Multi-phase Wavefield Inversion for Rock Media
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Solution Overview
Problem
Existing seismic wavefield inversion methods neglect surface waves, leading to inaccurate inversion of underground wavefields in soil-structure interaction systems, as they primarily focus on body waves and fail to consider the significant energy contribution of surface waves.
Innovation Solution
A multi-phase wavefield inversion method that separates and inverts both body waves and surface waves using Snell's Law of complex angles, extracting Rayleigh wave components and determining optimal incident angles through forward modeling and inversion theory, ultimately superposing single-phase wavefields to form total multi-phase wavefields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If existing inversion methods consider only body wave components, then the inversion process is simplified, but the inversion accuracy deteriorates due to neglecting surface wave energy which accounts for about 67% of total seismic waves
Solution Approach 1:
The patent segments the complex multi-phase inversion problem into distinct body wave inversion and surface wave inversion sub-problems. By separating the inversion processes and treating them independently with specialized methods for each wave type, the overall complexity is managed while maintaining high accuracy for both components.
Solution Approach 2:
The patent transforms the ground motion records from the time domain to the frequency domain using Fourier transform. This dimensional transformation enables the separation of body waves and surface waves based on their different frequency characteristics, allowing simultaneous inversion of both wave types without excessive complexity.
2Reliability
If ground motion records are treated as mixed waveforms containing both body waves and surface waves, then the representation of real seismic conditions is improved, but the inversion difficulty increases due to the need to separate and invert multiple wave phases simultaneously
Solution Approach 1:
The patent extracts surface wave components from the mixed ground motion records by identifying and isolating the Rayleigh wave portion based on its characteristic frequency content and polarization properties. This extraction allows the surface wave field to be inverted separately from body waves, reducing the coupling complexity while maintaining reliability.
Solution Approach 2:
The patent changes the representation parameters of ground motions by transforming from time-domain waveforms to frequency-domain spectra. This parameter transformation reveals the distinct frequency signatures of body waves and surface waves, enabling their separation and individual inversion without requiring complex simultaneous multi-phase inversion.
3Measurement precision
If surface wave components are included in the inversion, then the seismic input accuracy for soil-structure interaction systems is improved, but the computational requirements and processing complexity increase
Solution Approach 1:
The patent performs preliminary frequency analysis and wave phase identification before the main inversion process. By pre-separating body waves and surface waves based on their frequency characteristics and polarization properties, the subsequent inversion computations are significantly reduced in complexity and processing time while maintaining high accuracy.
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
This method improves inversion accuracy by considering the multi-phase property of seismic waves, aligning with real underground records, and provides more precise seismic input for soil-structure interaction systems, revealing accurate seismic response behaviors and damage mechanisms.
Implementation Method 1
Based on Snell's Law of complex angles and the forward modeling and inversion theory of body waves, Rayleigh wave components that strictly satisfy standard elliptic polarization characteristics in a half-space are extracted
Implementation Method 2
Rayleigh wave components that strictly satisfy standard elliptic polarization characteristics in a half-space are extracted
Implementation Method 3
based on the linear elastic characteristics of the half-space of rock media, the single-phase body wavefields and the single-phase Rayleigh wavefields are superposed to form the total multi-phase wavefields with the linear superposition principle
Data Source
AI summary
The present invention provides a multi-phase wavefield inversion method considering both body waves and surface waves in half-space of rock media to address the deficiency in existing methods that neglect surface wavefields. In the present invention, Rayleigh components that strictly satisfy standard elliptic polarization characteristics in a half-space are extracted with Snell's Law of complex angles and the forward modeling and inversion theory of body waves. Then, the phase separation is executed to separate the body and Rayleigh waves. The pre-arrival components of S-waves are truncated to solve optimal incident angles of body waves. Thus, a Rayleigh wavefield inversion is implemented with ground Rayleigh components, and a body wavefield inversion is implemented with ground body components and their incident angles. Finally, based on linear elastic characteristics of the half-space of rock media, single-phase body wavefields and Rayleigh wavefields are superposed to form total multi-phase wavefields with the linear superposition principle.