A model test apparatus and method for testing the drag rate effect of high-speed missile penetration into seabed soil.

Abstract

This invention belongs to the field of marine geotechnical engineering indoor testing technology, and discloses a model test device for testing the rate effect of missile high-speed penetration into seabed soil resistance. The device comprises four parts: a model box system, a reaction frame system, a missile excitation device, and a data acquisition module. This invention also provides a model test method for testing the rate effect of missile high-speed penetration into seabed soil resistance. Through the coordination of the various parts of the test device system, this invention utilizes the data acquisition module to extract the velocity and reaction force changes of the missile passing through water and soil layers at different penetration velocities and soil thicknesses. Finally, it plots the complete penetration velocity-depth curve and penetration resistance-depth curve of the missile, and uses the curves and penetration resistance calculation formula to inversely deduce soil strength parameters. Furthermore, it analyzes the mechanism by which the undrained shear strength of the soil is affected by the soil rate effect, providing a simple and efficient indoor test device and method for studying the high-speed soil resistance and rate effect of cohesive seabed soil.

Description

Technical Field

[0001] This invention relates to the field of laboratory testing technology in marine geotechnical engineering, and particularly to the study of soil rate effects during high-speed interaction between cohesive soil and seabed structures. By collecting data on the velocity and resistance fluctuations of missiles penetrating cohesive soil layers during experiments, the mechanism by which the undrained shear strength of cohesive soil is affected by soil rate effects is analyzed. This invention proposes a model test apparatus and method for testing the soil resistance rate effect during high-speed missile penetration into the seabed. Background Technology

[0002] The undrained shear strength of cohesive soil describes its ability to resist shear failure perpendicular to the shear plane under saturated undrained conditions, and is one of the key indicators for evaluating the strength of cohesive soil seabeds in marine engineering. In practical engineering, in addition to the inherent characteristics of the seabed (such as composition, water content, and sensitivity), the influence of external forces on the strength of cohesive soil cannot be ignored. For example, during the installation of a dynamic anchor, the anchor body moves at a 10... 1 Up to 10 2 s -1 The ultra-high speed at which the dynamic anchor contacts and penetrates the cohesive seabed significantly increases the undrained shear strength of the cohesive soil. Ignoring this effect would result in insufficient kinetic energy for the dynamic anchor to reach the intended depth, failing to provide adequate tension for the anchor chain and ultimately jeopardizing the operational safety of marine structures.

[0003] However, commonly used testing methods such as triaxial testing, circumferential shear testing, and vane shear testing cannot meet the requirements of high-speed shear testing in the 10-50 m / s range during dynamic anchor penetration, thus making it difficult to conduct research on the shear process of structures-cohesive seabed during dynamic anchor penetration. Furthermore, the insufficient accuracy of measuring elements and the limited acquisition frequency of traditional testing methods also make it difficult to collect accurate and efficient test data.

[0004] In summary, accurately assessing the influence mechanism of soil rate effect on the undrained shear strength of cohesive soil is of great significance for the study of high-speed penetration of dynamic anchors. However, existing experimental devices and methods are insufficient to meet the research needs. Therefore, it is necessary to propose a targeted research device and method to accurately study the influence of soil rate effect on the undrained shear strength of clay seabed. Summary of the Invention

[0005] To overcome the shortcomings of existing research methods and accurately assess the influence mechanism of soil rate effect on the undrained shear strength of cohesive soil, the primary problem this invention aims to solve is to provide a model test device for testing the rate effect of high-speed missile penetration into seabed soil. This device utilizes the velocity and resistance fluctuations of the missile penetrating soil of different thicknesses to plot penetration velocity-depth curves, thereby analyzing the influence mechanism of soil rate effect on penetration resistance. To this end, this invention adopts the following technical solution:

[0006] A model test device for testing the rate of high-speed missile penetration into seabed soil resistance is characterized by comprising four parts: a model box system, a reaction frame system, an excitation device, and a data acquisition module. The model box system consists of a model box, a support frame, and a soil sample box; the reaction frame system consists of a support frame, a horizontal fixing device, and an excitation device fixing device; the excitation device consists of a nail gun, a nail, and a missile; and the data acquisition module consists of a spoke-type force gauge, a high-speed camera, data acquisition equipment, and a computer.

[0007] The model box has a square bottom, with an outer side length of 200mm, a height of 500mm, and a wall thickness of 5mm, and is made of transparent acrylic sheet material. The opening at the bottom ensures that the missile can move freely during the test, so that the spoke-type force gauge only records the reaction force fluctuations during the missile's penetration and ejection from the soil sample.

[0008] The support frame consists of two halves, which lift the soil sample box and place it in the middle of the model box to facilitate the data visualization and collection of the process of the missile penetrating and ejecting the soil sample. A cylindrical area with a diameter of 100mm and a height of 200mm is left in the middle to place the soil sample box.

[0009] The soil sample box has an inner diameter of 100mm and a height of 200mm. It is made of transparent acrylic material, with an opening at the bottom and a thin plastic film to ensure the soil sample box is waterproof before missile penetration. The bottom of the soil sample box has a 0-100mm range for placing soil samples, and the upper 100-200mm range is set as a water layer to simulate the in-situ penetration process of the dynamic anchor. It is also equipped with four sets of concentric ring-shaped hollow supports with an outer diameter of 100mm, an inner diameter of 20mm, and a height of 20mm to adjust the soil sample thickness.

[0010] The reaction frame system adopts a portal frame design, welded from square hollow steel tubes, with a total height of 1100mm, a horizontal width of 360mm, an outer side length of 40mm for the hollow steel tubes, and an outer side length of 60mm for the upper support. Sliding grooves are provided on the top and sides of the support. Horizontal fixation devices are installed on both sides to limit the horizontal displacement of the model box during the test. An excitation device fixation device is installed on the top of the support for mounting the excitation device; the bottom surface of the excitation device fixation device is square with an outer wall of 40mm, an inner wall of 36mm, and a total length of 150mm.

[0011] The excitation device is a modified commercial small nail gun and nail. It uses a nail gun with an outer diameter of 36mm and a total length of 120mm, and a standard headless nail with a length of 42mm. A missile casing with a length of 30mm and an outer diameter of 7.6mm is machined according to the nail tip shape. During the test, the nail and missile are launched together. The nail gun can provide the missile with an excitation velocity of 10-40m / s, breaking through the velocity limit of existing test methods and solving the problem of the difficulty in conducting research on the rate effect of cohesive soil.

[0012] The spoke-type force gauge can monitor the reaction force fluctuations caused by the soil velocity effect during the model missile's entry into water and soil in real time. The spoke-type force gauge has a diameter of 143mm and is in the shape of a concentric ring. During the test, the missile can pass through it. The range is 0-100N and the accuracy is 0.01N, which meets the test load and accuracy requirements. The data output frequency is 12.8KHz.

[0013] The high-speed camera, employing a 100,000-frame-level high-speed black-and-white camera, records the relative positions of the missile throughout the entire process of missile launch, penetration into the soil sample, and ejection. Combined with duration calculations, it obtains the missile velocity changes at each stage of the experiment. The corresponding data output frequency is 12.8 kHz, corresponding to the spoke-type force gauge. The input frequency of the data acquisition device is also 12.8 kHz, corresponding to both the high-speed camera and the spoke-type force gauge, used to input the data acquired by both into a computer for analysis and research.

[0014] The experimental principle is as follows: Ensuring the initial missile penetration velocity, the water level in the soil sample box, and the top surface height of the soil sample remain constant, penetration tests were conducted on five groups of soil samples with different thicknesses: 20mm, 40mm, 60mm, 80mm, and 100mm. The velocity fluctuations during the missile's entry into the water, penetration, and ejection from the soil sample were calculated using the results captured by a high-speed camera. A complete velocity-depth curve was plotted. Furthermore, the resistance-depth curve plotted based on the reaction force of the spoke-type force gauge, along with the resistance calculation formula, was used to jointly analyze the influence mechanism of the soil rate effect on the undrained shear strength.

[0015] Another technical problem to be solved by the present invention is to propose a model test method for testing the resistance rate effect of missiles penetrating seabed soil at high speed, in combination with the above-mentioned test device.

[0016] A model test method for testing the drag rate effect of a missile penetrating seabed soil at high speed, characterized by the following steps:

[0017] Step (1) Soil sample preparation: Kaolin was used to prepare samples in the order of 20mm, 40mm, 60mm, 80mm and 100mm, with an inner diameter of 100mm. The initial undrained shear strength of the soil sample under low shear rate was determined by triaxial test or ring shear test.

[0018] Step (2) Equipment Installation: Place the spoke-type force gauge on a flat and stable ground, and place the model box on top, aligning the opening on the bottom of the model box with the center hole of the spoke-type force gauge. Place the support frame and soil sample box inside the box in sequence. Cover the bottom of the soil sample box with plastic sheeting for waterproofing, and place the support and soil sample on top, ensuring that the total height of the two is 100mm. Then add water to make the total height reach 180mm. Place the high-speed camera and matching tripod in front of the model box and adjust the viewing window and resolution. Then place the reaction frame system on the model box system and spoke-type force gauge in sequence, align the horizontal fixing device with the two sides of the model box, and adjust the excitation device fixing device so that the bottom circular hole is collinear with the center of the soil sample.

[0019] Step (3) Data acquisition device calibration: Connect the spoke-type force gauge and the high-speed camera to the control device and initialize the data. Apply a small pressure to the model box system to verify the sensitivity and accuracy of the data acquisition module.

[0020] Step (4) Installation of the firing device: After placing the missile on the outside of the nail, insert it into the firing port of the nail gun. Then place the firing device on the firing device holder, and after confirming that the movement path of the nail is collinear with the center of the soil sample and the opening of the model box, the test will officially begin.

[0021] Step (5) Penetration test: Launch a missile to penetrate the soil sample and exit, and collect data for the test.

[0022] Step (6) Repeat the test: Starting with a 20mm thick soil sample, repeat the test in sequence with thicknesses of 40mm, 60mm, 80mm and 100mm, until the missile cannot be launched or the test ends after 100mm. This is considered one set. Then adjust parameters such as the nail firing speed or the initial strength of the cohesive soil and repeat the test.

[0023] Step (7) Data Processing: Calculate the velocity of the missile entering the water, penetrating, and exiting soil samples of different thicknesses from the high-speed camera footage. Combine this with the exit velocities at depths of 20mm, 40mm, 60mm, 80mm, and 100mm to plot the penetration velocity-depth curve. Furthermore, plot the penetration resistance-depth curve using the resistance fluctuation curve from the spoke-type force gauge. According to the penetration resistance calculation formula (1):

[0024] ma = W b -F tip -F s -F D -F b (1)

[0025] In equation (1), m is the missile mass, a is the acceleration, and W... b For the missile's own weight, F tip For vertical penetration resistance, F s For lateral resistance, F D For drag resistance, Fs This is due to the buoyancy of the soil.

[0026] The specific calculation method is as follows:

[0027]

[0028] In equation (2) ρ s C represents the saturated density of the cohesive soil, determined before the test. d The drag resistance coefficient is 0.22 for cohesive soil; A t The cross-sectional area of ​​the missile is calculated using the following formula: Where d is the missile diameter of 7.6 mm; v is the real-time penetration velocity, obtained from the results captured by a high-speed camera.

[0029] F b =ρ′V s g (3)

[0030] In equation (3), ρ′ is the buoyant density of cohesive soil, which can be obtained by using the saturated density ρ of cohesive soil. s -1 is approximately calculated; ′V s The volume of the missile is calculated using the following formula: Where z is the missile length (30 mm); g = 9.8 m / s 2 This is the acceleration due to gravity.

[0031] The formulas for calculating end resistance and side friction resistance are:

[0032] F tip =R f (s u N kt A t (4)

[0033] F s =R f (αs u A s (5)

[0034] In equations (4) and (5), R f The strain rate coefficient is calculated using the following formula: Where β is the soil rate effect parameter, which is the focus of this study; s u The undrained shear strength of cohesive soil was determined before the test; A t A is the cross-sectional area of ​​the missile; s The side surface area of ​​the missile is calculated using the formula A. s =πdz; α is the interfacial friction coefficient; therefore, the method for calculating the strain rate coefficient can be summarized as equation (6):

[0035]

[0036] Equation (6) can analyze the trend of strain rate coefficient with different parameters and reveal the development mechanism of resistance with soil rate effect during high-speed penetration.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) This experimental method uses a nail gun to launch a missile, which solves the problem of low loading rate in traditional shear test methods and overcomes the shortcomings of existing high-speed test schemes, such as unsatisfactory shear effect and difficulty in data acquisition. In traditional shear tests, the loading rate can usually only reach 0.05 m / s, while this experimental method can increase the loading rate by nearly three orders of magnitude (providing an excitation velocity of 10-40 m / s), significantly improving the shear rate and enabling targeted indoor high-speed shear test research.

[0039] (2) The total height of this test device is 1100mm, and the total floor area is approximately 1m². 2 The device is simple, the procedure is straightforward, and the safety is relatively high. The shear interaction process between the missile and the cohesive soil sample is sufficient, providing adequate shear deformation. This method can be effectively applied to laboratory experimental research on high-speed penetration interactions of cohesive seabeds, exemplified by dynamic anchor installation problems.

[0040] (3) Data acquisition is carried out using a spoke-type force gauge with a high acquisition frequency and a high-speed camera. The velocity-depth and velocity-resistance curves of the missile penetration process can be plotted. The correlation coefficient of soil rate effect can be calculated by combining the calculation formula. The experimental principle is clear and the experimental method is feasible. After further optimization, it can be used for the analysis of dynamic anchor penetration operations in actual engineering. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of an indoor dynamic anchor high-speed penetration test device that takes into account the soil velocity effect.

[0042] Figure 2 This is a schematic diagram of the experimental setup model box system;

[0043] Figure 3 This is a schematic diagram of the reaction frame system of the test apparatus;

[0044] Figure 4 This is a schematic diagram of the activation device and the missile.

[0045] Figure 5 This is a schematic diagram of the data acquisition module;

[0046] Figure 6 This is a schematic diagram illustrating the method of filling soil sample boxes and plotting velocity-depth curves during the test process.

[0047] Labels in the figure: Model box system (100); Model box (101); Support frame (102); Soil sample box (103); Reaction frame system (200); Support (201); Horizontal fixer (202); Excitation device fixer (203); Excitation device (300); Nail gun (301); Nail (302); Missile (303); Data acquisition module (400); Spoke type force gauge (401); High-speed camera (402); Data acquisition device (403); Computer (404). Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0049] The bottom surface (101) of the model box is square, with an outer side length of 200mm, a height of 500mm, and a wall thickness of 5mm, and is made of transparent acrylic sheet material. The opening at the bottom ensures that the missile can move freely during the test, so that the spoke-type force gauge (401) only records the reaction force fluctuations during the missile's penetration and ejection from the soil sample.

[0050] The support frame (102) consists of two halves, which lift the soil sample box (103) and place it in the middle of the model box to facilitate the data visualization and collection of the process of the missile (303) penetrating and ejecting the soil sample. A cylindrical area with a diameter of 100 mm and a height of 200 mm is left in the middle to place the soil sample box (103).

[0051] The soil sample box (103) has an inner diameter of 100mm and a height of 200mm. It is made of transparent acrylic material, with an opening at the bottom and a thin plastic film attached to ensure the soil sample box (103) is waterproof before the missile (303) penetrates. The soil sample box (103) has a bottom layer of 0-100mm for placing soil samples, with the bottom surface as the zero point, and an upper layer of 100-200mm set as the water layer to simulate the in-situ penetration process of the dynamic anchor. In addition, four sets of concentric ring-shaped hollow supports with an outer diameter of 100mm, an inner diameter of 20mm, and a height of 20mm are provided to adjust the soil sample thickness.

[0052] The reaction frame system (200) adopts a portal frame form, welded from square hollow steel pipes, with a total height of 1100mm, a horizontal width of 360mm, an outer side length of 40mm for the hollow steel pipes, and an outer side length of 60mm for the upper support. Sliding grooves are provided on the top and sides of the support. Horizontal fixers are installed on both sides to limit the horizontal displacement of the test model box (101) during the test process. An excitation device fixer 203 is installed on the top of the support (201) for installing the excitation device. The bottom surface of the excitation device fixer is square with an outer wall of 40mm, an inner wall of 36mm, and a total length of 150mm.

[0053] The excitation device (300) is an improved version of a commercially available small nail gun (301) and a nail (302). It uses a nail gun (301) with an outer diameter of 36mm and a total length of 120mm, and a standard headless nail (302) with a length of 42mm. A missile casing with a length of 30mm and an outer diameter of 7.6mm is machined according to the nail tip shape. During the test, the nail (302) and the missile (303) are launched together. The nail gun (301) can provide the missile (303) with an excitation velocity of 10-40m / s, breaking through the velocity limit of existing test methods and solving the problem of the difficulty in conducting research on the rate effect of cohesive soil.

[0054] The spoke-type force gauge (401) can monitor in real time the reaction force fluctuations caused by the soil velocity effect during the entry of the model missile (303) into water and soil. The spoke-type force gauge (401) has a diameter of 143mm and is in the shape of a concentric ring. During the test, the missile can pass through it. The range is 0-100N and the accuracy is 0.01N, which meets the test load and accuracy requirements. The data output frequency is 12.8KHz.

[0055] The high-speed camera (402) is a 100,000-frame high-speed camera used to record the relative position of the missile (303) throughout the entire process of its launch, penetration into the soil sample, and ejection from the soil sample. It also calculates the velocity changes of the missile (303) during each stage of the experiment based on the duration. The corresponding data output frequency is 12.8 kHz, corresponding to the spoke-type force gauge. The input frequency of the data acquisition device (403) is 12.8 kHz, corresponding to both the high-speed camera and the spoke-type force gauge, used to input the data acquired by both into a computer for analysis and research.

[0056] The experimental principle is as follows: to ensure that the initial penetration speed of the missile (303), the water layer height in the soil sample box (103) and the top surface height of the soil sample are constant, after conducting missile penetration tests on five groups of soil samples with different thicknesses of 20mm, 40mm, 60mm, 80mm and 100mm respectively, the velocity interpolation of the missile (303) entering the water, penetrating the soil sample and exiting the soil sample in different thicknesses of soil samples is combined using the shooting results of the high-speed camera (402) to draw a complete velocity-depth curve, and the mechanism of the influence of soil rate effect on undrained shear strength is obtained by back-calculating the fluctuation difference of the spoke-type force gauge (401) and the calculation formula of penetration resistance.

[0057] Another technical problem to be solved by the present invention is to propose a model test method for testing the resistance rate effect of missiles penetrating seabed soil at high speed, in combination with the above-mentioned test device.

[0058] A model test method for testing the drag rate effect of a missile penetrating seabed soil at high speed, characterized by the following steps:

[0059] Step (1) Soil sample preparation: Soil samples were prepared using kaolin. The samples were saturated and consolidated in the order of 20mm, 40mm, 60mm, 80mm and 100mm. The initial undrained shear strength of the soil samples under low shear rate was determined by triaxial test or ring shear test.

[0060] Step (2) Equipment Installation: Place the spoke-type force gauge (401) on a flat and stable ground. Place the model box (101) on top of the force gauge and align the opening on the bottom with the center hole of the spoke-type force gauge (401). Place the support frame (102) and the soil sample box (103) inside the box in sequence. Cover the bottom of the soil sample box (103) with plastic sheeting for waterproofing. Place the support and fully saturated and consolidated soil samples on top according to the test groups, ensuring that the total height of the two is 100mm. Then add water to make the total height reach 180mm. According to the relative height of the soil samples, place the high-speed camera (402) and matching tripod directly in front of the model box (101) to ensure that the soil samples and the upper and lower cavities along the missile (303) penetration path can be completely captured in the frame. Then, the reaction frame system (200) is placed on the model box system (100) and the spoke-type force gauge (401) in sequence, the horizontal fixer (202) is attached to both sides of the model box (101), and the excitation device fixer (203) is adjusted so that the bottom circular hole is collinear with the center of the soil sample.

[0061] Step (3) Data Acquisition Device Calibration: Connect the spoke-type force gauge (401) and the high-speed camera (402) to the control device and initialize the data. Apply a small pressure to the model box system (100) and verify the sensitivity and accuracy of the spoke-type force gauge (401) according to the reaction force fluctuation curve. Adjust the position of the high-speed camera (402) according to the camera view.

[0062] Step (4) Installation of firing device: After the missile (303) is placed on the outside of the nail (302), it is inserted into the firing port of the nail gun (301). The firing device (300) is placed on the firing device holder (203). After confirming that the movement path of the nail (302) is collinear with the center of the soil sample and the opening of the model box (101), the test is officially started.

[0063] Step (5) Penetration Test: Launch the missile (303) through the hole in the firing device holder (203), penetrate the soil sample through the cavity above the soil sample, and exit from the bottom of the soil sample. After passing through the cavity below, it exits the test device through the hole on the bottom of the model box.

[0064] Step (6) Repeat the test: Starting with a 20mm thick soil sample, repeat the test in sequence with 40mm, 60mm, 80mm and 100mm thicknesses until the missile cannot be launched or the test ends after 100mm. This is considered one set. After that, adjust the firing speed of the nail (302) or the initial strength of the cohesive soil, and repeat the test again according to the above soil sample thickness.

[0065] Step (7) Data Processing: Calculate the velocity of the missile (303) as it enters the water, penetrates, and exits soil samples of different thicknesses, based on the images captured by the high-speed camera (402). Combine this with the exit velocities at depths of 20mm, 40mm, 60mm, 80mm, and 100mm to plot the penetration velocity-depth curve. Furthermore, plot the penetration resistance-depth curve using the resistance fluctuation curve from the spoke-type force gauge (401).

[0066] In summary, this invention proposes a model test apparatus and method for testing the rate resistance effect of high-speed missile penetration into seabed soil. Based on the test results under different penetration velocities and soil sample strengths, the soil rate coefficient is inferred, and the influence mechanism of the soil rate effect on the soil sample is evaluated.

Claims

1. A model test apparatus for testing the drag rate effect of a missile penetrating a seabed at high speed, comprising: The model box system (100) is used to complete the visual penetration test, including the model box (101), the support frame (102) and the soil sample box (103) for placing soil samples. The support frame (102) and the soil sample box (103) are placed in the model box (101) in sequence. The model box (101) and the soil sample box (103) are made of transparent acrylic material. The support frame (102) leaves the movement path of the missile penetration and ejection. The reaction frame system (200) includes a support (201), a horizontal fixer (202), and an excitation device fixer (203). The support (201) is used to fix the horizontal fixer (202) and the excitation device fixer (203). The horizontal fixer (202) is attached to the outer wall of the model box (101) to reduce the error caused by horizontal disturbance during the model box experiment. The excitation device fixer (203) is used to fix the excitation device (300). The firing device (300) includes a nail gun (301), a nail (302), and a missile (303), which provides kinetic energy for the launch of the missile (303); the missile (303) is fitted over the outside of the nail (302) and then inserted into the firing port of the nail gun (301); The data acquisition module (400) consists of a spoke-type force gauge (401), a high-speed camera (402), a data acquisition device (403), and a computer (404). The input and output frequencies of the spoke-type force gauge (401), the high-speed camera (402), and the data acquisition device (403) are all 12.8KHz to ensure the data acquisition accuracy of the missile (303) during its ultra-high-speed penetration process. The reaction frame system (200) is placed on the model box system (100) and the spoke-type force gauge (401), the horizontal fixer (202) is attached to both sides of the model box (101), and the excitation device fixer (303) is adjusted so that the bottom circular hole is collinear with the center of the soil sample.

2. The model test apparatus for testing the drag rate effect of high-speed missile penetration into seabed soil according to claim 1, characterized in that: The model box (101) in the model box system (100) has an opening at the bottom to ensure that there are no other obstructions besides the soil sample in the missile's (303) penetration path; the support frame (102) is used to place the soil sample box (103); the soil sample box (103) is filled with supports, soil sample and water from bottom to top according to the test requirements.

3. The model test apparatus for testing the drag rate effect of high-speed missile penetration into seabed soil according to claim 1, characterized in that: The horizontal fixer (202) is connected to the outer wall of the model box (101) to ensure the stability of the model box system (100). The excitation device fixer (203) is used to provide the reaction force required for the excitation device (300) and to ensure that the missile (303) can pass through the bottom of the soil sample box (103), the model box (101) and the center hole of the spoke-type force gauge (401) in sequence and accurately throughout the entire process of movement, and be captured by the high-speed camera (402).

4. The model test apparatus for testing the drag rate effect of high-speed missile penetration into seabed soil according to claim 3, characterized in that: The data acquisition system corresponding to the spoke-type force gauge (401) and the high-speed camera (402) has an acquisition frequency of 12.8KHz to meet the requirements for drawing the missile penetration velocity-depth curve and penetration resistance-depth curve.

5. The model test apparatus for testing the drag rate effect of high-speed missile penetration into seabed soil according to claim 4, characterized in that: Both the model box (101) and the soil sample box (103) are made of transparent acrylic material to ensure that the high-speed camera (402) can successfully capture images of the missile's movement throughout the entire penetration process.

6. A model test method for testing the velocity resistance effect of a missile penetrating a seabed soil at high speed, comprising using a model test apparatus for testing the velocity resistance effect of a missile penetrating a seabed soil at high speed as described in any one of claims 1-5, characterized in that, The specific steps are as follows: S01 Soil Sample Preparation: Soil samples were prepared using kaolin. The samples were saturated and consolidated in the order of 20mm, 40mm, 60mm, 80mm and 100mm. The initial undrained shear strength of the soil samples under low shear rate was determined by triaxial test or ring shear test. S02 Equipment Installation: Place the spoke-type force gauge (401) on a flat and stable ground, place the model box (101) on top, and align the opening on the bottom of the model box (101) with the center hole of the spoke-type force gauge (401); place the support frame (102) and the soil sample box (103) in sequence inside the model box (101); cover the bottom of the soil sample box (103) with plastic sheeting for waterproofing, place the support and fully saturated and consolidated soil sample on top, ensuring a total height of 100mm, and then add water to make the total height reach 180mm. According to the relative height of the soil sample, a high-speed camera (402) and a matching tripod are placed in front of the model box (101) to ensure that the soil sample and the upper and lower cavities along the missile (303) penetration path are completely captured in the frame; then the reaction frame system (200) is placed on the model box system (100) and the spoke-type force gauge (401) in sequence, the horizontal fixer (202) is attached to both sides of the model box (101), and the excitation device fixer (303) is adjusted so that the bottom round hole is collinear with the center of the soil sample; S03 Data Acquisition Device Calibration: Connect the spoke-type force gauge (401) and the high-speed camera (402) to the control device and initialize the data; apply a small pressure to the model box system (100) and verify the sensitivity and accuracy of the spoke-type force gauge (401) according to the reaction force fluctuation curve; adjust the position of the high-speed camera (500) according to the camera view; S04 Firing Device Installation: After placing the missile (303) on the outside of the nail (302), insert it into the firing port of the nail gun (301); and place the firing device (300) on the firing device holder (203). After confirming that the movement path of the nail (302) is collinear with the center of the soil sample and the opening of the model box (101), the test will officially begin. S05 Penetration Test: Launch missile (303) so that missile (303) is ejected from the hole of the trigger device holder (203), passes through the cavity above the soil sample and penetrates into the soil sample, and exits from the bottom of the soil sample; after passing through the cavity below, it exits the test device through the hole on the bottom of the model box (101). S06 Repeat Test: Starting with a 20mm thick soil sample, repeat the test in sequence with 40mm, 60mm, 80mm and 100mm thicknesses until the missile (303) cannot be fired or the test ends after 100mm. This is considered a set. After that, adjust the firing speed of the nail (302) or the initial strength of the cohesive soil, and repeat the test again according to the above soil sample thickness. S07 Data Processing: The data extracted by the data acquisition equipment (403) to the computer (404) includes high-speed photographs of the entire penetration process of the missile (303) and the reaction force fluctuations of the spoke-type force gauge (401); based on the high-speed photographs of the entire process, the velocity of the missile (303) when entering the water, penetrating and exiting soil samples of different thicknesses is calculated; and combined with the velocity of exiting at depths of 20mm, 40mm, 60mm, 80mm and 100mm, the penetration velocity-depth curve is plotted; in addition, the penetration resistance-depth curve is plotted in combination with the reaction force fluctuation curve of the spoke-type force gauge (401), according to the penetration resistance calculation formula (1): (1) In equation (1), m is the mass of the missile (303). For acceleration, For the missile (303)'s own weight, For vertical penetration resistance, For lateral resistance, For drag resistance, For soil buoyancy; The specific calculation method is as follows: (2) In formula (2) The saturated density of the cohesive soil was determined before the test. The drag resistance coefficient is 0.22 for cohesive soil. The cross-sectional area of ​​the missile (303) is calculated using the following formula: ,in The missile diameter is 7.6 mm; The real-time penetration speed is derived from the results captured by a high-speed camera. (3) In formula (3) The buoyant density of cohesive soil is obtained by using the saturated density of cohesive soil. Approximate calculations were performed. The volume of the missile (303) is calculated using the following formula: ,in The missile (303) is 30mm long; It is the acceleration due to gravity; The formulas for calculating end resistance and side friction resistance are: (4) (5) In equations (4) and (5) The strain rate coefficient is calculated using the following formula: ,in These are parameters related to soil rate effect. The undrained shear strength of cohesive soil was determined before the test. For the cross-sectional area of ​​the missile (303), The side surface area of ​​the missile (303) is calculated using the following formula: ; The coefficient of friction on the interface side; therefore, the method for calculating the strain rate coefficient can be summarized as equation (6): (6) Equation (6) can analyze the trend of strain rate coefficient with different parameters and reveal the development mechanism of resistance with soil rate effect during high-speed penetration.

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