Soil liquid-plastic limit tester

Abstract

The invention discloses a soil liquid-plastic limit tester, which comprises a sample cylinder, a conveyor belt, a measurement and control part, a water adding part, a stirring part and a conical part, and is characterized in that the sample cylinder is used for placing a soil sample; the one or more sample cylinders are mounted on the conveyor belt and move along with the conveyor belt, and the conveyor belt can perform reciprocating bidirectional movement; the measurement and control part is used for controlling the water adding part to add a preset amount of water into the sample cylinder, and / or controlling the stirring part to uniformly stir the water and the soil sample in the sample cylinder; the cone part comprises a cone instrument and a cone depth sensor, and the measurement and control part is used for controlling the cone instrument to fall and measuring the sinking depth of the cone instrument in a soil sample through the cone depth sensor. The soil liquid-plastic limit tester can automatically complete the soil liquid-plastic limit test, and compared with the soil liquid-plastic limit test based on manual operation in the prior art, particularly the prior art needs manual soil adjustment and repeated attempts to make the cone depth accord with the specification, the soil liquid-plastic limit tester greatly reduces the time and effort required by the test.

Description

Technical Field

[0001] This application relates to the field of geotechnical engineering testing and inspection, and more specifically, to a soil liquid limit and plastic limit tester. Background Technology

[0002] Soil liquid and plastic limits are important concepts in soil mechanics, encompassing both the liquid limit and the plastic limit. The liquid limit (WL) refers to the critical water content at which soil transitions from a plastic to a fluid state, representing the upper limit of soil moisture content. The plastic limit (WP) refers to the critical water content at which soil transitions from a plastic to a semi-solid state, representing the lower limit of soil moisture content. Soil liquid and plastic limits are typically determined through soil liquid and plastic limit tests. This test is a crucial component of geotechnical engineering testing, and the obtained data are essential for soil engineering classification and performance evaluation.

[0003] Existing methods for testing the liquid and plastic limits of soil are based on manual operation. The main steps include crushing the soil sample, adding a certain amount of water to the soil sample, mixing the soil sample and water evenly, and measuring the drop cone depth of the conic disc. If the measured cone depth is less than or greater than the cone depth required by the standard, water needs to be added to the soil sample or some of the water in the soil sample needs to be dried. After mixing evenly, the drop cone depth of the conic disc is measured again until the measured cone depth meets the cone depth required by the standard. The cone depth value is recorded and the moisture content of the soil sample is determined by the drying method. The above steps are repeated three times. Based on the three sets of cone depth values ​​and moisture content data obtained from the test, the liquid and plastic limits of the soil sample are calculated by the graphical method.

[0004] Existing soil liquid and plastic limit tests are cumbersome, often requiring multiple trials to prepare soil paste that precisely meets the cone depth specifications. The oven-drying method for determining moisture content requires drying in an oven for over 8 hours, a manual process that is time-consuming, labor-intensive, and inefficient. Furthermore, the cone depth specifications vary across different industries, requiring researchers to adhere to different specifications, further complicating the process. In addition, the oven-drying method calculates moisture content by measuring the weight change of the soil sample before and after drying. This process can be susceptible to measurement errors due to inadequate cleaning of the drying container, wear and tear on the container, and uneven mixing of the soil sample. Consequently, the obtained moisture content data may not exhibit an ideal linear relationship with the cone depth value, making it difficult to determine the liquid and plastic limits of the soil sample. Summary of the Invention

[0005] To at least partially solve the above-mentioned technical problems, this application proposes a soil liquid limit and plastic limit tester.

[0006] The device includes a sample cylinder, a conveyor belt, a measurement and control unit, a water addition unit, a stirring unit, and a conical part, wherein the sample cylinder is used to hold soil samples;

[0007] One or more of the sample cylinders are mounted on the conveyor belt and move with the conveyor belt, which is capable of bidirectional reciprocating movement.

[0008] The measurement and control unit is used to control the water addition unit to add a predetermined amount of water into the sample cylinder, and / or to control the stirring unit to mix the water and soil sample in the sample cylinder evenly; and

[0009] The conical part includes a conic section and a cone depth sensor. The measurement and control unit is used to control the descent of the conic section and to measure the sinking depth of the conic section in the soil sample through the cone depth sensor.

[0010] Preferably, the soil sample is a sample with an initial moisture content of 0 or a known moisture content.

[0011] Preferably, the measurement and control unit controls the water adding unit to add a predetermined amount of water into the sample cylinder according to the set water addition amount.

[0012] Preferably, the stirring unit includes a stirrer and a telescopic rod, the lower end of which is connected to the stirrer. The measurement and control unit is used to control the extension and retraction of the telescopic rod so as to stir the water and soil sample in the sample tube evenly through the stirrer.

[0013] Preferably, the mixing unit includes a compactor and a second telescopic rod, the lower end of which is connected to the compactor. The control unit is used to control the extension and retraction of the second telescopic rod to compress the soil sample through the compactor.

[0014] Preferably, when the cone angle of the conic section contacts the soil sample, the measurement and control unit releases the conic section, and the conic section falls into the soil sample solely by its own weight.

[0015] Preferably, the measurement and control unit calculates the moisture content of the soil sample based on the weight and initial moisture content of the soil sample and the amount of water added to the soil sample.

[0016] Preferably, the measurement and control unit calculates the liquid and plastic limits of the soil sample based on the sinking depth of the cone penetrometer and the water content of the soil sample.

[0017] Preferably, the soil liquid and plastic limit tester moves bidirectionally back and forth via the conveyor belt, repeatedly adding water to a soil sample multiple times and completing subsequent stirring and cone dip depth measurement. From the multiple sets of moisture content-depth data obtained, the data that meets the requirements and has the best linear relationship is selected to calculate the liquid and plastic limits of the soil sample.

[0018] Preferably, the soil liquid limit and plastic limit tester is a semi-automatic or fully automatic device.

[0019] This application also proposes a method for determining the liquid and plastic limits of soil, including the following steps:

[0020] A soil sample with known mass and moisture content is placed in a sample tube, and a predetermined amount of water is added to the sample tube.

[0021] Stir the water and soil sample in the sample tube until homogeneous;

[0022] The conic section is lowered into the sample cylinder, and the depth of the conic section in the soil sample is measured.

[0023] The soil moisture content is calculated based on the mass and moisture content of the soil sample and the volume of water added, and the soil liquid limit and plastic limit are calculated based on the soil moisture content and the subsidence depth.

[0024] The technical solution of this application improves the existing soil liquid and plastic limit test method and invents a new type of test equipment. The soil liquid and plastic limit tester of this application automatically controls the water addition unit to add a predetermined amount of water to a soil sample of known mass through the measurement and control unit, thereby achieving the purpose of knowing the moisture content of the soil sample. The control unit automatically mixes and compacts the soil sample, and the control unit automatically releases the cone apparatus. It also sets or records the parameters of each test step, and can automatically complete the soil liquid and plastic limit test. Since the moisture content of the soil sample is known and combined with the measured cone depth, the liquid and plastic limit value of the soil sample can be calculated at the same time. Compared to existing technologies that rely on manual operation for soil liquid and plastic limit testing, especially those requiring repeated manual stirring and adjustments to ensure the cone depth meets specifications, which can easily lead to uneven mixing and directly affect test results, the soil liquid and plastic limit tester of this application significantly reduces the time and effort required for the test and increases accuracy. Furthermore, the test method of this application can directly calculate the moisture content of the soil sample by adding a set amount of water to a soil sample with known moisture content or a dried sample. Unlike existing technologies that require measuring the moisture content of soil samples through drying, this method avoids the measurement errors of the drying method that lead to non-ideal linear relationships in the test results, making it difficult to determine the liquid and plastic limits of the soil sample and requiring rework.

[0025] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application, and the illustrative embodiments and descriptions thereof are used to explain this application. It should be understood that the drawings are illustrative, and the originals and elements are not necessarily drawn to scale. In the drawings:

[0027] Figure 1 The front view of the soil liquid limit and plastic limit tester is shown.

[0028] Explanation of the attached drawing numbers:

[0029] 1-Water reservoir, 2-Pressure plug, 3-Conduit, 4-Sample cylinder, 5-Conveyor belt, 6-House, 7-Agitator, 8-Compactor, 9-Cone concentrator, 10-Telescopic rod, 11-Cone depth sensor, 12-Control panel, 13-Calculator. Detailed Implementation

[0030] The technical solution of this application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Figure 1 A front view of the soil liquid limit and plastic limit tester according to this application is shown. Figure 1 As shown, the device includes a sample cylinder, a conveyor belt, a measurement and control unit, a water supply unit, a stirring unit, and a conical unit, wherein the sample cylinder is used to hold soil samples.

[0032] In some embodiments, the soil liquid limit and plastic limit tester of this application is a semi-automatic or fully automatic device.

[0033] In some embodiments, the soil measured by the soil liquid limit and plastic limit tester of this application is fine-grained soil.

[0034] In some embodiments of this application, the initial moisture content of the soil sample is 0, that is, the initial soil sample is a dried sample, or the soil sample is a sample with a known moisture content.

[0035] In this application, the initial moisture content of the soil sample refers to the moisture content of the soil sample when it is loaded into the sample tube.

[0036] In some embodiments, the sample cylinder 4 is cylindrical, with a sealed bottom and an open top.

[0037] In some embodiments, the soil liquid limit and plastic limit tester of this application further includes a housing 6.

[0038] In some embodiments, the measurement and control unit is able to measure and record the weight of the soil sample in the sample tube.

[0039] In some embodiments, the operator sets the amount of water added to the sample cylinder by the water addition unit in the measurement and control unit, inputs the weight of the soil sample, inputs the initial moisture content of the soil sample, and records the sinking depth of the cone penetrator in the soil sample.

[0040] In some embodiments, the measurement and control unit includes a control panel 12 and a calculator 13. The control panel 12 is located at the lower part of the housing 6 and is used for interaction with the operator. The calculator 13 is located at the upper part of the housing 6. The calculator 13 calculates the moisture content of the soil sample before measuring the cone depth based on the weight and initial moisture content of the soil sample and the amount of water added by the water adding part. Combined with the recorded sinking depth of the cone in the soil sample, the calculator calculates the liquid limit and plastic limit of the soil sample.

[0041] In the soil liquid limit and plastic limit tester of this application, one or more sample cylinders are mounted on a conveyor belt and move with the conveyor belt, which is capable of bidirectional reciprocating movement.

[0042] In some embodiments, the conveyor belt 5 is located on one side of the housing 6. Driven by a motor, the sample cylinder 4 moves with the conveyor belt 5. When the sample cylinder 4 moves below the water addition section, the stirring section, and the conical section, the measurement and control unit automatically controls the water addition section, the stirring section, and the conical section to perform their respective test operations. In some embodiments, when the center of the sample cylinder 4 is on a vertical line with the guide tube 3, the stirrer 7, the compactor 8, and the conical instrument 9, the measurement and control unit automatically performs water addition, stirring, compaction, and conical instrument release operations.

[0043] In the soil liquid limit and plastic limit tester of this application, the measurement and control unit is used to control the water addition unit to add a predetermined amount of water into the sample cylinder.

[0044] In some embodiments of this application, the measurement and control unit controls the water adding unit to add a predetermined amount of water into the sample cylinder according to the set water addition amount. In some other embodiments, the measurement and control unit controls the water adding unit to add a fixed amount of water into the sample cylinder according to the water addition amount set or defaulted by the device operator.

[0045] In some embodiments, the water filling section includes a water reservoir 1, a pressure plug 2, and a conduit 3. The pressure plug 2 is located on one side of the water reservoir 1 and is used to control the amount of water added each time. The conduit 3 is located on the other side of the water reservoir 1 and the added water flows into the sample cylinder 4 through the conduit 3.

[0046] In the soil liquid limit and plastic limit tester of this application, the measurement and control unit is used to control the stirring unit to stir the water and soil sample in the sample tube evenly.

[0047] In some embodiments of this application, the stirring unit includes a stirrer and a telescopic rod. The lower end of the telescopic rod is connected to the stirrer. The measurement and control unit is used to control the extension and retraction of the telescopic rod so as to stir the water and soil sample in the sample tube evenly through the stirrer.

[0048] In some embodiments of this application, the mixing unit includes a compactor and a second telescopic rod. The lower end of the second telescopic rod is connected to the compactor. The measurement and control unit is used to control the extension and retraction of the second telescopic rod so as to squeeze the soil sample through the compactor, expel the air in the soil sample, and make the soil sample dense.

[0049] In some embodiments, the upper ends of the telescopic rod 1 connecting the agitator and the telescopic rod 2 connecting the compactor are both connected to the housing 6.

[0050] In some embodiments, the stirrer 7 is connected to the lower end of the telescopic rod 1, the lower end of the stirrer 7 is connected to the stirring head, and a sealing cap is provided in the middle of the stirrer 7, the diameter of the sealing cap being slightly larger than the outer diameter of the sample cylinder 4.

[0051] In some embodiments, one end of the compactor 8 is connected to the lower end of the telescopic rod 2, and a disc is provided at the other end of the compactor 8. The diameter of the disc is slightly smaller than the inner diameter of the sample cylinder 4, and small holes are provided on the disc.

[0052] In the soil liquid and plastic limit tester of this application, the conical part includes a conical instrument and a cone depth sensor. The measurement and control unit is used to control the descent of the conical instrument and to measure the descent depth of the conical instrument in the soil sample through the cone depth sensor.

[0053] In some embodiments of this application, when the cone angle of the conic section contacts the soil sample, the measurement and control unit releases the conic section, and the conic section falls and sinks into the soil sample by its own weight.

[0054] In some embodiments, the conic section 9 is connected to the lower end of the telescopic rod 3, and the measurement and control unit controls the extension of the telescopic rod 3 so that the cone angle of the conic section contacts the soil sample.

[0055] In some embodiments, the upper end of the telescopic rod three connecting the cone apparatus is connected to the housing 6.

[0056] In some embodiments, the cone depth sensor 11 is located on the upper part of the housing 6 and is used to measure the sinking depth of the cone apparatus 9 as it falls freely into the soil sample.

[0057] In some embodiments of this application, the measurement and control unit calculates the moisture content of the soil sample based on the weight and initial moisture content of the soil sample and the amount of water added to the soil sample.

[0058] In this application, the moisture content of the soil sample refers to the moisture content of the soil sample during the cone depth test.

[0059] In some embodiments of this application, the measurement and control unit calculates the liquid and plastic limits of the soil sample in a double logarithmic coordinate system based on the sinking depth of the cone penetrometer and the water content of the soil sample.

[0060] In some embodiments of this application, the soil liquid and plastic limit tester moves bidirectionally back and forth by a conveyor belt, repeatedly adding water to a soil sample multiple times and completing subsequent stirring and cone dip depth measurement. From the multiple sets of moisture content-depth data obtained, the data that meets the requirements and has the best linear relationship is selected to calculate the liquid and plastic limits of the soil sample.

[0061] The method for determining the liquid and plastic limits of soil in this application includes the following steps:

[0062] A soil sample with known mass and moisture content is placed in a sample tube, and a predetermined amount of water is added to the sample tube.

[0063] Stir the water and soil sample in the sample tube until they are evenly mixed.

[0064] The conic section is lowered into the sample tube, and the depth of the conic section in the soil sample is measured.

[0065] The soil moisture content is calculated based on the mass and moisture content of the soil sample and the volume of water added, and the soil liquid limit and plastic limit are calculated based on the soil moisture content and the subsidence depth.

[0066] The following will use a soil liquid limit and plastic limit test as an example to further illustrate this point.

[0067] In this example, the soil liquid limit and plastic limit test includes the following steps:

[0068] ① Place the sample tube on the conveyor belt below the water tank, weigh a certain amount of dried sample (100g as an example) or a sample with known moisture content and put it into the sample tube. Enter the sample mass and initial moisture content on the control panel (the initial moisture content of the dried sample is 0).

[0069] ② Set the water volume for each addition on the control panel. Different water volumes can be selected depending on the soil properties. For example, for silt, you can set 10mL, 5mL, 5mL, 5mL… corresponding to soil moisture content of 10%, 15%, 20%, 25%… after each addition and mixing. For clay, you can set 20mL, 10mL, 10mL, 10mL… corresponding to soil moisture content of 20%, 30%, 40%, 50%… after each addition and mixing. After setting, click "Start Test" on the control panel.

[0070] ③ The pressure plug injects water from the water reservoir into the sample cylinder through the conduit according to the set water volume.

[0071] ④ Driven by the motor, the conveyor belt moves the sample tube to the bottom of the stirrer. The stirrer descends under the action of the telescopic rod, and the stirring head enters the sample tube. The sealing cover seals the sample tube to prevent the sample and water from being lost. The stirring head rotates to mix the sample and water evenly. After the stirring is finished, the stirrer rises under the action of the telescopic rod. During the rising process, the stirring head rotates as it rises, so that the sample carried on the stirring head completely falls off before leaving the sample tube.

[0072] ⑤ After the stirrer rises, the conveyor belt, driven by the motor, moves the sample cylinder to the bottom of the compactor. The compactor, driven by the telescopic rod, descends, expelling the gas in the sample from the small hole on the disc at the bottom of the compactor, thus compacting the sample.

[0073] ⑥ After the sample is compacted, the compactor rises under the drive of the telescopic rod, and the conveyor belt moves the sample cylinder to the bottom of the cone apparatus under the drive of the motor. The cone apparatus descends under the drive of the telescopic rod and stops descending when the cone tip just touches the sample surface.

[0074] ⑦ After the telescopic rod stops descending, the cone apparatus sinks into the sample under its own weight, and the cone depth sensor records the depth of the cone apparatus sinking.

[0075] ⑧ Driven by the motor, the conveyor belt moves the sample cylinder to the bottom of the water tank again, and repeats the test process from ③ to ⑦ to test the cone sinking depth corresponding to other moisture contents.

[0076] ⑨ The calculator calculates the moisture content of the sample before each cone depth measurement based on the sample mass, initial moisture content and amount of water added as set on the control panel. Based on the cone depth recorded by the cone depth sensor and the cone depth measured after each water addition, the calculator plots the moisture content-cone depth relationship graph in a double logarithmic coordinate system.

[0077] ⑩ The testers selected a set of data that met industry requirements and had the best linear relationship based on the moisture content-cone depth correspondence diagram, and thus obtained the liquid limit and plastic limit of the sample.

[0078] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the specific details in the above embodiments. The above embodiments are only for illustrative purposes and are not intended to limit the scope of protection of this invention.

[0079] Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and all such simple modifications fall within the protection scope of this application. It should also be noted that the specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not describe the various possible combinations separately. Furthermore, various different embodiments of this application can also be arbitrarily combined, as long as they do not violate the spirit of this application, and should also be considered as part of the content disclosed in this invention.

[0080] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; and the term "some embodiments" means "at least some embodiments".

Claims

1. A soil liquid and plastic limit tester, characterized in that, The device includes a sample cylinder, a conveyor belt, a measurement and control unit, a water addition unit, a stirring unit, and a conical part, wherein the sample cylinder is used to hold soil samples; One or more of the sample cylinders are mounted on the conveyor belt and move with the conveyor belt, which is capable of bidirectional reciprocating movement. The measurement and control unit is used to control the water addition unit to add a predetermined amount of water into the sample cylinder, and / or to control the stirring unit to mix the water and soil sample in the sample cylinder evenly; and The conical part includes a conic section and a cone depth sensor. The measurement and control unit is used to control the descent of the conic section and to measure the sinking depth of the conic section in the soil sample through the cone depth sensor.

2. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, The soil sample is a sample with an initial moisture content of 0 or a known moisture content.

3. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, The measurement and control unit controls the water addition unit to add a predetermined amount of water into the sample cylinder according to the set water addition amount.

4. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, The stirring unit includes a stirrer and a telescopic rod. The lower end of the telescopic rod is connected to the stirrer. The measurement and control unit is used to control the extension and retraction of the telescopic rod so as to stir the water and soil sample in the sample tube evenly through the stirrer.

5. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, The mixing unit includes a compactor and a second telescopic rod. The lower end of the second telescopic rod is connected to the compactor. The measurement and control unit is used to control the extension and retraction of the second telescopic rod to compress the soil sample through the compactor.

6. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, When the cone angle of the conic section contacts the soil sample, the measurement and control unit releases the conic section, and the conic section falls and sinks into the soil sample by its own weight.

7. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, The measurement and control unit calculates the moisture content of the soil sample based on its weight, initial moisture content, and the amount of water added to the soil sample.

8. The soil liquid limit and plastic limit tester according to claim 7, characterized in that, The measurement and control unit calculates the liquid and plastic limits of the soil sample based on the sinking depth of the cone penetrometer and the water content of the soil sample.

9. The soil liquid limit and plastic limit tester according to claim 8, characterized in that, The soil liquid and plastic limit tester moves bidirectionally back and forth via the conveyor belt, repeatedly adding water to a soil sample multiple times and completing subsequent stirring and cone dip depth measurement. From the multiple sets of moisture content-depth data obtained, the data that meets the requirements and has the best linear relationship is selected to calculate the liquid and plastic limits of the soil sample.

10. The soil liquid limit and plastic limit tester according to claim 1, characterized in that, The soil liquid limit and plastic limit tester is a semi-automatic or fully automatic device.

11. A method for determining the liquid and plastic limits of soil, characterized in that, The method includes the following steps: A soil sample with known mass and moisture content is placed in a sample tube, and a predetermined amount of water is added to the sample tube. Stir the water and soil sample in the sample tube until homogeneous; The conic section is lowered into the sample cylinder, and the depth of the conic section in the soil sample is measured. The soil moisture content is calculated based on the mass and moisture content of the soil sample and the volume of water added, and the soil liquid limit and plastic limit are calculated based on the soil moisture content and the subsidence depth.

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