A device and method for preparing sand and soil samples by water method

Abstract

The present invention discloses a device and method for preparing sand and soil samples using a water method, comprising a sample preparation tube and a three-axis sample preparation device. The sample preparation tube comprises a cylindrical tube, with upper and lower sealing covers respectively provided at both ends of the cylindrical tube. The ends of the upper and lower sealing covers facing the interior of the cylindrical tube are both provided with permeable stones. The end of the upper sealing cover facing the exterior of the cylindrical tube is connected to a control valve, which is in communication with the interior of the cylindrical tube. When preparing sand and soil samples using the water method, the sample preparation tube is placed in the three-axis sample preparation device, a test operating table is provided at the lower end of the three-axis sample preparation device, and a constraint ring is nested at the upper end of the three-axis sample preparation device. Saturated sand and soil samples with uniform density can be obtained.

Description

Technical Field

[0001] The invention belongs to the field of water-based sand and soil sample preparation, and relates to a water-based sand and soil sample preparation device and method. Background Art

[0002] Soil sampling is a fundamental step in geotechnical experiments. While researchers both domestically and internationally have attempted to obtain undisturbed samples by freezing, this method is limited in scope, often focusing on soft clays. Furthermore, the testing process is costly, and frozen samples are difficult to remove from the saturator due to ice cementation, resulting in incomplete frozen samples. Compared to clay, sand is more easily disturbed and difficult to obtain in its undisturbed state. Therefore, it is crucial to employ appropriate remolded sand sampling methods to simulate sands of varying origins in laboratory experiments. Currently, commonly used sand sampling methods include the layered wet tamping method and the raindrop method. Among them, the sand rain method prepares samples in the air. Although it can simulate the characteristics of natural sand deposition, its sample density is affected by the size of the sand outlet and the drop distance, which is difficult to control; the layered wet ramming method is one of the commonly used sample preparation methods for domestic and foreign scholars to study sand liquefaction. Its characteristic is that it can prepare samples with a large porosity ratio, but its limitations are also obvious, mainly manifested in severe soil stratification, so the uniformity of the sample is difficult to control; in addition, the traditional sand sampling method is easily disturbed by hydraulic action during the saturation process (passing airless water, back pressure saturation), causing structural changes in the soil, thereby affecting the test results. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a device and method for preparing sand samples by water method, which can obtain saturated sand samples with uniform density.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A device for preparing sand and soil samples by water method, comprising a sample preparation cylinder and a three-axis sample preparation device;

[0006] The sample preparation cylinder includes a cylindrical cylinder, and an upper sealing cover and a lower sealing cover are respectively sealed at both ends of the cylindrical cylinder. The ends of the upper sealing cover and the lower sealing cover facing the interior of the cylindrical cylinder are both provided with permeable stones. The end of the upper sealing cover facing the exterior of the cylindrical cylinder is connected to a control valve, and the control valve is communicated with the interior of the cylindrical cylinder.

[0007] When preparing sand and soil samples by water method, the sample preparation tube is arranged in the three-axis sample preparation device, the lower end of the three-axis sample preparation device is provided with a test operation table, and the upper end of the three-axis sample preparation device is nested with a constraint ring.

[0008] Preferably, rubber rings are provided at the connections between the upper sealing cover, the lower sealing cover and the cylindrical barrel.

[0009] Preferably, a spring-groove piston is provided inside the control valve.

[0010] Preferably, internal threads are provided at both ends of the cylindrical tube, external threads are provided on the circumferential surfaces of the upper sealing cover and the lower sealing cover, and the upper sealing cover and the lower sealing cover are respectively threadedly connected to the two ends of the cylindrical tube.

[0011] Preferably, a water valve is provided at one end of the lower sealing cover facing the outside of the cylindrical barrel, and the water valve is communicated with the inside of the cylindrical barrel.

[0012] Preferably, the upper sealing cover and the lower sealing cover are both made of tempered plastic, and the cylindrical barrel is made of tempered transparent plastic.

[0013] A method for preparing sand and soil samples using a water method based on any one of the above-mentioned devices comprises the following steps:

[0014] Step 1: Prepare sand and soil samples using either outdoor or indoor configuration;

[0015] When configuring outdoors, open the lower sealing cover and control valve of the cylinder in the outdoor site, press the end of the cylinder connected to the lower sealing cover into the sand, then close the control valve and lift the cylinder vertically upward to obtain the sand sample;

[0016] When configuring indoors, open the upper sealing cover of the water sample preparation device, inject water into the cylindrical tube, and add the test sand into the cylindrical tube; then seal the upper sealing cover and the cylindrical tube, close the control valve, and perform oscillation saturation for 5 to 10 minutes to obtain a sand sample;

[0017] Step 2: Take out the lower sealing cover of the sample preparation tube, nest the constraint ring at the upper end of the three-axis sample maker, place the test operating table at the bottom of the three-axis sample maker, place the sample preparation tube in the three-axis sample maker, lift the sample preparation tube to add the sand and soil sample into the three-axis sample maker, until all the sand and soil samples enter the three-axis sample maker from the sample preparation tube, first remove the constraint ring, and then take out the three-axis sample maker.

[0018] Preferably, after removing the restraint ring, first place a pressure plate above the sand sample, use a conduit plate to pass through the pressure plate and extend into the sand sample, apply 20-30kPa suction to the sand sample, take out the triaxial sampler, and wrap the latex film around the sand sample.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention utilizes the principle of atmospheric pressure to control the air pressure inside the sample preparation cylinder via a control valve. Under the influence of the pressure differential between atmospheric pressure and the air pressure inside the sample preparation cylinder, the original saturated sand sample can be directly extracted, reducing the disturbance of the soil sample. Based on the same principle, during the preparation and reshaping of the saturated sand sample, sufficient oscillation can be performed within the culture cylinder to ensure full contact between the sand and water, ultimately reaching a saturated state. By controlling the pressure differential, the soil sample is gradually placed inside the triaxial sample preparation device, thereby obtaining a saturated sand sample with uniform density. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the sample preparation tube device of the present invention;

[0022] Figure 2 This is a front view of the upper cover structure of the present invention;

[0023] Figure 3 This is a top view of the upper cover structure of the present invention;

[0024] Figure 4 This is a front view of the lower cover structure of the present invention;

[0025] Figure 5 This is a top view of the lower cover structure of the present invention;

[0026] Figure 6 A flow chart of the steps for preparing sand samples in the indoor configuration of the present invention;

[0027] Figure 7 This is a flow chart of the saturated sand sample loading steps of the present invention.

[0028] Among them: 1-cylindrical cylinder; 2-upper sealing cover; 3-lower sealing cover; 4-permeable stone; 5-control valve; 6-spring slot piston; 7-rubber ring; 8-preparation vessel; 9-funnel; 10-catheter; 11-three-axis sample maker; 12-test operating table; 13-restraint ring; 14-pressure plate; 15-filter paper; 16-latex film. DETAILED DESCRIPTION

[0029] The present invention is described in further detail below with reference to the accompanying drawings:

[0030] The device for preparing sand and soil samples by water method of the present invention comprises a sample preparation tube and a three-axis sample preparation device 11.

[0031] like Figure 1 As shown, the sample preparation tube includes a cylindrical tube 1, and an upper sealing cover 2 and a lower sealing cover 3 are respectively sealed at both ends of the cylindrical tube 1. The upper sealing cover 2 and the lower sealing cover 3 are both provided with a permeable stone 4 at one end facing the inside of the cylindrical tube 1, and the upper sealing cover 2 is connected to the end facing the outside of the cylindrical tube 1 with a control valve 5, which is connected to the inside of the cylindrical tube 1.

[0032] The upper and lower ends of the cylindrical tube 1 are both open, and both ends of the inner wall of the cylindrical tube 1 have internal threads. The upper sealing cover 2 and the lower sealing cover 3 are provided with external threads on their circumferential surfaces. The upper sealing cover 2 and the lower sealing cover 3 are respectively threadedly connected to the two ends of the cylindrical tube 1.

[0033] The connections between the upper sealing cover 2 and the lower sealing cover 3 and the cylindrical barrel 1 are both provided with rubber rings 7 to ensure sealing.

[0034] like Figure 4 and Figure 5 As shown, the upper sealing cover 2 and the lower sealing cover 3 are both made of tempered plastic. The thickness of the upper sealing cover 2 is 2 cm, and the thickness of the lower sealing cover 3 is 1 cm. A threaded hole is provided in the center of the upper sealing cover 2.

[0035] The cylindrical tube 1 is made of toughened transparent plastic, has a thickness of 5 mm and a height of 30 cm.

[0036] like Figure 2 and Figure 3 As shown, the control valve 5 is made of copper and is 15 cm long. A 2 cm long thread is provided at the lower end of the control valve 5, which engages with a threaded hole in the center of the upper sealing cover 2. A spring-loaded piston 6 is located within the control valve 5, which can be opened and closed by pressing, controlling the airflow and creating a pressure differential between the inside and outside.

[0037] When preparing sand and soil samples using the water method, the sample preparation tube is placed in the triaxial sample preparation device 11. The lower end of the triaxial sample preparation device 11 is provided with a test operation table 12, and the upper end of the triaxial sample preparation device 11 is nested with a constraint ring 13. The constraint ring 13 is used to fix the three-petal mold that constitutes the triaxial sample preparation device 11.

[0038] When using the device of the present invention to prepare sand and soil samples by water method, the following steps are included:

[0039] Step 1: Prepare sand and soil samples using either outdoor or indoor configuration;

[0040] During outdoor configuration, in an outdoor site with abundant water, open the lower sealing cover 3 and the control valve 5 of the cylindrical tube 1, press the end of the cylindrical tube 1 connected to the lower sealing cover 3 into the sand, then close the control valve 5, and lift the cylindrical tube 1 vertically upward to obtain an on-site saturated sand sample.

[0041] Indoor configuration, such as Figure 6 As shown, first determine the ratio of sand and water according to the saturated moisture content of different sands, take the test sand and place it in the preparation container 8, open the upper sealing cover 2 of the water sample preparation device, inject water into the cylindrical tube 1, and use the funnel 9 to add the test sand into the cylindrical tube 1; then seal the upper sealing cover 2 and the cylindrical tube 1, close the control valve 5, and perform oscillation saturation to obtain a sand sample.

[0042] Step 2, such as Figure 7 As shown, a three-axis sample preparation device 11 and a latex film 16 are installed on the test operating table 12, and the control valve 5 is opened. To ensure the success rate of sample preparation, the control valve 5 can be connected to the catheter 10. After applying a certain suction of 20-30kPa, the control valve 5 is closed. Unscrew the lower sealing cover 3 and stick the filter paper 15 on the lower end of the sample preparation tube. After the constraint ring 13 is nested at the upper end of the three-axis sample preparation device 11, the cylindrical tube 1 is placed into the three-axis sample preparation device 11, and the sample preparation tube is slowly lifted up so that the sand sample is slowly added into the three-axis sample preparation device 11. After this process is completed, the constraint ring 13 is removed, and a pressure plate 14 is installed above the sand sample. Suction is applied to the sand sample through the small holes in the pressure plate 14 and the catheter 10. Remove the three-axis sample preparation device 11, wrap the latex film 16 around the sand sample, and complete the installation of the sand sample.

[0043] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing sand and soil samples by water method, characterized in that: The invention comprises a water-based sand and soil sample preparation device, wherein the water-based sand and soil sample preparation device comprises a sample preparation cylinder and a three-axis sample preparation device (11); The sample preparation cylinder comprises a cylindrical cylinder (1), wherein both ends of the cylindrical cylinder (1) are respectively sealed with an upper sealing cover (2) and a lower sealing cover (3), and the ends of the upper sealing cover (2) and the lower sealing cover (3) facing the interior of the cylindrical cylinder (1) are both provided with a permeable stone (4), and the end of the upper sealing cover (2) facing the exterior of the cylindrical cylinder (1) is connected to a control valve (5), and the control valve (5) is communicated with the interior of the cylindrical cylinder (1); When the water method is used to prepare sand and soil samples, the sample preparation cylinder is arranged in the three-axis sample preparation device (11), the lower end of the three-axis sample preparation device (11) is provided with a test operation table (12), and the upper end of the three-axis sample preparation device (11) is nested with a constraint ring (13); The connections between the upper sealing cover (2) and the lower sealing cover (3) and the cylindrical barrel (1) are both provided with rubber rings (7); A spring-loaded piston (6) is provided inside the control valve (5); Internal threads are provided at both ends of the cylindrical barrel (1), external threads are provided on the circumferences of the upper sealing cover (2) and the lower sealing cover (3), and the upper sealing cover (2) and the lower sealing cover (3) are respectively threadedly connected to both ends of the cylindrical barrel (1); A water valve is provided at one end of the lower sealing cover (3) facing the outside of the cylindrical barrel (1), and the water valve is communicated with the inside of the cylindrical barrel (1); The water-based sand sample preparation method includes the following steps: Step 1: Prepare sand and soil samples using either outdoor or indoor configuration; When configuring outdoors, at an outdoor site, open the lower sealing cover (3) and the control valve (5) of the cylindrical tube (1), press the end of the cylindrical tube (1) connected to the lower sealing cover (3) into the sand, then close the control valve (5), and lift the cylindrical tube (1) vertically upward to obtain an on-site saturated sand sample; When configuring indoors, open the upper sealing cover (2) of the water-based sand sample preparation device, inject water into the cylindrical tube (1), and add the test sand into the cylindrical tube (1); then seal the upper sealing cover (2) and the cylindrical tube (1), close the control valve (5), and perform oscillation saturation for 5 to 10 minutes to obtain a sand sample; Step 2: Take out the lower sealing cover (3) of the sample preparation tube, nest the restraint ring (13) at the upper end of the triaxial sample preparation device (11), place the test operation table (12) at the bottom of the triaxial sample preparation device (11), place the sample preparation tube in the triaxial sample preparation device (11), lift the sample preparation tube to add the sand sample into the triaxial sample preparation device (11), until the sand sample enters the triaxial sample preparation device (11) from the sample preparation tube, first remove the restraint ring (13), and then take out the triaxial sample preparation device (11).

2. The method for preparing sand and soil samples by water method according to claim 1, characterized in that: The upper sealing cover (2) and the lower sealing cover (3) are both made of tempered plastic, and the cylindrical barrel (1) is made of tempered transparent plastic.

3. The method for preparing sand and soil samples by water method according to claim 1, characterized in that: After removing the restraining ring (13), first place a pressure plate on the sand sample, use the guide tube (10) to pass through the pressure plate and extend into the sand sample, apply 20-30kPa suction to the sand sample, take out the triaxial sample preparation device (11), and wrap the latex film (16) around the sand sample.

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