Earth-structure co-evolution seismic liquefaction analysis device and method based on seismic signals

Abstract

The invention discloses a seismic signal-based soil-structure co-evolution seismic liquefaction analysis device and method, and the method comprises the steps: obtaining geological and seismic data of a target region, and constructing a geometric ratio, time ratio and acceleration ratio co-scaling system based on a Bockingham Pi similarity theory; a seismic liquefaction multi-field coupling evolution device is constructed to evolve the soil liquefaction process of a target area, a distributed optical fiber sensor array and a micro pore pressure meter group are adopted to form a millimeter-level spatial resolution monitoring network, and a high-speed camera system is matched to synchronously capture pore water pressure, structural strain and a soil shear band expansion process. Total element time sequence correlation analysis of vibration triggering, seepage developing and structural catastrophe is achieved, the influence degree of the total element time sequence correlation analysis on the earthquake is further analyzed, and a direct basis is provided for engineering restoration priority and a reinforcement scheme.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical earthquake engineering technology, specifically to the processing and analysis of seismic wave signals, and in particular to a soil-structure co-evolution earthquake liquefaction analysis device and method based on seismic signals. Background Art

[0002] Liquefaction of strong earthquake sites is a nonlinear process in which the pore water pressure between soil particles increases due to cyclic shearing, and the shear strength and stiffness degrade. Due to differences in soil particle characteristics and structure, stress path, loading rate, etc., the soil at the site exhibits two types of failure modes: flow liquefaction or cyclic flow, both of which will lead to irreversible large deformation of the site. Previous earthquake damage studies have shown that earthquake liquefaction of sites generally occurs in saturated sandy soil layers within 10-20m below the surface, which has a destructive effect on underground structures. Damage to buried infrastructure that passes through liquefied strata, such as municipal pipeline corridors for sewage and waste liquids, and natural gas transmission pipelines, will lead to serious secondary disasters.

[0003] my country's earthquake belts are widely distributed and earthquake activities are frequent. In the past, major earthquakes (such as the Tangshan earthquake in 1976 and the Wenchuan earthquake in 2008) have observed damage to underground projects. Many cities in my country are located on the shores of lakes and seas, and liquefied strata are widely distributed. With the acceleration of urbanization and the increase in human activities, the risks and challenges brought by earthquake liquefaction are becoming increasingly prominent. There are an increasing number of underground projects that are high in demand, large in scale, shallow in depth, and encounter liquefied strata, such as planned soft soil tunnel projects, pipeline projects, and building pile foundations. Shallow buried tunnels and other underground structures have low stratum confining pressure, and the risk of site earthquake disasters is prominent when crossing liquefiable strata, which may also trigger a chain reaction and lead to wider social and economic impacts.

[0004] Traditional liquefaction assessment methods are mostly based on on-site investigations and empirical formulas, which make it difficult to accurately capture the dynamic coupling effects of seismic motion, soil, and structure.

[0005] Therefore, it is necessary to provide a soil-structure co-evolution seismic liquefaction analysis device and method based on seismic signals to solve the above technical problems. Summary of the invention

[0006] The present invention overcomes the deficiencies of the prior art and provides a soil-structure co-evolution seismic liquefaction analysis device and method based on seismic signals.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a soil-structure co-evolution seismic liquefaction analysis method based on seismic signals, comprising the following steps:

[0008] S1. Obtain geological and seismic wave signals in the target area;

[0009] S2, perform data enhancement and analysis on the seismic wave signal to obtain the acceleration, velocity and displacement information of the seismic wave;

[0010] S3. Based on the Bockinghamπ similarity theory, the similarity ratio between the model and the prototype structure is determined, and the frequency range of the input signal is adjusted through the frequency band broadening technology to ensure that the experimental signal is consistent with the actual ground motion spectrum characteristics;

[0011] S4, inputting the enhanced seismic wave signal into the seismic liquefaction multi-field coupling evolution device, simulating the shear seismic wave loading condition, controlling the soil-structure model in the device to conduct experiments, and observing the multi-field coupling dynamic evolution during the soil liquefaction process;

[0012] S5. Analyze the simulation experimental data and combine it with the characteristics of the seismic wave signal to determine the impact of the earthquake on the soil and structure.

[0013] In a preferred embodiment of the present invention, the method for acquiring data in S1 includes:

[0014] S11. Acquire geological data of the target area through geological exploration, wherein the geological data includes soil physical and mechanical parameters, groundwater depth and structural parameters;

[0015] S12. Acquire seismic wave signals in the target area through seismic monitoring equipment.

[0016] In a preferred embodiment of the present invention, the process of S2 processing the seismic wave signal specifically includes:

[0017] S21, preprocessing the seismic wave signal extracted in step S1;

[0018] S22, using continuous wavelet transform to analyze the time-frequency characteristics of the seismic waveform, identify and extract the shear wave part;

[0019] S23, performing data enhancement and analysis on the extracted shear wave signal to extract the acceleration, velocity and displacement information of the shear seismic wave.

[0020] In a preferred embodiment of the present invention, the data enhancement in step S23 comprises the following steps:

[0021] S231, performing Fourier transform on the shear wave signal, extracting a first amplitude spectrum sequence, generating a binary sequence marking the positions of wave peaks and wave troughs, and generating a sparse second amplitude spectrum sequence by point-by-point multiplication;

[0022] S232, reconstructing the second amplitude spectrum sequence based on the compressed sensing technology to obtain a fourth amplitude spectrum sequence, performing frequency domain truncation with twice the main frequency as the cutoff frequency, and generating a denoised third amplitude spectrum sequence;

[0023] S233, amplify the amplitude of the high-frequency weak signal segment in the third amplitude spectrum sequence and balance the low-frequency component, reconstruct the complex frequency domain signal in combination with the original phase spectrum, and output a high-resolution shear wave signal through inverse Fourier transform.

[0024] An earthquake liquefaction multi-field coupled evolution device, comprising: a transparent constraint model box unit, a transparent liquefied medium module, a soil-structure collaborative monitoring component and a multi-level variable frequency excitation system;

[0025] The transparent liquefied medium module is filled in the cavity of the transparent constraint model box unit;

[0026] The soil-structure collaborative monitoring component includes: an underground pipe gallery model and a pile foundation model pre-buried in the transparent liquefied medium module;

[0027] The multi-level variable frequency excitation system is fixed to the central axis of the bottom plate of the transparent constraint model box unit through a rigid connector, and is integrated with a vibration intensity grading control module.

[0028] In a preferred embodiment of the present invention, the transparent constraint model box unit includes: a side wall plate and a bottom supporting plate; wherein, the surface of the side wall plate is provided with an anti-glare coating, and the bottom supporting plate forms a sealed cavity with the side wall plate through an epoxy resin bonding process.

[0029] In a preferred embodiment of the present invention, the transparent liquefied medium module comprises:

[0030] Fused quartz sand is used as the solid skeleton material with a SiO content of 99.90% and a soil particle specific gravity of 2.21;

[0031] The liquid medium is prepared by mixing sodium bromide aqueous solution and blue food coloring, with a refractive index of 1.455-1.46;

[0032] Achieve distortion-free optical path by adjusting salt concentration;

[0033] The blue food coloring is added in an amount of 0.05%-0.1%, and the surface tension of the solution is adjusted by a small amount of detergent to ensure that the dyeing solution penetrates evenly and does not precipitate;

[0034] The transparent liquefied medium module is prepared in layers by an underwater sand rain method, with a controlled deposition rate of ≤1.0 cm / min and a final saturation of ≥99.5%.

[0035] In a preferred embodiment of the present invention, the soil-structure collaborative monitoring assembly further comprises: a distributed optical fiber sensor array and a micro-pore pressure gauge group;

[0036] The distributed optical fiber sensor array is arranged along the top plate of the underground pipe gallery model and the side wall of the pile foundation model to collect model strain and soil pressure time history data during the demonstration process;

[0037] The micro piezometer group is buried in the pile-soil interface area with a grid density of 20×20 mm.

[0038] In a preferred embodiment of the present invention, the multi-stage variable frequency excitation system comprises: a centrally mounted eccentric vibration motor and a double slider-slide rail module; wherein the centrally mounted eccentric vibration motor is rigidly connected to the bottom bearing plate via a flange;

[0039] It also includes a vibration intensity classification control module, which uses a PID closed-loop control module to link the variable frequency speed regulator to adjust the motor frequency and exciting force in real time;

[0040] The dual slider-slide rail module includes: a limit assembly and a damping assembly; the limit assembly includes: a limit slide rail arranged perpendicular to the vibration direction, and guide sliders symmetrically arranged on both sides of the bottom bearing plate; the damping assembly includes: a damping slider arranged below the limit slide rail, and a damping slide rail arranged parallel to the vibration direction.

[0041] A simulation method for an earthquake liquefaction multi-field coupled evolution device comprises the following steps:

[0042] S41, mixing fused quartz sand and sodium bromide aqueous solution according to the refractive index matching requirements and the physical and mechanical parameters of the land, adding 0.05%-0.1% by volume of blue food coloring and 0.005%-0.01% of detergent as a tension-reducing modifier, and using an underwater sand rain method to compact the sand in layers at a sand falling rate of 1.0 cm / min to prepare a transparent liquefied medium with a saturation of ≥99%;

[0043] S42. According to the buried depth of the structure in the target area, after scaling according to the geometric scale, when the medium is deposited to the corresponding depth, the underground pipe gallery model is successively buried along the longitudinal axis and the pile foundation model is vertically implanted on the transverse center line, and the distributed optical fiber sensor array is synchronously arranged and the distance between the measuring points of the pipe gallery top plate and the pile foundation side wall is controlled to be ≤5mm;

[0044] S43, locking the limit assembly to constrain the horizontal displacement to ±50mm, and setting the vertical displacement threshold of the preload damping assembly to ±2mm;

[0045] S44, compressing the time axis of the seismic wave acceleration time history signal enhanced in step S2 according to the time scale determined in step S3, and using a multi-level variable frequency excitation system to expand the main frequency of the signal to the range required by the model, covering the soil liquefaction sensitive frequency band;

[0046] The speed of the central eccentric vibration motor is adjusted in real time through the PID algorithm to achieve continuous adjustment of the excitation frequency. The dynamic range of the excitation force is 100-500N. When the micro-pore pressure gauge group detects the critical state of liquefaction, it automatically switches to the fixed frequency mode.

[0047] Step S45: During the vibration loading process, the distributed optical fiber sensor array is used to synchronously record the structural strain, pore water pressure and displacement field data at a sampling rate of 100 Hz, the micro pore pressure meter group is used to collect data at a frequency of 50 Hz, and the high-speed camera is used to collect data at a frame rate of 120 fps, so as to construct a full-factor observation link of "vibration triggering-seepage development-structural disaster".

[0048] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0049] (1) The present invention provides a soil-structure co-evolution earthquake liquefaction analysis method based on seismic signals. By acquiring geological and seismic data of the target area and constructing a co-scaling system of geometric ratio, time ratio and acceleration ratio based on Bockingham π similarity theory, an earthquake liquefaction multi-field coupled evolution device is constructed to evolve the soil liquefaction process in the target area. A distributed optical fiber sensor array and a micro-pore pressure gauge are used to form a millimeter-level spatial resolution monitoring network. A high-speed camera system is used to synchronously capture the pore water pressure, structural strain and soil shear band expansion process, thereby realizing the full-factor time series correlation analysis of "vibration triggering-seepage development-structural disaster", further analyzing its impact on earthquakes, and providing a direct basis for engineering repair priorities and reinforcement plans.

[0050] (2) The present invention constructs an immersive observation link of "vibration triggering-seepage development-structural disaster": the closed-loop variable frequency excitation system simulates seismic wave loading to trigger the dynamic accumulation of pore water pressure in saturated sand; a high-contrast three-dimensional seepage development network is formed in a transparent medium using a refractive index matching dye liquid to present the effective stress loss and pore water migration path of the soil in real time; the distributed optical fiber sensor is used to capture the critical characteristics of the disaster of the pipeline gallery floating and the pile foundation gradually sinking, and the high-speed camera is used to record the expansion of the soil shear band and the evolution of the structural displacement field at the millisecond level. Through the coordinated control of directional input of vibration energy, dynamic visualization of seepage and feedback of structural response, the link enables the observer to intuitively perceive the dynamic correlation of all factors of "soil softening-seepage penetration-structural instability" in the liquefaction process, and realizes non-destructive immersive observation from microscopic mechanism to macroscopic phenomenon. The device can realize full-cycle simulation from micro-earthquake induction to strong earthquake disasters, providing integrated experimental support of "phenomenon observation-mechanism analysis-verification and optimization" for engineering seismic design, and promoting the technological leap from empirical reinforcement to mechanism-driven protection for underground projects in liquefied areas.

[0051] (3) The present invention breaks through the opacity limitation of traditional sandy soil media through the refractive index matching design of fused quartz sand and sodium bromide solution, and realizes the full-process visual observation of the dynamic evolution of the seepage field during the liquefaction process for the first time.

[0052] (4) The present invention uses distributed optical fiber sensors and micro-pore water pressure gauges to achieve millimeter-level resolution monitoring of structural disasters and spatiotemporal evolution of pore water pressure, and the data sampling rate is increased to 100 Hz.

[0053] (5) The present invention reduces the vibration uniformity error to ±5% through a dual slide rail module and PID closed-loop control, and the excitation force control accuracy reaches ±1N, supporting full-condition simulation from low frequency (0.5Hz) to high frequency (20Hz), and small earthquake (0.05g) to strong earthquake (0.3g).

[0054] (6) The present invention integrates optical observation, mechanical sensing and vibration control technology to construct a quantitative correlation model of "medium flow-structural deformation-dynamic response", providing an experimental benchmark for the study of the chain mechanism of liquefaction disasters. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0056] Figure 1 It is a front view of a multi-field coupled evolution device for earthquake liquefaction according to a preferred embodiment of the present invention;

[0057] Figure 2 It is a side view of a seismic liquefaction multi-field coupled evolution device according to a preferred embodiment of the present invention;

[0058] Figure 3 1 is a top view of a multi-field coupled evolution device for earthquake liquefaction according to a preferred embodiment of the present invention;

[0059] In the figure: 1. Transparent constraint model box unit; 2. Transparent liquefied medium module; 3. Soil-structure collaborative monitoring component; 4. Multi-level variable frequency excitation system; 5. Side wall plate; 6. Bottom bearing plate; 7. Underground pipe gallery model; 8. Pile foundation model; 9. Distributed optical fiber sensor array; 10. Micro pore pressure gauge group; 11. Central eccentric vibration motor; 12. Vibration intensity classification control module; 13. PID closed-loop control module; 14. Variable frequency speed regulator; 15. Double slider-slide rail module; 16. Limit assembly; 17. Limit guide rail; 18. Guide slider; 19. Damping assembly; 20. Damping slider; 21. Damping slide rail; 22. Damper. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0062] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0063] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0064] The present invention provides a soil-structure co-evolution seismic liquefaction analysis method based on seismic signals, comprising the following steps:

[0065] S1. Obtain geological data and seismic wave signals of the target area.

[0066] S2. Perform data enhancement and analysis on the seismic wave signal to obtain the acceleration, velocity and displacement information of the seismic wave.

[0067] S3. Based on Bockinghamπ similarity theory, determine the geometric ratio, time ratio and acceleration ratio between the model and the target area, and construct a multi-field coupled evolution device for earthquake liquefaction;

[0068] The frequency range of the input signal is adjusted through the frequency band broadening technology to ensure that the experimental signal is consistent with the actual ground motion spectrum characteristics.

[0069] S4. Input the enhanced seismic wave signal into the earthquake liquefaction multi-field coupling evolution device to simulate the shear seismic wave loading condition, control the soil-structure model in the device to conduct experiments, and observe the multi-field coupling dynamic evolution during the soil liquefaction process.

[0070] S5. Analyze the simulation experimental data and combine it with the characteristics of the seismic wave signal to determine the impact of the earthquake on the soil and structure.

[0071] The present invention provides a soil-structure co-evolution earthquake liquefaction analysis method based on seismic signals. By acquiring geological and seismic data of a target area and constructing a co-scaling system of geometric ratio, time ratio and acceleration ratio based on Bockingham π similarity theory, an earthquake liquefaction multi-field coupling evolution device is constructed to evolve the soil liquefaction process in the target area. A distributed optical fiber sensor array and a micro-pore pressure gauge are used to form a millimeter-level spatial resolution monitoring network. A high-speed camera system is used to synchronously capture the pore water pressure, structural strain and soil shear band expansion process, so as to realize the full-factor time series correlation analysis of "vibration triggering-seepage development-structural disaster", further analyze the degree of its influence on earthquakes, and provide a direct basis for engineering repair priorities and reinforcement plans.

[0072] In step S1, the target area is first determined and the specific scope of the area is delineated, and then geological data and seismic wave signals are obtained respectively.

[0073] Step S11: Acquire geological data of the target area through geological exploration, the geological data including soil physical and mechanical parameters, groundwater depth and structural parameters. Specifically:

[0074] Physical and mechanical parameters of soil:

[0075] Soil type and gradation: Soil type and particle gradation curve of the liquefied layer in the target area (focus on obtaining equivalent particle size D50 and non-uniformity coefficient Cu). Soil type and gradation are used to match the particle size distribution of fused quartz sand in the earthquake liquefaction multi-field coupled evolution device.

[0076] Density and void ratio: The natural density, relative density (Dr), initial void ratio (e) of the soil are obtained through in-situ tests (such as CPT / SPT) or laboratory tests. 0). The density and porosity of the soil are used to adjust the sand-liquid ratio of the transparent liquefied medium module to ensure that the dry density of the sand in the seismic liquefaction multi-field coupled evolution device can accurately reflect the dynamic characteristics of the actual soil.

[0077] Permeability coefficient: Determine the vertical and horizontal permeability coefficients of soil (kv, kh). The permeability coefficient is used to guide the concentration adjustment of sodium bromide solution and control the similarity of the medium seepage rate in the earthquake liquefaction multi-field coupled evolution device with the actual site.

[0078] Groundwater depth: The depth of saturated sand layer and the range of water level fluctuation in the target area. The groundwater depth is used to determine the saturation height of transparent liquefied medium.

[0079] Structural parameters: geometric dimensions, burial depth, material elastic modulus and stiffness of underground structures (such as pipe gallery and pile foundation) in the target area. The prototype structural parameters are used to scale the pipe gallery model or pile foundation model in the device to a similar scale to ensure that the buried position (longitudinal axis / lateral centerline) in the earthquake liquefaction multi-field coupled evolution device is consistent with the actual situation.

[0080] Step S12: Acquire seismic wave signals in the target area through seismic monitoring equipment.

[0081] Seismic wave signals are time series data of ground motion recorded by seismographs distributed in different geographical locations. Seismic wave signals include but are not limited to information on longitudinal waves, shear waves, and other surface waves.

[0082] Through the above steps, the geological data obtained are used to build an earthquake liquefaction multi-field coupled evolution device, and the seismic wave signal is used to evolve the soil liquefaction process in the target area in the built earthquake liquefaction multi-field coupled evolution device. As a result, the seismic wave signal in the target area is converted into a dynamic evolution process that can be directly observed, which is convenient for further analysis of the seismic wave signal and assists the seismic wave signal characteristics to complete the judgment of the degree of earthquake impact on the target area.

[0083] Step S2: Perform data enhancement and analysis on the seismic wave signal to obtain the acceleration, velocity and displacement information of the seismic wave.

[0084] Step S21, preprocessing the seismic wave signal extracted in step S1, the preprocessing steps include filtering, removing the mean and normalizing to the interval [-1,1].

[0085] Step S22, using continuous wavelet transform (CWT) to analyze the time-frequency characteristics of the seismic waveform, identify and extract the shear wave (S wave) part. In this step, Morlet wavelet basis function is preferably used to capture the characteristics of the shear wave.

[0086] Step S23: perform data enhancement and analysis on the extracted shear wave signal to extract the acceleration, velocity and displacement information of the shear seismic wave.

[0087] The velocity and attenuation characteristics of shear waves are very sensitive to the physical state of the soil, especially for materials such as saturated sand. When sand liquefies, its stiffness decreases significantly, resulting in a decrease in the shear wave velocity. Therefore, by analyzing the shear wave signal, it is effective to assess whether the soil has experienced liquefaction.

[0088] The data enhancement in step S23 includes the following steps:

[0089] Step S231: First, perform Fourier transform on the extracted shear wave signal, extract the amplitude spectrum from it and mark it as the first amplitude spectrum sequence. Then analyze the peak and trough positions in the sequence curve to generate a binary random sequence (where the peak and trough positions are set to 1, and the rest are 0). Multiply this binary sequence with the first amplitude spectrum sequence point by point to retain the key frequency point information, and finally obtain the second amplitude spectrum sequence after sparse processing.

[0090] Step S232: Based on the compressed sensing technology, the sparse second amplitude spectrum sequence is used to perform signal reconstruction to obtain a fourth amplitude spectrum sequence. In order to further optimize the signal quality, a cutoff frequency that is twice the main frequency of the original signal is set, and the fourth amplitude spectrum sequence is truncated in the frequency domain to remove unnecessary ultra-high frequency noise and form a purer third amplitude spectrum sequence.

[0091] Step S233: For the high-frequency weak signal segment in the third amplitude spectrum sequence (e.g., the frequency segment corresponding to the target reservoir), the amplitude is amplified, and the low-frequency component is adjusted to achieve balance, so as to construct a broadband amplitude spectrum. Subsequently, the phase spectrum of the original shear wave signal is extracted, and it is combined with the above broadband amplitude spectrum to be reorganized into a frequency domain signal in complex form. Finally, this complex sequence is converted back to a time domain signal by inverse Fourier transform, so as to obtain a shear wave signal with high-resolution characteristics.

[0092] Furthermore, the reconstructed time domain signal is subjected to wavelet threshold denoising or spectral subtraction processing to suppress random noise, and finally the enhanced acceleration, velocity and displacement information is output.

[0093] The acquired seismic wave signals are enhanced and analyzed to obtain acceleration, velocity and displacement information. In particular, the acceleration, velocity and displacement information of shear seismic waves are described in detail as follows:

[0094] Acceleration: The acceleration of ground motion caused by seismic waves, that is, the rate of change of velocity per unit time, expressed in gravitational acceleration units of g. For shear seismic waves, acceleration data is a key parameter for evaluating the response of structures in earthquakes, and is directly related to the magnitude of the inertial force that the structure is not subject to.

[0095] Velocity: Velocity information of ground vibrations excited by seismic waves, that is, the rate of change of displacement per unit time. Velocity data is a key parameter for analyzing soil liquefaction phenomena. Higher ground velocity may cause liquefaction of saturated sand or other loose materials, thereby reducing their bearing capacity.

[0096] Displacement: The change in position relative to a fixed reference point. Displacement data indicates changes in topography after an earthquake.

[0097] In the above step S2, the acquired seismic wave signals are reconstructed through sparse processing and compressed sensing, which significantly reduces data redundancy and restores high-frequency weak signals. In addition, the resolution of high-frequency weak signals in seismic wave signals is improved by combining phase spectrum retention and broadband amplitude enhancement, ensuring the accuracy of subsequent soil liquefaction analysis. This step ensures that high-frequency weak signals are fully reconstructed in the compressed sensing process by first restoring and then truncating.

[0098] Step S3: Based on the Bockingham π similarity theory, the geometric ratio, time ratio and acceleration ratio of the model and the prototype structure are determined to construct an earthquake liquefaction multi-field coupled evolution device, and the frequency range of the input signal is adjusted by the frequency band broadening technology to ensure that the experimental signal is consistent with the actual ground motion spectrum characteristics.

[0099] Step S31: According to the dynamic response characteristics of the soil-structure system, the following core physical quantities are selected to construct similarity relationships:

[0100] Geometric scale L: the linear size ratio between the model and the prototype structure;

[0101] Time T: duration ratio of the dynamic loading process;

[0102] Acceleration a: The ratio of the earthquake acceleration amplitude.

[0103] Step S32: Based on Bockingham π similarity theory, derive the dimensionless π term: π 1 =a·T 2 / L;

[0104] Similarity ratio determination:

[0105] Geometric ratio (λ): sets the linear size ratio of the model to the prototype structure;

[0106] Time ratio (1 / √λ): According to the Froude criterion, the time scaling ratio is the inverse square root of the geometric ratio;

[0107] Acceleration ratio (1:1): Keep the acceleration amplitude of the model and prototype the same (e.g. 0.5g of the prototype corresponds to 0.5g of the model) to ensure the similarity of inertial forces.

[0108] Step S33: construct an earthquake liquefaction multi-field coupled evolution device according to the similarity ratio determined above. The earthquake liquefaction multi-field coupled evolution device is described in detail below.

[0109] Step S34, performing spectrum analysis on the enhanced seismic wave signal outputted in step S2, and extracting the main frequency (f_main) and the high-frequency attenuation slope therefrom;

[0110] Adjust the signal frequency component according to the time ratio (1 / √λ): expand the signal frequency range from the original [0, f_max] to [0, f_max×√λ] to match the dynamic response characteristics of the model after scaling;

[0111] The effective frequency band (0.1-100Hz) is retained through the FIR filter to suppress high-frequency noise.

[0112] Step S3 ensures that the model experiment can reproduce the dynamic response of the prototype soil-structure system under earthquake action (such as liquefaction-induced settlement and structural instability mode) through strict constraints of geometric ratio (λ), time ratio (1 / √λ) and acceleration ratio (1:1). The frequency band broadening technology solves the frequency distortion problem caused by model scaling, making the input signal spectrum characteristics consistent with the target ground motion, providing high-fidelity experimental conditions for step S4.

[0113] Step S4, inputting the enhanced seismic wave signal into the seismic liquefaction multi-field coupled evolution device, simulating the shear seismic wave loading condition, controlling the soil-structure model in the device to conduct experiments, and observing the multi-field coupled dynamic evolution during the soil liquefaction process.

[0114] like Figure 1-Figure 3 As shown, the present invention also provides an earthquake liquefaction multi-field coupling evolution device for evolving the soil liquefaction process in the target area. The earthquake liquefaction multi-field coupling evolution device comprises: a transparent constraint model box unit 1, a transparent liquefaction medium module 2, a soil-structure collaborative monitoring component 3 and a multi-level variable frequency excitation system 4.

[0115] Among them, the transparent liquefied medium module 2 is filled in the cavity of the transparent constraint model box unit 1; the soil-structure collaborative monitoring component 3 includes: an underground pipeline corridor model 7 and a pile foundation model 8 pre-buried in the transparent liquefied medium module 2; the multi-level variable frequency excitation system 4 is fixed to the central axis of the bottom plate of the transparent constraint model box unit 1 through a rigid connector, and is integrated with a vibration intensity grading control module 12, which is used to simulate the liquefaction response of saturated sand under seismic wave excitation and reproduce the dynamic interaction phenomenon between soil and structure in the liquefied site.

[0116] like Figure 1-Figure 3 As shown, the transparent constrained model box unit 1 includes: a side wall plate 5 and a bottom bearing plate 6. Among them, the side wall plate 5 is made of high-transmittance polycarbonate plate with a size of 200mm (length) × 200mm (width) × 250mm (height), which can clearly observe the dynamic response of the soil from multiple angles, and has the characteristics of a large observation field and low boundary effect. The top of the transparent constrained model box unit 1 adopts an open design, which is convenient for medium laying, structural model layout and other operations during sample preparation. The surface of the side wall plate 5 is formed with a gradient coating with a refractive index of 1.458 through a sol-gel process, and the optical matching error with the transparent medium is ≤1.0%. The bottom bearing plate 6 is rigidly connected to the central eccentric vibration motor through waterproof bolts to realize power input, and is bonded and sealed to the side wall plate 5 through epoxy resin, and the flatness error is controlled within 1mm / m 2 To ensure uniform vibration transmission.

[0117] Under dynamic load, the fused silica sand and common engineering site sand (Fujian standard sand) show similar qualitative laws in dynamic deformation and dynamic strength changes during liquefaction, which can truly simulate the impact of seismic waves on soil in the target area; and the density of fused silica sand is lighter than standard sand, so it is easier to liquefy under vibration conditions. The above characteristics make fused silica sand an ideal material for studying soil liquefaction behavior.

[0118] The transparent liquefied medium module 2 of the device is made of spherical fused quartz sand (SiO 2 The content is 99.9%, the specific gravity is 2.21) and the sodium bromide aqueous solution (concentration 28-32wt%) mixed system, and the liquid surface tension is adjusted by adding 0.08vol% brilliant blue dye and 0.008% sodium dodecylbenzene sulfonate to avoid the decrease of medium transmittance caused by dye agglomeration. When the underwater sand rain method is used for preparation, the sand falling rate is 1.0cm / min, and the layered compaction is carried out to a saturation of ≥99.5%. During the deposition process, an underground pipe gallery model 7 (scale ratio 1:30, elastic modulus 1.8GPa) is buried at an elevation of 150mm, and a pile foundation model 8 (aspect ratio 10:1, axial stiffness matching degree>95%) of carbon fiber is implanted at an elevation of 200mm. After the sample is prepared, it is left to stand for 1h to eliminate the excess pore pressure.

[0119] like Figure 1 As shown, the soil-structure collaborative monitoring component 3 includes: an underground pipeline gallery model 7, a pile foundation model 8, a distributed optical fiber sensor array 9 and a micro pore pressure meter group 10.

[0120] Among them, the underground pipe gallery model 7 is formed by 3D printing of polyurethane composite materials, with an elastic modulus of 1.5-2.0GPa. The underground pipe gallery model 7 is precisely buried along the longitudinal axis of the transparent constraint model box unit 1. The pile foundation model 8 is made of carbon fiber reinforced resin-based composite materials with an aspect ratio of 10:1. The pile foundation model 8 is vertically implanted into the transverse center line of the sand medium to form a physically similar system that highly matches the mechanical properties of the prototype structure. The distributed optical fiber sensor array 9 is arranged along the top plate of the underground pipe gallery model 7 and the side wall of the pile foundation model 8, specifically covering the surface of the structure in a continuous winding manner to achieve millimeter-level spatial resolution acquisition of model strain and soil pressure time-history data. The micro-pore pressure gauge group 10 is buried in the pile-soil interface area at a grid density of 20×20mm, with a range of 0-10kPa and a precision design of 0.1kPa, which can accurately capture the transient distribution characteristics of excess pore water pressure during the liquefaction process.

[0121] like Figure 1-Figure 2 As shown, the multi-stage variable frequency excitation system 4 includes: a centrally mounted eccentric vibration motor 11 and a double slider-slide rail module 15; wherein, the centrally mounted eccentric vibration motor 11 is rigidly connected to the bottom bearing plate 6 via a flange, and its vibration intensity grading control module 12 is linked in real time with the variable frequency speed regulator 14 via a PID closed-loop control module 13, so as to realize continuous adjustment of the motor frequency within the range of 0.5-20Hz with a step accuracy of 0.1Hz / s, and the dynamic control range of the exciting force covers 100-500N.

[0122] The double slider-slide rail module 15 includes a limit assembly 16 and a damping assembly 19 .

[0123] The limiting assembly 16 includes: a limiting slide rail 17 arranged perpendicular to the vibration direction, and guide sliders 18 symmetrically arranged on both sides of the bottom bearing plate 6. The limiting assembly 16 converts the point-like exciting force of the eccentric motor into a uniform vibration field of the entire device through the restraining effect of the guide sliders 18.

[0124] The damping assembly 19 includes: a damping slider 20 disposed below the limit slide rail 17, and a damping slide rail 21 arranged parallel to the vibration direction. The damping slide rail 21 has a built-in magnetorheological damper 22 that adjusts the damping force in real time according to the vertical displacement threshold (±2mm), effectively suppressing the vertical leakage of vibration energy, thereby suppressing the vertical jump of the device.

[0125] When the pore pressure ratio Ru≥0.85, the system automatically switches to the fixed-frequency vibration mode (12 Hz, 300 N), and maintains the dynamic balance between soil softening and structural response by phase locking of the exciting force-frequency, thereby completely reproducing the temporal evolution law of soil-structure dynamic interaction during the liquefaction disaster process.

[0126] In step S4, the simulation process using the earthquake liquefaction multi-field coupled evolution device specifically includes:

[0127] Step S41, sample preparation: fused silica sand and sodium bromide aqueous solution are mixed according to the refractive index matching requirements and the physical and mechanical parameters of the land, and 0.05%-0.1% by volume of blue food coloring and 0.005%

[0128] -0.01% of detergent tension-reducing modifier, the underwater sand rain method was used to compact the sand in layers at a sand falling rate of 1.0 cm / min to prepare a transparent liquefied medium with a saturation of ≥99%.

[0129] Step S42, structure burial: according to the buried depth of the structure in the target area, after scaling according to the geometric scale, when the medium is deposited to the corresponding depth, the underground corridor model 7 is buried along the longitudinal axis and the pile foundation model 8 is vertically implanted on the transverse center line, and the distributed optical fiber sensor array 9 is deployed simultaneously and the distance between the measuring points of the corridor roof and the pile foundation side wall is controlled to be ≤5mm.

[0130] Step S43, vibration constraint: locking limit assembly 16 to constrain horizontal displacement to ±50mm, preload damping assembly 19 sets the vertical displacement threshold to ±2mm.

[0131] Step S44, dynamic loading: compress the time axis of the seismic wave acceleration time history signal enhanced in step S2 according to the time scale (1 / √λ) determined in step S3, and use the multi-level variable frequency excitation system 4 to expand the signal main frequency to the required range of the model (0.5-20Hz), covering the soil liquefaction sensitive frequency band (5-15Hz);

[0132] The speed of the centrally mounted eccentric vibration motor 11 is adjusted in real time through the PID algorithm to achieve continuous adjustment of the excitation frequency of 0.5-20 Hz and an excitation force dynamic range of 100-500 N (accuracy ±1 N). When the micro-pore pressure gauge group 10 detects the critical state of liquefaction, it automatically switches to the fixed frequency mode (12 Hz, 300 N).

[0133] Step S45, use the distributed fiber optic sensor array 100 with a sampling rate of 100 Hz, the micro pore pressure meter group 10 with a collection frequency of 50 Hz and the high-speed camera with a frame rate of 120 fps to synchronously record the structural strain, pore water pressure and displacement field data, and build a full-factor observation link of "vibration triggering-seepage development-structural disaster".

[0134] This process achieves immersive visual analysis of multiple physical fields in the liquefaction process through the coordination of dye tracing, structural disaster feedback and optical tracking, providing an efficient and practical solution for revealing the physical and mechanical mechanisms of the earthquake liquefaction process.

[0135] The present invention constructs an immersive observation link of "vibration triggering-seepage development-structural disaster": by simulating seismic wave loading through a closed-loop variable frequency excitation system, the dynamic accumulation of pore water pressure in saturated sand is triggered; a high-contrast three-dimensional seepage development network is formed in a transparent medium using a refractive index matching dye liquid, which presents the effective stress loss of the soil and the migration path of pore water in real time; the critical characteristics of the disaster of the floating of the pipeline gallery and the gradual sinking of the pile foundation are captured simultaneously with the help of distributed optical fiber sensors, and the expansion of the soil shear band and the evolution of the structural displacement field are recorded at the millisecond level with the help of high-speed cameras. Through the coordinated control of directional input of vibration energy, dynamic visualization of seepage and feedback of structural response, the link enables observers to intuitively perceive the dynamic correlation of all factors of "soil softening-seepage penetration-structural instability" in the liquefaction process, and realizes non-destructive immersive observation from microscopic mechanisms to macroscopic phenomena. The device can realize full-cycle simulation from micro-earthquake induction to strong earthquake disasters, providing integrated experimental support of "phenomenon observation-mechanism analysis-verification and optimization" for engineering seismic design, and promoting the technological leap from empirical reinforcement to mechanism-driven protection for underground projects in liquefied areas.

[0136] Step S5: Based on the recorded structural strain, pore water pressure and displacement field data, combined with the characteristics of the seismic wave signal in the target area, soil liquefaction degree assessment, structural damage analysis and ground motion-disaster correlation analysis are performed respectively. Specifically:

[0137] The liquefaction degree of soil was assessed using the pore pressure ratio analysis method. The excess pore water pressure was monitored by a micro-pore pressure meter group 10, the pore pressure ratio was calculated, and the area proportion with pore pressure ratio > 0.9 was counted to quantify the liquefaction range.

[0138] Structural damage analysis: The distributed optical fiber sensor array 9 is used to monitor the tunnel roof strain and the lateral soil pressure of the pile foundation, and the buoyancy of the tunnel and the lateral displacement angle of the pile foundation are calculated respectively. The safety factor is calculated based on the lateral displacement angle of the pile foundation and the design allowable value.

[0139] Earthquake-disaster correlation analysis: Compare the acceleration response spectrum of the enhanced seismic wave with the structural response spectrum to identify the resonant frequency range; correlate the temporal evolution of seismic motion parameters (acceleration peak a_{max}amax, main frequency f_{main}fmain) and structural response (ΔH, θ).

[0140] Through the above analysis process, the comprehensive impact of the earthquake on the soil (liquefaction degree) and structure (damage level) can be quickly determined, providing a direct basis for engineering repair priorities and reinforcement plans.

[0141] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A soil-structure co-evolution seismic liquefaction analysis method based on seismic signals, characterized in that: The following steps are involved: S1. Obtain geological and seismic wave signals in the target area; S2, perform data enhancement and analysis on the seismic wave signal to obtain the acceleration, velocity and displacement information of the seismic wave; S3. Based on the Bockinghamπ similarity theory, the similarity ratio between the model and the prototype structure is determined, and the frequency range of the input signal is adjusted through the frequency band broadening technology to ensure that the experimental signal is consistent with the actual ground motion spectrum characteristics; S4, inputting the enhanced seismic wave signal into the seismic liquefaction multi-field coupling evolution device, simulating the shear seismic wave loading condition, controlling the soil-structure model in the device to conduct experiments, and observing the multi-field coupling dynamic evolution during the soil liquefaction process; S5. Analyze the simulation experimental data and combine it with the characteristics of the seismic wave signal to determine the impact of the earthquake on the soil and structure.

2. The soil-structure co-evolution seismic liquefaction analysis method based on seismic signals according to claim 1 is characterized in that: The method for acquiring data in S1 includes: S11. Acquire geological data of the target area through geological exploration, wherein the geological data includes soil physical and mechanical parameters, groundwater depth and structural parameters; S12. Acquire seismic wave signals in the target area through seismic monitoring equipment.

3. The soil-structure co-evolution seismic liquefaction analysis method based on seismic signals according to claim 1 is characterized in that: The processing process of the seismic wave signal in S2 specifically includes: S21, preprocessing the seismic wave signal extracted in step S1; S22, using continuous wavelet transform to analyze the time-frequency characteristics of the seismic waveform, identify and extract the shear wave part; S23, performing data enhancement and analysis on the extracted shear wave signal to extract the acceleration, velocity and displacement information of the shear seismic wave.

4. The soil-structure co-evolution seismic liquefaction analysis method based on seismic signals according to claim 3 is characterized in that: The data enhancement in step S23 includes the following steps: S231, performing Fourier transform on the shear wave signal, extracting a first amplitude spectrum sequence, generating a binary sequence marking the positions of wave peaks and wave troughs, and generating a sparse second amplitude spectrum sequence by point-by-point multiplication; S232, reconstructing the second amplitude spectrum sequence based on the compressed sensing technology to obtain a fourth amplitude spectrum sequence, performing frequency domain truncation with twice the main frequency as the cutoff frequency, and generating a denoised third amplitude spectrum sequence; S233, amplify the amplitude of the high-frequency weak signal segment in the third amplitude spectrum sequence and balance the low-frequency component, reconstruct the complex frequency domain signal in combination with the original phase spectrum, and output a high-resolution shear wave signal through inverse Fourier transform.

5. A multi-field coupled evolution device for earthquake liquefaction, characterized in that: include: Transparent constraint model box unit, transparent liquefied medium module, soil-structure collaborative monitoring component and multi-level variable frequency excitation system; The transparent liquefied medium module is filled in the cavity of the transparent constraint model box unit; The soil-structure collaborative monitoring component includes: an underground pipe gallery model and a pile foundation model pre-buried in the transparent liquefied medium module; The multi-level variable frequency excitation system is fixed to the central axis of the bottom plate of the transparent constraint model box unit through a rigid connector, and is integrated with a vibration intensity grading control module.

6. The earthquake liquefaction multi-field coupled evolution device according to claim 5, characterized in that: The transparent constrained model box unit comprises: a side wall plate and a bottom bearing plate; wherein the surface of the side wall plate is provided with an anti-glare coating, and the bottom bearing plate forms a sealed cavity with the side wall plate through an epoxy resin bonding process.

7. The earthquake liquefaction multi-field coupled evolution device according to claim 5, characterized in that: The transparent liquefied medium module comprises: Fused quartz sand is used as the solid skeleton material with a SiO content of 99.90% and a soil particle specific gravity of 2.21; The liquid medium is prepared by mixing sodium bromide aqueous solution and blue food coloring, with a refractive index of 1.455-1.46; Achieve distortion-free optical path by adjusting salt concentration; The blue food coloring is added in an amount of 0.05%-0.1%, and the surface tension of the solution is adjusted by a small amount of detergent to ensure that the dyeing solution penetrates evenly and does not precipitate; The transparent liquefied medium module is prepared in layers by an underwater sand rain method, with a controlled deposition rate of ≤1.0 cm / min and a final saturation of ≥99.5%.

8. The earthquake liquefaction multi-field coupled evolution device according to claim 5, characterized in that: The soil-structure collaborative monitoring assembly also includes: a distributed optical fiber sensor array and a micro-pore pressure meter group; The distributed optical fiber sensor array is arranged along the top plate of the underground pipe gallery model and the side wall of the pile foundation model to collect model strain and soil pressure time history data during the demonstration process; The micro piezometer group is buried in the pile-soil interface area with a grid density of 20×20 mm.

9. The earthquake liquefaction multi-field coupled evolution device according to claim 5, characterized in that: The multi-stage variable frequency excitation system comprises: a centrally mounted eccentric vibration motor and a double slider-slide rail module; wherein the centrally mounted eccentric vibration motor is rigidly connected to the bottom bearing plate via a flange; It also includes a vibration intensity classification control module, which uses a PID closed-loop control module to link the variable frequency speed regulator to adjust the motor frequency and exciting force in real time; The dual slider-slide rail module includes: a limit assembly and a damping assembly; the limit assembly includes: a limit slide rail arranged perpendicular to the vibration direction, and guide sliders symmetrically arranged on both sides of the bottom bearing plate; the damping assembly includes: a damping slider arranged below the limit slide rail, and a damping slide rail arranged parallel to the vibration direction.

10. A simulation method for an earthquake liquefaction multi-field coupled evolution device according to any one of claims 5 to 9, characterized in that: The following steps are involved: S41, mixing fused quartz sand and sodium bromide aqueous solution according to the refractive index matching requirements and the physical and mechanical parameters of the land, adding 0.05%-0.1% by volume of blue food coloring and 0.005%-0.01% of detergent as a tension-reducing modifier, and using an underwater sand rain method to compact the sand in layers at a sand falling rate of 1.0 cm / min to prepare a transparent liquefied medium with a saturation of ≥99%; S42. According to the buried depth of the structure in the target area, after scaling according to the geometric scale, when the medium is deposited to the corresponding depth, the underground pipe gallery model is successively buried along the longitudinal axis and the pile foundation model is vertically implanted on the transverse center line, and the distributed optical fiber sensor array is synchronously arranged and the distance between the measuring points of the pipe gallery top plate and the pile foundation side wall is controlled to be ≤5mm; S43, locking the limit assembly to constrain the horizontal displacement to ±50mm, and setting the vertical displacement threshold of the preload damping assembly to ±2mm; S44, compressing the time axis of the seismic wave acceleration time history signal enhanced in step S2 according to the time scale determined in step S3, and using a multi-level variable frequency excitation system to expand the main frequency of the signal to the range required by the model, covering the soil liquefaction sensitive frequency band; The speed of the central eccentric vibration motor is adjusted in real time through the PID algorithm to achieve continuous adjustment of the excitation frequency. The dynamic range of the excitation force is 100-500N. When the micro-pore pressure gauge group detects the critical state of liquefaction, it automatically switches to the fixed frequency mode. Step S45: During the vibration loading process, the distributed optical fiber sensor array is used to synchronously record the structural strain, pore water pressure and displacement field data at a sampling rate of 100 Hz, the micro pore pressure meter group is used to collect data at a frequency of 50 Hz, and the high-speed camera is used to collect data at a frame rate of 120 fps, so as to construct a full-factor observation link of "vibration triggering-seepage development-structural disaster".

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