Fine-grained soil saturation control test device and test method thereof

Abstract

The application discloses a kind of fine-grained soil saturation control test devices, it is related to geotechnical engineering equipment technical field, and its technical scheme main points are as follows: including round hole tray, moisture cylinder and with its airtight combination moisture cylinder cover, round hole tray is bolted with fine-grained soil sample, sample ring cutter, upper water-permeable stone and lower water-permeable stone, moisture cylinder cover is equipped with six round holes, is fixed with dropping tube in round hole through rubber plug, dropping tube outlet is opposite fine-grained soil sample, dropping tube is connected with hose, infusion bottle in sequence, hose is equipped with control switch;The application also discloses the test method of the test device: including the following steps: S1: sampling;S2: calculate water supplement amount;S3: fixed sample on round hole tray;S4: sample is placed in moisture cylinder;S5: install water supplement device;S6: continue to water;S7: calculate saturation, and carry out soil mechanics test.The application has the effects of reasonable structure, reliable performance, convenient operation, data acquisition is convenient, accurate, low carbon green, preparation efficiency is high.

Description

A test apparatus and test method for controlling the saturation of fine-grained soil Technical Field

[0001] This invention relates to the field of geotechnical engineering equipment technology, and more specifically, to a test device and test method for controlling the saturation of fine-grained soil. Background Technology

[0002] Unsaturated fine-grained soils are widely found in nature, and testing their characteristic parameters presents numerous challenges. Controlling the saturation level of fine-grained soil samples in laboratory tests is one of the fundamental technical conditions affecting the testing of the physical and mechanical properties of unsaturated soils, such as strength, permeability, and deformation. Simulating the actual working conditions of fine-grained soils with different saturations in the laboratory is currently one of the difficulties in laboratory geotechnical testing, and corresponding testing equipment and methods are lacking. Current domestic and international geotechnical testing standards also lack corresponding test method specifications. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned problems by providing a fine-grained soil saturation control test device and its test method. The device has a reasonable structure, reliable performance, convenient operation, and easy data acquisition. It solves the problem of unifying indoor simulation and actual working conditions of fine-grained soil with different saturation levels, and provides a basic technical path for indoor testing of the physical and mechanical properties of unsaturated fine-grained soil. It can provide scientific and accurate technical parameters for geotechnical engineering investigation, design, and construction.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a fine-grained soil saturation control test device, comprising a perforated tray, a moisturizing cylinder, and a moisturizing cylinder cover, wherein the moisturizing cylinder and the moisturizing cylinder cover are sealed together; the top of the perforated tray is provided with six fine-grained soil samples in a single layer and symmetrically arranged at the center; the bottom and top surfaces of the fine-grained soil samples are covered with filter paper; the bottom and top of the fine-grained soil samples are respectively provided with a lower permeable stone and a perforated upper permeable stone; the top and bottom surfaces of the perforated upper permeable stone are respectively provided with a circular steel pressure ring and a sample ring cutter for cutting the fine-grained soil samples; the circular steel pressure ring is provided with two fixing screws. The circular steel pressure ring is used to detachably fix the fine-grained soil sample, the sample ring cutter, the upper permeable stone, and the lower permeable stone to the top surface of the circular tray via two fixing bolts. The moisturizing cylinder cover has six symmetrically distributed circular holes, each containing a rubber stopper. A dropper is inserted through the center of the rubber stopper and is connected to the outside and the inner cavity of the moisturizing cylinder. The center position of the dropper outlet corresponds to the center position of the fine-grained soil sample. A flexible tube is connected to the inlet end of the dropper, and a drip bottle is connected to the inlet end of the flexible tube. The flexible tube is equipped with a control switch near the drip bottle.

[0005] The testing method for this experimental apparatus includes the following steps:

[0006] S1: According to the test requirements of different saturation of the test samples, take several standard fine-grained soil samples from the undisturbed sample using a sample ring cutter.

[0007] S2: Number, weigh, determine the moisture content of fine-grained soil samples, calculate the dry weight of the test soil, and calculate the amount of water to be added for each fine-grained soil sample.

[0008] S3: Cover the top and bottom surfaces of the fine-grained soil sample with filter paper, place pre-wetted and saturated lower permeable stones and perforated upper permeable stones at the bottom and top of the fine-grained soil sample respectively, and fix each fine-grained soil sample to the top surface of the perforated tray with a circular steel pressure ring and fixing bolts.

[0009] S4: Fill the moisturizing cylinder with water, place the tray with the fine soil sample fixed in the round hole horizontally in the moisturizing cylinder, cover the moisturizing cylinder with the lid, so that the round hole of the lid is aligned with each sample, and apply a layer of petroleum jelly to the surface of the lid seam to prevent air leakage.

[0010] S5: Connect the dropper, hose, and drip bottle in a sealed series. Suspend the drip bottle on the top of the moisturizing cylinder cover. Fix each dropper in the round hole of the cylinder cover with a rubber stopper. Align the dropper outlet vertically with the center of each fine-grained soil sample. Pour the required amount of water for the corresponding fine-grained soil sample into each drip bottle after calculating the saturation level.

[0011] S6: Turn on the control switch on the hose so that the water in each drip bottle drips through the hose and dropper onto the permeable stone of each fine soil sample, and then seeps into the fine soil sample through the permeable stone and filter paper to continuously replenish water;

[0012] S7: After completing the above steps, take out the sample, weigh the total weight of the sample ring cutter and soil, calculate the precise saturation of each sample, and conduct soil mechanics tests.

[0013] In summary, the present invention has the following beneficial effects:

[0014] (1) The test device of the present invention uses non-electric operation for sample preparation, with low energy consumption and extremely low water consumption, which is a low-carbon and green sample preparation method.

[0015] (2) The test device of the present invention can prepare multiple test samples of fine-grained soil with different saturations at one time, which improves the sample preparation efficiency;

[0016] (3) The test device of the present invention achieves precise control of the saturation of fine-grained soil test samples during the sample preparation process. The sample is quantitatively saturated by dripping water, hose and dropper, and the fine-grained soil sample reaches the precise saturation value, which improves the accuracy of experimental data.

[0017] (4) The test device of the present invention has a simple sample preparation procedure, is easy to operate, and the sample quantity can be prepared as needed. Attached Figure Description

[0018] Figure 1 is a structural diagram of the experimental device in an embodiment of the present invention;

[0019] Figure 2 is a front view of the internal structure of the moisturizing cylinder of the test device in an embodiment of the present invention;

[0020] Figure 3 is a top view of the internal structure of the moisturizing cylinder of the test device in an embodiment of the present invention;

[0021] Figure 4 is a cross-sectional view of the test device in an embodiment of the present invention;

[0022] Figure 5 is a diagram of the fine-grained soil sample fixing structure of the test device in an embodiment of the present invention;

[0023] Figure 6 is a top view of the annular steel pressure ring and the perforated permeable stone of the test device in an embodiment of the present invention.

[0024] In the diagram: 1. Perforated tray; 2. Fine-grained soil sample; 3. Moisturizing cylinder; 4. Moisturizing cylinder cover; 5. Dropper; 6. Tube; 7. Hanging bottle; 8. Perforated hole; 9. Rubber stopper; 10. Annular steel pressure ring; 11. Fixing bolt; 12. Sample ring cutter; 13. Perforated upper permeable stone; 14. Lower permeable stone; 15. Control switch. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be described in further detail below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0027] Example:

[0028] As shown in Figures 1 to 6, a fine-grained soil saturation control test device includes a circular perforated tray 1, a moisturizing cylinder 3, and a moisturizing cylinder cover 4. The moisturizing cylinder 3 and the moisturizing cylinder cover 4 are sealed together. The top of the circular perforated tray 1 has six fine-grained soil samples 2 arranged in a single layer and symmetrically on the center. The bottom and top surfaces of the fine-grained soil samples 2 are covered with filter paper. The bottom and top of the fine-grained soil samples 2 are respectively provided with a lower permeable stone 14 and a perforated upper permeable stone 13. The top and bottom surfaces of the perforated upper permeable stone 13 are respectively provided with a circular steel pressure ring and a sample ring cutter 12 for cutting the fine-grained soil samples 2. The circular steel pressure ring is provided with two fixing bolts 1. 1. A circular steel pressure ring secures the fine-grained soil sample 2, sample ring cutter 12, upper permeable stone, and lower permeable stone 14 to the top surface of the tray 1 with circular holes 8 via two fixing bolts 11. The moisturizing cylinder cover 4 has six symmetrically distributed circular holes 8, each containing a rubber stopper 9. A dropper 5 passes through the center of the rubber stopper 9, connecting the outside to the inner cavity of the moisturizing cylinder 3. The center of the outlet of the dropper 5 corresponds to the center of the fine-grained soil sample 2. A flexible tube 6 is connected to the inlet of the dropper 5, and a drip bottle 7 is connected to the inlet of the flexible tube 6. The flexible tube 6 has a control switch 15 located near the drip bottle 7.

[0029] The testing method of the testing apparatus of the present invention includes the following steps:

[0030] S1: According to the test requirements of different saturation of the test samples, take 1 to 6 standard ring cutter specimens from the undisturbed sample using a test soil cutting ring cutter, and prepare the standard ring cutter specimens in accordance with Clause 4.5.2 of the "Standard for Geotechnical Test Methods" (GB / T50123-2019);

[0031] S2: Number the fine-grained soil sample 2, weigh it (m0), determine the moisture content of the sample (ω0), and calculate the dry weight of the soil (m). d Calculate the amount of water required for each fine-grained soil sample 2;

[0032] S3: Cover the top and bottom surfaces of the fine soil sample 2 with filter paper, place pre-wetted and saturated lower permeable stone 14 and perforated upper permeable stone 13 at the bottom and top of the fine soil sample 2 respectively, and fix each fine soil sample 2 to the top surface of the round hole 8 tray 1 by a circular steel pressure ring and fixing bolt 11.

[0033] S4: Fill the moisturizing tank with water to a depth of 2-4 cm, place the tray 1 with six fine soil samples 2 fixed in the round hole 8 horizontally in the moisturizing tank body 3, cover the moisturizing tank lid 4, so that the round hole 8 of the lid is directly facing each sample on the tray 1 with the round hole 8 below, and apply a layer of petroleum jelly to the surface of the lid seam to prevent air leakage.

[0034] S5: Connect the dropper 5, hose 6, and bottle 7 in a sealed series. The bottle 7 is suspended on the top of the moisturizing cylinder cover 4. Each dropper 5 is fixed in the cylinder cover hole 8 by a rubber stopper 9. The outlet of the dropper 5 is vertically aligned with the center of each fine soil sample 2. Each bottle 7 is filled with the amount of water required after calculating the saturation of the corresponding fine soil sample 2.

[0035] The required amount of water (accurate to 0.01 g) to reach a certain degree of saturation for fine-grained soil sample 2 was determined by the following method:

[0036] △m w =0.01×(ω'-ω0)×m0 / (1+0.01ω0); (△m w —Required water to be added to the soil sample, ω'—Required saturated water content for fine-grained soil sample 2, ω0—Water content of fine-grained soil sample 2 before saturation, m0—Dry mass of fine-grained soil sample 2)

[0037] Where: ω'=е·S r / G S ;(e—void ratio of fine-grained soil sample 2, S) r —Required saturation, G S —Specific gravity of soil particles); e = G S ·ρ w / ρ d -1; (ρ w —The density of water, ρ d —Dry density of fine-grained soil sample 2)

[0038] Measurement of saturation of fine-grained soil sample 2 after saturation: S r =G S ·ω / е

[0039] ω=m(1+0.01ω0) / m0-1, (ω—moisture content of saturated fine-grained soil sample 2, m—mass of saturated fine-grained soil sample 2).

[0040] S6: Turn on the control switch 15 on the hose 6 so that the water in each drip bottle 7 drips through the hose 6 and the dropper 5 onto the permeable stone on the upper surface of each fine soil sample 2. The water then seeps into the fine soil sample 2 through the permeable stone and filter paper. The water replenishment process should be carried out slowly, using a continuous extremely small flow rate. Intermittent water replenishment can also be used. The water replenishment process should be controlled within about 12 hours. The saturation time depends on the permeability of the soil sample, generally (1 to 3 days).

[0041] S7: After completing the above steps, remove the sample, weigh the total weight of the sample ring and soil, and calculate the precise saturation of each sample according to formula 4.7.5 of the "Standard for Geotechnical Testing Methods" (GB / T50123-2019). Perform relevant soil mechanics tests on the test samples.

[0042] Experimental Principle: The experimental apparatus of this invention is mainly used to provide an indoor experimental device for preparing samples of fine-grained soil with different saturation levels from an initially unsaturated state. Based on the density and particle specific gravity of the test fine-grained soil sample 2, the required saturation value and moisture content of the sample are calculated, obtaining the difference in moisture content between the sample and the existing undisturbed sample. The required amount of water to be added to the sample is calculated based on its weight. The experimental apparatus is used to uniformly add the required amount of water to the fine-grained soil sample 2, so that the moisture content and saturation of the fine-grained soil sample 2 reach the required saturation value. After completion, relevant geotechnical tests are performed on the fine-grained soil sample 2 to obtain the physical and mechanical data indicators under the corresponding saturation values.

[0043] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A test apparatus for controlling the saturation of fine-grained soil, characterized in that: The device includes a perforated tray (1), a moisturizing cylinder (3), and a moisturizing cylinder cover (4). The moisturizing cylinder (3) and the moisturizing cylinder cover (4) are sealed together. The top of the perforated tray (1) has six fine-grained soil samples (2) arranged in a single layer and symmetrically arranged in a center. The bottom and top surfaces of the fine-grained soil samples (2) are covered with filter paper. The bottom and top of the fine-grained soil samples (2) are respectively provided with a lower permeable stone (14) and a perforated upper permeable stone (13). The top and bottom surfaces of the perforated upper permeable stone (13) are respectively provided with a circular steel pressure ring and a sample ring cutter (12) for cutting the fine-grained soil samples (2). The circular steel pressure ring is provided with two fixing bolts (11). The circular steel pressure ring is secured to the fine-grained soil samples by the two fixing bolts (11). Sample (2), the sample ring cutter (12), the upper permeable stone, and the lower permeable stone (14) are detachably fixed on the top surface of the round hole tray (1). The moisturizing cylinder cover (4) is provided with six symmetrically distributed round holes (8). A rubber stopper (9) is provided in the round hole (8). A dropper (5) is passed through the center of the rubber stopper (9). The dropper (5) is connected to the outside and the inner cavity of the moisturizing cylinder (3). The center position of the outlet of the dropper (5) corresponds to the center position of the fine-grained soil sample (2). A hose (6) is connected to the inlet end of the dropper (5). A drip bottle (7) is connected to the inlet end of the hose (6). A control switch (15) is provided near the drip bottle (7).

2. The test method of the fine-grained soil saturation control test device according to claim 1, characterized in that: The steps include: S1: According to the test requirements of different saturation levels of the test samples, take several standard fine-grained soil samples (2) from the original sample using a sample ring cutter (12); S2: Number, weigh, determine the moisture content of the sample, calculate the dry weight of the test soil, and calculate the amount of water required for each fine-grained soil sample (2); S3: Cover the top and bottom surfaces of the fine-grained soil sample (2) with filter paper, place pre-moistened saturated permeable stones (14) and perforated permeable stones (13) at the bottom and top of the fine-grained soil sample (2) respectively, and fix each fine-grained soil sample (2) to the top surface of the perforated tray (1) using a circular steel pressure ring and fixing bolts (11); S4: Fill the moisturizing tank (3) with water, and place the perforated tray (1) with the fine-grained soil sample (2) fixed inside the moisturizing tank (3) horizontally. S5: Cover the moisturizing cylinder with the lid (4) so ​​that the round hole (8) of the lid is aligned with each sample. Apply a layer of Vaseline to the surface of the lid seam to prevent air leakage. S6: Connect the dropper (5), hose (6), and bottle (7) in a sealed series. The bottle (7) is suspended on the top of the moisturizing cylinder lid (4). Each dropper (5) is fixed in the round hole (8) of the lid with a rubber stopper (9). The outlet of the dropper (5) is vertically aligned with the center of each fine soil sample (2). Each bottle (7) is filled with the amount of water required after calculating the saturation of the corresponding fine soil sample (2). S7: Turn on the control switch (15) on the hose (6) so that the water in each bottle (7) drips through the hose (6) and dropper (5) onto the permeable stone on the upper part of each fine soil sample (2). The water seeps into the fine soil sample (2) through the permeable stone and filter paper, and water is continuously replenished. S7: After the above steps are completed, take out the sample, weigh the sample ring cutter (12) and the total weight of the soil, calculate the precise saturation of each sample, and conduct soil mechanics tests.

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