Test device and method for analyzing coupling law of sensing array and soil deformation

Abstract

The present application relates to sensing technology and seabed topography monitoring field, aims at providing a kind of test device and method for analyzing the coupling law of sensing array and soil deformation.The device includes the main box of top opening and the scanning mechanism arranged at the opening, side push mechanism and vertical push mechanism are arranged in the main box;Variable volume test cavity is formed by deformable side plate and multiple side push oil cylinders arranged in side push mechanism, and vertical push bottom plate and multiple side push oil cylinders arranged in vertical push mechanism, for containing test soil and burying sensing array.The present application uses telescopic oil cylinder and push plate combined mechanism to simulate soil settlement, lifting and collapse, which can realize the simulation of soil in multiple directions, different displacement deformation variables and deformation speed, and the main device is simple to process and low in material cost.The deformation coupling law of sensing array with different scales and different burial depths, different soil, different scales, different deformation variables can be studied.

Description

Technical Field

[0001] This invention relates to the fields of sensing technology and seabed topography monitoring, and more specifically, to a device and method for analyzing the coupling law between a sensing array and soil deformation. Background Technology

[0002] Traditional oil and natural gas are insufficient to meet the ever-increasing energy demands of modern industry, prompting countries worldwide to actively seek new energy sources. Seafloor natural gas hydrates, as an important green energy source with abundant global reserves, represent a promising alternative. Existing research indicates that natural gas hydrates are highly susceptible to decomposition under disturbance, leading to changes in the physical properties of sediments in hydrate reservoir areas, reduced shear strength, and alterations in seafloor topography. Therefore, monitoring seafloor topography and stratigraphic deformation is crucial for the exploration and exploitation of natural gas hydrates.

[0003] Existing non-contact seabed observation technologies suffer from low accuracy, long cycles, and inability to detect subtle deformations. However, with the development of microelectromechanical sensors and communication technologies, sensor arrays, which offer advantages such as self-organization, stable data transmission, and timeliness, can be deployed onto the seabed, becoming the optimal choice for monitoring seabed topography and stratigraphic deformation. However, due to the complex deformation patterns, large and uneven deformation of sediments in areas containing seabed natural gas hydrates, the deformation coupling between the sensor array and the seabed sediments is complex, affecting the accuracy of the sensor array in sensing topographic changes and making it difficult to reconstruct topographic deformation.

[0004] To improve the accuracy and reliability of sensor arrays in monitoring seabed sediment deformation, it is necessary to propose new technologies suitable for analyzing the coupling between sensor arrays and soil deformation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an experimental device and method for analyzing the coupling law between the sensor array and soil deformation.

[0006] To solve the technical problem, the solution of the present invention is:

[0007] An experimental apparatus for analyzing the coupling law between a sensor array and soil deformation is provided, comprising a main housing with a top opening and a scanning mechanism disposed at the opening; the front and rear housing plates of the main housing are arranged parallel to each other, and their edges on the same side are fixedly connected by a side housing plate; the main housing also includes a side-pushing mechanism and a vertical-pushing mechanism; wherein,

[0008] The side-pushing mechanism includes a side-pushing fixed plate and at least four side-pushing inner plates. The side-pushing fixed plate is fixedly connected to the other side edge of the front and rear box plates. Each side-pushing inner plate is located inside the main box structure. Multiple side-pushing cylinders are fixedly installed on the side-pushing fixed plate and correspond one-to-one with each side-pushing inner plate. The latter is connected to the movable end of each side-pushing cylinder through a ball joint structure. Adjacent side-pushing inner plates are movably connected to form deformable side plates. The deformable side plates are clearance-fitted with the sides and bottom of the main box.

[0009] The vertical push mechanism includes a vertical push fixed plate and at least four vertical push inner plates. The vertical push fixed plate is fixedly connected to the front and rear housing plates, the side housing plates, and the bottom edge of the side push fixed plate. Multiple vertical push cylinders are fixedly mounted on the vertical push fixed plate. A horizontal vertical push inner plate is installed on the movable end of each vertical push cylinder. Each vertical push inner plate has a downwardly extending guard plate structure on both sides. The vertical dimension of the guard plate structure is greater than the maximum extension stroke of the vertical push cylinder. Each vertical push inner plate is arranged parallel inside the main housing structure to form a vertical push bottom plate. The vertical push inner plates are in a movable sealed fit with each other and with the main housing structure.

[0010] The front and rear box plates, side box plates, deformable side plates and vertical push bottom plate together constitute a variable volume test chamber for holding test soil and burying sensor arrays; each side push cylinder and vertical push cylinder is connected to the corresponding hydraulic station through oil pipes, and each hydraulic station is equipped with a motor and a motor control board, the latter being connected to the signal receiving and processing unit and the host computer in sequence through signal lines.

[0011] The scanning mechanism includes a lead screw and a slide rail that pass through the front and rear housing plates. A lead screw motor is provided at the end of the lead screw, and the body of the slider is movably mounted on the slide rail. The upper end of the slider is nested on the lead screw, and the lower end is fixedly equipped with a three-dimensional laser scanner.

[0012] The test chamber contains test soil, and a tubular sensor array is embedded inside the test soil. The sensor array has multiple strain gauges and monitoring units, and each monitoring unit integrates an accelerometer, a gyroscope, and a magnetometer. Multiple earth pressure cells are embedded alternately along the length of the sensor array. The sensor array and each earth pressure cell are connected to a signal receiving and processing unit and a host computer in sequence via signal lines.

[0013] As a preferred embodiment of the present invention, the movable sealing fit between each vertical push inner plate and between the vertical push inner plate and the main box structure is achieved by the following method: grooves are provided at both ends of the vertical push inner plate, and wear-resistant rubber strips are embedded in the grooves; on the surface of the guard plate structure on both sides of the vertical push inner plate, a horizontal groove is provided near the upper and lower edges, and wear-resistant rubber strips are embedded in the grooves.

[0014] As a preferred embodiment of the present invention, each side-push inner plate is approximately located on the same plane, and the ball joint structure is installed at the center of each side-push inner plate. By controlling the start and stop of the motors and the speed of the different hydraulic stations, the side-push cylinders can obtain different extension and retraction lengths, enabling the deformable side plates to perform side-push or oblique-push operations.

[0015] As a preferred embodiment of the present invention, a MEMS nine-axis sensor is provided at the geometric center of each side push inner plate and vertical push inner plate.

[0016] As a preferred embodiment of the present invention, on two adjacent side-push inner plates, one side-push inner plate is provided with a protruding structure on its side, and the other side-push inner plate is provided with a groove structure on its side. The protruding structure and the groove structure are spliced ​​together to form a movable mechanism that cooperates with each other.

[0017] As a preferred embodiment of the present invention, the lead screw motor is fixedly installed on the outside of the front housing plate or the rear housing plate; the lead screw motor is provided with an oil inlet and an oil outlet, and the lead screw is driven to rotate by controlling the change of the inlet and outlet of hydraulic oil.

[0018] As a preferred embodiment of the present invention, the sensor array is covered with a protective flexible tube made of PVC material; the front and rear panels and side panels of the main housing are all transparent acrylic sheets.

[0019] This invention further provides an experimental method for analyzing the coupling law between the sensor array and soil deformation using the aforementioned experimental device, including:

[0020] (1) Deploy the sensor network and earth pressure cell

[0021] The test chamber of the test device is filled with test soil, and multiple sensor arrays are vertically inserted and horizontally buried in the soil. They are cascaded into a sensor network through signal lines, and several earth pressure cells are arranged along with each sensor array.

[0022] (2) Obtain soil deformation monitoring data

[0023] The shape of the test soil is changed by using the lateral thrust mechanism and vertical thrust mechanism in the test device to simulate the changes in complex seabed topography; soil deformation monitoring data is obtained by using a sensor network and earth pressure cell, spatial displacement data of the soil surface is obtained by using a three-dimensional laser scanner, and the monitoring data is transmitted to the host computer through a signal line.

[0024] (3) Data processing and analysis

[0025] By combining monitoring data and the mechanical properties of the test soil, the spatial displacement data of the soil surface is compared with the soil deformation data acquired by the sensor array to determine the transfer coefficient. Through the verification and calibration of the monitoring data, error compensation for the coupling between the sensor array and soil deformation is achieved, and the soil deformation shape is reconstructed using the sensor network.

[0026] As a preferred embodiment of the present invention, step (3) includes:

[0027] A transformation matrix is ​​established between the geographic coordinate system and the body coordinate system based on the monitoring units; the acceleration vector and magnetic induction intensity vector are calculated based on the measurement data of the accelerometers and magnetometers in the monitoring units; the rotation angle of the current spatial attitude of the sensor array is calculated analytically to determine the relative position coordinates of each link node; the spatial attitude of the sensor network is reconstructed by fitting the curve segments between the nodes through cubic spline interpolation, and the topographic deformation map reconstructed based on the monitoring data is obtained; combined with the transfer coefficient obtained through simulation experiments, the displacement of the soil surface in the monitoring area of ​​the sensor network is further estimated.

[0028] As a preferred embodiment of the present invention, in step (3), the monitoring data includes: soil strain obtained by earth pressure cell, surface deformation of sensor array obtained by strain gauge, acceleration and magnetic induction intensity obtained by sensor array, spatial displacement data of soil surface obtained by three-dimensional laser scanner, and cylinder displacement data in side thrust mechanism and vertical thrust mechanism; the mechanical properties of the test soil include deformation modulus, compression modulus, and stress-strain characteristics.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. Considering that the sensor array needs to be in full contact with the soil to achieve deformation coupling, and taking into account the sensitivity to sensing surface deformation of the soil, this invention innovatively proposes an experimental device and method for analyzing the deformation coupling law between the sensor array and the soil. This invention embeds the sensor array in the soil and uses lateral and vertical thrust mechanisms to change the soil deformation. This allows for the study of the deformation coupling law between sensor arrays of different scales and burial depths and soils of different types, scales, and deformations. It determines the optimal structure and burial depth conditions of the sensor array in the target monitoring area, reduces the error of monitoring data obtained by the seabed sensor array, and ultimately achieves high-precision monitoring and reconstruction of subtle topographic deformations.

[0031] 2. This invention innovatively proposes to use a combined mechanism of telescopic hydraulic cylinder and push plate to simulate soil settlement, lifting and collapse. It can simulate soil in multiple directions, different displacement deformation and deformation rate. Moreover, the main device is simple to process and has low material cost.

[0032] 3. This invention utilizes a 3D laser scanner to scan the deformation of the soil surface and combines this data with soil pressure sensor data and the mechanical properties of the measured soil. This data is then compared with the soil deformation data acquired by the sensor array, enabling the verification and calibration of the sensor array monitoring data. Based on this, a further model for coupling and error compensation between the sensor array and soil deformation can be established, improving the accuracy of monitoring data in practical engineering applications of the sensor array. Therefore, this invention has significant value for current marine topographic deformation monitoring technology. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention;

[0034] Figure 2 This is a schematic diagram of the side thrust mechanism;

[0035] Figure 3 A schematic diagram of the protruding and recessed structures in the side-push inner plate;

[0036] Figure 4 A schematic diagram of the vertical thrust mechanism of the main device;

[0037] Figure 5 A schematic diagram of a single vertical push inner plate and guard plate structure;

[0038] Figure 6 A schematic diagram showing the deployment of the deformation coupling monitoring mechanism;

[0039] Figure 7 This is a schematic diagram of the coordinate system and terrain monitoring of the sensor network.

[0040] The attached figures are labeled as follows: 1 Main housing; 1-1 Side housing plate; 1-1-1 Front housing plate; 1-1-2 Rear housing plate; 1-2 Slide rail; 1-3 Side push fixing plate; 1-4 Vertical push fixing plate; 2 Side push mechanism; 2-1 Side push cylinder; 2-2 Ball joint structure; 2-3 Side push inner plate; 2-4 Movable mechanism; 3 Vertical push mechanism; 3-1 Vertical push cylinder; 3-2 Vertical push inner plate; 3-2-1 Protective plate structure; 3-2-2 Wear-resistant rubber strip; 4 Scanning mechanism; 4-1 Lead screw motor; 4-1-1 Oil inlet; 4-1-2 Oil outlet; 4-2 Lead screw; 4-3 Slider; 4-4 3D laser scanner; 5 Strain gauge; 6 Earth pressure cell; 7 Monitoring unit. Detailed Implementation

[0041] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, so as to enable those skilled in the art to understand and read it. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0042] Meanwhile, terms such as "front," "rear," "side," "upper," "lower," and "middle" used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Any changes or adjustments to these relative terms, without any substantial alteration to the technical content, should be considered as part of the scope of the invention.

[0043] The signal receiving and processing unit described in this invention is a circuit module or component located between the signal source and the host computer. Those skilled in the art can select different types and functions of signal receiving and processing units to implement according to the characteristics of different signal sources.

[0044] like Figure 1 As shown, the experimental device for analyzing the coupling law between the sensor array and soil deformation according to the present invention includes a main box 1 with a top opening and a scanning mechanism 4 located at the opening; the front box plate 1-1-1 and the rear box plate 1-1-2 of the main box 1 are arranged in parallel, and their edges on the same side are fixedly connected by a side box plate 1-1; the main box 1 also includes a side pushing mechanism 2 and a vertical pushing mechanism 3. For easy observation, the front box plate 1-1-1, the rear box plate 1-1-2, and the side box plate 1-1 are all transparent acrylic sheets.

[0045] like Figure 2 As shown, the side-push mechanism 2 includes a side-push fixed plate 1-3 and four side-push inner plates 2-3. The side-push fixed plate 2-3 is fixedly connected to the other side edge of the front box plate 1-1-1 and the rear box plate 1-1-2. Each side-push inner plate 2-3 is located inside the main box structure. Multiple side-push cylinders 2-1 are vertically fixed on the side-push fixed plate 1-3 and correspond one-to-one with each side-push inner plate 2-3. The side-push inner plates 2-3 are connected to the movable ends of each side-push cylinder 2-1 through a ball joint structure 2-2. A corrugated dust cover can be installed on the movable end. Adjacent side-push inner plates 2-3 are connected by a movable mechanism 2-4 to form deformable side plates. The deformable side plates are clearance-fitted with the sides and bottom of the main box 1. An example structure of the movable structure 2-4 is as follows: On two adjacent side-push inner plates 2-3, one side-push inner plate 2-3 has a protruding structure on its side, and the other side-push inner plate 2-3 has a grooved structure on its side. The protruding structure and the grooved structure are spliced ​​together to form a mutually cooperating movable mechanism 2-4. Each side-push inner plate 2-3 is approximately located in the same vertical plane. A ball joint structure 2-2 is installed at the center of each side-push inner plate 2-3. By controlling the start / stop and speed of the motors of different hydraulic stations, the side-push cylinder 2-1 can achieve different extension / retraction lengths, enabling the deformable side plates to perform lateral or oblique pushing actions, thereby applying lateral pressure to the test soil in different directions to induce deformation. A MEMS nine-axis sensor is installed at the geometric center of each side-push inner plate 2-3 to acquire motion data and monitor the tilt angle and displacement of the deformable side plates.

[0046] Figure 1 , 4 Figure 5 shows an example structure of a vertical push mechanism 3 equipped with four vertical push inner plates 3-2. The vertical push mechanism 3 includes a vertical push fixing plate 1-4 and four vertical push inner plates 3-2. The vertical push fixing plate 1-4 is fixedly connected to the bottom edges of the front housing plate 1-1-1, the rear housing plate 1-1-2, the side housing plate 1-1, and the side push fixing plate 2-3. Each vertical push inner plate 3-2 is parallel to each other and arranged inside the main housing structure, together forming a vertical push base plate. Multiple vertical push cylinders 3-1 are vertically fixed on the vertical push fixing plate 1-4, each corresponding to one of the vertical push inner plates 3-2, which are connected to the movable ends of each cylinder 3-2. A MEMS nine-axis sensor can be placed at the geometric center of the vertical push inner plate.

[0047] Each vertical thrust inner plate 3-2 has downwardly extending protective plate structures 3-2-1 on both sides. Grooves are parallel to each other along the upper and lower edges of each protective plate structure 3-2-1, and wear-resistant rubber strips 3-2-2 are embedded within these grooves. Simultaneously, grooves are also formed on the side edges at both ends of each vertical thrust inner plate 3-2, and filled with wear-resistant rubber strips. The wear-resistant rubber strips 3-2-2 are used to achieve a seal during relative movement between the moving structures. Specifically, during the vertical thrusting process, there will be height differences between the vertical thrust inner plates 3-2, and relative movement will also occur between the vertical thrust inner plates 3-2 and the main box structure. To prevent soil from falling through the gaps between adjacent vertical thrust inner plates 3-2 and between the vertical thrust inner plates 3-2 and the main box structure, the above-mentioned design is necessary to achieve a sealing fit.

[0048] The front chamber plate 1-1-1, rear chamber plate 1-1-2, side chamber plate 1-1, deformable side plates, and vertical thrust base plate together constitute a variable-volume test chamber. Test soil can be contained within the test chamber, and a strip-shaped sensor array is embedded inside the soil. The sensor array is covered with a protective flexible PVC sleeve. The sensor array has multiple strain gauges 5 and monitoring units 7, each monitoring unit 7 integrating an accelerometer, gyroscope, and magnetometer. Multiple earth pressure cells 6 are embedded alternately along the length of the sensor array. The sensor array and each earth pressure cell 6 are sequentially connected to a signal receiving and processing unit and a host computer via signal lines.

[0049] Each side-push cylinder 2-1 and vertical push cylinder 3-1 is connected to a corresponding hydraulic station via oil pipes. Each hydraulic station is equipped with a motor and a motor control board. The motor control board is connected to a signal receiving and processing unit and a host computer via signal lines. The scanning mechanism 4 includes a lead screw 4-2 and a slide rail 1-2 that pass through the front housing plate 1-1-1 and the rear housing plate 1-1-2. A lead screw motor 4-1 is provided at the end of the lead screw 4-2. The body of the slider 4-3 is movably mounted on the slide rail 1-2. The upper end of the slider 4-3 is nested on the lead screw 4-2, and the lower end is fixedly equipped with a three-dimensional laser scanner 4-4. The lead screw motor 4-1 is fixedly mounted on the outside of the front housing plate 1-1-1 or the rear housing plate 1-1-2. The lead screw motor 4-1 is provided with an oil inlet 4-1-1 and an oil outlet 4-1-2. The lead screw motor 4-1 can drive the lead screw 4-2 to rotate, thereby driving the slider 4-3 to perform linear reciprocating motion, which in turn drives the displacement operation of the 3D scanner 4-4. The speed of the lead screw motor 4-1 can be controlled by changing the hydraulic oil flow, thereby controlling the movement speed of the slider 4-3.

[0050] like Figure 3 As shown in the figure, the protruding structure (left extended portion) and the grooved structure (dashed line portion) of the side-push inner plate 2-3 are illustrated. Adjacent side-push inner plates 2-3 are connected by two fitting structures to form an embedded movable connection. This allows them to make relative displacement within a certain range under the pulling force of each side-push cylinder 2-1 after being assembled into a deformable side plate. This enables the deformable side plate to perform upward or downward tilting actions, thereby simulating the process of soil collapse and lateral displacement.

[0051] The four side-push cylinders 2-1 of the side-push mechanism 2 are controlled by four side-push hydraulic stations (not shown in the figure). The motors of the side-push hydraulic stations receive control commands via RS485 communication and are controlled by a motor control board in a 6-way valve box (two of which are spares). The motor control board communicates with the host computer via an RS232 to USB module. The host computer obtains the motor operation data of the hydraulic stations and sends commands to control the start and stop of the motors and their speed of the different side-push hydraulic stations, so that the four side-push cylinders obtain oil at different speeds, thereby extending and retracting by different lengths. This allows the large side-push inner plate to perform oblique pushing operations. The motion data is obtained by a MEMS nine-axis sensor installed at the geometric center of the four side-push inner plates, which completes the precise monitoring of the tilt angle and displacement of the large side-push inner plate.

[0052] Taking a vertical push mechanism 3 with 7 vertical push inner plates 3-2 as an example ( Figure 4 Four of them are shown. The long, vertical inner plate 3-2 is connected to the movable end of the vertical push cylinder 3-1. The different extension and retraction movements of the vertical push cylinder 3-1 drive the vertical push inner plate 3-2 to produce different movements in the vertical direction, which can make the vertical push bottom plate squeeze the test soil, thereby producing a squeezing deformation effect in the vertical direction.

[0053] In the vertical thrust mechanism 3, each vertical thrust cylinder 3-1 below the vertical thrust inner plate 3-2 is connected to a vertical thrust hydraulic station (not shown in the figure). The vertical thrust cylinder 3-1 is a servo cylinder with a built-in displacement sensor. The displacement sensor and the proportional directional valve form a synchronous circuit. When the vertical thrust cylinder group is working, the displacement sensor returns a position signal, and the proportional directional valve amplifies and outputs a control signal. The control signal of one proportional directional valve is set as the reference signal, and the other is set as the follow signal to perform closed-loop error control and complete the synchronous operation of the vertical thrust cylinder 3-1. The motors of the vertical thrust hydraulic stations receive control commands via RS485 communication and are controlled by an 8-channel valve box (one channel as a backup). The host computer sends commands to the motor control board in the 8-channel valve box via a USB-to-RS232 module, controlling the motor actions of each vertical thrust hydraulic station, which in turn controls the vertical thrust cylinders 3-1 under each vertical thrust inner plate 3-2. The five vertical thrust cylinder groups can move upwards and downwards respectively, simultaneously causing the soil in the corresponding inner plate area to rise or settle. The movement distance of the vertical thrust inner plate 3-2 can be precisely controlled by the hydraulic station or accurately calculated by the displacement sensors built into the vertical thrust cylinders 3-1. The host computer controls the 6-channel and 8-channel valve boxes respectively to control the individual or coordinated actions of the side thrust mechanism 2 and the vertical thrust mechanism 3, realizing the simulation of complex seabed topographic changes.

[0054] Figure 6 An example of the sensor array arrangement in the experimental setup is shown. Strain gauges 5 are distributed in three directions on the protective shell of each sensor array. The coupled deformation monitoring mechanism consists of the sensor array, the strain gauges 5 attached to the protective shell, and the earth pressure cell 6 buried in the soil along with the sensor array. The strain gauges 5 output a positive voltage when under tension, and their three-directional arrangement characterizes the bending direction at various locations on the sensor array. Several monitoring units 7 are arranged on each sensor array, each integrating an accelerometer, gyroscope, and magnetometer. When the sensor array deforms, the monitoring units 7 perform analytical calculations on the current spatial attitude. All monitoring units 7 communicate with the STM32 main control chip via the I2C protocol. The calculation results are sent to the data processor, and the main control chip centrally processes the data from each monitoring unit 7 to obtain the state of the entire sensor array. The calculation results, including the bending direction and degree of deformation at various locations, are then displayed in real-time on the host computer via a serial port. Subsequently, the SD card is read and written via the SDIO host interface to achieve long-term recording of the shape changes of the sensor array. The sensing array is protected by a long PVC flexible tube shell, enabling bending from -90° to 90°. Data from strain gauges 5 distributed on the array shell are centrally processed and analyzed by a data acquisition instrument. The maximum values ​​measured by strain gauges 5 in three directions at each location are considered the maximum deformation of the sensing array at that point, thus obtaining the surface strain sequence E of the sensing array during the deformation of the soil at the current burial depth. o ={εo1 , ε o2 ...}; Earth pressure cells 6, arranged along the axis of the sensing array and adjacent to the sensing array, acquire earth pressure data F = {f} generated by the soil at their respective depths during deformation via a matching digital frequency meter. s1 f s2 , ...}.

[0055] To analyze the coupling relationship between the sensor array and soil deformation, this invention monitors and reconstructs the terrain shape using a sensor array. For the two types of soil deformation, multiple sensor arrays are cascaded into a sensor network to acquire soil deformation data and reconstruct the terrain deformation shape. Figure 7 The diagram shows the coordinate system of the sensor network and a schematic diagram of terrain monitoring.

[0056] The test method of the present invention specifically includes the following steps:

[0057] (1) Deploy the sensor network and earth pressure cell

[0058] The test chamber of the test device is filled with test soil, and multiple sensor arrays are vertically inserted and horizontally buried in the soil. They are cascaded into a sensor network through signal lines, and several earth pressure cells are arranged along with each sensor array.

[0059] The test soil in the main test chamber was prepared with reference to sediments collected from the seabed hydrate area. The various physical and mechanical properties of the test soil (stress-strain characteristics, Poisson's ratio, shear modulus, deformation modulus, etc.) could be measured using a dynamic / static triaxial apparatus and a direct shear apparatus. Before the test, the upper surface of the soil was smoothed with a shovel to compare the shape changes of the soil surface in the 3D imaging of the 3D laser scanner 4-4 before and after the test.

[0060] (2) Obtain soil deformation monitoring data

[0061] The shape of the test soil is changed by using the lateral thrust mechanism 2 and the vertical thrust mechanism 3 in the test device to simulate the changes in complex seabed topography; soil deformation monitoring data is obtained by using a sensor network and earth pressure cell 6, spatial displacement data of the soil surface is obtained by using a three-dimensional laser scanner 4-4, and the monitoring data is transmitted to the host computer through a signal line.

[0062] The stress-strain curve of the sampled soil can be obtained through mechanical tests of the soil in step (1) and the stress-strain relationship of structural soft soil based on the Duncan one-dimensional model. Combined with the monitoring data of each earth pressure cell 6, F={f s1 f s2 ...} can be used to obtain the strain E of the soil at the given depth. s ={ε s1 , ε s2 , ...}, corresponding variable E sThe soil displacement S = {s1, s2, ...} at the buried depth is obtained by integration, which is the soil displacement along the direction of the earth pressure cell. Simultaneously, a 3D laser scanner (4-4) scans the upper surface of the soil in the test chamber, displaying the spatial displacement of the soil surface as a 3D image. The obtained deformation state of the sensor array can be written to a memory card via data transmission or transmitted to a host computer via serial port for real-time display, facilitating long-term storage and real-time display of monitoring results.

[0063] (3) Data processing and analysis

[0064] By combining monitoring data and the mechanical properties of the test soil, the spatial displacement data of the soil surface is compared with the soil deformation data acquired by the sensor array; through the evaluation and calibration of the monitoring data, error compensation of the coupling between the sensor array and soil deformation is achieved, and the soil deformation shape is reconstructed using the sensor network.

[0065] By analyzing the relationship between the theoretical displacement of the soil surface (the actual stroke of the vertical or side thrust cylinder) and the actual displacement (acquired by a 3D laser scanner), and by comparing it with the monitoring results of a sensor array buried at a depth h in the soil, the transmission coefficient between the soil deformation displacement measured by the sensor array and the surface displacement of the soil at this burial depth can be obtained. This allows for the study of the transmission coefficient at different burial depths.

[0066] The following is an illustrative example of the error compensation and soil deformation shape reconstruction process in step (3):

[0067] Step (1): Establish the transformation matrix R between the geographic coordinate system {A} and the body coordinate system {B} based on the monitoring unit. AB ;

[0068] Based on the change in the spatial attitude of the monitoring unit, {B} can be obtained from {A} by rotating it with Euler angles. Following the rotation order of ZXY, first rotate {A} by an angle γ around the Z-axis to obtain the first intermediate coordinate system, then rotate {A} by an angle θ around the Y-axis of the first intermediate coordinate system to obtain the second intermediate coordinate system, and then rotate {B} by an angle α around the X-axis of the second intermediate coordinate system. All rotations are performed according to the right-hand screw rule. The transformation matrix from coordinate system {A} to {B} is expressed by formula (1):

[0069]

[0070] Among them, R γ R θ R α These are rotation matrices for three rotation angles γ, θ, and α, respectively.

[0071] Step (2): The accelerometer and magnetometer of the monitoring unit measure gravity data a and magnetic data b;

[0072] Accelerometers and magnetometers measure acceleration vectors and magnetic flux density vectors along the X, Y, and Z axes of coordinate system {B}, where a = [a x a y a z ] T b = [b x b y b z ] T , where a x a y a z Let a be the component of a on the {B} axes, and b be the component of a on the {B} axes. x b y b z These are the components of b on the {B} three axes;

[0073] Transformation matrix R AB Each column in the table represents the body coordinates based on the monitoring unit after the geographic coordinates are rotated. Therefore, gravity data a and magnetic data b can be further expressed as formula (2):

[0074]

[0075] in, It is R AB The transpose of the matrix, where g is the acceleration due to gravity. η is the Earth's magnetic field vector, and η is the magnetic flux density of the Earth's magnetic field. It is the angle between the X-axis and the geomagnetic vector in coordinate system {B};

[0076] Step (3): The monitoring unit analyzes and calculates the rotation angles γ, θ, and α of the current spatial attitude to determine the relative position coordinates;

[0077] Transform formula (2) in step (2) to obtain the rotation angles γ, θ, and α, which are expressed by formula (3):

[0078]

[0079] The sensor network has a mesh-like linked structure, with each link node connecting several links. Monitoring units are arranged on the links, and the link length between nodes is fixed at d. The link node U at the bottom corner of the sensor network link... 11 As a reference point, the node U connected to this node 21 Link vector Q 21 It can be expressed by formula (4):

[0080]

[0081] So U 21 The coordinates are U11 coordinates plus Q 21 Repeating the above process, the next node connected by the link can be calculated until U. ij U 11 Q represents the link node located in the first row and first column of the sensor network. 21 This represents the link vector in the second row and first column of the network, where i and j represent the row and column numbers of the linked nodes in the sensor network, respectively. ij This represents the link node located in the i-th row and j-th column of the sensor network;

[0082] Among them, the monitoring data of strain gauges and earth pressure cells are used to compensate for the error of the sensing array, with Q... 21 Taking the links listed above as an example:

[0083] During soil deformation, the surface of the sensing array will experience stretching or compression, and the link length is no longer a fixed value. At this time, the surface strain ε of the sensing array measured by the strain gauge will change. o1 The link length d used in formula (4) is used to compensate for the link length after compensation. o1 Then the following relation should hold:

[0084] d o1 =(1+ε o1 )d (5)

[0085] Earth pressure cells are arranged horizontally along the sensor array, and the obtained displacement S = {s1, s2, ...} can be used to verify the displacement coordinates in the z-axis direction of the corresponding link vector Q. Accordingly, Q... 21 Deformation coupling index ξ of soil s1 It can be represented as:

[0086]

[0087] Therefore, for the sensing array as a whole, the deformation coupling coefficient Ξ between the sensing array and the soil can be expressed as:

[0088] Ξ=(1-Πξ sl )×100%, l=1, 2,...(7)

[0089] Where l represents the link number on a sensor array, ξ sl This indicates the deformation coupling index between the link and the soil.

[0090] Clearly, the closer Ξ is to 1, the stronger the deformation coupling ability between the sensing array and the soil. The corresponding definitions are: Ξ ≥ 80% is considered strong deformation coupling ability; 80% > Ξ ≥ 60% is considered relatively strong deformation coupling ability; 60% > Ξ ≥ 40% is considered relatively weak deformation coupling ability; and 40% > Ξ ≥ 0% is considered weak deformation coupling ability.

[0091] By repeating the above process for different sensor arrays, data compensation and deformation coupling assessment of the entire sensor network can be completed.

[0092] Step (4): After obtaining the relative position coordinates of each link node in step (3), the curve segments between the nodes are fitted by cubic spline interpolation to complete the spatial attitude reconstruction of the sensor network.

[0093] The interpolation method in step (4) is characterized by interpolation under three sets of two-dimensional coordinates. It is assumed that for coordinates in space (x... O y O , z O ) and (X P y P , z P ) is two nodes connected by a link, in (x O y O ) and (x P y P Interpolation in ) produces a sequence (x) m y m ), in (y O , z O ) and (y P , z P Interpolation generates a sequence (y) in ) n , z n ), in (x O , z O ) and (X P , z P Interpolation generates a sequence (x) in ) k , z k The three-dimensional coordinate sequence (x) obtained after interpolation. r y r , z r This can be expressed by formula (8):

[0094]

[0095] Where r, m, n, k represent the serial numbers, and r = 1, 2, 3, 4, 5;

[0096] Finally, the obtained sequence (x) r y r , z r The data is then processed in Matlab software, characterized by using a cubic curve to smoothly connect (x) O y O , z O ) and (X P y P , z PBy obtaining the terrain deformation map reconstructed by the spatial attitude of the sensor network, and combining it with the transfer coefficient obtained from the simulation test in the main device, the displacement of the soil surface in the sensor network monitoring area can be further estimated.

[0097] In this invention, different types of soil can be tested to obtain the deformation coupling relationship between the sensor array and different soils, which can be used to quantitatively evaluate the deformation coupling capability between the sensor array and the soil.

[0098] Acceleration caused by ground movement and magnetic disturbances in the environment may affect the measurements of the accelerometer and magnetometer in the monitoring unit. Additional sensors (such as gyroscopes) can be added to assist in spatial attitude analysis.

[0099] The above description is merely a specific embodiment of the present invention and is not intended to limit the invention. Obviously, the present invention can have many variations. For example, those skilled in the art can also use other existing technical means and other data processing and analysis methods based on actual experimental monitoring conditions and error compensation accuracy control requirements. Any modifications or variations made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An experimental device for analyzing the coupling law between a sensor array and soil deformation, comprising a main box with a top opening and a scanning mechanism disposed at the opening; characterized in that, The front and rear panels of the main housing are arranged parallel to each other, and their edges on the same side are fixedly connected by a side panel; the main housing also includes a side-pushing mechanism and a vertical-pushing mechanism; wherein... The side-pushing mechanism includes a side-pushing fixed plate and at least four side-pushing inner plates. The side-pushing fixed plate is fixedly connected to the other side edge of the front and rear box plates. Each side-pushing inner plate is located inside the main box structure. Multiple side-pushing cylinders are fixedly mounted on the side-pushing fixed plate and correspond one-to-one with each side-pushing inner plate. The latter are connected to the movable end of each side-pushing cylinder through a ball joint structure. Adjacent side-pushing inner plates are movably connected to form deformable side plates. The deformable side plates are clearance-fitted with the sides and bottom of the main box. Each side-pushing inner plate is approximately located on the same plane. The ball joint structure is installed at the center of each side-pushing inner plate. By controlling the start and stop of the motors and the speed of the different hydraulic stations, the side-pushing cylinders can obtain different extension and retraction lengths, enabling the deformable side plates to perform side-pushing or oblique-pushing operations. The vertical push mechanism includes a vertical push fixed plate and at least four vertical push inner plates. The vertical push fixed plate is fixedly connected to the front and rear housing plates, the side housing plates, and the bottom edge of the side push fixed plate. Multiple vertical push cylinders are fixedly mounted on the vertical push fixed plate. A horizontal vertical push inner plate is installed on the movable end of each vertical push cylinder. Each vertical push inner plate has a downwardly extending guard plate structure on both sides. The vertical dimension of the guard plate structure is greater than the maximum extension stroke of the vertical push cylinder. Each vertical push inner plate is arranged parallel inside the main housing structure to form a vertical push bottom plate. The vertical push inner plates are in a movable sealed fit with each other and with the main housing structure. The front and rear box plates, side box plates, deformable side plates and vertical push bottom plate together constitute a variable volume test chamber for holding test soil and burying sensor arrays; each side push cylinder and vertical push cylinder is connected to the corresponding hydraulic station through oil pipes, and each hydraulic station is equipped with a motor and a motor control board, the latter being connected to the signal receiving and processing unit and the host computer in sequence through signal lines. The scanning mechanism includes a lead screw and a slide rail that pass through the front and rear housing plates. A lead screw motor is provided at the end of the lead screw, and the body of the slider is movably mounted on the slide rail. The upper end of the slider is nested on the lead screw, and the lower end is fixedly equipped with a three-dimensional laser scanner. The test chamber contains test soil, and a tubular sensor array is embedded inside the test soil. The sensor array has multiple strain gauges and monitoring units, and each monitoring unit integrates an accelerometer, a gyroscope, and a magnetometer. Multiple earth pressure cells are embedded alternately along the length of the sensor array. The sensor array and each earth pressure cell are connected to a signal receiving and processing unit and a host computer in sequence via signal lines.

2. The experimental apparatus according to claim 1, characterized in that, The movable sealing fit between each vertical push inner plate and between the vertical push inner plate and the main box structure is achieved in the following way: grooves are provided at both ends of the vertical push inner plate, and wear-resistant rubber strips are embedded in the grooves; on the surface of the guard plate structure on both sides of the vertical push inner plate, a horizontal groove is provided near the upper and lower edges, and wear-resistant rubber strips are embedded in the grooves.

3. The experimental apparatus according to claim 1, characterized in that, MEMS nine-axis sensors are placed at the geometric center of each side push inner plate and vertical push inner plate.

4. The experimental apparatus according to claim 1, characterized in that, On two adjacent side-push inner plates, one side-push inner plate has a protruding structure on its side, and the other side-push inner plate has a groove structure on its side. The protruding structure and the groove structure are spliced ​​together to form a movable mechanism that cooperates with each other.

5. The experimental apparatus according to claim 1, characterized in that, The lead screw motor is fixedly installed on the outside of the front or rear housing plate; the lead screw motor is provided with an oil inlet and an oil outlet, and the lead screw is driven to rotate by controlling the change in the amount of hydraulic oil entering and leaving the machine.

6. The experimental apparatus according to claim 1, characterized in that, The sensor array is protected by a flexible PVC sleeve; the front and rear panels and side panels of the main housing are all made of transparent acrylic sheets.

7. A test method for analyzing the coupling law between the sensor array and soil deformation using the test device described in claim 1, characterized in that, include: (1) Deploy the sensor network and earth pressure cell The test chamber of the test device is filled with test soil, and multiple sensor arrays are vertically inserted and horizontally buried in the soil. They are cascaded into a sensor network through signal lines, and several earth pressure cells are arranged along with each sensor array. (2) Obtain soil deformation monitoring data The shape of the test soil is changed by using the lateral thrust mechanism and vertical thrust mechanism in the test device to simulate the changes in complex seabed topography; soil deformation monitoring data is obtained by using a sensor network and earth pressure cell, spatial displacement data of the soil surface is obtained by using a three-dimensional laser scanner, and the monitoring data is transmitted to the host computer through a signal line. (3) Data processing and analysis By combining monitoring data and the mechanical properties of the test soil, the spatial displacement data of the soil surface is compared with the soil deformation data acquired by the sensor array to determine the transfer coefficient. Through the verification and calibration of the monitoring data, error compensation for the coupling between the sensor array and soil deformation is achieved, and the soil deformation shape is reconstructed using the sensor network.

8. The method according to claim 7, characterized in that, Step (3) includes: A transformation matrix is ​​established between the geographic coordinate system and the body coordinate system based on the monitoring units; the acceleration vector and magnetic induction intensity vector are calculated based on the measurement data of the accelerometers and magnetometers in the monitoring units; the rotation angle of the current spatial attitude of the sensor array is calculated analytically to determine the relative position coordinates of each link node; the spatial attitude of the sensor network is reconstructed by fitting the curve segments between the nodes through cubic spline interpolation, and the topographic deformation map reconstructed based on the monitoring data is obtained; combined with the transfer coefficient obtained through simulation experiments, the displacement of the soil surface in the monitoring area of ​​the sensor network is further estimated.

9. The method according to claim 7, characterized in that, In step (3), the monitoring data includes: soil strain obtained by earth pressure cell, surface deformation of sensor array obtained by strain gauge, acceleration and magnetic induction intensity obtained by sensor array, spatial displacement data of soil surface obtained by three-dimensional laser scanner, and cylinder displacement data in side thrust mechanism and vertical thrust mechanism; the mechanical properties of the test soil include deformation modulus, compression modulus, and stress-strain characteristics.

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