Test device and method for simulating wave-induced liquefaction behavior of bottom-sitting offshore net cage foundation

Abstract

This application provides an experimental apparatus and method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation. The apparatus includes: a seabed soil model box, comprising a loading frame and a box body, the box body being used to contain the seabed soil required for the experiment; a pore pressure gauge support is provided at the bottom of the box body; a cage loading system, including a loading device, a scaled-down model of the cage, and a counterweight, the scaled-down model of the cage contacting the upper surface of the seabed soil; the counterweight being placed flat on top of the scaled-down model of the cage; the loading device can operate in two modes: horizontal load control and displacement control, simulating vertical load through the counterweight to achieve loading along different paths; a data monitoring and acquisition system, used to collect at least one of foundation settlement information, foundation pore water pressure information, horizontal displacement information of the scaled-down model of the cage, and tilt angle change information; a controller is connected to a servo motor and the data monitoring and acquisition system. This application can effectively simulate the wave-induced liquefaction state of a bottom-mounted marine cage foundation.

Description

Technical Field

[0001] This application relates to the field of civil engineering model testing, specifically to a test apparatus and method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation. Background Technology

[0002] Bottom-mounted marine cages are crucial infrastructure for shallow-sea aquaculture in my country. Their seabed foundations are susceptible to wave-induced liquefaction under wave action, leading to cage instability and significant economic losses. Therefore, studying wave-induced liquefaction behavior is essential for preventing major engineering losses. Due to the large size of the cages and foundations, in-situ experiments are difficult, costly, and rare. Therefore, it is necessary to simulate the foundation environment and wave action of bottom-mounted marine cages in a laboratory setting.

[0003] A review of existing technical literature revealed that, in terms of theoretical analysis, researchers employed fluid-structure-soil coupled numerical models (such as FSSI-CAS) and elastoplastic constitutive models (such as the PZⅢ model) to analyze the progressive liquefaction process of loose seabeds under wave loading. In terms of physical experiments, Zhejiang University and other institutions conducted model tests on wave-seabed interaction using a centrifuge device with a high-gravity wave generator. By observing the pore pressure accumulation characteristics of sandy and cohesive seabeds, they validated relevant liquefaction analysis models. Regarding submerged foundations, Liao et al. pioneered the observation of the pore pressure response of submerged foundation ground under wave action, analyzing the liquefaction depth and distribution patterns of the seabed surrounding the foundation, providing data support for the stability evaluation of submerged foundations.

[0004] Despite the existence of various simulation methods, current technologies still have many shortcomings: traditional wave flume tests focus on horizontal periodic waves, making it difficult to fully reproduce the complex effects of waves in the real marine environment; furthermore, existing equipment often can only measure single responses such as soil settlement, pore pressure, or structural displacement, lacking a comprehensive monitoring system within the same model test, making it difficult to fully capture the coupled response process of the foundation and soil under wave action. Therefore, there is an urgent need to introduce new testing devices and methods that can simulate the process of wave cyclic loading on the seabed soil where the bottom-mounted marine cage foundation is located within the same system, and record response variables such as foundation settlement, displacement, tilt, and pore pressure in real time. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of this application is to provide a test device and method for simulating wave-induced liquefaction behavior of the foundation of a bottom-mounted marine cage.

[0006] A first aspect of this application provides a test apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, comprising: The seabed soil model box includes a loading frame and a box body, the box body being located inside the loading frame and used to hold the seabed soil required for the test; a pore pressure gauge support is provided at the bottom of the box body. A gabion loading system includes a loading device, a scaled-down model of the gabion, and a counterweight. The scaled-down model is located above the gabion body and contacts the upper surface of the seabed soil inside the gabion. The counterweight is placed flat on top of the scaled-down model. The scaled-down model is mounted on the loading end of the servo motor of the loading device. The loading device is used to apply loads to the scaled-down model. The loading device can operate in two modes: horizontal load control and displacement control. The counterweight simulates vertical loads to achieve loading along different paths. The data monitoring and acquisition system is used to collect at least one of the following: foundation settlement information, foundation pore water pressure information, horizontal displacement information of the scaled-down model of the cage, and tilt angle change information; The controller is connected to both the servo motor and the data monitoring and acquisition system.

[0007] Optionally, the box is a square aluminum alloy box with a completely open top. One side of the box is a transparent acrylic panel to facilitate observation of soil behavior. The bottom of the box is provided with an aluminum alloy support base for engaging with the base of the loading frame.

[0008] Optionally, the pore pressure gauge bracket is a resin bracket consisting of two vertical plates connected together. The two vertical plates have corresponding holes at different heights to install pore water pressure sensors at different depths in the soil.

[0009] Optionally, the loading device further includes: The loading rod has one end connected to the loading end of the servo motor, and the other end connected to the scaled-down model of the mesh cage via a bearing; A force sensor is located between the loading rod and the servo motor to enable the servo motor to load a controllable force load.

[0010] Optionally, the scaled-down model of the gabion is designed from a scaled-down physical gabion of a preset size and is an aluminum alloy truss structure. The scaled-down model of the gabion has four sinking foundations at its bottom, which are placed on the seabed soil. A crossbar is provided in the middle of the scaled-down model of the gabion. The end of the crossbar near the gabion body is inserted into the bearing, and the two ends of the crossbar are respectively connected to the scaled-down model of the gabion by bolts, thereby realizing the hinged connection between the scaled-down model of the gabion and the loading device.

[0011] Optionally, the counterweight includes an upper counterweight and a lower counterweight, the lower counterweight having a recess that matches the shape of the scaled-down model of the wire mesh cage, so as to securely press down on the scaled-down model of the wire mesh cage.

[0012] Optionally, the data monitoring and acquisition system includes: A pore water pressure sensor is installed on a pore pressure gauge bracket at the bottom of the housing. A vertical laser displacement sensor is installed on the loading frame beam above the scaled-down model of the cage to monitor the settlement of the cushion foundation. A horizontal laser displacement sensor is installed on the side wall of the model box to monitor the horizontal displacement of the scaled-down model of the wire mesh box; An inclination sensor is located at the bottom center of the counterweight block to obtain the inclination angle of the scaled-down model of the wire mesh cage. The data acquisition device is connected to the pore water pressure sensor, the vertical laser displacement sensor, the horizontal laser displacement sensor, and the tilt sensor, respectively.

[0013] A second aspect of this application provides a test method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, implemented using the aforementioned test apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, comprising: Prepare seabed soil according to the test requirements, install pore water pressure sensors, fill the seabed soil into the box to the specified height, and make the soil saturated. Then install the scaled-down model of the net box, loading device and counterweight. Turn on the data monitoring and acquisition system, warm up and ensure that all sensors are running stably, and then pre-compress the scaled-down model of the cage. Cyclic loads were applied to a scaled-down model of a wire mesh cage using a wire mesh cage loading system, and data was collected. Experimental results were obtained based on the collected data.

[0014] Optionally, the test results include at least one of the following: the relationship between force and displacement of the scaled-down model of the gabion under different loading paths, the trend of pore water pressure accumulation before soil failure, and the influence of loading frequency on the liquefaction of the interface soil.

[0015] Optionally, when the maximum settlement of the cushion foundation exceeds 10 mm, the cushion foundation can be considered completely unstable, the test can be terminated and the experimental data can be saved; or, the test can be terminated and the experimental data can be saved after 500 loading cycles.

[0016] The experimental device provided in this application for simulating wave-induced liquefaction behavior of bottom-mounted marine cage foundations utilizes a servo motor to apply horizontal cyclic loads with multiple loading paths to a scaled-down model of the cage. By combining the model's scale ratio to determine the characteristics of the horizontal cyclic loads, it can better simulate the wave loads transmitted from the in-situ bottom-mounted cage to the foundation. Simultaneous testing and analysis of multiple physical parameters are conducted on the cage's submerged foundation, including measuring foundation settlement deformation, structural tilt angle changes, and pore water pressure, to explore the seabed response around the foundation and the foundation's instability and failure modes. This device can apply vertical loads via counterweights and horizontal loads via servo motors, simulating the simultaneous action of bidirectional loads, which better reflects actual engineering conditions. This effectively simulates the wave-induced liquefaction state of bottom-mounted marine cage foundations and allows for further scaled-down model testing, showing promising application prospects in marine engineering, geotechnical engineering, and other fields.

[0017] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0018] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of an experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, according to an exemplary embodiment. Figure 1 ; Figure 2 This is a schematic diagram of the structure of an experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, according to an exemplary embodiment. Figure 2 ; Figure 3 This is a schematic diagram of the structure of a seabed soil model box according to an exemplary embodiment; Figure 4 The following is a schematic diagram of the structure of a pore pressure gauge bracket according to an exemplary embodiment, wherein: (a) is a front view, (b) is a side view, (c) is a top view, and (d) is a schematic diagram of the overall structure; Figure 5 This is a schematic diagram of a scaled-down model of a wire mesh cage according to an exemplary embodiment.

[0019] In the diagram: 1 is the loading frame, 2 is the data acquisition instrument, 3 is the vertical laser displacement sensor, 4 is the horizontal laser displacement sensor, 5 is the box body, 5-1 is the main body of the model box, 5-2 is the bolt, 6 is the pore pressure gauge bracket, 7 is the scaled-down model of the net cage, 8 is the tilt sensor, 9 is the pore water pressure sensor, 10 is the counterweight, 11 is the loading rod, 12 is the servo motor, and 13 is the controller. Detailed Implementation

[0020] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0021] To address the limitations of large-scale in-situ marine experimental research, such as high difficulty, limited opportunities, and high costs, as well as the shortcomings of existing experimental devices in fully reproducing the complex effects of waves in the real marine environment and in completely capturing the coupled response process of the foundation and soil under wave action, this application provides an experimental device for simulating the wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, in order to solve the aforementioned problems.

[0022] Reference Figure 1 and Figure 2 As shown in one embodiment of this application, an experimental device for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation includes a seabed soil model box, a cage loading system, a data monitoring and acquisition system, and a controller 13. The seabed soil model box includes a loading frame 1 and a box body 5. The box body 5 is located inside the loading frame 1 and is used to contain the seabed soil required for the experiment. A pore pressure gauge support 6 is provided at the bottom of the box body 5. The cage loading system includes a loading device, a scaled-down cage model 7, and a counterweight 10. The scaled-down cage model 7 is located above the box body 5 and contacts the upper surface of the seabed soil inside the box body 5. The counterweight 10 is placed flat on the scaled-down cage model 7. Top; The scaled-down model 7 of the gabion is located at the loading end of the servo motor 12 of the loading device. The loading device is used to apply load to the scaled-down model 7 of the gabion. The loading device can simulate wave load by performing two control modes in the horizontal direction: load control and displacement control. Different vertical counterweights are used to simulate the vertical load of the gabion under different operating modes, thereby realizing loading along different paths. The data monitoring and acquisition system is used to collect at least one of the following: foundation settlement information, foundation pore water pressure information, horizontal displacement information of the scaled-down model of the gabion, and tilt angle change information. The controller 13 is connected to the servo motor 12 and the data monitoring and acquisition system respectively.

[0023] Specifically, the scaled-down model 7 of the gabion is a bottom-mounted gabion scaled-down model. The loading device includes a servo motor 12, which can be controlled by a computer program to achieve load control or displacement control modes and supports multiple cyclic loading paths. The servo motor 12 applies cyclic loads simulating waves, and simultaneously monitors parameters such as seabed soil pore water pressure, foundation displacement, and tilt angle, achieving comprehensive simulation and analysis of the seabed liquefaction process of the bottom-mounted gabion under wave action. The controller 13 can be a computer, used for loading settings and data recording.

[0024] It should be noted that the different operating modes refer to the difference between having an automatic feeding system and not having one. The vertical load of a cage with a feeding system is significantly greater than that of a cage without a feeding system.

[0025] In the embodiments described above, the servo motor 12 can apply horizontal cyclic loads with multiple loading paths to the scaled-down model 7 of the net cage. By combining the model's scale ratio to determine the characteristics of the horizontal cyclic loads, the wave loads transmitted from the in-situ bottom-mounted net cage to the foundation can be better simulated. Simultaneous testing and analysis of multiple physical parameters are performed on the net cage's submerged foundation, including measuring foundation settlement deformation, structural tilt angle changes, and pore water pressure in the foundation, to explore the seabed response around the foundation and the foundation instability failure mode. This device can apply vertical loads via the counterweight 10 and horizontal loads via the servo motor 12, simulating the simultaneous action of horizontal and vertical bidirectional loads, which is more closely related to actual engineering conditions and effectively simulates the wave-induced liquefaction state of the bottom-mounted marine net cage foundation.

[0026] In order to simulate and reproduce the marine environment, in some specific embodiments of this application, reference is made to... Figure 3 As shown, the box 5 is a cubic aluminum alloy box, made of 8mm thick aluminum alloy plate, 450mm long, 450mm wide and 300mm high. The edges of the plate are sealed with waterproofing material to effectively restore the drainage conditions around the seabed. The top is completely open. One side of the box 5 is a transparent acrylic plate to facilitate observation of soil behavior. The bottom of the box 5 is equipped with aluminum alloy vertical rods for engaging with the base of the loading frame 1 (the U-shaped frame outside the box).

[0027] Specifically, the outer observation surface of the main body 5-1 of the seabed soil model box is replaced with a transparent acrylic plate to observe the soil behavior during the experiment; the bottom edge of the main body 5-1 of the model box is fitted with an aluminum alloy vertical rod that extends beyond the edge of the loading frame base by bolts 5-2, which is used to engage with the loading frame base and prevent relative slippage.

[0028] In the above embodiments of this application, the main body 5-1 of the model box is fixed by an aluminum alloy vertical rod and bolts 5-2, which can ensure its stability and avoid the impact of slippage on the test results.

[0029] To facilitate the installation of the pore water pressure sensor, in some specific embodiments of this application, reference is made to... Figure 4 As shown, the pore pressure gauge bracket 6 is a resin bracket, which is composed of two vertical plates connected together. The two vertical plates have corresponding holes at different heights to install pore water pressure sensors 9 at different depths in the soil.

[0030] Specifically, a resin pore manometer bracket is installed inside the housing 5. It consists of two L-shaped uprights, each 40mm long, 30mm wide, and 240mm high, with corresponding openings at the front and back, connected together to install the pore manometer.

[0031] For example, the box contains four 3D-printed multilayer pore pressure gauge brackets that can fix the pore pressure sensor at different depths.

[0032] To simulate vertical loads and horizontal wave loads, in some specific embodiments of this application, the loading device includes a loading rod 11, a force sensor, etc., wherein: the servo motor 12 is mounted on the column of the loading frame 1, and the loading frame is used to provide support and installation foundation; one end of the loading rod 11 is connected to the loading end of the servo motor 12, and the other end is connected to the scaled-down model 7 of the net cage through a bearing; the force sensor is located between the loading rod 11 and the servo motor 12, and is used to realize the controllable force load that the servo motor 12 applies to the model.

[0033] Specifically, the side of the housing 5 has a recessed structure for placing the loading rod 11. A bearing is installed at the end of the loading rod 11 for mounting the scaled-down model of the wire mesh cage.

[0034] To predict and reproduce the behavior of a full-size prototype net cage in a real marine environment, a scaled-down model of the net cage is set up. In some specific embodiments of this application, reference is made to... Figure 5 As shown, the scaled-down model 7 of the gabion is designed from a scaled-down solid gabion of a preset size. It is an aluminum alloy truss structure. Four sinking foundations are provided under the scaled-down model 7, which are placed on the seabed soil. A crossbar is provided in the middle of the scaled-down model 7. The end of the crossbar near the box body 5 is inserted into the bearing at the end of the loading rod 11 and connected to the bearing. The bearing is connected to the scaled-down model of the gabion through the crossbar. The two ends of the crossbar are respectively connected to the scaled-down model of the gabion through bolts, thereby realizing the hinged connection between the scaled-down model of the gabion and the loading device, ensuring stable load transfer.

[0035] For example, the scaled-down model of the wire mesh cage is 170mm long, 170mm wide, and 110mm high. The corresponding example size is a wire mesh cage body that is 68m long, 68m wide, and 40m high. The scaled-down ratio is determined by the length ratio, which is 1 / 400 here.

[0036] The embodiments described above in this application, using a scaled-down model of the cage, can reproduce the instability process of a bottom-mounted cage on a wave-induced liquefied seabed with extremely high fidelity.

[0037] In some specific embodiments of this application, the counterweight 10 includes an upper counterweight and a lower counterweight. The lower counterweight has a recess that matches the shape of the scaled-down model 7 of the wire mesh cage, so as to securely press down on the scaled-down model 7 of the wire mesh cage.

[0038] Specifically, the counterweight 10 is an iron metal block with an anti-corrosion coating.

[0039] To comprehensively monitor information such as soil settlement, pore pressure, or structural displacement, and to fully capture the coupled response process of the foundation and soil under wave action, in some specific embodiments of this application, the data monitoring and acquisition system includes a pore water pressure sensor 9, a vertical laser displacement sensor 3, a horizontal laser displacement sensor 4, an inclination sensor 8, and an acquisition instrument 2. Specifically: the pore water pressure sensor 9 is installed on the pore pressure gauge bracket 6 at the bottom of the box 5; the vertical laser displacement sensor 3 is installed at the bottom of the loading frame beam above the scaled-down model of the gabion, used to monitor the settlement of the cushion foundation; the horizontal laser displacement sensor 4 is located on the side wall of the model box, used to monitor the horizontal displacement of the scaled-down model of the gabion; the inclination sensor 8 is located at the bottom center of the counterweight block 10, used to obtain the tilt angle of the scaled-down model of the gabion; and the acquisition instrument 2 is connected to the pore water pressure sensor 9, the vertical laser displacement sensor 3, the horizontal laser displacement sensor 4, and the inclination sensor 8 respectively.

[0040] It should be noted that the settlement of the cushion foundation is part of the whole. Due to the tilt, the vertical settlement of the cushion foundation is not the same as the overall settlement. The above embodiment of this application tested the settlement of all four cushion foundations, and the sum of the settlement of the four foundations is the overall settlement.

[0041] Specifically, displacement sensors are placed above and on both sides of the cage 5 to simultaneously monitor the horizontal displacement and foundation settlement of the cage; pore water pressure sensors 9 collect pore water pressure at different depths in the soil; a screw hole is provided in the center of the lower counterweight block for installing tilt sensors 8 to facilitate monitoring the tilt state of the cage model. The collected displacement, tilt angle, pore pressure, and other data are uploaded by the data acquisition instrument 2 to the controller 13 for real-time recording and analysis. The data monitoring and acquisition system can realize simultaneous testing and analysis of multiple parameters.

[0042] In the embodiments described above, a servo motor 12 is used to apply horizontal cyclic loads with multiple loading paths to a scaled-down model 7 of the net cage. By modeling the marine net cage under wave action using a full-size finite element model, applying corresponding wave loads, and analyzing its mechanical response, the characteristics of the horizontal cyclic load are determined by combining the scaled-down model with the model's scaling-up ratio. This allows for a better simulation of wave loads transmitted from the in-situ bottom-mounted net cage to the foundation. Simultaneous testing and analysis of multiple physical parameters are conducted on the net cage's submerged foundation, including measuring foundation settlement deformation, structural tilt angle changes, and pore water pressure in the foundation, to explore the seabed response around the foundation and the foundation instability failure mode. This device can simulate the simultaneous action of horizontal and vertical bidirectional loads, better reflecting actual engineering conditions.

[0043] It should be noted that by establishing a corresponding model through finite element modeling and then analyzing and calculating it using corresponding software, the expected results can be obtained. Specifically, existing numerical analysis methods can be used to achieve this.

[0044] Based on the same concept, another embodiment of this application provides a test method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, implemented using the test apparatus in any of the above embodiments. The method includes: S1. Sample preparation and device assembly: Prepare seabed soil according to test requirements, install pore water pressure sensor 9, fill seabed soil into box 5 to the specified height, and make the soil saturated. Then install the scaled-down model of the net box 7, loading device and counterweight 10. S2. System debugging and pre-compression: Turn on the data monitoring and acquisition system, warm up and run to ensure stable operation of each sensor, and then pre-compress the scaled-down model 7 of the wire mesh cage. S3. Conduct cyclic loading tests and collect data: Apply cyclic loads to the scaled-down model 7 of the net cage using the net cage loading system and collect data. Obtain test results based on the collected data.

[0045] Specifically, in S1, the seabed soil inside the model box required for the experiment is configured. The soil is a mixture of quartz sand with different particle sizes. After installing the pore water pressure sensor inside the experimental box, the soil is filled and brought to saturation. Finally, the scaled-down model of the net cage and the loading device are installed and adjusted to simulate the state of the soil and net cage in real-world conditions. S1 can be performed using the following steps: S11, Pore water pressure sensor installation. Secure the pore pressure sensor in the slot of the 3D printed bracket and secure it with cable ties. Lead out the sensor cable, tidy up the wiring harness, and connect it to the data acquisition unit.

[0046] S12, Preparation and Filling of Seabed Soil. Prepare seabed soil according to the experimental design ratio, and fill it into the model box in batches (layers) until the specified height. After each filling, add water until the soil is saturated, maintaining the water level 5mm above the mud surface. Use a small vibrating mixer to compact the soil, ensuring uniform distribution and full saturation. After filling, allow the soil to stand for 24 hours to prevent air bubbles or stratification.

[0047] S13. Connect the scaled-down model of the gabion to the loading device via a crossbar. Position the base-mounted scaled-down gabion model at the preset position on the loading rod end, ensuring uniform contact between the foundation and the soil surface. Connect the scaled-down gabion model to the servo motor loading end via the crossbar, securing both ends of the crossbar with bolts. Activate the vertical laser displacement sensor (while simultaneously referencing the vertical displacement gauge laser) to assist in adjusting the position of the scaled-down gabion model, ensuring its center is aligned with the central axis of the model box.

[0048] S14, Installation of counterweight and tilt sensor. Place the counterweight stably on top of the scaled-down model of the wire mesh cage, using the recessed structure at the bottom of the counterweight for positioning, ensuring a tight fit between the counterweight and the scaled-down model. Install the tilt sensor in the central recess of the counterweight and connect the sensor cable to the data acquisition unit.

[0049] Specifically, the main steps of S2 are as follows: After the test apparatus is installed, turn on the data acquisition instrument and computer, and preheat for 45 minutes. Check the signals of the horizontal displacement sensor, vertical displacement sensor, pore pressure sensor, and tilt sensor one by one to ensure they are normal. Perform zero-point calibration on the sensors and record the initial readings (such as initial pore pressure, initial displacement, etc.). Simulate the application of a small-amplitude load and observe whether the data changes are continuous and stable. If any abnormalities occur, check the wiring or sensor installation. After confirming that all sensors are working properly, preload the cage model. After preloading, the formal test can be carried out. During preloading, apply a vertical preload (simulating the cage's own weight) to the cage model using a loading device. Maintain the preload stable and leave the load statically for 30-40 minutes, observing the foundation settlement changes during this period. Record all initial data after preloading as the test baseline values.

[0050] Specifically, in step S3, the required cyclic load loading path is set in the controller, and the gabion loading system is started to apply the cyclic load. Cyclic load is applied to the scaled-down gabion model through the cyclic loading system. The test is terminated and the experimental data is saved when any of the following conditions are met: (1) When the maximum settlement of the cushion foundation exceeds 10 mm, the cushion foundation can be considered to be completely unstable; (2) After 500 loading cycles. The test results include at least one of the following: the relationship between the force and displacement of the scaled-down gabion model under different loading paths, the trend of pore water pressure accumulation before soil failure, and the influence of loading frequency on the liquefaction of the interface soil.

[0051] For example, when S3 conducts a cyclic loading test on the interface, it sets the load wave shape, frequency, amplitude, and number of cycles according to the simulated wave characteristics. It sets the data acquisition frequency to ensure the capture of dynamic changes in load and response. After starting the loading system, the data acquisition program is started simultaneously. The consistency between the load output curve and the set curve is monitored in real time. The movement state of the cage model and whether cracks or bulges appear on the soil surface are observed. If a sudden change occurs in the pore pressure sensor data, check whether the sensor is covered by soil; if the loading device makes abnormal noise, the test is stopped immediately, and the installation and loading settings are checked for correctness.

[0052] It should be noted that in some other implementation methods, the conditions for terminating the test can be adjusted arbitrarily and appropriately according to the specific test requirements.

[0053] Compared to wave flume tests, the apparatus described in the embodiments of this application is simpler to manufacture and more economical. Based on specific experimental requirements, soil and water are added to the simulation chamber. A servo motor is used to simulate wave action, combining vertical and horizontal wave loads. Based on wave characteristics (such as wave spectrum), the finite element method is used to perform hydrodynamic analysis of the cage under wave loads. This method integrates the ability to simulate complex ocean wave loads and simultaneously observe multiple responses of the foundation. It can recreate complex marine environments and can synchronously observe the multi-parameter responses of the model and soil in real time. The data is accurate, the method is effective and simple, thus effectively simulating the wave-induced liquefaction state of the foundation of a bottom-mounted marine cage. Further scaled-down model tests can be conducted based on this, showing promising application prospects in marine engineering, geotechnical engineering, and other fields.

[0054] The preferred features in the above embodiments can be used individually in any embodiment, or in any combination thereof, provided they do not conflict with each other. Furthermore, parts not described in detail in the embodiments can be implemented using existing technologies.

[0055] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0057] In the description of the embodiments in this application, "multiple" means two or more, unless otherwise explicitly specified. In this application, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0058] The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or devices.

[0059] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. An experimental device for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, characterized in that, include: The seabed soil model box includes a loading frame and a box body, wherein the box body is located inside the loading frame and is used to hold the seabed soil required for the test; A pressure gauge bracket is installed at the bottom of the box body; A gabion loading system includes a loading device, a scaled-down model of the gabion, and a counterweight. The scaled-down model is located above the gabion body and contacts the upper surface of the seabed soil inside the gabion. The counterweight is placed flat on top of the scaled-down model. The scaled-down model is mounted on the loading end of the servo motor of the loading device. The loading device is used to apply loads to the scaled-down model. The loading device can operate in two modes: horizontal load control and displacement control. The counterweight simulates vertical loads to achieve loading along different paths. The data monitoring and acquisition system is used to collect at least one of the following: foundation settlement information, foundation pore water pressure information, horizontal displacement information of the scaled-down model of the cage, and tilt angle change information; The controller is connected to both the servo motor and the data monitoring and acquisition system.

2. The experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation as described in claim 1, characterized in that, The box is a square aluminum alloy box with a completely open top. One side of the box is a transparent acrylic panel to facilitate observation of soil behavior. The bottom of the box is provided with an aluminum alloy support base for engaging with the base of the loading frame.

3. The experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 1, characterized in that, The pore pressure gauge bracket is a resin bracket consisting of two vertical plates connected together. The two vertical plates have corresponding holes at different heights to install pore water pressure sensors at different depths in the soil.

4. The experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 1, characterized in that, The loading device further includes: The loading rod has one end connected to the loading end of the servo motor, and the other end connected to the scaled-down model of the mesh cage via a bearing; A force sensor is located between the loading rod and the servo motor to enable the servo motor to load a controllable force load.

5. The experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 4, characterized in that, The scaled-down model of the gabion is designed from a scaled-down version of a pre-defined gabion and is an aluminum alloy truss structure. Four sinking foundations are provided below the scaled-down model of the gabion, and the sinking foundations are placed on the seabed soil. A crossbar is provided in the middle of the scaled-down model of the gabion. The end of the crossbar near the gabion body is inserted into the bearing, and the two ends of the crossbar are respectively connected to the scaled-down model of the gabion by bolts, thereby realizing the hinged connection between the scaled-down model of the gabion and the loading device.

6. The experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 1, characterized in that, The counterweight includes an upper counterweight and a lower counterweight. The lower counterweight has a recess that matches the shape of the scaled-down model of the wire mesh cage, so as to securely press down on the scaled-down model of the wire mesh cage.

7. The experimental apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 1, characterized in that, The data monitoring and acquisition system includes: A pore water pressure sensor is installed on a pore pressure gauge bracket at the bottom of the housing. A vertical laser displacement sensor is installed on the loading frame beam above the scaled-down model of the cage to monitor the settlement of the cushion foundation. A horizontal laser displacement sensor is installed on the side wall of the model box to monitor the horizontal displacement of the scaled-down model of the wire mesh box; An inclination sensor is located at the bottom center of the counterweight block to obtain the inclination angle of the scaled-down model of the wire mesh cage. The data acquisition device is connected to the pore water pressure sensor, the vertical laser displacement sensor, the horizontal laser displacement sensor, and the tilt sensor, respectively.

8. A test method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation, implemented using the test apparatus for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation as described in any one of claims 1-7, characterized in that, include: Prepare seabed soil according to the test requirements, install pore water pressure sensors, fill the seabed soil into the box to the specified height, and make the soil saturated. Then install the scaled-down model of the net box, loading device and counterweight. Turn on the data monitoring and acquisition system, warm up and ensure that all sensors are running stably, and then pre-compress the scaled-down model of the cage. Cyclic loads were applied to a scaled-down model of a wire mesh cage using a wire mesh cage loading system, and data was collected. The experimental results were obtained based on the collected data.

9. The experimental method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 8, characterized in that, The test results include at least one of the following: the relationship between force and displacement of the scaled-down model of the gabion under different loading paths, the trend of pore water pressure accumulation before soil failure, and the effect of loading frequency on the liquefaction of the interface soil.

10. The test method for simulating wave-induced liquefaction behavior of a bottom-mounted marine cage foundation according to claim 8, characterized in that, When the maximum settlement of the cushion foundation exceeds 10 mm, the cushion foundation can be considered completely unstable, the test should be terminated and the experimental data saved; or, the test should be terminated and the experimental data saved after 500 loading cycles.

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