Surface-Wave Free-Field Inversion Using Multi-Mode Dispersion
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Solution Overview
Problem
Existing seismic inversion methods for soil-structure interaction systems ignore the influence of higher dispersive modes of surface waves in layered media, leading to inaccurate seismic input and response assessment.
Innovation Solution
A multi-mode surface-wave free-field inversion method based on dispersion properties, utilizing energy flux density and modal participation factors to decompose and superimpose single-mode surface-wave free fields, considering the joint effect of multiple dispersive modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only fundamental mode is considered in surface wave inversion, then the inversion process is simplified, but the inversion accuracy deteriorates due to ignoring higher dispersive modes
Solution Approach 1:
The patent segments the surface wave field into multiple independent dispersive modes (fundamental mode and higher modes). Each mode is inverted separately using mode-specific participation factors, allowing the complex multi-mode inversion to be decomposed into simpler single-mode inversions while maintaining high accuracy by capturing the contribution of each mode individually.
Solution Approach 2:
The patent introduces mode participation factors as new parameters that quantify the contribution of each dispersive mode to the total surface wave field. By calculating and applying these participation factors for different modes, the method transforms the inversion problem to account for frequency-dependent modal contributions, thereby improving inversion accuracy without excessive complexity.
2Measurement precision
If higher dispersive modes are included in surface wave inversion, then the inversion accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent divides the surface wave field into distinct dispersive modes, each with its own characteristics and participation factors. This segmentation allows the computational task to be distributed across multiple simpler single-mode inversions rather than one complex multi-mode inversion, reducing overall computational complexity while maintaining accuracy.
Solution Approach 2:
The patent calculates mode participation factors for multiple dispersive modes beyond just the fundamental mode. By including higher modes in the inversion process through these participation factors, the method achieves more accurate results by capturing the complete modal content of the surface wave field without requiring full complexity of simultaneous multi-mode inversion.
3Measurement precision
If surface wave dispersion properties are considered, then the seismic input accuracy is improved, but the analysis complexity increases
Solution Approach 1:
The patent utilizes dispersion curves and mode participation factors as key parameters that capture the frequency-dependent behavior of surface waves. By incorporating these parameters into the inversion process, the method accounts for dispersion properties without requiring complex full-waveform analysis, thereby improving seismic input accuracy while managing analysis complexity through parameter-based approaches.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves inversion accuracy by quantitatively identifying and superposing single-mode free fields, providing accurate seismic excitation for seismic analysis and revealing the real failure mechanism of structures.
Implementation Method 1
the ground surface-wave components with dispersion properties are transferred from the time domain to the frequency domain and decomposed into harmonic components composed of a single frequency by the Fast Fourier Transform (FFT) technology
Implementation Method 2
surface waves exhibit unique dispersion properties: the propagation phase velocity of surface waves is related to the frequency, with harmonic components of different frequency components exhibiting different propagation velocities
Data Source
AI summary
A multi-mode surface-wave free-field inversion method based on dispersion properties of layered media addresses the inaccuracy in existing methods that ignore higher modes. A novel approach for characterizing the participation quantity of each mode is proposed based on an energy flux density, which is applied to calculate a modal participation factor through dispersion curves and the frequency-domain dynamic stiffness matrix. Next, the ground surface-wave components with dispersion properties are transferred from the time domain to the frequency domain and decomposed into harmonic components composed of individual frequencies by the Fast Fourier Transform technology. These harmonic components continue to be decoupled as multiple modes by the modal participation factors, with each single-mode component being inverted to construct single-mode surface-wave free fields. Finally, all single-mode surface-wave free fields are superimposed following the mode superposition principle to form the multi-mode surface-wave free fields.