Test device and test method for maximum dry density test of sand

Abstract

The present invention discloses a testing device and a testing method for a maximum dry density test of sand and soil. The testing device includes a base, a sample container, a fixed platform, a compacting assembly, a vibration assembly, and a control assembly. The sample container is used to hold a soil sample to be tested. The fixed platform is fixedly connected to the base, and the fixed platform is provided with a first fixed groove for installing the sample container. The compacting assembly includes a driving device and a compacting hammer. The driving device is connected to the base, and the compacting hammer is coaxially arranged with the sample container. The driving device drives the compacting hammer to rise. The vibration assembly includes a vibrator and a percussion hammer. The vibrator is installed at the bottom of the fixed platform, and the percussion hammer is installed on the fixed platform. When the vibrator is started, the percussion hammer swings and percusses the side wall of the sample container. The control assembly is electrically connected to the driving device, and the control assembly is electrically connected to the vibration assembly. When compacting the soil sample to be tested, the testing device drives the percussion hammer to percuss the sample container through the vibrator, thereby reducing the porosity of the soil sample and reducing the test error.

Description

Technical Field

[0001] The present invention relates to the technical field of testing devices, in particular to a testing device and a testing method for a maximum dry density test of sand. Background Art

[0002] The maximum dry density test is a basic physical property test experiment that must be carried out on sand samples before various tests are carried out. It is one of the most basic physical parameters to characterize soil properties. The maximum dry density of soil is very important for measuring the degree of density and for subsequent geotechnical test research and the establishment of engineering construction plans. In the existing technology, the compaction equipment used for soil samples repeatedly compacts the soil samples with a compacting hammer. During the compaction process, a vibrating fork is used to knock on both sides of the container at a certain frequency to assist in vibration compaction. The equipment requires at least two people to collaborate in the test, which consumes manpower costs. The striking intensity or frequency of the compacting hammer and the vibrating fork cannot be restored during the parallel tests of different groups, resulting in the test results being seriously affected by human factors. Summary of the Invention

[0003] In order to solve at least one of the above technical problems, the present invention provides a testing device and a testing method for a maximum dry density test of sand, and the technical solutions adopted are as follows:

[0004] The testing device for the maximum dry density test of sand provided by the present invention includes a base, a sample container, a fixed platform, a compaction assembly, a vibration assembly, and a control assembly. The sample container is used to hold the soil sample to be tested; the fixed platform is fixedly connected to the base, and the fixed platform is provided with a first fixed groove for installing the sample container; the compaction assembly includes a driving device and a compaction hammer, the driving device is connected to the base, the compaction hammer is coaxially arranged with the sample container, and the driving device drives the compaction hammer to rise; the vibration assembly includes a vibrator and a knock hammer, the vibrator is installed at the bottom of the fixed platform, and the knock hammer is installed on the fixed platform. When the vibrator is started, the knock hammer swings and knocks the side wall of the sample container; the control assembly is electrically connected to the driving device, and the control assembly is electrically connected to the vibration assembly.

[0005] In certain embodiments of the present invention, the testing device includes an insulation component, which includes a heating wire, a heat conductor, and a temperature sensor. The heating wire is electrically connected to the control component, and the temperature sensor is electrically connected to the control component. The temperature sensor is installed at the bottom of the sample container to monitor the temperature of the soil sample to be tested, and the heating wire is connected to the sample container through the heat conductor.

[0006] In certain embodiments of the present invention, the heat conducting member is configured as a cylindrical structure, the heating wire is fixed to the cylindrical structure, the side wall of the sample container is provided with a slot corresponding to the cylindrical structure, and the cylindrical structure is made of metal.

[0007] In certain embodiments of the present invention, the testing device includes a telescopic member, and the knock hammer is mounted on the fixed platform via the telescopic member, and the telescopic member is used to keep the knock hammer in contact with the side walls of sample containers of different specifications.

[0008] In certain embodiments of the present invention, the compacting hammer includes a guide column and a weight slidably mounted on the guide column. The guide column is coaxially arranged with the sample container. The weight falls freely along the guide column to compact the soil sample to be tested in the sample container.

[0009] In certain embodiments of the present invention, the driving device includes a driving member and a transmission chain, the transmission chain is equipped with a driving block, the heavy hammer is provided with a driving groove corresponding to the driving block, and the driving block and the driving groove can be contacted and connected to drive the heavy hammer to rise during the rotation of the transmission chain.

[0010] In certain embodiments of the present invention, the compaction assembly includes a mounting frame, the drive device is fixed to the mounting frame, and the base includes a support column, which is threadedly connected to the mounting frame to adjust the height distance of the drive device relative to the base.

[0011] In certain embodiments of the present invention, the testing device includes a plurality of buffer springs, one end of each buffer spring is connected to the fixed platform, and the other end of each buffer spring is connected to the base.

[0012] The present invention also provides a testing method for a maximum dry density test of sand, comprising:

[0013] Take the dried or fully air-dried soil sample to be tested and pour it into the sample container three times;

[0014] heating the soil sample in the sample container and maintaining the surface temperature of the soil sample at a first preset temperature;

[0015] Level the surface of the soil sample and press it slightly. After the surface temperature of the soil sample stabilizes at the first preset temperature, start compacting the first layer of soil. While compacting, knock on the side wall of the sample container. Repeat compacting the surface of the soil sample until the volume of the soil sample remains unchanged.

[0016] Perform the second and third sample loading, tapping, and compacting. Before the third sample loading, install a collar on the opening of the sample container;

[0017] After the last compaction is completed, remove the ring and use a soil trimmer to scrape off excess soil sample flush with the top surface of the container. Weigh the mass of the soil sample in the sample container and record the volume of the soil sample, and calculate the maximum dry density of the soil sample.

[0018] In certain embodiments of the present invention, before pouring the soil sample to be tested into the sample container, the soil sample is kneaded by hand or rolled on a rubber plate with a round wooden stick to be evenly mixed.

[0019] Embodiments of the present invention have at least the following beneficial effects: The testing device is equipped with a compaction assembly and a vibration assembly. While compacting the soil sample to be tested, the device simultaneously vibrates and strikes the sample container with a hammer, promoting particle rearrangement and reducing the intergranular spaces within the soil sample. This effectively reduces the risk of interlocking particles causing breakage during compaction, thereby enhancing test results. By setting different container volumes, the particle size range of the sand sample tested can be expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 Schematic diagram of the structure of the test device for the maximum dry density test of sand;

[0022] Figure 2 for Figure 1 A schematic cross-sectional view of the provided test apparatus;

[0023] Figure 3 for Figure 2 A schematic diagram of the structure of the compaction assembly in the provided test device;

[0024] Figure 4 for Figure 2 A schematic diagram of the structure of the compaction assembly in the provided test device;

[0025] Figure 5 for Figure 2 Schematic diagram of the structure of the insulation component in the provided test device.

[0026] : Reference numerals: 110, base; 111, support column; 112, foot cup; 120, fixed platform; 121, buffer spring; 130, sample container; 200, compaction assembly; 210, drive device; 211, drive member; 212, transmission chain; 213, drive block; 214, reduction gearbox; 215, mounting bracket; 220, guide column; 221, palm plate; 230, heavy hammer; 310, vibrator; 320, knocking hammer; 330, telescopic member; 410, heating wire; 420, heat conductor; 430, temperature sensor; 500, control assembly; 600, display assembly. DETAILED DESCRIPTION

[0027] The following combination Figures 1 to 5 Embodiments of the present invention are described in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0028] In the description of the present invention, it should be understood that if the terms "center", "middle", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The features defined as "first" and "second" are used to distinguish the feature names, and do not have special meanings. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0029] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may 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 the above terms in the present invention based on the specific circumstances.

[0030] The maximum dry density test is a basic physical property test experiment that must be carried out on sand samples before various tests are carried out. It is one of the most basic physical parameters to characterize soil properties. The maximum dry density of soil is very important for the measurement of density and subsequent calculations in engineering practice. In the existing technology, the vibration compaction equipment used for soil samples repeatedly compacts the soil samples with a compacting hammer, and uses a vibrating fork to knock on both sides of the container at a certain frequency during the compaction process to assist in vibration compaction. During the parallel tests of different groups, the knocking intensity or frequency of the compacting hammer and the vibrating fork cannot be restored, resulting in the test results being seriously affected by human factors. At the same time, for sand samples with irregular particle shapes that are prone to interlocking, it is difficult to rearrange the particles to the maximum density state by compaction alone, which will also lead to large deviations in the results of the maximum dry density test.

[0031] The present invention relates to a testing device for a maximum dry density test of sand and soil. The testing device comprises a base 110, a sample container 130, a fixed platform 120, a compacting assembly 200, a vibration assembly, and a control assembly 500. The sample container 130 is used to hold a soil sample to be tested. The fixed platform 120 is fixedly connected to the base 110 and is provided with a first fixing groove for mounting the sample container 130. The compacting assembly 200 comprises a driving device 210 and a compacting hammer. The driving device 210 is connected to the base 110 and the compacting hammer is coaxially arranged with the sample container 130. The driving device 210 drives the compacting hammer to rise. The vibration assembly comprises a vibrator 310 and a striking hammer 320. The vibrator 310 is mounted on the bottom of the fixed platform 120 and the striking hammer 320 is mounted on the fixed platform 120. When the vibrator 310 is started, the striking hammer 320 swings and strikes the side wall of the sample container 130. The control assembly 500 is electrically connected to the driving device 210 and the control assembly 500 is electrically connected to the vibration assembly. The testing device is provided with a compaction component 200 and a vibration component. While compacting the soil sample to be tested, the sample container 130 is struck by a hammer 320 to reduce the pores between particles inside the soil sample, so as to make the test results more accurate.

[0032] It is understood that in some embodiments, the fixed platform 120 is further provided with a second fixed groove for accommodating a larger-sized sample container 130, so that the testing device is suitable for soil sample tests of containers of different specifications. Specifically, the second fixed groove is coaxially arranged with the first fixed groove, and the use of a larger-sized sample container 130 helps to eliminate the boundary effect of smaller particles, while being able to test sand materials with a wider range of particle sizes. In this embodiment, the first fixed groove is suitable for fixing a sample container 130 with an inner diameter of 50 mm, and the second fixed groove is suitable for fixing a sample container 130 with an inner diameter of 100 mm. In other embodiments, the specifications of the first fixed groove and the second fixed groove can be adjusted according to the test requirements.

[0033] Furthermore, the testing device includes a heat preservation assembly, which includes a heating wire 410, a heat conductor 420, and a temperature sensor 430. The heating wire 410 is electrically connected to the control assembly 500, and the temperature sensor 430 is electrically connected to the control assembly 500. The temperature sensor 430 is installed at the bottom of the sample container 130 to monitor the temperature of the soil sample to be tested. The heating wire 410 is connected to the sample container 130 through the heat conductor 420. It can be understood that the provision of a heat preservation assembly to maintain the soil sample in the sample container 130 at a constant temperature can not only eliminate the influence of temperature changes on the density of the soil sample during the test and improve the accuracy of the test results, but also can adjust the temperature of the soil sample in the sample container 130 through the heating wire 410 and the heat conductor 420 to make it closer to the ambient temperature in actual engineering applications in different regions, thereby providing more reliable test data for subsequent engineering practice.

[0034] With reference to the accompanying drawings, the heat conductor 420 is configured as a cylindrical structure, and the sidewall of the sample container 130 is provided with a slot corresponding to the cylindrical structure. Specifically, multiple heating wires 410 are provided, and the multiple heating wires 410 are evenly distributed along the axial direction of the cylindrical structure to improve heat conduction efficiency and evenly heat the soil sample within the sample container 130. It will be understood that the heat conductor 420 is configured as a metal component to better transfer heat from the heating wire 410 to the sample container 130, thereby changing the temperature of the soil sample. In this embodiment, the heating wire 410 is disposed within the heat conductor 420, that is, the heating wire 410 is integrally fixed within the heat conductor 420 during the manufacturing process to better transfer heat from the heating wire 410 to the heat conductor 420. To accommodate different processing requirements, the heating wire 410 can also be fixed to the sidewall of the cylindrical structure by gluing or other methods to achieve heat transfer.

[0035] Furthermore, the testing device includes a telescopic member 330, and the knocking hammer 320 is installed on the fixed platform 120 through the telescopic member 330. It can be understood that the telescopic member 330 is used to keep the knocking hammer 320 in contact with the side walls of the sample containers 130 of different specifications, thereby ensuring that when the vibrator 310 is started, the knocking hammer 320 can drive the internal particles of the soil sample to roll by knocking on the side walls of the sample container 130, thereby reducing the pores between the soil sample particles during the compaction process. Specifically, the telescopic member 330 has a fixed end fixedly connected to the fixed platform 120 and a telescopic end connected to the knocking hammer 320. In this embodiment, the telescopic end adopts a pull rod structure for step-by-step adjustment, which is the same as the principle of the luggage case pull rod structure. In other embodiments, the telescopic member 330 can also be provided with a stepless adjustment structure to adjust the distance between the telescopic end and the fixed end.

[0036] Specifically, the striking hammer 320 includes a swinging portion fixedly connected to the telescopic end of the telescopic member 330 and a striking portion for striking the side wall of the sample container 130. In this embodiment, the striking portion is configured as a stainless steel cylindrical structure, and the swinging portion is configured as a spring. The spring should have a longitudinal stiffness greater than a transverse stiffness to limit the swinging direction of the striking portion, so that the striking portion continuously strikes the side wall of the sample container 130 under the action of the vibrator 310, causing the soil sample particles to rearrange, thereby making the soil sample to be tested more compact under the dual action of vibration and striking, thereby improving the accuracy of the test results. It is understood that in other embodiments, the swinging portion can also be configured as a flexible rod structure that can shake, and the striking portion can be configured as a spherical structure or other structure.

[0037] With reference to the accompanying drawings, the compacting hammer includes a guide post 220 and a weight 230 slidably mounted on the guide post 220. The guide post 220 is coaxially arranged with the sample container 130. The weight 230 freely falls along the guide post 220 to compact the soil sample to be tested in the sample container 130. It can be understood that the guide post 220 is used to limit the direction of the weight 230's fall so that it can repeatedly compact the soil sample in the sample container 130. Specifically, a palm plate 221 is provided at the end of the guide post 220 that extends into the sample container 130. The palm plate 221 is loosely fitted with the inner wall of the sample container 130. The weight 230 freely falls to the palm plate 221 and applies a uniform impact force to the surface of the soil sample through the palm plate 221 to enhance the compaction effect while preventing excessive local pressure from causing soil sample particles to break.

[0038] Furthermore, the drive device 210 includes a drive member 211 and a transmission chain 212. It will be appreciated that a reduction gearbox 214 is disposed between the drive member 211 and the transmission chain 212 to regulate the rotational speed of the transmission chain 212. The transmission chain 212 is equipped with a drive block 213. A weight 230 is provided with a drive slot corresponding to the drive block 213. The drive block 213 is in contact with the drive slot to drive the weight 230 upward during rotation of the transmission chain 212. Specifically, the weight 230 has a first position after free fall and a second position after being raised. After the drive block 213 drives the weight 230 from the first position to the second position, the drive block 213 drops out of the drive slot. Under the action of gravity, the weight 230 free falls from the second position to the first position to compact the soil sample surface. In this embodiment, two drive blocks 213 are provided, evenly spaced along the transmission chain 212 to ensure that the interval between two consecutive drops of the weight is equal, facilitating calculation of the number of tests. In other embodiments, an intermittent motion mechanism such as a ratchet structure or a groove wheel structure may be used to achieve the lifting and free fall of the weight 230 .

[0039] Furthermore, the compaction assembly 200 includes a mounting bracket 215, to which the drive device 210 is fixed, and the base 110 includes a support column 111, which is threadedly connected to the mounting bracket 215 to adjust the height distance of the drive device 210 relative to the base 110. Referring to the accompanying drawings, an adjustment thread is provided at one end of the support column 111 connected to the mounting bracket 215, and an adjustment nut is connected to the mounting bracket 215. By rotating the adjustment nut, the relative height between the mounting bracket 215 and the base 110 can be adjusted, and the drive device 210 and the mounting bracket 215 can also be leveled. In other embodiments, the relative distance between the mounting bracket 215 and the support column 111 can also be adjusted by snapping or plugging.

[0040] Furthermore, the testing device includes a plurality of buffer springs 121, one end of the buffer spring 121 is connected to the fixed platform 120, and the other end is connected to the base 110. It can be understood that the buffer spring 121 is provided between the fixed platform 120 and the base 110 to provide a vibration margin for the fixed platform 120. In conjunction with the accompanying drawings, the fixed platform 120 is also provided with a avoidance hole for accommodating the support column 111. The support column 111 and the avoidance hole are clearance-matched to avoid interference with the support column 111 when the fixed platform 120 vibrates. In some embodiments, the plurality of buffer springs 121 are evenly distributed at the four corners of the fixed platform 120. In conjunction with the accompanying drawings, in this embodiment, four buffer springs 121 are provided, and the four buffer springs 121 are respectively provided at the four corners of the fixed platform 120. In other embodiments, the plurality of buffer springs 121 can also be evenly arranged along the circumference of the sample container 130 to ensure the horizontality of the fixed platform 120 while providing a buffering effect for the fixed platform 120.

[0041] Specifically, in this embodiment, each of the four legs of the base 110 is provided with a foot cup 112 to support the test device and perform a leveling operation. The specific structure and leveling operation of the foot cup 112 belong to the prior art and will not be described in detail here.

[0042] Furthermore, the testing device includes a display component 600, which is electrically connected to the control component 500. The display component 600 is used for the test personnel to read the test parameters such as soil sample temperature, number of hammer drops, vibration frequency, etc. in real time, which facilitates the recording of the test and the calculation of the test results.

[0043] The present invention also provides a testing method for a maximum dry density test of sand, comprising:

[0044] Pour the soil sample to be tested, which has been dried or fully air-dried, into the sample container 130 in three batches;

[0045] heating the soil sample in the sample container 130 and maintaining the surface temperature of the soil sample at a first preset temperature;

[0046] Level the surface of the soil sample and slightly compress it. After the surface temperature of the soil sample stabilizes at a first preset temperature, begin compacting the first layer of soil. While compacting, tap the side wall of the sample container 130. Repeatedly compact the surface of the soil sample until the volume of the soil sample remains unchanged.

[0047] Perform the second and third sample loading, tapping, and compacting. Before the third sample loading, install a collar at the opening of the sample container 130;

[0048] After the last compaction, remove the ring, use a soil trimmer to scrape off excess soil sample flush with the top surface of the container, weigh the mass of the soil sample in the sample container 130 and record the volume of the soil sample, and calculate the maximum dry density of the soil sample.

[0049] Furthermore, before pouring the soil sample to be tested into the sample container 130, it is kneaded by hand or rolled on a rubber pad with a wooden stick to disperse and mix it evenly. It is understood that the soil sample to be tested is pre-treated, and the vibration and tapping operations during the test process change the particle arrangement within the soil sample, reduce the pores between the particles, and make the soil sample reach the densest state for compaction, thereby obtaining more reliable test data.

[0050] The testing device and testing method provided by the present invention implement multiple processes on the soil sample being tested, including vibration, compaction, and tapping on the sidewalls. This prevents irregularly shaped particles from interlocking through their edges and corners, causing the particles within the soil sample to roll, reducing pores and achieving the densest state for compaction. This improves the accuracy of the test results and prevents particle breakage caused by compacting the loose soil sample. The testing device also includes an insulation component to regulate the temperature of the soil sample within the sample container 130, eliminating the impact of the test environment on the temperature of the soil sample, making the test results more reliable for subsequent engineering applications.

[0051] Throughout this specification, references to "one embodiment," "some examples," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" refer to specific features, structures, materials, or characteristics described in conjunction with the embodiment or example in at least one embodiment or example of the present invention. In this specification, the illustrative use of these terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0052] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A testing device for maximum dry density test of sand, characterized by: include Base (110); A sample container (130), wherein the sample container (130) is used to contain a soil sample to be tested; A fixed platform (120), the fixed platform (120) is fixedly connected to the base (110), and the fixed platform (120) is provided with a first fixing groove for mounting the sample container (130); A compacting assembly (200), the compacting assembly (200) comprising a driving device (210) and a compacting hammer, the driving device (210) being connected to the base (110), the compacting hammer being coaxially arranged with the sample container (130), and the driving device (210) driving the compacting hammer to rise; A vibration assembly, the vibration assembly comprising a vibrator (310) and a knock hammer (320), the vibrator (310) being mounted on the bottom of the fixed platform (120), the knock hammer (320) being mounted on the fixed platform (120), and when the vibrator (310) is started, the knock hammer (320) swings and knocks the side wall of the sample container (130); a control component (500), the control component (500) being electrically connected to the driving device (210), and the control component (500) being electrically connected to the vibration component; A heat preservation component, the heat preservation component comprising a heating wire (410), a heat conducting member (420), and a temperature sensor (430); the heating wire (410) is electrically connected to the control component (500); the temperature sensor (430) is electrically connected to the control component (500); the temperature sensor (430) is installed at the bottom of the sample container (130) to monitor the temperature of the soil sample to be tested; the heating wire (410) is connected to the sample container (130) through the heat conducting member (420); the heat conducting member (420) is configured as a cylindrical structure; the heating wire (410) is fixed to the cylindrical structure; a slot corresponding to the cylindrical structure is provided on the side wall of the sample container (130); the cylindrical structure is made of metal; A telescopic member (330), the striking hammer (320) is mounted on the fixed platform (120) via the telescopic member (330), and the telescopic member (330) is used to keep the striking hammer (320) in contact with the side walls of sample containers (130) of different specifications.

2. The testing device for maximum dry density test of sand according to claim 1, characterized in that: The compacting hammer comprises a guide post (220) and a weight (230) slidably sleeved on the guide post (220); the guide post (220) and the sample container (130) are coaxially arranged; the weight (230) falls freely along the guide post (220) to compact the soil sample to be tested in the sample container (130).

3. The testing device for maximum dry density test of sand according to claim 2, characterized in that: The driving device (210) comprises a driving member (211) and a transmission chain (212); the transmission chain (212) is provided with a driving block (213); the weight (230) is provided with a driving slot corresponding to the driving block (213); the driving block (213) and the driving slot can be in contact and connected to each other so that the weight (230) is driven to rise during the rotation of the transmission chain (212).

4. The testing device for maximum dry density test of sand according to claim 2, characterized in that: The compaction assembly (200) includes a mounting frame (215), the driving device (210) is fixed to the mounting frame (215), and the base (110) includes a support column (111), and the support column (111) is threadedly connected to the mounting frame (215) to adjust the height distance of the driving device (210) relative to the base (110).

5. The testing device for maximum dry density test of sand according to any one of claims 1 to 4, characterized in that: The testing device comprises a plurality of buffer springs (121), one end of each buffer spring (121) is connected to the fixed platform (120), and the other end is connected to the base (110).

6. A test method for maximum dry density of sand, characterized in that: The testing device for testing the maximum dry density of sand according to any one of claims 1 to 5, further comprising: Take the dried or fully air-dried soil sample to be tested and pour it into the sample container three times; heating the soil sample in the sample container and maintaining the surface temperature of the soil sample at a first preset temperature; Level the surface of the soil sample and press it slightly. After the surface temperature of the soil sample stabilizes at the first preset temperature, start compacting the first layer of soil. While compacting, knock on the side wall of the sample container. Repeat compacting the surface of the soil sample until the volume of the soil sample remains unchanged. Perform the second and third sample loading, tapping, and compacting. Before the third sample loading, install a collar on the opening of the sample container; After the last compaction is completed, remove the ring and use a soil trimmer to scrape off excess soil sample flush with the top surface of the container. Weigh the mass of the soil sample in the sample container and record the volume of the soil sample, and calculate the maximum dry density of the soil sample.

7. The method for testing the maximum dry density of sand according to claim 6, wherein: Before pouring the soil sample to be tested into the sample container, rub it with your hands or use a round wooden stick to roll it on a rubber board and mix it evenly.

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