Ejection type indoor penetration test device and application thereof

Abstract

The application discloses a kind of indoor penetration test device of ejection and application thereof, the device includes: model box, for accommodating test soil sample and water body;Penetration probe assembly, for penetration test soil sample;Ejection drive unit, installed at the top of model box, for providing controllable initial penetration speed for penetration probe assembly;Data acquisition unit, for collecting physical parameters in the process of penetration;Wherein, ejection drive unit includes spring, drive piece for compressing spring, and mechanical trigger mechanism, mechanical trigger mechanism is configured to release spring after being compressed to predetermined stroke, to eject penetration probe assembly.The application fundamentally solves the problem that the speed of existing free-fall penetration instrument is uncontrollable, repeatability is poor and data acquisition is imperfect when applied indoors, and provides a reliable experimental method for in-depth study of the mechanical response and strain rate effect of soft soil under high strain rate.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering testing equipment technology, and in particular to a catapult-type indoor penetration test device and its application. Background Technology

[0002] With the continuous advancement of deep-sea engineering, polar surveys, and nearshore soft soil development, the demand for evaluating the mechanical properties of ultra-soft, weakly saturated sediments is increasing. These sediments typically exhibit extremely high water content (often greater than 100%), a distinct fluid-plastic state, weak structure, extremely low strength, and high sensitivity to strain rates, making them difficult to sample and preserve in their original state. Conventional laboratory testing and large-scale in-situ exploration equipment face significant challenges. Currently widely used in-situ testing methods, such as the pore pressure static cone penetration test (CPTu), spherical probes, and full-flow probes, are primarily used for in-situ seabed surveys. While these methods can obtain information about sediment strength and sedimentary characteristics to some extent, they are unsuitable for systematic research on highly sensitive soft soils in a laboratory environment due to the large size of the equipment, high testing costs, complex operation, and uncontrollable testing environment.

[0003] Free-fall penetrometers (FFPs) are widely used in marine engineering to rapidly assess the shear strength and sedimentary structure characteristics of soft soils, serving as an effective means of evaluating the physical and mechanical properties of shallow sediments. However, in field testing, FFPs are limited by factors such as drop height, environmental disturbance, and wave interference, resulting in poor repeatability and controllability of the penetration process. Furthermore, it is difficult to systematically control and compare the penetration rate, energy input, and soil response under identical testing conditions. Indoor scaled-down FFP models, often limited by their mass and drop height, struggle to meet the field FFP testing conditions (such as penetration rate), thus restricting their application in the study of dynamic response mechanisms and strain rate effects in soft soils. The strain rate effect of soil refers to the change in its mechanical properties (such as shear strength, stiffness, and pore pressure response) with strain rate (the rate of change of strain per unit time, measured in seconds) during stress and deformation. - The phenomenon that changes significantly due to changes in ¹).

[0004] Therefore, there is an urgent need to develop an experimental device suitable for indoor controlled environments that can simulate free-fall penetration conditions, so as to realize the systematic simulation of the penetration process of marine ultrasoft sediments in a visualization model box.

[0005] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problem of how to provide a highly controllable, reliable and repeatable test environment for indoor research on the mechanical behavior of soft soil under high strain rates, and to propose a projectile-type indoor penetration test device and its application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An ejector-type indoor penetration test device includes: a model box for containing a test soil sample and a water body; a penetration probe assembly for penetrating the test soil sample; an ejector drive unit mounted on the top of the model box for providing a controllable initial penetration speed to the penetration probe assembly; and a data acquisition unit for acquiring physical parameters during the penetration process. The ejector drive unit includes a spring, a drive element for compressing the spring, and a mechanical trigger mechanism configured to release the spring after it has been compressed to a predetermined stroke, thereby ejecting the penetration probe assembly.

[0008] In some embodiments, the mechanical triggering mechanism includes at least one spring hook capable of locking the spring and a disc mechanism for triggering the release of the spring hook.

[0009] In some embodiments, the driving element is an electric actuator, and the compression of the spring is adjusted by controlling the stroke of the electric actuator, thereby controlling the initial penetration speed.

[0010] In some embodiments, the model box is composed of multiple sub-tanks joined together by flanges and seals, at least one of the sub-tanks is provided with a transparent observation window, and a drain valve is provided at the bottom of the model box.

[0011] In some embodiments, a guide rail system located on top of the model housing is also included, and the ejection drive unit is movably disposed on the guide rail system to adjust the penetration position of the penetration probe assembly. The guide rail system includes a circumferential slide rail and a radial slide rail disposed on the circumferential slide rail, and the ejection drive unit is mounted on the radial slide rail.

[0012] In some embodiments, the penetration probe assembly includes a probe rod and a cone head disposed at the front end of the probe rod. At least a portion of the sensors of the data acquisition unit are integrated inside or on the surface of the probe rod. The sensors include one or more of the following: accelerometer, pore pressure sensor, strain gauge, cone tip resistance sensor, sidewall friction sensor, and angular acceleration sensor.

[0013] In some embodiments, the data acquisition unit includes an acquisition circuit board integrated in the penetrating probe assembly. The acquisition circuit board integrates a processor, a memory, and a computer program stored in the memory. When the computer program is executed by the processor, it is used to control the sensor to acquire and store data.

[0014] The present invention also provides a penetration probe for a projectile-type indoor penetration testing device, comprising: a probe rod; a cone head connected to the front end of the probe rod; and a data acquisition module integrated inside or on the surface of the probe rod. The data acquisition module includes an accelerometer, a pore pressure sensor, a strain gauge, a cone tip resistance sensor, a sidewall friction sensor, an angular acceleration sensor, a memory, and a processor. The memory stores a computer program, which, when executed by the processor, is used to acquire and store data from the accelerometer, pore pressure sensor, strain gauge, cone tip resistance sensor, sidewall friction sensor, and angular acceleration sensor during the penetration process.

[0015] The present invention also provides a method for a projectile-type penetration test using the device described in any of the preceding claims, comprising the following steps: S1: filling the model box with a test soil sample and injecting water; S2: operating the drive component to compress the spring to a predetermined stroke; S3: triggering the mechanical triggering mechanism to release the spring, thereby projecting the penetration probe assembly into the test soil sample with a predetermined initial velocity; S4: acquiring physical parameter data during the penetration process through the data acquisition unit.

[0016] In some embodiments, in step S3, the predetermined initial velocity is between 6 m / s and 12 m / s; the physical parameter data collected in step S4 includes one or more of the following: penetration acceleration, pore water pressure, penetration depth, cone tip resistance, sidewall friction, and angular velocity.

[0017] The beneficial effects of this invention compared to the prior art include: This invention utilizes a launch drive unit comprised of a spring, an electric actuator, and a mechanical triggering mechanism. This unit precisely controls and rapidly releases the elastic potential energy of the spring, providing a stable, repeatable, and precisely adjustable high initial penetration speed for the penetration probe assembly, effectively simulating the high-speed conditions of free-fall penetration. Combined with a penetration probe integrating multiple types of sensors and a high-speed data acquisition unit, it achieves synchronous and high-precision acquisition of key physical parameters such as acceleration and pore water pressure during penetration. Furthermore, the movable guide rail system and modularly assembled model box enable multiple repeatable penetration tests at different locations on the same soil sample, facilitating observation. This combination of technical features constitutes a highly controllable, data-rich, and repeatable indoor penetration test platform. It fundamentally solves the problems of uncontrollable speed, poor repeatability, and incomplete data acquisition in existing free-fall penetration instruments used indoors. This provides a reliable experimental method for in-depth research on the mechanical response and strain rate effect of soft soil under high strain rates, constructing a highly reliable indoor physical simulation platform capable of accurately revealing the strain rate effect mechanism of soft soil.

[0018] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the ejector-type indoor penetration test device in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the ejection drive unit and guide rail system in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the ejection-type penetration mechanism in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1-Safety railing; 2-First sub-tank; 3-Second sub-tank; 4-Third sub-tank; 5-Observation window; 6-Base tank; 7-Drain valve; 8-Hanging ladder; 9-Ejection system; 10-Radial slide rail; 11-Circumferential slide rail; 901-Support top plate; 902-Support column; 903-Electric actuator; 904-Disc trigger mechanism; 905-Adjusting nut; 906-Spring hook; 907-Adjusting rod; 908-Force transmission ring; 909-Spring outer sleeve; 910-Spring; 12-Probe; 13-Pulley; 14-Compression spring; 15-Probe sleeve; 16-Spring sleeve cover; 17-Steel cable. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0024] It should be noted that the directional terms such as left, right, up, down, top, and bottom used in this embodiment are only relative concepts or are based on the normal use of the product, and should not be considered as restrictive.

[0025] This invention proposes a catapult-type indoor penetration testing device and its application. By mechanically launching the penetrator, a stable and adjustable initial velocity is provided, enabling high-precision testing of the dynamic response of sediments at different energy levels. Simultaneously, this device can be combined with high-speed imaging, pore pressure sensing, and strain acquisition systems to synchronously monitor the entire penetration process, effectively compensating for the poor repeatability, weak controllability, and unadjustable simulation environment of free-fall tests. This meets the experimental requirements for studying the coupling mechanism of mechanical properties and strain rate in weak sediments.

[0026] The ejector-type indoor penetration test device provided in this embodiment of the invention includes: a model box for containing test soil samples and water bodies; a penetration probe assembly for penetrating the test soil sample; an ejector drive unit installed on the top of the model box for providing a controllable initial penetration speed for the penetration probe assembly; and a data acquisition unit for acquiring physical parameters during the penetration process. The ejector drive unit includes a spring, a drive component for compressing the spring, and a mechanical triggering mechanism configured to release the spring after it has been compressed to a predetermined stroke, thereby ejecting the penetration probe assembly.

[0027] The mechanical triggering mechanism includes at least one spring hook capable of locking the spring and a disc mechanism that triggers the release of the spring hook.

[0028] The driving component is an electric actuator. The compression of the spring is adjusted by controlling the stroke of the electric actuator, thereby controlling the initial penetration speed.

[0029] The model box is composed of multiple sub-tanks assembled by flanges and seals, and at least one sub-tank is equipped with a transparent observation window 5. A drain valve 7 is installed at the bottom of the model box.

[0030] The device also includes a guide rail system located on top of the model housing, on which the ejection drive unit is movably mounted to adjust the insertion position of the penetration probe assembly. The guide rail system includes a circumferential slide rail 11 and a radial slide rail 10 disposed on the circumferential slide rail 11, on which the ejection drive unit is mounted.

[0031] The penetration probe assembly includes a probe rod and a cone head disposed at the front end of the probe rod. At least a portion of the sensors of the data acquisition unit are integrated inside or on the surface of the probe rod. The sensors include one or more of the following: accelerometer, pore pressure sensor, strain gauge, cone tip resistance sensor, sidewall friction sensor, and angular acceleration sensor.

[0032] The data acquisition unit includes an acquisition circuit board integrated into the penetration probe assembly. The acquisition circuit board integrates a processor, a memory, and a computer program stored in the memory. When the computer program is executed by the processor, it is used to control the sensor to acquire and store data.

[0033] This invention also provides a penetration probe for a projectile-type indoor penetration testing device, comprising: a probe rod; a cone head connected to the front end of the probe rod; a data acquisition module integrated inside or on the surface of the probe rod, the data acquisition module including an accelerometer, a pore pressure sensor, a strain gauge, a cone tip resistance sensor, a sidewall friction sensor, an angular acceleration sensor, a memory, and a processor, the memory storing a computer program, which, when executed by the processor, is used to acquire and store data from the accelerometer, pore pressure sensor, strain gauge, cone tip resistance sensor, sidewall friction sensor, and angular acceleration sensor during the penetration process.

[0034] This invention also provides a method for a projectile-type penetration test using the device described above, comprising the following steps: S1: Fill the model box with test soil samples and add water. The test soil samples are saturated soft soil with a moisture content greater than 100%.

[0035] S2: Operate the drive component to compress the spring to a predetermined stroke.

[0036] S3: Trigger the mechanical triggering mechanism to release the spring, thereby ejecting the penetration probe assembly into the test soil sample with a predetermined initial velocity; the predetermined initial velocity is between 6 m / s and 12 m / s.

[0037] S4: Collect physical parameter data during the penetration process through the data acquisition unit. The collected physical parameter data includes one or more of the following: penetration acceleration, pore water pressure, penetration depth, cone tip resistance, sidewall friction, and angular velocity.

[0038] Before performing step S3, the procedure also includes step S0: moving the position of the ejection drive unit on the guide rail system to select different penetration points.

[0039] This invention also provides a test method for determining the strain rate effect of soft soil, comprising: using the method described in any of the preceding claims, performing at least two ballistic penetration tests on the same soft soil sample at different predetermined initial velocities; acquiring physical parameter data for each test; and analyzing the relationship between the mechanical properties of the soft soil and the penetration velocity or strain rate based on the physical parameter data.

[0040] This invention also provides a catapult drive device for penetration testing, comprising: a bracket; a spring mounted on the bracket; an electric actuator for compressing the spring; and a mechanical triggering mechanism including at least one spring hook capable of locking the spring and a disc mechanism for triggering the release of the spring hook; wherein the stroke of the electric actuator is adjustable to control the amount of spring compression.

[0041] The following describes specific embodiments of the present invention.

[0042] To address the problems of unstable speed, difficult control, and poor repeatability in existing free-fall penetration tests under indoor conditions, and to support the study of soft soil mechanical behavior under multi-strain rate conditions, this embodiment proposes a compact and functionally integrated launch-type indoor penetration test device. This device adopts a modular design, integrating a model housing, penetration probe assembly, launch drive unit (launch system 9), speed adjustment device, and data acquisition unit. It possesses advantages such as controllable penetration speed, abundant measurement parameters, and good experimental repeatability, and can be widely used for determining soft soil mechanical parameters, dynamic response analysis, and verification of related theoretical models.

[0043] Connection relationship of each module: The model box is the main structure of the equipment. The catapult drive unit is installed on the top of the model box. The speed adjustment device is part of the catapult drive unit. The data acquisition unit is integrated into the penetration probe assembly. The penetration probe assembly is installed at the front end of the catapult drive unit before operation, in preparation for launch.

[0044] The data acquisition unit is primarily a high-speed acquisition circuit board integrated into the penetration probe assembly. It automatically collects and records data from various sensors during the high-speed penetration process. These sensors include: a bore pressure sensor, a cone tip resistance sensor, a sidewall friction sensor, and an angular acceleration sensor. The data acquisition unit is triggered by a magnetic trigger sensor mounted on the ejection drive unit. A Hall sensor is installed inside the penetration probe assembly, while a magnetic ring is mounted on the ejection drive unit. When the penetration probe assembly is lifted upwards, during the spring compression phase, the probe moves, and the internal Hall sensor passes through the magnetic ring. The change in the magnetic field triggers the data acquisition unit to collect data. The data acquisition unit begins operating before the probe is ejected, completely recording the entire ejection process.

[0045] The device includes: 1. Model Box: The model box is composed of four 1m high, 1m diameter cylindrical steel tanks stacked together. The number of tanks can be increased or decreased according to experimental needs. Waterproof seals and bolted connections are provided between the tanks. The second section has a transparent observation window for easy visual monitoring. The bottom of the model box has drainage holes and a water loading function to simulate real seabed conditions. The top of the model box is equipped with a catapult drive unit, a safety railing 1, and a side ladder 8.

[0046] The tank body is designed with flange rings on the upper and lower edges. During installation, the flanges correspond one-to-one with the holes on them. A rubber gasket with the same structure as the flange is installed between the flanges, namely a perforated annular rubber gasket. When connecting and installing the upper and lower tank bodies, the bolts and nuts are installed in the following order: bolts, gaskets, flanges, gaskets, and nuts, thereby achieving a fixed connection between the upper and lower tank bodies. A seal is achieved by compressing the rubber gasket between the flanges.

[0047] The observation window is made of transparent acrylic and is connected to the second tank section via a flange structure. Rubber gaskets between the flanges provide a seal. Since the first section is located at the bottom and is generally used for filling test soil samples, the observation window is usually located in the second section to observe the probe's entry into the soil. However, the position of the observation window can still be adjusted according to the desired observation location in the specific experiment. Transparent observation windows can be installed in other sections of the tank (the second, third, or fourth section is acceptable; the first section is generally used for filling soil samples and does not require a viewing window).

[0048] The drain hole is installed at the bottom of the first tank section and connected to a manually controlled valve. The valve is closed during operation and can be opened after operation to automatically drain the water inside the model box. Alternatively, a water pipe can be connected to directly fill the drain hole with water to fill the model box.

[0049] 2. Penetration Probe Assembly: This includes the penetration probe, penetration rod, and retrieval ring. The penetration probe includes a penetration cone located at the foremost end of the probe. The penetration cone is connected to the penetration rod. The penetration cone can be a standard CPT (static cone test) cone, spherical, or conical. The penetration rod integrates sensors such as a triaxial gyroscope, accelerometer, and strain gauge to achieve dynamic response acquisition.

[0050] 3. Ejection System 9: A single spring is compressed by pulling a pressure spring plate through an electric push rod. After compression, the three spring hooks are released by a disc trigger mechanism (mechanical trigger mechanism) to achieve instantaneous ejection.

[0051] 4. Speed ​​adjustment device: By adjusting the compression stroke of the electric actuator to control the release of energy of the spring, the initial penetration speed can be adjusted between 6 and 12 m / s.

[0052] 5. Penetrator Recovery Assembly: This includes a steel cable attached to the recovery ring on the probe. The recovery ring, with the steel cable attached, is connected after the penetration probe assembly for rapid recovery of the penetrator after the test, suitable for repeated testing.

[0053] like Figure 1As shown, the ejector-type indoor penetration test device provided in this embodiment includes a model box composed of multiple cylindrical tanks (first sub-tank 2, second sub-tank 3, third sub-tank 4, and base tank 6) spliced ​​together. Each tank has a diameter of 1 meter and a height of 1 meter, with a total of 4 sections. The second sub-tank 3 is equipped with a transparent observation window 5, which facilitates the deployment of high-speed camera equipment to observe soil deformation during the penetration process.

[0054] like Figure 2 As shown, the top of the model box is equipped with a circular slide rail guide mechanism (guide rail system). The guide rail system includes a circumferential slide rail 11, a radial slide rail 10 set on the circumferential slide rail 11, and a circular plate (disc). The radial slide rail 10 is mounted on the disc. Multiple pulleys 13 are installed on the circumference of the bottom of the disc, and a lower positioning hole is opened. The bottom plate of the ejection system 9 has an upper positioning hole and a groove. By placing the groove of the ejection system 9 on the pulley 13, it can be installed on the disc and horizontally positioned. Adjust the ejection system 9 to move circumferentially along the top surface of the model box. When it moves to the designated penetration point, insert the positioning pin into the upper and lower positioning holes and tighten it to lock it. The centerline of the guide rail system coincides with the centerline of the model box, ensuring that the penetration path is consistent with the axis of the soil sample each time. The pulley enables the ejection system 9 to move in a circular motion with the disk, and the radial slide rail 10 enables the ejection system 9 to move radially on the disk. By combining the two, the ejection point can cover the internal space of the model slot, making it easy to adjust the position of the ejection system 9 and realize multiple ejections from a single sample preparation.

[0055] A ladder 8 is installed on the outside of the model box, and is hung on the edge of the top frame of the model box. The ladder 8 is used by personnel to enter the top platform to adjust the experimental device, such as manually loading the probe or manually connecting the probe rod. A drain valve 7 is installed at the bottom of the model box, and the drain valve 7 is threadedly connected to the base tank 6 for easy drainage and maintenance.

[0056] In one embodiment, the penetration probe assembly, the ejection system 9, the speed regulation device, the penetration body recovery assembly, and the guide rail system form an ejection-type penetration mechanism (e.g., Figure 3 As shown in the diagram, it mainly includes a bracket, an electric actuator 903, a disc triggering mechanism 904, an adjusting nut 905, a spring hook 906, an adjusting rod 907, a force transmission ring 908, a spring outer sleeve 909, a spring 910, a probe 12, a pulley 13, a compression spring 14, a probe sleeve 15, a spring sleeve cover 16, and a steel cable 17. The bracket includes a bracket top plate 901 and a support column 902. The support column 902 is a steel column, and its upper and lower parts are fixedly connected to other structures by nuts. The specific structure and function are as follows:

[0057] 1. Spring Energy Storage System: A vertically arranged spring 910 is used (which can be replaced according to the requirements of probe mass and ejection speed, etc.). The upper end of the spring 910 is fixed and after installation, the upper end of the spring 910 is limited and fixed by the spring sleeve cover 16, and the lower end is connected to a compression spring plate 14 (compression spring component). The compression spring plate 14 is connected to the middle sleeve outside the probe 12 (i.e., probe sleeve 15) and forms the force transmission path of the spring 910. The compression spring plate 14 is a circular thin steel sheet with a diameter slightly smaller than the inner diameter of the spring outer sleeve 909 and larger than the diameter of the spring 910, and is welded to the bottom of the probe sleeve 15. When the electric push rod 903 is pulled up, the spring hook 906 (the grab hook assembly of the triggered component) drives the probe 12 and the probe sleeve 15 to move upward together. At this time, the compression spring plate 14 will move upward as well, compressing the spring 910. Driven by the electric actuator 903, the spring hook 906 is connected to the probe 12 and moves upward together. At this time, it drives the pressure spring 14 to compress the spring 910 upward, thus completing the energy storage.

[0058] 2. Sleeve and Probe Connection Mechanism: The probe 12 and probe sleeve 15 are connected by a force transmission ring 908, ensuring stable force transmission when the spring 910 stores energy and instantaneous separation upon release. The probe sleeve 15 is also rigidly connected to the compression spring 14, moving upwards with the probe 12 during energy storage, effectively compressing the spring 910. The force transmission ring 908 is a ring structure nested within the probe sleeve 15 and can slide within it. When the top of the probe sleeve 15 narrows, preventing the force transmission ring 908 from passing through, the probe sleeve 15 moves upwards during the ascent of the probe 12, which in turn moves the compression spring 14 upwards, compressing the spring 910. After the probe 12 is released, the spring 910 is simultaneously released, and the probe 12 is ejected by the action of the probe sleeve 15 and the force transmission ring 908. The probe sleeve 15 and the spring plate 14 are rigidly connected, and the whole can slide up and down in the spring outer sleeve 909. The probe sleeve 15 and the spring outer sleeve 909 are clearance fit. To ensure smooth sliding and reduce energy loss, a lubricant can be provided between the probe sleeve 15 and the spring outer sleeve 909 or the sliding parts can be made of a material with a low coefficient of friction (such as a polytetrafluoroethylene bushing).

[0059] 3. Electric actuator 903: The electric actuator 903 is mounted on the top plate 901 of the bracket. During operation, it outputs thrust in a vertical upward direction, driving the spring hook 906 to move upward. By setting the stroke of the electric actuator 903, the upward lifting distance during the penetration preparation stage can be precisely controlled.

[0060] 4. Spring Hook Release Mechanism (Release Mechanism): The spring hook 906 is used to hook the probe 12 when the electric actuator 903 is pulled up. Simultaneously, the force transmission ring 908 on the probe 12 drives the probe sleeve 15 and the pressure spring 14 upwards. After rising to a preset height, the spring hook 906 contacts and presses against the inner inclined surface (guide inclined surface) of the disc trigger mechanism 904 (trigger component), causing the hook to flip outwards, thus opening the spring hook 906 and instantly separating the probe 12 from the spring 910, completing a high-speed release. The spring hook 906 is installed at the front end of the electric actuator (electric actuator 903), presenting a three-grip structure. It can move around a rotating axis, automatically close, and grip the tail end of the probe 12. The guide inclined surface is a flared opening made of high-strength alloy. The disc trigger mechanism 904 has a circular opening at its center, through which the central axis of the electric actuator 903 can pass. Simultaneously, the bottom of this circular opening extends downwards, forming a flared opening, thus creating the guide inclined surface. The spring hook 906 is a long rod-shaped structure with its movable shaft in the middle. A spring (an elastic element, not shown in the figure) holds its upper end to maintain automatic closure. When the spring hook 906 moves upward, its upper end contacts the guide slope, causing the upper part of the spring hook 906 to retract inward, compressing the spring 910, while the lower part of the spring hook 906 opens under the action of the lever. The preset height is set according to the initial velocity requirement. Different speed settings are marked on the adjusting rod 907. Tightening the adjusting nut 905 to the corresponding position limits the disc trigger mechanism 904 to the position of the adjusting nut 905, thus allowing it to be adjusted to the preset position according to the speed requirement. The disc trigger mechanism 904 is precision-machined and adjusted to ensure that multiple spring hooks can be released synchronously and instantaneously to avoid lateral disturbance to the probe 12.

[0061] 5. Disc Trigger Mechanism 904 and Speed ​​Adjustment Structure: The disc trigger mechanism 904 is mounted on the adjusting rod 907, which is vertically arranged and connected to the spring sleeve cover 16. The adjusting nut 905 can be adjusted up and down on the adjusting rod 907, thereby changing the height of the disc trigger position, i.e., controlling the upward lifting distance of the spring hook 906, and thus adjusting the compression of the spring 910, achieving adjustable control of the initial ejection speed. The adjusting rod 907 is a threaded rod that passes through the disc trigger mechanism 904. Adjusting nuts 905 are installed at the top and bottom of the passing part, and the height of the disc trigger mechanism 904 is adjusted by adjusting the nuts 905.

[0062] 6. Guide Rail System: As described above, this guide rail system allows the ejection system to move radially along the top surface of the model housing and achieve precise locking via positioning holes. This structure facilitates penetration tests of the same sample at multiple different locations, improving the repeatability and validity of test data. The positioning holes are located on the radial slide rail 10. The probe 12 contains an acceleration sensor that measures the acceleration in the x, y, and z axes during descent. This acceleration is used for orientation correction during data processing; even with an inclined launch, the acceleration data can be corrected to equivalent vertical launch data.

[0063] 7. Probe Retrieval and Reset: The top of the probe 12 is provided with a retrieval hole. Before the test, the steel cable 17 is connected to this hole. After the penetration test is completed, the probe can be slowly retrieved to the initial position by manually lifting the steel cable 17, thus completing the closed-loop operation of the test cycle and preparing for the next loading.

[0064] The operation method of this embodiment is as follows: 1. Sample preparation: The obtained deep-sea sediments or artificially prepared saturated silty clay (150% water content) are filled into the model box, with the filling height reaching the middle of the observation window. The mixture is laid in layers, and water is injected at the top to simulate the hydrostatic pressure environment, so that the sediments are saturated and consolidated.

[0065] 2. Ejection system settings: The ejection system is mounted on the top guide rail system of the model box. The penetration probe is fixed to the axis of the ejection system via a connecting rod. An electric actuator drives a compression spring to compress the spring to a set stroke. The release device is a mechanical trigger mechanism. Different compression amounts are set according to experimental requirements, corresponding to initial velocities in the range of 6~12 m / s. Because the spring energy storage system uses a high-stiffness compression spring with an optimal elastic coefficient of 10.3 kN / m, and the probe mass is approximately 580g, the corresponding relationship between spring compression and initial velocity is as follows: 90mm compression corresponds to an initial velocity of 12m / s; 67.5mm compression corresponds to an initial velocity of 9m / s; and 45mm compression corresponds to an initial velocity of 6m / s.

[0066] 3. Data acquisition unit configuration: The probe is equipped with a triaxial accelerometer, pore pressure sensor, and IMU (inertial measurement unit), with a sampling frequency of 5kHz. A high-speed camera system (>1000 fps) and auxiliary light source are installed outside the model box, and the system is triggered in advance to achieve full data acquisition linkage during the experiment.

[0067] 4. Test execution procedure: ① Start the electric actuator and pull the pressure spring to the predetermined stroke. At this time, the spring hook is quickly ejected due to contact with the disc trigger mechanism; ② The spring releases its stored energy instantaneously, pushing the penetrometer to accelerate vertically down along the guide rail system, passing through the water body and entering the sedimentary soil layer; ③ During the penetration process, multi-source data such as acceleration signal, pore pressure response, and high-speed image are recorded synchronously in real time; ④ After the penetrometer stops, wait for the pore pressure to stabilize, and the recording ends; ⑤ After the penetration is completed, manually pull the penetrometer rod with the steel cable to lift the probe to the top, check and wipe the surface, release residual pressure, reset the ejection system, and realize the recovery and repositioning of the penetrometer.

[0068] 5. Multi-point testing function (top rail system): If repeated testing is required, the ejection system can move along the radial and circumferential guide rails of the top disc to achieve multi-point penetration testing within a horizontal range of ±300 mm and a circumferential range of 360°, and to conduct spatial uniformity analysis and repeatability comparison experiments.

[0069] 6. Data Processing and Analysis: The acquired data can be used for strength inversion, pore pressure response analysis, and strain rate influence studies: using data from the accelerometer built into the penetration probe, velocity and displacement can be obtained through numerical integration; combined with the pore pressure curve, the excess pore pressure response, dissipation characteristics, and inversion consolidation coefficient Cv can be analyzed; high-speed images can be extracted to analyze the water-soil coupling disturbance morphology during penetration; by comparing the resistance, excess pore pressure, and strain characteristics under different penetration velocities, the influence of strain rate on the shear strength of soft soil can be evaluated.

[0070] The embodiments of the present invention have the following beneficial effects: This device enables controlled and repeatable tests under the same sediment and boundary conditions with different loading rates, providing a unified platform for studying the strength variation, strain rate effect, and pore pressure response of marine soft soils under high-speed conditions. It can also serve as an experimental verification platform for constructing strain rate-sensitive soil strength models and pore pressure dissipation theory inversion models. Specifically:

[0071] 1. The penetration speed is controllable and highly repeatable, with multiple adjustable settings.

[0072] 2. Supports high initial velocity penetration mode, suitable for multi-strain rate studies.

[0073] 3. The visualization window, combined with high-speed imaging technology (using a camera), facilitates the observation of soil deformation processes.

[0074] 4. Complete data acquisition, supporting shear strength inversion and pore pressure response analysis.

[0075] 5. The device has a compact structure and is suitable for high-frequency repeatability testing needs in laboratories.

[0076] 6. The top guide rail system supports multi-point penetration testing, improving data coverage and accuracy.

[0077] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.

Claims

1. A projectile-type indoor penetration test device, characterized in that, include: The model box is used to hold test soil samples and water bodies; Penetration probe assembly, used to penetrate the test soil sample; A catapult drive unit, mounted on the top of the model housing, is used to provide a controllable initial penetration velocity for the penetration probe assembly; A data acquisition unit is used to acquire physical parameters during the penetration process; wherein, the ejection drive unit includes a spring, a drive member for compressing the spring, and a mechanical triggering mechanism, the mechanical triggering mechanism being configured to release the spring after it has been compressed to a predetermined stroke, so as to eject the penetration probe assembly.

2. The apparatus according to claim 1, characterized in that, The mechanical triggering mechanism includes at least one spring hook capable of locking the spring and a disc mechanism that triggers the release of the spring hook.

3. The apparatus according to claim 1, characterized in that, The driving component is an electric actuator. The compression of the spring is adjusted by controlling the stroke of the electric actuator, thereby controlling the initial penetration speed.

4. The apparatus according to claim 1, characterized in that, The model box is composed of multiple sub-tanks spliced ​​together by flanges and seals. At least one of the sub-tanks is provided with a transparent observation window (5), and a drain valve (7) is provided at the bottom of the model box.

5. The apparatus according to claim 1, characterized in that, It also includes a guide rail system located on the top of the model box, the ejection drive unit being movably mounted on the guide rail system to adjust the insertion position of the penetration probe assembly, the guide rail system including a circumferential slide rail (11) and a radial slide rail (10) mounted on the circumferential slide rail (11), the ejection drive unit being mounted on the radial slide rail (10).

6. The apparatus according to claim 1, characterized in that, The penetration probe assembly includes a probe rod and a cone head disposed at the front end of the probe rod. At least a portion of the sensors of the data acquisition unit are integrated inside or on the surface of the probe rod. The sensors include one or more of the following: accelerometer, pore pressure sensor, strain gauge, cone tip resistance sensor, sidewall friction sensor, and angular acceleration sensor.

7. The apparatus according to claim 1, characterized in that, The data acquisition unit includes an acquisition circuit board integrated in the penetrating probe assembly. The acquisition circuit board integrates a processor, a memory, and a computer program stored in the memory. When the computer program is executed by the processor, it is used to control the sensor to acquire and store data.

8. A penetration probe for a projectile-type indoor penetration testing device, characterized in that, include: probe; A cone-shaped head connected to the front end of the probe rod; A data acquisition module is integrated inside or on the surface of the probe. The data acquisition module includes an accelerometer, a bore pressure sensor, a strain gauge, a cone tip resistance sensor, a sidewall friction sensor, an angular acceleration sensor, a memory, and a processor. The memory stores a computer program, which, when executed by the processor, is used to acquire and store data from the accelerometer, bore pressure sensor, strain gauge, cone tip resistance sensor, sidewall friction sensor, and angular acceleration sensor during the penetration process.

9. A method for a projectile-type penetration test using the device described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Fill the model box with test soil samples and add water; S2: Operate the drive component to compress the spring to a predetermined stroke; S3: Trigger the mechanical triggering mechanism to release the spring, thereby ejecting the penetration probe assembly into the test soil sample with a predetermined initial velocity; S4: Collect physical parameter data during the penetration process through the data acquisition unit.

10. The method according to claim 9, characterized in that, In step S3, the predetermined initial velocity is between 6 m / s and 12 m / s; the physical parameter data collected in step S4 includes one or more of the following: penetration acceleration, pore water pressure, penetration depth, cone tip resistance, sidewall friction, and angular velocity.

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