reached Dr1, and then the static penetration test was started. The test results showed that the cone tip resistance value qc1 when the density was 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 sounding experiment is carried out. During the static sounding experiment, 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 step S3 and step S6, a physical model between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe is established 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. 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, cohesion c and internal friction angle. However, the direct shear test is an indoor test and cannot obtain the relevant mechanical properties of the undisturbed soil in situ. Therefore, the penetration resistance of the simulated lunar soil at the same density is obtained through the static penetration test in the in-situ test. Through the direct shear test, the shear strength index of the simulated lunar soil and the density are used to establish a physical model; then, through the static penetration test, the penetration resistance of the simulated lunar soil and the density are used to establish a physical model. Finally, the shear strength index of the simulated lunar soil is linked to the penetration resistance through the density, and the physical model of the penetration resistance and shear strength index of the simulated lunar soil is obtained.

[0068] In this article, the directional words such as front, back, top, and bottom involved are defined by the positions of the parts in the drawings and the positions of the parts relative to each other, just for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different ways of use and placement, and the use of the directional words should not limit the scope of protection claimed in this application.

[0069] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An in-situ testing device for the shear strength index of simulated lunar soil, characterized in that: include: Loading rack; A crossbeam which is vertically slidably mounted on the loading platform; A static penetration probe rod, which is installed on the crossbeam; A compact cylinder group, located below the static penetration probe rod, comprising a plurality of layered compact cylinders, each of which is detachably connected in sequence along a vertical direction, and each of which is used to contain simulated lunar soil of different densities; 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 rod to move, so that the static sounding probe rod is inserted into one of the layered dense cylinders.

2. The in-situ testing device for 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, and the connecting flanges of two adjacent layered dense tubes are abutted and detachably connected by fasteners.

3. The in-situ testing device for 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 crossbeam to drive the crossbeam to move vertically.

4. An in-situ testing device for 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 device for shear strength index of simulated lunar soil according to claim 1, characterized in that: A controller is also included, and the controller is connected to the motor.

6. The in-situ testing device for 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 device for shear strength index of simulated lunar soil according to claim 6, characterized in that: 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.

8. The in-situ testing device for 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 crossbeam.

9. The in-situ testing device for 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 layered compacting cylinder is supported on the bearing platform.

10. An in-situ test method for the shear strength index of simulated lunar soil, characterized by: An in-situ testing device for shear strength index of simulated lunar soil as described in any one of claims 1 to 9 is used, and the device comprises the following steps: S1. Prepare simulated lunar soil samples with different densities; S2. Test the shear strength index of simulated lunar soil with different densities through direct shear test; S3. Establish a physical model between the density and shear strength of the simulated lunar soil through regression method; S4, placing each simulated lunar soil sample of a certain density into a group of the dense cylinders; S5, driving the crossbeam downward by the driving assembly, penetrating the static penetration probe into the simulated lunar soil, and measuring the resistance of the static penetration probe; S6. Establishing a physical model between the simulated lunar soil density and the resistance of the static penetration probe rod by regression method; S7. Using the two physical models obtained in step S3 and step S6, a physical model between the shear strength index of the simulated lunar soil and the resistance of the static penetration probe is established to measure the shear strength index of the simulated lunar soil.

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