A test system and monitoring method for a submarine landslide disaster chain of bed erosion

Abstract

A kind of submarine landslide disaster chain test system and monitoring method for realizing bottom erosion belong to the field of marine engineering, geotechnical disaster physical simulation and test technology, including water tank main module, source item generation module, bottom erosion-shallow buried pipeline response module and multi-source monitoring and synchronous acquisition module.Firstly, the conditions of setting water depth, flow rate and tank body inclination are formed by water tank main body and circulating water supply module;Secondly, the underwater slope sliding or landslide material continuous release boundary is formed by source item generation module, and the landslide material moves along the water tank and then enters the erosion reaction zone, which produces scouring, erosion and bed surface incision effect on the bottom model;At the same time, the overlying water body is disturbed by the movement of landslide material and the process of bottom erosion, and surge response is formed;Finally, synchronous monitoring and unified analysis are carried out by multi-source monitoring and synchronous acquisition module.The present application can realize the test simulation of submarine landslide-bottom erosion damage-shallow buried pipeline response-surge response disaster chain process.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering, physical simulation and testing technology of rock and soil geological disasters. It relates to a test system and monitoring method for realizing submarine landslide disaster chain of bed erosion. In particular, it relates to a test system and monitoring method for simulating the entire process of submarine landslide movement, bed erosion and destruction, shallow buried pipeline response and surge response in a long flume test platform, and for simultaneously monitoring the expansion of erosion pits, bed incision, exposure or partial suspension of shallow buried pipelines and water disturbance processes. Background Technology

[0002] Submarine landslides are a typical, widespread, and highly destructive marine geological hazard. They can cause continuous movement along the seabed, engulfing and carrying away the subsurface, leading to rapid attenuation, exposure, and even localized suspension of the overlying layers of shallow-buried pipelines beneath the seabed. Simultaneously, submarine landslides can also trigger tsunami waves, thus creating a chain reaction of disaster effects: submarine landslide – seabed destruction – shallow-buried pipeline failure – swell response. Therefore, conducting indoor model tests that can simultaneously simulate submarine landslide movement, seabed erosion evolution, shallow-buried pipeline exposure / suspension, and water wave response is of great significance for revealing the evolution mechanism of the submarine landslide disaster chain and assessing the risks of shallow-buried pipeline projects.

[0003] Existing indoor testing facilities can be broadly categorized into two types: one primarily focuses on the triggering of underwater slope instability and the landslide initiation process, emphasizing the instability mechanism of landslides under the influence of gravity, slope changes, or local disturbances; the other primarily focuses on the movement, deposition, and interaction of landslides with marine structures, emphasizing the migration distance, depositional morphology, impact loads, and structural response of landslides. While these testing facilities have played a significant role in studying the initiation mechanism of submarine landslides and landslide-structure interactions, they still lack specific simulation capabilities for the scouring, erosion, and bed cutting processes that occur during the continuous movement of landslides on the erosive seabed.

[0004] For example, Chinese invention patent CN108894182A discloses a landslide triggering device and method for flume testing of submarine landslides. This scheme mainly causes the slope to become unstable under its own weight by changing the slope angle, which is suitable for studying the instability triggering process of slopes. However, it is difficult to simulate various triggering factors such as shallow gas overflow, slope toe excavation, and local scour, and their impact on the landslide initiation mechanism. Chinese invention patent CN120721519A discloses a three-dimensional mechanical analysis experimental system for submarine landslide-seabed-pipeline. This scheme focuses on landslide movement and its mechanical interaction with pipelines, but its bed conditions are mainly considered as transport boundaries, failing to reflect the erodibility of the bed material and making it difficult to continuously simulate the bed erosion process under the action of the landslide body.

[0005] Furthermore, the existing indoor test systems and monitoring methods related to submarine landslides still have the following shortcomings: (1) They lack the test simulation function of submarine landslide erosion bed, making it difficult to obtain quantitative results of erosion development, erosion pit expansion, bed incision and bed shape evolution; (2) They lack the loading method that can form a continuous and controllable landslide release boundary, making it difficult to reproduce the development process of overburden attenuation, pipeline exposure and even local suspension under the pipeline under long-term erosion conditions; (3) In turbid water and high sediment content environments, the existing observation methods mostly rely on local visualization or post-event measurement, lacking the ability to identify the erosion pit expansion, bed incision and overburden attenuation process in real time.

[0006] Therefore, there is an urgent need for a long flume test system and monitoring method for submarine landslide erosion of the substrate and its engineering disaster-causing effects. This system should be able to continuously simulate landslide occurrence and substrate erosion, overburden layer attenuation, pipeline exposure or partial suspension, and surge response processes on the same test platform, thereby providing experimental support for the study of submarine landslide disaster chain mechanisms and risk assessment of shallow buried pipelines. Summary of the Invention

[0007] The purpose of this invention is to provide a test system and monitoring method for submarine landslide disaster chains that realizes seabed erosion, focusing on solving the following problems: ① reproducing the chain disaster process of submarine landslide movement, seabed erosion and destruction, shallow buried pipeline response and surge response within the same platform; ② synchronously and quantitatively acquiring the attenuation of overburden thickness and pipeline stress evolution below the seabed for shallow buried pipelines; ③ recording the surge time history triggered by water disturbance; ④ achieving real-time identification of erosion pit expansion, seabed incision and critical exposure moments in turbid water and high sediment content environments.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A test system for submarine landslide disaster chain to realize bed erosion is provided. The test system includes a flume main module, a source term generation module, a bed erosion-shallow buried pipeline response module, and a multi-source monitoring and synchronous acquisition module.

[0009] The main module of the water tank includes a water tank, energy dissipation material inside the water tank, a bottom support steel frame at the bottom of the water tank, hydraulic jacks on the side of the water tank, a water supply tank connected to the water tank via water pipes and a high-pressure water pump, an unloading box, and a filter screen arranged between the unloading box (7) and the water supply tank; the water tank is a transparent trough-shaped structure with an open top, forming an upstream source term generation zone, a middle landslide movement zone, and a recessed middle and downstream erosion reaction zone along the length of the trough. Specifically: the main module of the water tank includes a water tank, a bottom support steel frame, hydraulic jacks, water pipes, a water supply tank, a high-pressure water pump, an unloading box, a filter screen, and energy dissipation material. The water tank is a transparent trough-shaped structure with an open top, forming an upstream source term generation zone, a middle landslide movement zone, and a recessed middle and downstream erosion reaction zone along the length of the trough. The water tank is installed on a supporting steel frame at the bottom of the tank. A hydraulic jack is positioned between the bottom of the water tank and the supporting steel frame. By adjusting the extension and retraction height of the hydraulic jack, the macroscopic inclination angle of the water tank relative to the ground is adjustable within a range of -°. A water supply tank is connected to the water tank via a water pipe. A high-pressure water pump is installed on the water pipe to provide a stable water supply or directional flow to the water tank. The downstream drainage end of the water tank returns to the water supply tank via a water pipe, forming a circulating water supply path. A discharge box and filter screen are located between the downstream drainage end of the water tank and the water supply tank, used for solid-liquid separation and recovery of the water, landslide material, and bottom bed particles after the experiment. Energy-dissipating material is installed at the inlet, outlet, and downstream side of the erosion reaction zone of the water tank. The energy-dissipating material is a detachable wave-damping grid, used to weaken water flow reflection, reduce boundary disturbances, and stabilize the flow field within the tank.

[0010] The source term generation module includes an adjustable slope plate, air vents, an underwater slope model, a baffle, a pressure plate, a high-pressure air tank, a vent pipe, a pressure controller, an electric scraper, a telescopic robotic arm, an L-shaped material guide hopper, and a hydraulic gate, all located in the upstream source term generation area of ​​the water tank. The adjustable slope plate has air vents connected to the high-pressure air tank via vent pipes. The pressure controller controls the gas pressure, ventilation time, and ventilation rate entering the air vents. The pressure plate is located above the underwater slope model, which is situated on the upper surface of the adjustable slope plate. The baffle is located at the foot of the adjustable slope plate. The electric scraper is connected to the telescopic robotic arm fixed within the water tank. The L-shaped material guide hopper is located in the upstream source term generation area of ​​the water tank and is equipped with a hydraulic gate. Specifically: An adjustable slope plate is installed in the upstream source term generation area of ​​the water tank. Its lower end smoothly connects to the bottom or middle landslide movement area of ​​the water tank, and the local inclination angle of its plate surface relative to the bottom of the water tank is continuously adjustable within a range of -°. The adjustable slope plate includes an upper slope plate section and a lower slope plate section that are hinged to each other, and the slope shape is adjusted through the hinge nodes between the plates. The vents are an array of holes that penetrate through the surface of the adjustable slope plate. The vents are connected to a high-pressure gas storage tank located outside the water tank through a vent pipe. A pressure controller is installed between the high-pressure gas storage tank and the vent pipe to control the gas pressure, venting time, and venting rate entering the vents, so as to simulate the underwater slope instability triggering process under shallow gas overflow or overpressure gas disturbance conditions.

[0011] The underwater slope model is layered and filled onto the upper surface of an adjustable-angle slope slab. The baffle, a detachable enclosure, is positioned at the toe of the adjustable-angle slope slab to restrict toe slippage during filling, saturation, and pre-consolidation. A pressure plate is positioned above the underwater slope model to apply a pre-load, ensuring repeatable initial compaction, water content, and consolidation. An electric scraper is mounted on the free end of a telescopic robotic arm, which is fixed to the upper support of the water tank. During testing, the telescopic robotic arm drives the electric scraper to extend into the toe of the underwater slope model, weakening the toe constraint through localized scraping to simulate the process of toe excavation or localized scouring triggering underwater slope instability.

[0012] The L-shaped material guide bucket is used to form a continuous and controllable landslide release boundary. The L-shaped material guide bucket is located in the upstream source term generation area of ​​the flume, at or above the upper end of the adjustable slope plate. The L-shaped material guide bucket includes a vertical inflow section and an outflow section arranged along the slope surface of the adjustable slope plate. The vertical inflow section is connected to an external mud tank or an external pumping unit, and the outlet of the outflow section faces downstream of the adjustable slope plate. A hydraulic gate is located at the outlet of the L-shaped material guide bucket. By adjusting the opening of the hydraulic gate, the cross-sectional area of ​​the outlet is controlled, changing the outflow velocity, outflow thickness, and release duration of the landslide material, thereby simulating the process of a submarine landslide continuously moving along the bed and eroding the bed.

[0013] The source term generation module has two operating modes: the first is the underwater slope initiation mode, which uses an adjustable slope angle slope plate, an underwater slope model, baffles, and pressure plates to form an underwater slope body with preset slope angle, physical property parameters, and consolidation state. Overpressure gas is generated through a high-pressure gas storage tank, vent pipe, pressure controller, and vents to trigger the initiation, or excavation is triggered at the slope toe using a telescopic robotic arm and an electric scraper. The second is the continuous release mode, which uses an L-shaped material guide bucket and a hydraulic gate to form a landslide material input boundary with controllable speed, thickness, and duration. Both operating modes can be used independently to provide initial and boundary conditions for different types of submarine landslide source terms.

[0014] The substrate erosion-shallow buried pipeline response module includes a pipeline model, pipeline fasteners, a substrate model, and a filler block. The substrate model is set in the middle and lower reaches of the erosion reaction zone of the water tank and laid along the width or length of the water tank. It contains a pipeline model connected to the pipeline fasteners, the installation height and angle of which are adjustable. The filler block is placed between the bottom of the erosion reaction zone and the substrate model. Specifically: The substrate model is a layered substrate structure that can be filled and eroded. It can be formed by layering sand, silt, clay, or similar materials according to preset thickness, gradation, moisture content, and density. Color marker layers or particle marker layers can be set in the substrate model to identify the depth of incision, erosion interface, and changes in substrate morphology. The filler blocks are detachable rigid blocks placed between the bottom of the erosion reaction zone and the substrate model; the upper surface of the filler blocks constitutes the local support boundary or incident transition boundary of the substrate model. By replacing filler blocks of different heights, slopes, or shapes, the local geometry of the substrate model, the initial slope of the bed surface, and the incident angle of landslide material can be adjusted, thereby comparing the erosion behavior of submarine landslides on the substrate under different substrate boundary conditions.

[0015] The pipeline model is embedded inside the substrate model, with its axis arranged along the width or length of the water tank. Pipeline fixing components are installed below the substrate model, on both sides of the substrate model, or inside the sidewall of the water tank. These fixing components are connected to the pipeline model and are used to control the initial burial depth, axial direction, support method, and overburden thickness of the pipeline model. By adjusting the installation height and angle of the pipeline fixing components, the response process of shallow-buried pipelines under landslide erosion under different burial depths, directions, and constraints can be simulated. A coordinate reference is set on the outer wall of the water tank corresponding to the erosion reaction zone. This coordinate reference includes a graduated grid arranged along the length of the water tank and vertically, and uses the initial elevation of the substrate model as the measurement reference to record the expansion range of the erosion pit, the depth of the incision in the substrate, the exposed height of the pipeline model, and the local overhang length below the pipeline model.

[0016] The multi-source monitoring and synchronous acquisition module includes a piezoelectric force sensor, a fiber Bragg grating sensor, a soil pressure sensor, a pore pressure sensor, a 3D laser scanner, an electrode probe, a wave height meter, an acoustic Doppler current profiler, a high-speed camera, an acoustic emission sensor, a multi-channel data acquisition instrument, and a monitoring computer. The piezoelectric force sensor is installed between the pipeline model and the pipeline fixing components to monitor the impact force on the pipeline model. The fiber Bragg grating sensor is axially or circumferentially attached along the outer surface of the pipeline model to monitor the strain response of the pipeline model during landslide impact, subsoil erosion, and localized suspension processes. Specifically: Earth pressure sensors and pore pressure sensors are embedded inside the underwater slope model, the subgrade model, or at key locations in both to monitor changes in earth pressure, pore water pressure, and effective stress before and after underwater slope instability. A 3D laser scanner is mounted on a support above the water tank to acquire the 3D morphology of the subgrade model before and after the test. Electrode probes are arranged in an array along the longitudinal and transverse directions of the subgrade model to collect changes in resistivity or conductivity within the subgrade model, thereby identifying the moments of subgrade incision, erosion interface movement, and critical exposure of shallow-buried pipelines. Acoustic emission sensors are positioned on the outer side of the water tank bottom corresponding to the erosion reaction zone to collect acoustic emission signals generated by landslide material particle collisions, subgrade particle initiation, and subgrade surface damage, thereby identifying active erosion zones and the intensity of subgrade damage.

[0017] Wave height meters are arranged along the length of the flume, preferably forming a sequence along the central axis of the flume, to monitor the time history, propagation velocity, and frictional attenuation of surge waves generated by water disturbance during landslide movement and bed erosion. An acoustic Doppler current profiler is mounted on the upper support of the flume, with its measuring section facing the water within the flume, to acquire velocity profiles and water disturbance characteristics near the landslide movement zone or erosion response zone. A high-speed camera is positioned outside or above the transparent sidewall of the flume to record underwater slope instability, landslide material movement, bed erosion pit expansion, pipeline model exposure, and surge wave propagation processes.

[0018] The multi-channel data acquisition instrument is connected to piezoelectric force sensors, fiber optic grating sensors, soil pressure sensors, pore pressure sensors, electrode probes, wave height meters, acoustic Doppler current profilers, and acoustic emission sensors, and is also connected to a high-speed camera, a 3D laser scanner, and a monitoring computer via trigger or time signal connections. The monitoring computer is used to control data acquisition, record test parameters, display real-time monitoring curves, and perform time axis alignment and synchronous storage of different monitoring data. Therefore, the multi-source monitoring and synchronous acquisition module enables unified triggering, synchronous acquisition, and correlation analysis of source term monitoring, subsoil erosion identification, shallow buried pipeline response monitoring, and surge response monitoring.

[0019] The modules of the submarine landslide disaster chain simulation test system work together as follows: First, the water tank body and the circulating water supply module establish the set water depth, flow velocity, and tank inclination angle conditions; then, the source term generation module creates the underwater slope initiation or continuous release boundary of landslide material; after the landslide material moves along the water tank, it enters the erosion reaction zone and causes scouring, erosion, and bed surface incision on the bed model; the erosion development of the bed model further causes the overlying layer thickness of the pipeline model to decrease, and the pipeline model to be exposed or partially suspended; at the same time, the movement of landslide material and the bed erosion process disturb the overlying water and generate a surge response; finally, the multi-source monitoring and synchronous acquisition module synchronously monitors and uniformly analyzes the landslide source term, bed erosion, pipeline response, and surge response, thereby realizing the experimental simulation of the submarine landslide-bed erosion damage-shallow buried pipeline response-surge response disaster chain process.

[0020] The experimental scale was determined based on the on-site prototype conditions, laboratory equipment dimensions, and experimental objectives. For landslide motion, surge propagation, and velocity response processes dominated by gravity and inertia, the Frode similarity relation was used for scale conversion. For the processes of bed erosion, shallow buried pipeline stress, and bed incision, similarity checks were performed based on the particle size, density, shear strength of the bed material, pipeline burial depth, and flow intensity to ensure that the model test results could reflect the main dynamic characteristics of the prototype submarine landslide disaster chain process.

[0021] This invention also provides a method for monitoring submarine landslide disaster chains caused by seabed erosion, based on the aforementioned submarine landslide disaster chain test system, comprising the following steps: Step 1: Construct test boundary conditions and establish the initial subgrade-shallow buried pipeline state to obtain initial test state data. Specifically, this includes: Step 1.1: Based on the target working conditions, including water depth, slope angle, landslide size, subgrade material properties, shallow buried pipeline depth, and hydrodynamic conditions, determine the model test scale, macroscopic inclination angle of the trench, water depth, flow velocity, landslide source term conditions, subgrade model thickness, and initial burial depth of the pipeline model.

[0022] Step 1.2: Based on the macroscopic inclination angle, water depth, and flow velocity conditions of the tank determined in Step 1.1, the tank is installed on the support steel frame at the bottom of the tank. The macroscopic inclination angle of the tank relative to the ground is adjusted by hydraulic jacks. The water supply tank, water pipes, and high-pressure water pump are connected to form a circulating water supply path. Energy dissipation materials are arranged at the inlet end, outlet end, or downstream side of the erosion reaction zone of the tank to obtain stable boundary conditions of the tank.

[0023] Step 1.3: Based on the bed geometry and landslide incident conditions determined in Step 1.1, install filling blocks in the erosion reaction zone, and construct the bed model in layers above or near the filling blocks; install pipeline models and pipeline fasteners inside the bed model according to the preset burial depth, and record the initial bed surface elevation of the bed model, the initial burial depth of the pipeline model, the thickness of the overburden layer, and the axial direction of the pipeline model to obtain the initial bed-shallow buried pipeline status data.

[0024] Step 2: Based on the initial test state data obtained in Step 1, complete the deployment, calibration, and synchronous triggering settings of the monitoring elements to obtain the synchronous acquisition system. Specifically, this includes: Step 2.1: Install a piezoelectric force sensor between the pipeline model and the pipeline fixture, and arrange a fiber optic grating sensor on the outer surface of the pipeline model to obtain the force and strain response of the pipeline model.

[0025] Step 2.2: Earth pressure sensors and pore pressure sensors are installed in the proposed layout area of ​​the underwater slope model, inside the bed model, or at key locations in the erosion reaction zone to obtain changes in earth pressure and pore water pressure during the underwater slope instability and bed erosion process.

[0026] Step 2.3: Arrange the electrode probe array along the longitudinal and transverse directions in the substrate model, and arrange the acoustic emission sensor on the outer side of the bottom of the water tank corresponding to the erosion reaction zone to form an electro-acoustic multi-source erosion identification unit.

[0027] Step 2.4: Arrange a 3D laser scanner and a high-speed camera above and to the side of the water tank, set up a wave height meter sequence along the length of the water tank, and set up an acoustic Doppler current profiler in the landslide movement zone or erosion reaction zone to obtain the bed morphology, landslide movement images, surge time history and velocity profile.

[0028] Step 2.5: Connect the piezoelectric force sensor, fiber optic grating sensor, soil pressure sensor, pore pressure sensor, electrode probe, wave height meter, acoustic Doppler current profiler, and acoustic emission sensor to the multi-channel data acquisition instrument. Then, synchronize the multi-channel data acquisition instrument, high-speed camera, 3D laser scanner, and monitoring computer in terms of time and trigger to complete zero-point calibration and sensitivity calibration, thus obtaining the synchronous acquisition system.

[0029] Step 3: Based on the synchronous acquisition system obtained in Step 2, generate the submarine landslide source term and trigger landslide movement, thus obtaining the landslide source term input process. Specifically, this includes: Step 3.1: When the underwater slope initiation mode is adopted, the underwater slope model is filled in layers on the adjustable slope slope plate. The slope toe and lateral deformation of the underwater slope model are restricted by the baffle. The underwater slope model is pre-compressed and consolidated by the pressure plate to obtain an underwater slope model with preset slope angle, water content and consolidation state.

[0030] Step 3.2: Based on the underwater slope model obtained in Step 3.1, instability and initiation of sliding are caused by either overpressure gas triggering or slope toe excavation triggering. The overpressure gas triggering method involves applying controlled gas pressure to the bottom of the underwater slope model through a high-pressure gas tank, vent pipe, pressure controller, and vent to reduce local effective stress and trigger instability. The slope toe excavation triggering method involves using a telescopic robotic arm to drive an electric scraper to locally scrape or unload the slope toe of the underwater slope model, thereby weakening the slope toe constraint and triggering instability.

[0031] Step 3.3: When the continuous release mode is adopted, the L-shaped material guide bucket is connected to the external mud bucket or external pumping unit, so that the landslide material enters the upper part of the adjustable slope plate through the L-shaped material guide bucket, and the opening of the outlet is adjusted by the hydraulic gate. Based on the hydraulic gate opening and the flow rate of the external pumping unit, the outflow velocity, outflow thickness and release duration of the landslide material are controlled to obtain a continuous and controllable landslide source term input process.

[0032] Step 4: Based on the landslide source term input process obtained in Step 3, simultaneously collect data on bed erosion, shallow buried pipeline response, and surge response to obtain full-process monitoring data of the disaster chain. Specifically, this includes: Step 4.1: After the landslide material moves along the water channel and enters the erosion reaction zone, the movement of the landslide material, the scouring and erosion of the bed model, the expansion of the erosion pit and the exposure of the pipeline model are recorded by a high-speed camera. The three-dimensional morphology of the bed surface of the bed model is obtained by a three-dimensional laser scanner before the test, at key moments during the test or after the test.

[0033] Step 4.2: Real-time acquisition of resistivity or conductivity changes inside the bed model using an electrode probe array; real-time acquisition of acoustic emission signals from particle collisions and bed surface damage using an acoustic emission sensor; obtaining data on bed surface incision, electrical anomalies, acoustic emission event rate, and acoustic emission energy rate.

[0034] Step 4.3: Real-time acquisition of the impact force and strain response of the pipeline model using piezoelectric force sensors and fiber optic grating sensors to obtain shallow buried pipeline response data.

[0035] Step 4.4: Collect surge time history using wave height meter sequence, collect water velocity profile using acoustic Doppler current profiler, and collect changes in soil pressure and pore water pressure inside the underwater slope model or bottom bed model using soil pressure sensor and pore pressure sensor to obtain hydrodynamic response and soil internal response data.

[0036] Step 4.5: The data obtained in steps 4.1 to 4.4 are uniformly triggered, synchronously sampled, displayed in real time, and synchronously stored using a multi-channel data acquisition instrument and a monitoring computer to obtain monitoring data of the entire disaster chain of submarine landslide-bed erosion and damage-shallow buried pipeline response-surge response.

[0037] Step 5: Based on the full-process monitoring data of the disaster chain obtained in Step 4, conduct multi-source data fusion identification to obtain the evolution of subgrade erosion, the critical exposure time of shallow-buried pipelines, and the characteristics of surge propagation. Specifically, this includes: Step 5.1: Align the data obtained from the high-speed camera, 3D laser scanner, electrode probe, acoustic emission sensor, piezoelectric force sensor, fiber optic grating sensor, wave height meter, and acoustic Doppler current profiler with time axis to obtain a multi-source monitoring dataset under a unified time reference.

[0038] Step 5.2: Based on the three-dimensional morphology of the bed surface obtained by the three-dimensional laser scanner and the image sequence obtained by the high-speed camera, extract the length, width, depth, volume and bed surface incision rate of the erosion pit; based on the resistivity or conductivity changes obtained by the electrode probe array, identify the bed surface incision location and the movement process of the erosion interface; based on the acoustic emission event rate and energy rate obtained by the acoustic emission sensor, identify the bed damage intensity and changes in the active erosion zone, and obtain the bed erosion evolution results.

[0039] Step 5.3: Based on the erosion evolution results of the subgrade obtained in Step 5.2, and combined with the initial burial depth of the pipeline model and the initial bed surface elevation of the subgrade model, calculate the decay process of the overburden thickness of the pipeline model over time; when the thickness of the subgrade model above the pipeline model decays to zero or reaches the preset exposure criterion, determine the critical exposure time of the pipeline model; when the bed surface below the pipeline model continues to cut downward and forms a cavity, determine the local suspended length and suspended development process of the pipeline model.

[0040] Step 5.4: Based on the data obtained from the piezoelectric force sensor and fiber optic grating sensor, calculate the peak force, impulse, peak strain, and strain development process of the pipeline model; based on the data obtained from the wave height meter and acoustic Doppler current profiler, calculate the surge wave height, propagation speed, friction loss, and water velocity profile changes to obtain the response of the shallow buried pipeline and the surge wave propagation characteristics.

[0041] Step 5.5 involves performing correlation analysis on the bed erosion evolution results obtained in Step 5.2, the critical exposure and local suspension results of shallow buried pipelines obtained in Step 5.3, and the pipeline response and surge propagation characteristics obtained in Step 5.4 to establish the temporal correspondence between landslide source term input, bed erosion intensity, shallow buried pipeline response and surge response, and obtain the full-process evolution results of the submarine landslide disaster chain.

[0042] Step 6: Based on the evolution results of the entire submarine landslide disaster chain obtained in Step 5, the experimental conditions are changed and repeated experiments are conducted to obtain comparative results under different boundary conditions. Specifically, this includes: Step 6.1: Replace the filler blocks with different heights, slopes, or shapes to change the local geometry of the subgrade model and the incident angle of the landslide material. Repeat steps 1 to 5 to obtain the subgrade erosion and shallow buried pipeline response results under different subgrade boundary conditions.

[0043] Step 6.2: Change the adjustable slope angle, the slope angle of the slope plate, the physical property parameters of the underwater slope model, the overpressure gas pressure, the excavation depth at the slope toe, the outflow conditions of the L-shaped material guide bucket, the opening degree of the hydraulic gate, or the initial burial depth of the pipeline model, and repeat steps 1 to 5 to obtain the disaster chain response results under different landslide source terms, triggering conditions, and shallow buried pipeline layout conditions.

[0044] Step 6.3 involves comparative analysis of the geometry of erosion pits, bed incision rate, overburden thickness attenuation of pipeline models, critical exposure time, local suspended length, pipeline stress-strain response, and surge propagation characteristics under different working conditions, forming a simulation test database for submarine landslide erosion bed disaster chains.

[0045] The present invention has the following beneficial effects: (1) This invention enables continuous simulation of the disaster chain process of submarine landslide-bed erosion-shallow pipeline response-surge response. Specifically, this invention integrates the main body of the water tank with the circulating water supply module, the source term generation module, the bed erosion-shallow pipeline response module, and the multi-source monitoring and synchronous acquisition module within the same water tank. The water tank provides a continuous hydrodynamic boundary, the source term generation module generates the underwater slope initiation or continuous release of landslide material, the bed erosion and shallow pipeline response processes are reproduced through the bed model and pipeline model, and the water disturbance process is synchronously recorded through a wave height meter and an acoustic Doppler current profiler. Therefore, this invention can continuously characterize the temporal correlation between submarine landslide movement, bed erosion, shallow pipeline exposure or partial suspension, and surge response within the same experimental platform.

[0046] (2) This invention can generate multiple types of adjustable input conditions for submarine landslide source terms, improving the comparability of test results under different triggering mechanisms and release boundary conditions. Specifically, the source term generation module simultaneously sets up an adjustable slope angle ramp, an underwater slope model, a baffle, a pressure plate, a high-pressure gas storage tank, a vent pipe, a pressure controller, a vent, an electric scraper, a telescopic robotic arm, an L-shaped material guide bucket, and a hydraulic gate. Among them, the high-pressure gas storage tank, vent pipe, pressure controller, and vent can generate overpressure gas triggering conditions; the electric scraper and telescopic robotic arm can generate slope toe excavation triggering conditions; and the L-shaped material guide bucket and hydraulic gate can generate a continuous release boundary for landslide material with controllable outflow velocity, outflow thickness, and release duration. Therefore, this invention can simulate both the underwater slope instability and initiation process and the bed erosion process under continuous landslide material input conditions.

[0047] (3) This invention can quantitatively obtain information on subsoil erosion, overburden thickness attenuation in shallow buried pipelines, critical exposure time, local suspension length, and pipeline stress-strain response. Specifically: The subsoil erosion-shallow buried pipeline response module sets up a fillable and erodible subsoil model, and buries a pipeline model within the subsoil model; the initial burial depth, axial direction, support method, and overburden thickness of the pipeline model are controlled by pipeline fixing components; the local geometry of the subsoil model and the incident angle of landslide materials are adjusted by filling blocks; simultaneously, the stress and strain responses of the pipeline model are obtained by piezoelectric force sensors and fiber optic grating sensors, respectively. Therefore, this invention can synchronously correlate and analyze the subsoil erosion process with the shallow buried pipeline exposure, local suspension, and mechanical response processes.

[0048] (4) This invention can improve the real-time identification capability of bed erosion processes in turbid water and high sediment content environments. Specifically: the multi-source monitoring and synchronous acquisition module is equipped with electrode probes, acoustic emission sensors, high-speed cameras, and three-dimensional laser scanners. Among them, the electrode probe array can identify bed incision and erosion interface movement based on changes in resistivity or conductivity within the bed model; the acoustic emission sensors can identify active erosion areas and bed damage intensity based on acoustic emission signals generated by particle collisions and bed damage; the high-speed camera and three-dimensional laser scanner can acquire the expansion of erosion pits and changes in bed morphology. Therefore, even in turbid water and high sediment content environments, this invention can still continuously identify the expansion of erosion pits, bed incision, and critical exposure moments of shallow buried pipelines. Attached Figure Description

[0049] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the submarine landslide disaster chain test system for realizing bed erosion according to the present invention; In the diagram: 1. Water tank; 2. Steel frame supporting the tank bottom; 3. Hydraulic jack; 4. Water pipe; 5. Water supply tank; 6. High-pressure water pump; 7. Unloading box; 8. Filter screen; 9. Adjustable slope plate; 10. Air vent; 11. Energy dissipation material; 12. Underwater slope model; 13. Baffle; 14. Pressure plate; 15. High-pressure air storage tank; 16. Vent pipe; 17. Pressure controller; 18. Electric scraper; 19. Telescopic robotic arm; 20. L-shaped material guide hopper; 21. 22. Hydraulic gate; 23. Pipeline model; 24. Pipeline fastener; 25. Piezoelectric force sensor; 26. Fiber optic grating sensor; 27. Soil pressure sensor; 28. Pore pressure sensor; 29. ​​3D laser scanner; 30. Electrode probe; 31. Subsoil model; 32. Filler block; 33. Wave height meter; 34. Acoustic Doppler current profiler; 35. High-speed camera; 36. Acoustic emission sensor; 37. Multi-channel data acquisition unit; 38. Monitoring computer. Detailed Implementation

[0050] To enhance understanding of the present invention, the specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings and technical solutions.

[0051] like Figure 1 As shown, this embodiment provides a submarine landslide disaster chain simulation test system for realizing seabed erosion. The submarine landslide disaster chain simulation test system includes a main water tank module, a source term generation module, a seabed erosion-shallow buried pipeline response module, and a multi-source monitoring and synchronous acquisition module. The submarine landslide disaster chain simulation test system is used to simulate the generation of submarine landslide source terms, the movement of landslide materials along the seabed, seabed erosion and damage, shallow buried pipeline response, and surge response processes within the same water tank 1, and to synchronously acquire and correlate these processes through multi-source monitoring.

[0052] (1) Installation of the test system and setting of water tank boundary conditions; In this embodiment, the water tank 1 adopts a transparent trough-shaped structure with an open top, which facilitates observation from the side and above of underwater slope instability, landslide material movement, bed erosion, pipeline model 22 exposure, and surge propagation process. The water tank 1 is arranged along its length as follows: an upstream source term generation zone, a middle landslide movement zone, and a recessed mid-to-downstream erosion reaction zone.

[0053] A water tank 1 is installed on a bottom support steel frame 2, and a hydraulic jack 3 is positioned between the bottom of the water tank 1 and the bottom support steel frame 2. Before the test, the macroscopic inclination angle of the water tank 1 relative to the ground is adjusted to a preset value by adjusting the extension height of the hydraulic jack 3 according to the target working conditions. In this embodiment, the macroscopic inclination angle can be set to any value within the range of 0-2.5°, for example, 1°, to form the overall slope conditions for the landslide material to move along the length of the tank.

[0054] Water tank 1 is connected to water supply tank 5 via water pipe 4, and a high-pressure water pump 6 is installed on water pipe 4. During the test, the high-pressure water pump 6 delivers water from water supply tank 5 to water tank 1 to form a stable water supply or directional flow. The downstream drainage end of water tank 1 returns to water supply tank 5 via water pipe 4 to form a circulating water supply path. A discharge box 7 and a filter screen 8 are installed between the downstream drainage end of water tank 1 and water supply tank 5. The discharge box 7 is used to receive landslide materials, bed particles, and sand-laden water discharged after the test, and the filter screen 8 is used to separate solid particles and circulating water, thereby realizing the recovery of landslide materials and bed particles and the recycling of test water.

[0055] Energy dissipation material 11 is installed at the inlet, outlet, or downstream side of the erosion reaction zone of the water tank 1. The energy dissipation material 11 can be a wave-damping grid, used to weaken water flow reflection, reduce backflow disturbance, and stabilize the flow field in the tank. Before the test, the high-pressure water pump 6 is started to circulate water, and the water depth, flow velocity, and free liquid level in the water tank 1 are basically stable.

[0056] (2) Installation and debugging of the source item generation module; The source term generation module is located in the upstream source term generation area of ​​the water tank 1, and includes an adjustable slope plate 9, an air hole 10, an underwater slope model 12, a baffle 13, a pressure plate 14, a high-pressure air storage tank 15, an air pipe 16, a pressure controller 17, an electric scraper 18, a telescopic robotic arm 19, an L-shaped material guide bucket 20, and a hydraulic gate 21.

[0057] An adjustable slope plate 9 is positioned upstream of the water tank 1, with its lower end smoothly connected to the bottom or middle landslide area of ​​the water tank 1. The adjustable slope plate 9 comprises an upper slope plate segment and a lower slope plate segment that are hinged together. By adjusting the hinge joints between the plates, the local slope angle of the adjustable slope plate 9 can be continuously adjusted within the range of 0-60°. In this embodiment, the adjustable slope plate 9 can be adjusted to 30° according to the experimental purpose and locked using a limiting fixing component to form the initial slope boundary of the underwater slope model 12.

[0058] An adjustable slope plate 9 has air holes 10 on its surface, which are an array of holes penetrating the plate surface. The air holes 10 are connected to a high-pressure gas storage tank 15 outside the water tank 1 via a vent pipe 16. A pressure controller 17 is located between the high-pressure gas storage tank 15 and the vent pipe 16. During the test, the pressure controller 17 is used to control the gas pressure, ventilation time, and ventilation rate entering the air holes 10, thereby creating a controlled overpressure gas disturbance at the bottom of the underwater slope model 12 to simulate the underwater slope instability triggering process under the action of shallow gas overflow or overpressure gas.

[0059] When using the underwater slope initiation and sliding mode, the underwater slope model 12 is layered and filled onto the upper surface of the adjustable slope angle slab 9. The material of the underwater slope model 12 can be clay, silt, sand, or similar materials, depending on the target working conditions, or a mixed mud and sand mixture can be used. During the filling process, a baffle 13 is installed at the toe of the adjustable slope angle slab 9 to limit the toe slippage of the underwater slope model 12 during filling, saturation, and consolidation. After the underwater slope model 12 is filled, a pressure plate 14 is installed on top of it, and a preload is applied through the pressure plate 14 to make the underwater slope model 12 reach the preset density, water content, and consolidation state.

[0060] After the underwater slope model 12 reaches the predetermined state, two triggering methods can be used to induce instability and initiate sliding. The first method is overpressure gas triggering, which involves applying controlled gas pressure to the bottom of the underwater slope model 12 through the high-pressure gas tank 15, the vent pipe 16, the pressure controller 17, and the vent 10, thereby reducing the local effective stress of the underwater slope model 12 and causing instability. The second method is toe excavation triggering, which involves using the telescopic robotic arm 19 to drive the electric scraper blade 18 to extend into the toe of the underwater slope model 12, locally scraping the toe to weaken the toe support and induce instability of the underwater slope model 12. The electric scraper blade 18 is located at the free end of the telescopic robotic arm 19, which is fixed to the upper support of the water tank 1.

[0061] When using the continuous release mode, an L-shaped material guide hopper 20 is installed in the upstream source generation area of ​​the water tank 1. The L-shaped material guide hopper 20 is located above the upper slope section of the adjustable slope plate 9, and includes a vertical inflow section and an outflow section arranged along the slope direction of the adjustable slope plate 9. The vertical inflow section is connected to an external mud tank or an external pumping unit, and the outlet of the outflow section faces downstream of the adjustable slope plate 9. A hydraulic gate 21 is installed at the outlet of the L-shaped material guide hopper 20. By adjusting the opening of the hydraulic gate 21, the cross-sectional area of ​​the outlet is controlled, thereby changing the outflow velocity, outflow thickness, and release duration of the landslide material. In this embodiment, the L-shaped material guide hopper 20 and the hydraulic gate 21 can form a landslide material input boundary with a duration of tens of seconds to several minutes to simulate the process of landslide material continuously moving along the bed and eroding the bed.

[0062] The aforementioned underwater slope initiation mode and continuous release mode can be implemented sequentially or independently. For example, the initial landslide movement can be formed first through the underwater slope initiation mode, and then the subsequent landslide material can be replenished through the L-shaped material guide bucket 20 and the hydraulic gate 21 to simulate the continuous replenishment and long-term erosion of the seabed after the initiation of the submarine landslide.

[0063] (3) Layout of the substrate erosion-shallow buried pipeline response module; The substrate erosion-shallow buried pipeline response module is set in the middle and lower downstream erosion reaction zone of the water tank 1, including pipeline model 22, pipeline fastener 23, substrate model 30 and filling block 31.

[0064] Before the experiment, filler blocks 31 are installed in the erosion reaction zone according to the target bed boundary conditions. The filler blocks 31 are detachable rigid blocks that can be placed between the bottom of the erosion reaction zone and the bed model 30. The upper surface of the filler blocks 31 forms a local supporting boundary or a transition boundary for landslide material ingress into the bed model 30. By replacing filler blocks 31 with different heights, slopes, or shapes, the initial bed slope, local geometry, and landslide material ingress angle of the bed model 30 can be changed. In this embodiment, inclined filler blocks or square filler blocks can be used to compare the erosion pit expansion and bed surface incision process under different bed boundary conditions.

[0065] After the filling block 31 is installed, the substrate model 30 is layered and filled within the erosion reaction zone. The substrate model 30 is a layered substrate structure that can be filled and eroded, and can be formed by layering sand, silt, clay, or similar materials according to a preset thickness, gradation, moisture content, and density. In this embodiment, the substrate model 30 can be made of silty sand or a mixture of mud and sand, laid in layers according to a preset thickness and then leveled and compacted. To facilitate the identification of erosion depth and the bed surface incision process, a color marker layer or particle marker layer can be set inside the substrate model 30, so that the movement process of the erosion interface can be identified through images, electrical signals, or profile observations after erosion occurs.

[0066] Pipeline model 22 is embedded inside the substrate model 30 and can be a circular pipe model to simulate shallow-buried subsea pipelines. The axis of pipeline model 22 can be arranged along the width or length of the water tank 1. In this embodiment, taking the arrangement of pipeline model 22 along the width of the tank as an example, the landslide material moves along the length of the tank and laterally crosses the area where pipeline model 22 is located, thereby simulating the process of landslide material eroding the overlying layer of the shallow-buried pipeline and causing the pipeline model 22 to be partially exposed or suspended.

[0067] Pipeline fixing components 23 are installed below the subgrade model 30, on both sides of the subgrade model 30, or on the inner side wall of the water tank 1, and are connected to the pipeline model 22. By adjusting the installation height and angle of the pipeline fixing components 23, the initial burial depth, axial direction, support method, and overlay thickness of the pipeline model 22 can be controlled. In this embodiment, during the filling process of the subgrade model 30, the pipeline fixing components 23 are installed first, and then the pipeline model 22 is fixed to the pipeline fixing components 23. Subsequently, the subgrade material is backfilled to form the overlay, and the initial axial elevation of the pipeline model 22, the outer diameter of the pipeline model 22, the initial bed surface elevation of the subgrade model 30, and the overlay thickness of the pipeline model 22 are recorded.

[0068] A transparent coordinate reference is fixedly installed on the outer wall of the water tank 1 corresponding to the erosion reaction zone. The transparent coordinate reference includes a scale grid arranged along the length and vertical direction of the water tank 1. The scale grid is mutually calibrated with the initial bed surface elevation of the substrate model 30, the initial axis position of the pipeline model 22, and the outer diameter of the pipeline model 22. It is used to quantitatively record the expansion range of the erosion pit, the incision depth of the bed surface, the exposure height of the pipeline model 22, and the local overhang length below the pipeline model 22 without disturbing the flow field in the tank and the substrate model 30.

[0069] (4) Deployment of multi-source monitoring and synchronous acquisition modules; The multi-source monitoring and synchronous acquisition module includes a piezoelectric force sensor 24, a fiber optic grating sensor 25, an earth pressure sensor 26, a pore pressure sensor 27, a three-dimensional laser scanner 28, an electrode probe 29, a wave height meter 32, an acoustic Doppler current profiler 33, a high-speed camera 34, an acoustic emission sensor 35, a multi-channel data acquisition instrument 36, and a monitoring computer 37.

[0070] A piezoelectric force sensor 24 is disposed between the pipeline model 22 and the pipeline fixing component 23 to acquire the impact force experienced by the pipeline model 22 during landslide material impact, bed erosion, and local suspension. A fiber optic grating sensor 25 is axially or circumferentially attached to the outer surface of the pipeline model 22 to acquire the strain response of the pipeline model 22 during overburden attenuation, exposure, and local suspension.

[0071] Earth pressure sensor 26 and pore pressure sensor 27 can be embedded inside the underwater slope model 12, inside the substrate model 30, or at key locations in the erosion reaction zone. When deployed inside the underwater slope model 12, earth pressure sensor 26 and pore pressure sensor 27 are used to monitor changes in earth pressure, pore water pressure, and effective stress before and after underwater slope instability; when deployed inside the substrate model 30, earth pressure sensor 26 and pore pressure sensor 27 are used to monitor changes in internal stress and pore water pressure of the substrate during landslide material impact and substrate erosion.

[0072] A 3D laser scanner 28 is mounted on a support above the water tank 1 to acquire the 3D morphology of the bed surface of the substrate model 30 before, during, and after the experiment. Electrode probes 29 are arranged in an array along the longitudinal, transverse, and depth directions of the substrate model 30 to collect changes in the resistivity or conductivity inside the substrate model 30. When erosion occurs, the material distribution, pore structure, water content, and sediment intrusion state inside the substrate model 30 change, resulting in changes in resistivity or conductivity. Based on this, the bed surface incision, erosion interface movement, and critical exposure moments of the pipeline model 22 can be identified.

[0073] Acoustic emission sensor 35 is installed on the outer wall of the water tank 1 corresponding to the erosion reaction zone to collect acoustic emission signals generated by the collision of landslide material particles, the initiation of bottom bed particles, and the destruction of the bed surface. By analyzing the acoustic emission event rate, energy rate, and frequency characteristics, changes in the active erosion zone and the intensity of bed surface destruction can be identified.

[0074] Wave height meters 32 are arranged along the length of the flume 1, preferably forming a sequence along the central axis of the flume. Wave height meters 32 are used to monitor the time history, propagation velocity, and friction loss of surging waves generated by disturbances in the water body during landslide material movement and bed erosion. Acoustic Doppler current profilers 33 are mounted on the upper support of the flume 1, with their measuring section facing the water body within the flume 1. They are used to obtain velocity profiles and water disturbance characteristics near the landslide movement zone or erosion response zone.

[0075] High-speed camera 34 is positioned outside or above the transparent sidewall of tank 1 to record underwater slope instability, landslide material movement, erosion pit expansion, pipeline model 22 exposure, and surge propagation. The field of view of high-speed camera 34 should cover at least one key area among the upstream source term generation area, the middle landslide movement area, and the middle and downstream erosion response area; when it is necessary to acquire images of the entire process simultaneously, multiple high-speed cameras 34 can be deployed along the length of the tank.

[0076] The multi-channel data acquisition unit 36 ​​is connected to the piezoelectric force sensor 24, fiber optic grating sensor 25, soil pressure sensor 26, pore pressure sensor 27, electrode probe 29, wave height meter 32, acoustic Doppler current profiler 33, and acoustic emission sensor 35, respectively. It also connects to the high-speed camera 34, 3D laser scanner 28, and monitoring computer 37 via trigger or time signal connections. The monitoring computer 37 is used to control the sampling frequency, record experimental parameters, display real-time monitoring curves, and perform time axis alignment and synchronous storage of different monitoring data. Before the experiment, zero-point calibration and sensitivity calibration are performed on each sensor, and multi-source monitoring is initiated using a unified trigger signal.

[0077] This embodiment takes the continuous release of landslide material and its erosion of the seabed containing shallow buried pipelines as an example, and provides a method for monitoring submarine landslide disaster chains that achieve seabed erosion. This method is based on a submarine landslide disaster chain testing system and includes the following steps: Step 1: Construct test boundary conditions and form the initial bed-shallow buried pipeline state to obtain initial test state data.

[0078] Step 1.1: Determine the test scale, water depth, macroscopic inclination angle of the tank, slope angle of the adjustable slope plate 9, substrate model 30 material, pipeline model 22 burial depth, and landslide material release conditions based on the target working conditions. In this embodiment, the Frode similarity relation can be used to determine the parameters related to water depth, flow velocity, and surge propagation. Furthermore, the similarity of the substrate material particle size, density, shear strength, and pipeline model 22 burial depth is combined to perform a similarity check on the substrate erosion and shallow-buried pipeline response process.

[0079] Step 1.2: Based on the water tank boundary conditions determined in Step 1.1, install the water tank 1 on the bottom support steel frame 2, and adjust the macroscopic tilt angle of the water tank 1 relative to the ground using hydraulic jacks 3; connect the water supply tank 5, water pipe 4 and high-pressure water pump 6 to form a circulating water supply path, and arrange energy dissipation materials 11 at the inlet and outlet of the water tank 1; start the high-pressure water pump 6, adjust it to the set water depth and flow rate, and obtain stable water tank boundary conditions.

[0080] Step 1.3: Based on the substrate boundary conditions determined in Step 1.1, filler blocks 31 are installed within the erosion reaction zone, and substrate model 30 is layered and constructed on top of the filler blocks 31. During the construction process, a color marker layer or particle marker layer is set inside the substrate model 30 according to the experimental purpose. Subsequently, pipeline fixing components 23 are installed, and pipeline model 22 is fixed to the pipeline fixing components 23. The pipeline model 22 is adjusted to the preset burial depth and axial direction, and then substrate material is backfilled to form the overlay layer. The initial bed surface elevation of substrate model 30, the initial axial position of pipeline model 22, the outer diameter of pipeline model 22, the thickness of the overlay layer of pipeline model 22, and the transparent coordinate reference position are recorded to obtain the initial substrate-shallow buried pipeline state data.

[0081] Step 2: Based on the initial bed-shallow buried pipeline status data obtained in Step 1, complete the deployment, calibration and synchronous triggering settings of monitoring elements to obtain the synchronous acquisition system.

[0082] Step 2.1: Install a piezoelectric force sensor 24 between the pipeline model 22 and the pipeline fixing component 23, and attach a fiber Bragg grating sensor 25 to the outer surface of the pipeline model 22; connect the piezoelectric force sensor 24 and the fiber Bragg grating sensor 25 to the multi-channel data acquisition instrument 36 for real-time acquisition of the force and strain response of the pipeline model 22.

[0083] Step 2.2: Earth pressure sensors 26 and pore pressure sensors 27 are installed inside the bed model 30 or at key locations in the erosion reaction zone to acquire changes in earth pressure and pore water pressure during the impact of landslide materials and bed erosion. When this embodiment needs to simultaneously simulate the underwater slope initiation process, earth pressure sensors 26 and pore pressure sensors 27 can also be installed synchronously inside the underwater slope model 12.

[0084] Step 2.3: Array of electrode probes 29 is arranged in the longitudinal, transverse and depth directions within the bed model 30, and acoustic emission sensors 35 are arranged on the outer wall of the water tank 1 corresponding to the erosion reaction zone to form an electro-acoustic multi-source erosion identification unit, which is used to identify bed surface incision, erosion interface movement and bed surface damage intensity.

[0085] Step 2.4: A three-dimensional laser scanner 28 is placed above the water tank 1, and a high-speed camera 34 is placed on the outside or above the transparent sidewall of the water tank 1; a series of wave height meters 32 are arranged along the length of the water tank 1, and an acoustic Doppler velocity profiler 33 is arranged in the landslide movement zone or erosion reaction zone to obtain the bed surface morphology of the bed model 30, images of landslide material movement, surge time history and velocity profile.

[0086] Step 2.5: Connect the piezoelectric force sensor 24, fiber optic grating sensor 25, soil pressure sensor 26, pore pressure sensor 27, electrode probe 29, wave height meter 32, acoustic Doppler current profiler 33, and acoustic emission sensor 35 to the multi-channel data acquisition instrument 36. Then, synchronize the multi-channel data acquisition instrument 36, high-speed camera 34, 3D laser scanner 28, and monitoring computer 37 in terms of time and trigger synchronization. After completing zero-point calibration, sensitivity calibration, and sampling frequency setting, a synchronous acquisition system is obtained.

[0087] Step 3: Based on the synchronous acquisition system obtained in Step 2, generate a continuously controllable landslide source term input process.

[0088] Step 3.1: Place the landslide material in an external mud bucket and connect it to the vertical inlet section of the L-shaped material guide hopper 20 via an external pumping unit. The landslide material can be a mixture of mud and sand, a particle-mud mixture, or other similar materials, and its density, viscosity, particle size distribution, and moisture content are determined according to the target working conditions.

[0089] Step 3.2: Adjust the position of the L-shaped material guide hopper 20 so that its outflow section is arranged along the slope direction of the adjustable slope plate 9, and the outflow outlet faces the downstream direction of the water tank 1. Adjust the opening of the hydraulic gate 21 to the preset value, and at the same time set the flow rate of the external pumping unit to control the outflow velocity, outflow thickness and release duration of the landslide material.

[0090] Step 3.3: Activate the unified trigger signal of the monitoring computer 37 and the multi-channel data acquisition instrument 36, then turn on the external pumping unit and open the hydraulic gate 21, allowing the landslide material to enter the water tank 1 through the L-shaped material guide bucket 20. The landslide material moves downstream along the adjustable slope plate 9 and the bottom of the water tank 1, forming a continuous and controllable landslide source input process.

[0091] Step 4: Based on the landslide source term input process obtained in Step 3, simultaneously collect data on bed erosion, shallow buried pipeline response, and surge response to obtain full-process monitoring data of the disaster chain.

[0092] Step 4.1: After the landslide material enters the erosion reaction zone, it causes scouring, erosion, and bed surface incision on the bed model 30. A high-speed camera 34 records the movement of the landslide material, the expansion of the erosion pit, the bed surface incision, the exposure of the pipeline model 22, and the process of local suspension beneath the pipeline model 22. A 3D laser scanner 28 acquires the 3D morphology of the bed surface of the bed model 30 before the experiment, at key moments during the experiment, or after the experiment.

[0093] Step 4.2: The electrode probe array 29 collects real-time data on changes in resistivity or conductivity within the bed model 30, while the acoustic emission sensor 35 collects real-time acoustic emission signals generated by particle collisions and bed surface damage. Through the electrode probes 29 and the acoustic emission sensor 35, bed surface incision, erosion interface movement, changes in active erosion zones, and the intensity of bed surface damage can be identified in turbid water and high-sediment environments.

[0094] Step 4.3: The piezoelectric force sensor 24 collects the impact force on the pipeline model 22 in real time, and the fiber Bragg grating sensor 25 collects the strain response of the pipeline model 22 in real time. As the substrate model 30 is gradually cut down, the thickness of the overlay layer on the pipeline model 22 gradually decreases. The piezoelectric force sensor 24 and the fiber Bragg grating sensor 25 record the changes in the mechanical response of the pipeline model 22 during critical exposure and local suspension processes.

[0095] Step 4.4: Wave height meter 32 serially collects the time history of surge waves caused by landslide material movement and bed erosion in real time; acoustic Doppler velocity profiler 33 collects the velocity profile of the landslide movement zone or erosion reaction zone; earth pressure sensor 26 and pore pressure sensor 27 collect the changes in earth pressure and pore water pressure inside the bed model 30.

[0096] In step 4.5, the multi-channel data acquisition instrument 36 and the monitoring computer 37 uniformly trigger, synchronously sample, display in real time and synchronously store the data obtained in steps 4.1 to 4.4 to obtain the monitoring data of the entire process of the disaster chain of submarine landslide-bed erosion and damage-shallow buried pipeline response-surge response.

[0097] Step 5: Based on the disaster chain monitoring data obtained in Step 4, conduct multi-source data fusion identification to obtain the evolution of subsoil erosion, the critical exposure time of shallow buried pipelines, and the characteristics of surge propagation.

[0098] Step 5.1: Align the data obtained from the high-speed camera 34, 3D laser scanner 28, electrode probe 29, acoustic emission sensor 35, piezoelectric force sensor 24, fiber optic grating sensor 25, wave height meter 32, acoustic Doppler current profiler 33, soil pressure sensor 26, and pore pressure sensor 27 with the time axis to obtain a multi-source monitoring dataset under a unified time reference.

[0099] Step 5.2: Based on the image sequence recorded by the high-speed camera 34 and the transparent coordinate reference of the outer wall of the water tank 1, extract the extent of the erosion pit along its path, the depth of the bed surface incision, the exposure height of the pipeline model 22, and the local overhang length below the pipeline model 22. Based on the three-dimensional morphology of the bed surface obtained by the three-dimensional laser scanner 28, calculate the length, width, depth, volume, and bed surface incision rate of the erosion pit.

[0100] Step 5.3: Based on the resistivity or conductivity changes collected by the electrode probe array 29, identify the bed incision location and the movement process of the erosion interface; based on the acoustic emission event rate and energy rate collected by the acoustic emission sensor 35, identify the bed damage intensity and changes in the active erosion zone. Compare and verify the electrical identification results, acoustic identification results, image identification results, and three-dimensional morphological measurement results to obtain the bed erosion evolution results.

[0101] Step 5.4: Based on the erosion evolution results of the substrate obtained in Step 5.3, and combining the initial bed surface elevation of the substrate model 30, the initial axis position of the pipeline model 22, and the outer diameter of the pipeline model 22, calculate the decay process of the overburden thickness of the pipeline model 22 over time. When the thickness of the substrate model 30 above the pipeline model 22 decays to zero or reaches the preset exposure criterion, determine the critical exposure time of the pipeline model 22; when the substrate model 30 below the pipeline model 22 continues to cut downwards and forms a cavity, determine the local overhang length and overhang development process below the pipeline model 22.

[0102] Step 5.5: Based on the data collected by the piezoelectric force sensor 24 and the fiber optic grating sensor 25, calculate the peak force, impulse, peak strain, and strain development process of the pipeline model 22. Based on the data collected by the wave height meter 32 and the acoustic Doppler current profiler 33, calculate the surge wave height, propagation velocity, friction loss, and velocity profile variation. Subsequently, perform correlation analysis on the landslide source term input process, bed erosion evolution results, pipeline model 22 response results, and surge propagation characteristics to obtain the full-process evolution results of the submarine landslide disaster chain.

[0103] Step 6: Based on the evolution results of the entire process of the submarine landslide disaster chain obtained in Step 5, change the test conditions and conduct repeated tests to obtain comparative results under different boundary conditions.

[0104] Step 6.1: Replace the filler block 31 with one of different height, slope or shape, change the local geometry of the bed model 30 and the incident angle of the landslide material, and repeat steps 1 to 5 to obtain the bed erosion and shallow buried pipeline response results under different bed boundary conditions.

[0105] Step 6.2: Change the slope angle of the adjustable slope plate 9, the density of landslide material, the flow rate of landslide material, the opening degree of the hydraulic gate 21, the initial burial depth of the pipeline model 22, the axial direction of the pipeline model 22, or the material parameters of the bed model 30, and repeat steps 1 to 5 to obtain the disaster chain response results under different landslide source terms and shallow buried pipeline layout conditions.

[0106] Step 6.3 involves comparative analysis of the geometric characteristics of erosion pits, bed incision rate, overburden thickness decay process of pipeline model 22, critical exposure time, local suspended length, stress-strain response of pipeline model 22, and surge propagation characteristics under different working conditions, forming an experimental database of submarine landslide erosion bed disaster chains.

[0107] Alternative implementation methods for underwater slope initiation and sliding conditions; In another embodiment, the submarine landslide disaster chain simulation test system can be used to simulate the process of underwater slope initiation and inducing bed erosion. This implementation differs from the aforementioned continuous release mode in that the landslide source term is generated by the instability of the underwater slope model 12, rather than by continuous input from the L-shaped material guide bucket 20.

[0108] Specifically, the adjustable slope angle slab 9 is first adjusted to the target slope angle, and then an underwater slope model 12 is filled in layers on its upper surface. During the filling process, the deformation of the toe and sides of the underwater slope model 12 is restricted by the baffle 13, and the underwater slope model 12 is pre-compressed and consolidated by the pressure plate 14. After reaching the predetermined consolidation state, the underwater slope model 12 is destabilized by using an overpressure gas triggering method or a slope toe excavation triggering method.

[0109] When the overpressure gas triggering method is used, controlled gas pressure is applied to the bottom of the underwater slope model 12 through the high-pressure gas storage tank 15, the vent pipe 16, the pressure controller 17, and the vent 10, causing the pore pressure at the bottom of the underwater slope model 12 to increase, the effective stress to decrease, and instability to occur. When the slope toe excavation triggering method is used, the telescopic robotic arm 19 drives the electric scraper 18 to locally scrape, excavate, or unload the slope toe of the underwater slope model 12, causing the slope toe support of the underwater slope model 12 to weaken and instability to occur.

[0110] After the underwater slope model 12 became unstable, the landslide material moved downstream along the channel 1 and entered the erosion reaction zone, causing scouring, erosion, and bed shearing on the bed model 30. Subsequently, the bed erosion, shallow pipeline response, and surge response data were simultaneously collected and processed using the methods described in steps 4 and 5, thereby obtaining the full-process evolution results of the submarine landslide disaster chain under the conditions of underwater slope initiation.

[0111] Through the above-described embodiments, this invention can simulate the bed erosion and damage process under conditions of continuous release of landslide material and underwater slope initiation, and can simultaneously acquire data on the response of shallow-buried pipelines and surge response. Therefore, this invention provides repeatable, comparable, and quantifiable indoor experimental methods for studying the disaster chain mechanism of submarine landslides, risk assessment of shallow-buried pipelines, and disaster prevention and mitigation design of submarine engineering projects.

[0112] The above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Any equivalent substitutions or adjustments made by those skilled in the art to the dimensions of components, installation positions, number of sensors, and test parameters without departing from the concept of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A test system for submarine landslide disaster chains to realize bed erosion, characterized in that, The submarine landslide disaster chain test system includes a flume main module, a source term generation module, a bed erosion-shallow buried pipeline response module, and a multi-source monitoring and synchronous acquisition module. Specifically: The main module of the water tank includes a water tank (1), energy dissipation material (11) inside the water tank (1), a bottom support steel frame (2) at the bottom of the water tank (1), a hydraulic jack (3) on the side of the water tank (1), a water supply tank (5) connected to the water tank through a water pipe (4) and a high-pressure water pump (6), a discharge box (7), and a filter screen (8) arranged between the discharge box (7) and the water supply tank (5); the water tank (1) is a transparent trough-shaped structure with an open top, and forms an upstream source term generation area, a middle landslide movement area and a recessed middle and downstream erosion reaction area along the length of the trough; The source term generation module includes an adjustable slope plate (9), vents (10), an underwater slope model (12), a baffle (13), a pressure plate (14), a high-pressure gas storage tank (15), a vent pipe (16), a pressure controller (17), an electric scraper (18), a telescopic robotic arm (19), an L-shaped material guide hopper (20), and a hydraulic gate (21) located in the upstream source term generation area of ​​the water tank (1). The adjustable slope plate (9) is provided with vents (10) that are connected to the high-pressure gas storage tank (15) through the vent pipe (16). The pressure, ventilation time, and ventilation rate of the gas entering the vent (10) are controlled by the pressure controller (17); the pressure plate (14) is located above the underwater slope model (12), the underwater slope model (12) is set on the upper surface of the adjustable slope slope plate (9), and the baffle (13) is set at the foot of the adjustable slope slope plate (9); the electric scraper (18) is connected to the telescopic mechanical arm (19) fixed in the water tank (1); the L-shaped material guide bucket (20) is set in the upstream source generation area of ​​the water tank (1) and is equipped with a hydraulic gate (21); The substrate erosion-shallow buried pipeline response module includes a pipeline model (22), a pipeline fixing component (23), a substrate model (30), and a filling block (31). The substrate model (30) is set in the middle and lower downstream erosion reaction zone of the water tank (1) and laid along the width or length of the water tank (1). It contains a pipeline model (22) connected to the pipeline fixing component (23), wherein the installation height and installation angle of the pipeline fixing component (23) are adjustable. The filling block (31) is set between the bottom of the erosion reaction zone and the substrate model (30). The multi-source monitoring and synchronous acquisition module includes a piezoelectric force sensor (24), a fiber optic grating sensor (25), a soil pressure sensor (26), a pore pressure sensor (27), a three-dimensional laser scanner (28), an electrode probe (29), a wave height meter (32), an acoustic Doppler current profiler (33), a high-speed camera (34), an acoustic emission sensor (35), a multi-channel data acquisition instrument (36), and a monitoring computer (37); it is used to achieve unified triggering, synchronous acquisition, and correlation analysis of source term monitoring, subsoil erosion identification, shallow buried pipeline response monitoring, and surge response monitoring.

2. The submarine landslide disaster chain test system for realizing seabed erosion according to claim 1, characterized in that, In the main module of the water tank: The water tank (1) is installed on the bottom support steel frame (2). The hydraulic jack (3) is set between the bottom of the water tank (1) and the bottom support steel frame (2). By adjusting the extension height of the hydraulic jack (3), the macroscopic tilt angle of the water tank (1) relative to the ground can be adjusted within the range of 0-2.5°. The water supply tank (5) is connected to the water tank (1) through the water pipe (4). The high-pressure water pump (6) is set on the water pipe (4) to provide a stable water supply or directional flow to the water tank (1). The downstream drainage of the water tank (1) The water flows back to the water supply tank (5) through the water pipe (4) to form a circulating water supply path; the unloading box (7) and the filter screen (8) are set between the downstream drainage end of the water tank (1) and the water supply tank (5) for solid-liquid separation and recycling of the water body, landslide material and bottom bed particles after the test; the energy dissipation material (11) is set at the inlet end, outlet end and downstream side of the erosion reaction zone of the water tank (1). The energy dissipation material (11) is a detachable wave-damping grid, which is used to weaken water flow reflection, reduce boundary disturbance and stabilize the flow field in the tank.

3. The submarine landslide disaster chain test system for realizing bed erosion according to claim 2, characterized in that, In the source item generation module: The lower end of the adjustable slope plate (9) is smoothly connected to the bottom or middle landslide movement area of ​​the water tank (1), and the local inclination angle of its plate surface relative to the bottom of the water tank (1) is continuously adjustable within the range of 0-60°; the adjustable slope plate (9) includes an upper slope plate section and a lower slope plate section that are hinged to each other, and the slope shape is adjusted through the hinge nodes between the plates; the air hole (10) is an array of holes that are set through the plate surface of the adjustable slope plate (9), and the air hole (10) is connected to the high pressure gas storage tank (15) set outside the water tank (1); the pressure controller (17) is set between the high pressure gas storage tank (15) and the vent pipe (16) to simulate the underwater slope instability triggering process under shallow gas overflow or overpressure gas disturbance conditions. The underwater slope model (12) is layered and filled on the upper surface of the adjustable slope slab (9); the baffle (13) is a detachable enclosure component, set at the toe of the adjustable slope slab (9), used to restrict the toe slippage of the underwater slope model (12) during filling, saturation and preloading consolidation processes; the pressure plate (14) is set above the underwater slope model (12), used to apply a preloading load to the underwater slope model (12), so that the underwater slope model (12) The initial compaction, water content and consolidation state are repeated; the electric scraper (18) is set at the free end of the telescopic mechanical arm (19), and the telescopic mechanical arm (19) is fixed on the upper support of the water tank (1); during the test, the telescopic mechanical arm (19) drives the electric scraper (18) to extend into the slope toe of the underwater slope model (12) and weakens the slope toe constraint by local scraping to simulate the process of underwater slope instability triggered by slope toe excavation or local scouring; The L-shaped material guide bucket (20) is located at the upper end or above the adjustable slope plate (9) to form a continuous and controllable landslide release boundary. The L-shaped material guide bucket (20) includes a vertical inflow section and an outflow section arranged along the slope direction of the adjustable slope plate (9). The vertical inflow section is connected to an external mud bucket or an external pumping unit. The outlet of the outflow section faces the downstream direction of the adjustable slope plate (9). The hydraulic gate (21) is set at the outlet of the L-shaped material guide bucket (20). By adjusting the opening of the hydraulic gate (21), the cross-sectional area of ​​the outlet is controlled, and the outflow velocity, outflow thickness and release duration of the landslide material are changed, thereby simulating the process of the submarine landslide continuously moving along the bed and eroding the bed.

4. The submarine landslide disaster chain test system for realizing bed erosion according to claim 3, characterized in that, The source item generation module has two working modes: The first type is the underwater slope initiation mode, which is to form an underwater slope body with a preset slope angle, physical property parameters and consolidation state by using an adjustable slope slope plate (9), an underwater slope model (12), a baffle (13) and a pressure plate (14), and to form an overpressure gas trigger by using a high-pressure gas storage tank (15), a vent pipe (16), a pressure controller (17) and a vent (10), or to form a slope toe excavation trigger by using a telescopic mechanical arm (19) and an electric scraper (18). The second type is the continuous release mode, which forms a landslide material input boundary with controllable speed, thickness and duration through L-shaped material guide bucket (20) and hydraulic gate (21); Both working modes can be used independently, providing different types of initial and boundary conditions for submarine landslide source terms.

5. The submarine landslide disaster chain test system for realizing seabed erosion according to claim 4, characterized in that, In the subsoil erosion-shallow buried pipeline response module: The substrate model (30) is a layered substrate structure that can be filled and eroded. It is formed by filling layers of sand, silt, clay or similar materials according to preset thickness, gradation, moisture content and density. Color marker layers or particle marker layers can be set in the substrate model (30) to identify the depth of bed incision, erosion interface and changes in substrate morphology. The filling block (31) is a detachable rigid block. The upper surface of the filling block (31) constitutes the local support boundary or incident transition boundary of the substrate model (30). By replacing the filling blocks (31) with different heights, slopes or shapes, the local geometry of the substrate model (30), the initial slope of the bed surface and the incident angle of landslide materials can be adjusted, so as to compare the erosion behavior of the submarine landslide on the substrate under different substrate boundary conditions. The pipeline model (22) is embedded inside the subgrade model (30), with its axis arranged along the width or length of the water tank (1); the pipeline fixing component (23) is located below the subgrade model (30), on both sides of the subgrade model (30), or on the inner side of the side wall of the water tank (1); the pipeline fixing component (23) is connected to the pipeline model (22) and is used to control the initial burial depth, axis direction, support method, and overlay thickness of the pipeline model (22); by adjusting the installation height of the pipeline fixing component (23) and The installation angle can simulate the response process of shallow buried pipelines under different burial depths, directions and constraints when affected by landslide erosion. The outer wall of the water tank (1) corresponding to the erosion reaction zone is set with a coordinate reference. The coordinate reference includes a scale grid arranged along the length of the tank and the vertical direction. The initial bed surface elevation of the bottom bed model (30) is used as the measurement reference to record the expansion range of the erosion pit, the depth of the bed surface incision, the exposure height of the pipeline model (22) and the local suspended length below the pipeline model (22).

6. The submarine landslide disaster chain test system for realizing seabed erosion according to claim 5, characterized in that, In the multi-source monitoring and synchronous acquisition module: The piezoelectric force sensor (24) is installed between the pipeline model (22) and the pipeline fixing component (23) to monitor the impact force on the pipeline model (22); the fiber optic grating sensor (25) is attached axially or circumferentially along the outer surface of the pipeline model (22) to monitor the strain response of the pipeline model (22) during landslide impact, bed erosion and local suspension processes; the soil pressure sensor (26) and pore pressure sensor (27) are buried inside the underwater slope model (12), inside the bed model (30) or at key locations of both to monitor the changes in soil pressure, pore water pressure and effective stress before and after the underwater slope instability. The three-dimensional laser scanner (28) is mounted on a support above the water tank (1) to acquire the three-dimensional morphology of the bed surface of the bed model (30) before and after the experiment; the electrode probes (29) are arranged in an array along the longitudinal and transverse directions of the bed model (30) to collect changes in resistivity or conductivity inside the bed model (30) and identify the bed surface incision, erosion interface movement, and critical exposure time of shallow buried pipelines; the acoustic emission sensor (35) is located on the outer side of the bottom of the water tank (1) corresponding to the erosion reaction zone to collect acoustic emission signals generated by the collision of landslide material particles, the initiation of bed particles, and bed surface damage, and to identify the active erosion zone and The strength of the bed surface damage; the wave height meter (32) is arranged along the length of the water tank (1) to monitor the time history, propagation speed and frictional attenuation of the surge waves generated by the disturbance of the water body during the landslide movement and bed erosion process; the acoustic Doppler velocity profiler (33) is set on the upper support of the water tank (1), with its measurement section facing the water body in the tank, to obtain the velocity profile and water disturbance characteristics near the landslide movement area or erosion reaction area; the high-speed camera (34) is set on the outside or above the transparent sidewall of the water tank (1) to record the underwater slope instability, landslide material movement, bed erosion pit expansion, pipeline model (22) exposure and surge wave propagation process; The multi-channel data acquisition instrument (36) is connected to the piezoelectric force sensor (24), fiber optic grating sensor (25), soil pressure sensor (26), pore pressure sensor (27), electrode probe (29), wave height meter (32), acoustic Doppler current profiler (33) and acoustic emission sensor (35), respectively, and is connected to the high-speed camera (34), three-dimensional laser scanner (28) and monitoring computer (37) for trigger signal or time signal connection; the monitoring computer (37) is used to control data acquisition, record test condition parameters, display real-time monitoring curves, and complete time axis alignment and synchronous storage of different monitoring data.

7. The submarine landslide disaster chain test system for realizing bed erosion according to claim 6, characterized in that, The modules of the submarine landslide disaster chain simulation test system are configured as follows: First, the water tank body and the circulating water supply module are used to set the water depth, flow velocity and tank inclination conditions; then, the source term generation module is used to form the underwater slope initiation or landslide material continuous release boundary; after the landslide material moves along the water tank (1), it enters the erosion reaction zone and produces scouring, erosion and bed surface cutting on the bed model (30); the erosion development of the bed model (30) further causes the overlying layer thickness of the pipeline model (22) to decrease, the pipeline model (22) to be exposed or partially suspended; at the same time, the movement of landslide material and the bed erosion process disturb the overlying water and form a surge response; finally, the multi-source monitoring and synchronous acquisition module is used to synchronously monitor and uniformly analyze the landslide source term, bed erosion, pipeline response and surge response, so as to realize the experimental simulation of the disaster chain process of submarine landslide-bed erosion damage-shallow buried pipeline response-surge response.

8. The submarine landslide disaster chain test system for realizing bed erosion according to claim 7, characterized in that, The scale of the model test was determined based on the on-site prototype conditions, laboratory equipment dimensions, and test objectives. For landslide motion, surge propagation, and velocity response processes dominated by gravity and inertia, the scale transformation was performed using the Frode similarity relation. For the processes of subsoil erosion, shallow buried pipeline stress, and bed surface incision, similarity checks are performed based on the particle size, density, shear strength of the subsoil material, pipeline burial depth, and flow intensity.

9. A method for monitoring submarine landslide disaster chains caused by bed erosion, characterized in that, Based on the submarine landslide disaster chain test system according to any one of claims 1-8, the system includes the following steps: Step 1: Construct test boundary conditions and establish the initial subgrade-shallow buried pipeline state to obtain initial test state data; specifically: Step 1.1: Based on the target working conditions, water depth, slope angle, landslide body size, subgrade material properties, shallow buried pipeline burial depth and hydrodynamic conditions, determine the model test scale, trench macro-inclination angle, water depth, flow velocity, landslide source term conditions, subgrade model (30) thickness and pipeline model (22) initial burial depth; Step 1.2: Based on the macroscopic inclination angle, water depth and flow velocity conditions of the tank determined in Step 1.1, the water tank (1) is installed on the bottom support steel frame (2). The macroscopic inclination angle of the water tank (1) relative to the ground is adjusted by hydraulic jack (3). The water supply tank (5), water pipe (4) and high pressure water pump (6) are connected to form a circulating water supply path. Energy dissipation material (11) is arranged at the inlet end, outlet end or downstream side of the erosion reaction zone of the water tank (1) to obtain stable water tank boundary conditions. Step 1.3: Based on the bed geometry and landslide incident conditions determined in Step 1.1, filler blocks (31) are installed in the erosion reaction zone, and bed model (30) is layered and filled above or in the adjacent area of ​​filler blocks (31); pipeline model (22) and pipeline fasteners (23) are installed inside the bed model (30) according to the preset burial depth, and the initial bed surface elevation of the bed model (30), the initial burial depth of the pipeline model (22), the thickness of the overburden layer and the axial direction of the pipeline model (22) are recorded to obtain the initial bed-shallow buried pipeline status data; Step 2: Based on the initial test state data obtained in Step 1, complete the deployment, calibration, and synchronous triggering settings of the monitoring elements to obtain the synchronous acquisition system; specifically: Step 2.1, install a piezoelectric force sensor (24) between the pipeline model (22) and the pipeline fixture (23), and arrange a fiber optic grating sensor (25) on the outer surface of the pipeline model (22) to obtain the force and strain response of the pipeline model (22); Step 2.2, soil pressure sensors (26) and pore pressure sensors (27) are installed in the proposed layout area of ​​the underwater slope model (12), inside the bed model (30) or at key locations in the erosion reaction zone to obtain changes in soil pressure and pore water pressure during the underwater slope instability and bed erosion process; Step 2.3: Arrange an array of electrode probes (29) in the longitudinal and transverse directions within the substrate model (30), and arrange an acoustic emission sensor (35) on the outer side of the bottom of the water tank (1) corresponding to the erosion reaction zone to form an electro-acoustic multi-source erosion identification unit; Step 2.4: A three-dimensional laser scanner (28) and a high-speed camera (34) are arranged above and to the side of the water tank (1), a wave height meter (32) sequence is arranged along the length of the water tank (1), and an acoustic Doppler velocity profiler (33) is arranged in the landslide movement zone or erosion reaction zone to obtain the bed surface morphology, landslide movement images, surge time history and velocity profile; Step 2.5: Connect the piezoelectric force sensor (24), fiber optic grating sensor (25), soil pressure sensor (26), pore pressure sensor (27), electrode probe (29), wave height meter (32), acoustic Doppler current profiler (33), and acoustic emission sensor (35) to the multi-channel data acquisition instrument (36), and synchronize the multi-channel data acquisition instrument (36), high-speed camera (34), three-dimensional laser scanner (28) with the monitoring computer (37) in time and trigger synchronization to complete zero-point calibration and sensitivity calibration, and obtain the synchronous acquisition system; Step 3: Based on the synchronous acquisition system obtained in Step 2, generate the submarine landslide source term and trigger landslide movement to obtain the landslide source term input process; specifically: Step 3.1 When the underwater slope initiation mode is adopted, the underwater slope model (12) is filled in layers on the adjustable slope slope plate (9). The slope toe and lateral deformation of the underwater slope model (12) are restricted by the baffle (13), and the underwater slope model (12) is pre-compressed and consolidated by the pressure plate (14) to obtain the underwater slope model (12) with the preset slope angle, water-bearing state and consolidation state. Step 3.2: Based on the underwater slope model (12) obtained in Step 3.1, use overpressure gas triggering or slope toe excavation triggering to make it unstable and start sliding; Step 3.3: When the continuous release mode is adopted, the L-shaped material guide bucket (20) is connected to the external mud bucket or external pumping unit so that the landslide material enters the upper part of the adjustable slope plate (9) through the L-shaped material guide bucket (20) and the opening of the outlet is adjusted by the hydraulic gate (21); the outflow velocity, outflow thickness and release duration of the landslide material are controlled by the hydraulic gate (21) and the flow rate of the external pumping unit, so as to obtain a continuous and controllable landslide source term input process. Step 4: Based on the landslide source term input process obtained in Step 3, simultaneously collect data on bed erosion, shallow buried pipeline response, and surge response to obtain full-process monitoring data of the disaster chain; specifically: Step 4.1 After the landslide material moves along the water channel (1) and enters the erosion reaction zone, the movement of the landslide material, the scouring and erosion of the bed model (30), the expansion of the erosion pit and the exposure process of the pipeline model (22) are recorded by a high-speed camera (34). The three-dimensional morphology of the bed surface of the bed model (30) is obtained by a three-dimensional laser scanner (28) before the test, at key moments during the test or after the test. Step 4.2: Real-time acquisition of the internal resistivity or conductivity changes of the bed model (30) through the electrode probe (29) array, and real-time acquisition of particle collision and bed surface destruction acoustic emission signals through the acoustic emission sensor (35) to obtain data on bed surface incision, electrical anomaly, acoustic emission event rate and acoustic emission energy rate; Step 4.3: Real-time acquisition of the impact force and strain response of the pipeline model (22) by piezoelectric force sensor (24) and fiber optic grating sensor (25) to obtain shallow buried pipeline response data; Step 4.4: Collect the surge time history using a wave height meter (32), collect the water velocity profile using an acoustic Doppler current profiler (33), and collect the changes in soil pressure and pore water pressure inside the underwater slope model (12) or bed model (30) using an earth pressure sensor (26) and a pore pressure sensor (27) to obtain hydrodynamic response and soil internal response data; Step 4.5: The data obtained in Steps 4.1 to 4.4 are uniformly triggered, synchronously sampled, displayed in real time and synchronously stored by the multi-channel data acquisition instrument (36) and the monitoring computer (37) to obtain the full-process monitoring data of the disaster chain of submarine landslide-bed erosion and damage-shallow buried pipeline response-surge response. Step 5: Based on the full-process monitoring data of the disaster chain obtained in Step 4, conduct multi-source data fusion identification to obtain the evolution of subgrade erosion, the critical exposure time of shallow-buried pipelines, and the characteristics of surge propagation; specifically: Step 5.1: Align the data obtained from the high-speed camera (34), 3D laser scanner (28), electrode probe (29), acoustic emission sensor (35), piezoelectric force sensor (24), fiber optic grating sensor (25), wave height meter (32) and acoustic Doppler current profiler (33) with the time axis to obtain a multi-source monitoring dataset under a unified time reference. Step 5.2: Based on the three-dimensional morphology of the bed surface obtained by the three-dimensional laser scanner (28) and the image sequence obtained by the high-speed camera (34), extract the length, width, depth, volume and bed surface incision rate of the erosion pit; based on the resistivity or conductivity changes obtained by the electrode probe array (29), identify the bed surface incision position and the movement process of the erosion interface; based on the acoustic emission event rate and energy rate obtained by the acoustic emission sensor (35), identify the bed damage intensity and changes in the active erosion zone, and obtain the bed erosion evolution results; Step 5.3: Based on the erosion evolution results of the subgrade obtained in Step 5.2, and combined with the initial burial depth of the pipeline model (22) and the initial bed surface elevation of the subgrade model (30), calculate the decay process of the overburden thickness of the pipeline model (22) over time; when the thickness of the subgrade model (30) above the pipeline model (22) decays to zero or reaches the preset exposure criterion, determine the critical exposure time of the pipeline model (22); when the bed surface below the pipeline model (22) continues to cut down and form a cavity, determine the local suspended length and suspended development process of the pipeline model (22); Step 5.4: Based on the data obtained from the piezoelectric force sensor (24) and fiber optic grating sensor (25), calculate the peak force, impulse, peak strain and strain development process of the pipeline model (22); based on the data obtained from the wave height meter (32) and acoustic Doppler current profiler (33), calculate the surge wave height, propagation speed, friction loss and water velocity profile change, and obtain the response of the shallow buried pipeline and the surge wave propagation characteristics. Step 5.5 involves performing correlation analysis on the bed erosion evolution results obtained in Step 5.2, the critical exposure and local suspension results of shallow buried pipelines obtained in Step 5.3, and the pipeline response and surge propagation characteristics obtained in Step 5.4 to establish the temporal correspondence between landslide source term input, bed erosion intensity, shallow buried pipeline response and surge response, and obtain the full-process evolution results of the submarine landslide disaster chain. Step 6: Based on the evolution results of the entire submarine landslide disaster chain obtained in Step 5, change the experimental conditions and conduct repeated experiments to obtain comparative results under different boundary conditions; specifically: Step 6.1, replace the filling blocks (31) with different heights, slopes or shapes, change the local geometry of the bed model (30) and the incident angle of landslide material, repeat steps 1 to 5, and obtain the bed erosion and shallow buried pipeline response results under different bed boundary conditions; Step 6.2, change the slope angle of the adjustable slope plate (9), the physical parameters of the underwater slope model (12), the overpressure gas pressure, the excavation depth at the slope toe, the outflow conditions of the L-shaped material guide bucket (20), the opening degree of the hydraulic gate (21) or the initial burial depth of the pipeline model (22), and repeat steps 1 to 5 to obtain the disaster chain response results under different landslide source conditions, triggering conditions and shallow buried pipeline layout conditions; Step 6.3: Compare and analyze the geometry of the erosion pit, the bed cutting rate, the attenuation of the overburden thickness of the pipeline model (22), the critical exposure time, the local suspended length, the pipeline stress strain response and the surge propagation characteristics under different working conditions to form a simulation test database of submarine landslide erosion bed disaster chain.

10. A method for monitoring submarine landslide disaster chains caused by bed erosion according to claim 9, characterized in that, In step 3.2, the overpressure gas triggering method is: applying controlled gas pressure to the bottom of the underwater slope model (12) through the high-pressure gas storage tank (15), the air pipe (16), the pressure controller (17) and the air hole (10) to reduce the local effective stress and trigger instability; the slope toe excavation triggering method is: using the telescopic mechanical arm (19) to drive the electric scraper (18) to locally scrape or unload the slope toe of the underwater slope model (12) to weaken the slope toe constraint and trigger instability.

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