Simulation test device and determination method for bubble migration of underwater gas-bearing soil under dynamic impact

Abstract

This invention provides a simulation test device and method for measuring bubble migration in underwater aerated soil under dynamic impact. The device includes a hammer, guide tube, protective tube, compaction tube, base plate, soil sample, fine-mesh soft metal mesh, and micro-hydrogen balloons. The impact of the hammer falling on the soil simulates wave cyclic load. By recording the number of micro-balloons in soil blocks at different locations after compaction, the migration direction and distribution law of bubbles in underwater aerated soil under dynamic impact can be obtained, thereby studying the migration law of closed bubbles in the soil under wave load.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of civil engineering test, and particularly relates to a simulation test device and a determination method for bubble migration of underwater gas-containing soil under dynamic impact. BACKGROUND

[0002] There is a large amount of shallow gas in seabed soil. The average organic matter content in the sediment of the Yellow River in China is 0.79%, and the biodegradable part accounts for 1% to 3% of the total organic matter. Under aerobic conditions, carbon dioxide is generated by degradation, and under anaerobic conditions, methane, hydrogen sulfide and other gases are generated. The presence of gas has a great influence on the undrained shear strength of the seabed soil. The greater the content, the smaller the strength of the soil shear zone. In the engineering construction of soft soil areas, geotechnical engineering problems caused by free gas in the seabed often occur, and in severe cases, even major disasters can be caused. The presence of gas will increase the possibility of seabed liquefaction, and further lead to the occurrence of submarine landslides.

[0003] It is found through retrieval that the application number 202211600334.3 "Soil particle migration model test device and method considering complex traffic-environmental effects" provides a scheme for simulating the migration of soil particles under complex traffic-environmental effects. However, this scheme only studies the migration of soil particles caused by the suction effect of pore water pressure during the migration of soil water from the warm end to the cold end under freeze-thaw action, and cannot determine the migration direction of bubbles in underwater gas-containing soil under dynamic impact.

[0004] It is found through retrieval that the application number 202010556479.2 "Frozen soil model and construction method of frozen soil water migration model" provides a frozen soil model and a construction method of a frozen soil water migration model. However, this scheme only combines the capillary water migration mechanism and the film water migration mechanism to more comprehensively explain the soil frost heaving phenomenon, and does not involve the study of the migration direction of bubbles in underwater gas-containing soil under dynamic impact.

[0005] The migration and release process of free gas in seabed soil can also cause damage to engineering facilities, blowout and even explosion, resulting in serious engineering accidents. In addition, the presence and migration of free gas in seabed soil can lead to global warming, marine engineering risks and marine geological disasters. Therefore, it is of great significance to understand the existence and migration rules of free gas in underwater soil. SUMMARY

[0006] The present application aims at solving the problems in the prior art, and provides a bubble migration simulation test device and a determination method for underwater air-containing soil under dynamic impact, wherein the migration direction and distribution law of the bubbles in the underwater air-containing soil under the dynamic impact can be obtained by recording the number of micro hydrogen balloons in the soil blocks at different positions after the compaction, and the migration law of the closed bubbles in the soil under the wave load can be further studied.

[0007] The bubble migration simulation test device for the underwater air-containing soil under the dynamic impact comprises a hammer 1, a guide cylinder 2, a protection cylinder 3, a compaction cylinder 4, a bottom plate 5, a soil sample 6, a fine-pore soft metal mesh 7 and micro hydrogen balloons 8.

[0008] The hammer 1 is equipped with the guide cylinder 2, and there is a certain gap between the hammer 1 and the guide cylinder 2, so that the hammer can freely fall.

[0009] The guide cylinder 2 is made of corrosion-resistant metal, and the wall thickness is about 3 mm.

[0010] The compaction cylinder 4 and the protection cylinder 3 are filled with water, and the water surface is lower than the top of the protection cylinder but higher than the surface of the hammer.

[0011] The soil sample 6 is a representative air-dried soil sample, which is placed on a rubber plate and rolled by a wooden roller, and then passes through a 5 mm mesh screen.

[0012] The fine-pore soft metal mesh 7 is easy to cut, so that the soil can be taken out after the compaction is completed.

[0013] The micro hydrogen balloons 8 are closed at the blowing port and have high elasticity, and simulate the bubbles in water.

[0014] The bubble migration simulation determination method for the underwater air-containing soil under the dynamic impact adopts the connection of the bubble migration simulation test device for the underwater air-containing soil under the dynamic impact, and the specific steps are as follows:

[0015] ① Test device assembly: the compaction cylinder 4 is fixed on the bottom plate 5, and the protection cylinder 3 is installed through the connecting device.

[0016] ② Different sizes of micro hydrogen balloons 8 are blown, and the blowing port is closed.

[0017] ③ Place soil sample 6 on a rubber board and crush it with a wooden roller. Pass it through a sieve of about 5mm. Mix the sieved soil sample with a miniature hydrogen balloon 8 of the same size. Put soil sample 6 into the compaction cylinder 4 in three batches. Gently compact and flatten the sample before putting in the next layer of soil sample. Place a fine-mesh soft metal mesh on top of the top layer of soil sample to prevent the soil sample from being washed away by water during the compaction process.

[0018] ④ Pour water into the cylinder along the cylinder wall until the water level is below the top of the casing but above the hammer surface;

[0019] ⑤ Raise the hammer 1 to a certain height, but not above the water surface, and compact it according to the prescribed number of compaction times. Let the hammer fall freely and act on the entire soil sample 6 at a uniform speed. After compaction, divide the fine-mesh soft metal mesh 7, cut the soil with a metal sheet, and take soil in 5 layers. Each layer of soil is divided into 6 pieces, for a total of 30 pieces. Record the number of micro hydrogen balloons 8 in soil pieces at different locations.

[0020] ⑥ The size of the micro hydrogen balloons 8 in soil sample 6, the falling distance of hammer 1 and the impact frequency were changed in turn. Steps ① to ⑤ were repeated to conduct multiple sets of tests. The number of micro hydrogen balloons 8 in soil blocks at different locations was recorded to determine the distribution of air bubbles in underwater air-bearing soil after dynamic impact.

[0021] Furthermore, by changing the size of the micro-hydrogen balloons 8 in soil sample 6, the falling distance of hammer 1, and the compaction frequency, the number of micro-hydrogen balloons 8 in soil blocks at different locations after compaction under different working conditions was recorded. Based on the distribution of micro-hydrogen balloons 8, the migration direction and distribution law of air bubbles in underwater air-bearing soil under dynamic impact were obtained, and the migration law of closed air bubbles in soil under wave load was studied.

[0022] Beneficial effects

[0023] This invention provides a simulation test device and method for measuring the migration of air bubbles in underwater air-bearing soil under dynamic impact. The device includes a hammer 1, a guide tube 2, a protective tube 3, a compaction tube 4, a base plate 5, a soil sample 6, a fine-mesh soft metal mesh 7, and micro-hydrogen balloons 8. By changing the size of the micro-hydrogen balloons 8 in the soil sample 6, the falling distance of the hammer 1, and the compaction frequency, the number of micro-hydrogen balloons 8 in soil blocks at different locations after compaction under different working conditions is recorded. Based on the distribution of the micro-hydrogen balloons 8, the migration direction and distribution law of air bubbles in underwater air-bearing soil under dynamic impact are obtained, and the migration law of closed air bubbles in the soil under wave load is studied.

[0024] The advantages of this invention are as follows:

[0025] ① By measuring the number of micro hydrogen balloons of different sizes, hammers of different falling distances, and compaction frequencies, the number of micro hydrogen balloons in soil clods at different locations after compaction under different working conditions can be studied.

[0026] ② The distribution of micro hydrogen balloons can be used to determine the migration direction and distribution pattern of air bubbles in underwater gas-bearing soil under dynamic impact, and then the migration pattern of closed air bubbles in the soil under wave load can be studied. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the device structure described in this invention;

[0028] Figure 2 This is a top view of the hammer described in this invention;

[0029] Labeling explanation: 1. Hammer; 2. Guide tube; 3. Shield tube; 4. Compactor tube; 5. Base plate; 6. Soil sample; 7. Fine-mesh soft metal mesh; 8. Miniature hydrogen balloon. Detailed Implementation

[0030] The present invention will now be further described in conjunction with the accompanying drawings and embodiments.

[0031] like Figure 1 and Figure 2 As shown, the underwater air-bearing soil bubble migration simulation test device under dynamic impact includes a hammer 1, a guide tube 2, a protective tube 3, a compaction tube 4, a base plate 5, a soil sample 6, a fine-pore soft metal mesh 7, and a miniature hydrogen balloon 8.

[0032] The hammer 1 is equipped with a guide tube 2. There is a certain gap between the hammer 1 and the guide tube 2 so that the hammer can fall freely. The hammer 1 has a rectangular cross-section and the hammer body has evenly distributed holes to allow water to flow through the holes without causing excessive local water pressure.

[0033] The guide cylinder 2 is made of corrosion-resistant metal with a wall thickness of about 3mm and has uniformly distributed exhaust holes with a diameter of about 6mm at both ends.

[0034] The compaction cylinder 4 and the protective casing 3 are filled with water, with the water level below the top of the protective casing but above the surface of the hammer, and the compaction cylinder and the protective casing are sealed and leak-proof.

[0035] The soil sample 6 is a representative air-dried soil sample, which is placed on a rubber board and crushed with a wooden roller. It is then passed through a sieve of about 5 mm. The amount of soil sample is not less than 20 kg. The soil sample is uniformly mixed with micro hydrogen balloons 8.

[0036] The fine-mesh soft metal mesh 7 is easy to cut so that the soil can be removed in sections after compaction.

[0037] The miniature hydrogen balloon 8 is sealed at the air inlet and has high elasticity, simulating air bubbles in water.

[0038] The method for simulating and measuring bubble migration in underwater air-bearing soil under dynamic impact involves connecting the aforementioned underwater air-bearing soil bubble migration simulation test apparatus. The specific steps are as follows:

[0039] ① Assembly of the test apparatus: Fix the compaction cylinder 4 on the base plate 5, install the protective cylinder 3 through the connecting device, and seal the protective cylinder and the compaction cylinder to prevent water leakage;

[0040] ② Blow up miniature hydrogen balloons of different sizes 8, and seal the air inlets;

[0041] ③ Place soil sample 6 on a rubber board and crush it with a wooden roller. Pass it through a sieve of about 5mm. Mix the sieved soil sample with a miniature hydrogen balloon 8 of the same size. Fill the compaction cylinder 4 with soil sample 6 in three batches, gently compact and flatten it before adding the next layer of soil sample. Place a fine-mesh soft metal mesh on top of the top layer of soil sample to prevent the soil sample from being washed away by water during the compaction process.

[0042] ④ Pour water into the cylinder along the cylinder wall until the water level is below the top of the casing but above the hammer surface;

[0043] ⑤ Raise the hammer 1 to a certain height, but not above the water surface, and compact it according to the prescribed number of compaction times. Let the hammer fall freely and act on the entire soil sample 6 at a uniform speed. After compaction, divide the fine-mesh soft metal mesh 7, cut the soil with a metal sheet, and take soil in 5 layers. Each layer of soil is divided into 6 pieces, for a total of 30 pieces. Record the number of micro hydrogen balloons 8 in soil pieces at different locations.

[0044] ⑥ The size of the micro hydrogen balloons 8 in soil sample 6, the falling distance of hammer 1 and the impact frequency were changed in turn. Steps ① to ⑤ were repeated to conduct multiple sets of tests. The number of micro hydrogen balloons 8 in soil blocks at different locations was recorded to determine the distribution of air bubbles in underwater air-bearing soil after dynamic impact.

[0045] The above-described apparatus is a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A simulation test device for bubble migration in underwater air-bearing soil under dynamic impact, characterized in that, Includes hammer (1), guide tube (2), protective tube (3), compaction tube (4), base plate (5), soil sample (6), fine-mesh soft metal mesh (7), and miniature hydrogen balloon (8); The hammer (1) is equipped with a guide tube (2). There is a certain gap between the hammer (1) and the guide tube (2) so that the hammer can fall freely. The hammer (1) has a rectangular cross-section and the hammer body has evenly distributed holes, allowing water to flow through the holes without causing excessive local water pressure. The guide tube (2) is made of corrosion-resistant metal with a wall thickness of 3mm and has uniformly distributed exhaust holes with a diameter of 6mm at both ends. The compaction cylinder (4) and the protective casing (3) are filled with water. The water level is lower than the top of the protective casing but higher than the surface of the hammer. The compaction cylinder and the protective casing are sealed and do not leak water. The soil sample (6) is a representative air-dried soil sample, which is placed on a rubber board and crushed with a wooden roller. It is then passed through a 5mm sieve. The amount of soil sample is not less than 20kg. The soil sample is uniformly mixed with micro hydrogen balloons (8). The fine-mesh soft metal mesh (7) is easy to cut so that the soil can be removed in sections after compaction; The micro hydrogen balloon (8) is sealed at the air inlet and has high elasticity, simulating air bubbles in water.

2. A method for simulating and measuring bubble migration in underwater air-bearing soil under dynamic impact, characterized in that, The connection steps for the underwater air-bearing soil bubble migration simulation test device under dynamic impact as described in claim 1 are as follows: ① Assembly of the test apparatus: Fix the compaction cylinder (4) on the base plate (5), install the protective cylinder (3) through the connecting device, and seal the protective cylinder and the compaction cylinder to prevent water leakage; ② Blow up miniature hydrogen balloons of different sizes (8), and seal the air inlet; ③ Place the soil sample (6) on a rubber board and crush it with a wooden roller. Pass it through a 5mm sieve. Mix the sieved soil sample with a miniature hydrogen balloon (8) of the same size. Put the soil sample (6) into the compaction cylinder (4) in three batches. Gently compact and flatten it before putting in the next layer of soil sample. Place a fine-mesh soft metal mesh on top of the top layer of soil sample to prevent the soil sample from being washed away by the water flow during the compaction process. ④ Pour water into the cylinder along the cylinder wall until the water level is below the top of the casing but above the hammer surface; ⑤ Raise the hammer (1) to a certain height, but not above the water surface, and compact it according to the specified number of compaction times. The hammer falls freely and acts on the entire soil sample (6) at a uniform speed. After compaction, divide the fine-mesh soft metal mesh (7), cut the soil with a metal sheet, and take soil in 5 layers. Each layer of soil is divided into 6 pieces, for a total of 30 pieces. Record the number of micro hydrogen balloons (8) in soil pieces at different locations. ⑥ The size of the micro hydrogen balloons (8) in the soil sample (6), the falling distance of the hammer (1) and the impact frequency were changed in turn. Steps ① to ⑤ were repeated to conduct multiple sets of tests. The number of micro hydrogen balloons (8) in the soil block at different locations was recorded to determine the distribution of air bubbles in the underwater air-bearing soil after dynamic impact.

3. The method according to claim 2, characterized in that, By changing the size of the micro hydrogen balloons (8) in the soil sample (6), the falling distance of the hammer (1), and the compaction frequency, the number of micro hydrogen balloons (8) in soil blocks at different locations after compaction under different working conditions was recorded. Based on the distribution of micro hydrogen balloons (8), the migration direction and distribution law of air bubbles in underwater gas-bearing soil under dynamic impact were obtained, and the migration law of closed air bubbles in soil under wave load was studied.

Images