Surface Wave Prospecting Using Vector Wavenumber Transform
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Solution Overview
Problem
Current passive source surface wave geophysical exploration methods cannot extract higher modes of surface wave dispersion curves, and require specific arrangements of observation arrays, limiting their applicability in engineering geophysical exploration.
Innovation Solution
The proposed method employs the Vector Wavenumber Transform Method (VWTM) to obtain dispersion graphs from vibration data, extracting both fundamental and higher modes of surface wave dispersion curves, and uses these to establish an initial stratigraphic model for inversion, allowing for arbitrary arrangement of observation arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive source surface wave method is used, then environmental influence is reduced, but higher modes of dispersion curves cannot be extracted
Solution Approach 1:
The patent changes the data processing parameters by introducing a vector wavenumber transform method that operates in the frequency-wavenumber domain. This transformation allows the extraction of both fundamental and higher modes dispersion curves from passive source data by analyzing the energy distribution across different wavenumber components, thereby recovering information that was previously inaccessible with conventional SPAC methods
Solution Approach 2:
The patent transitions from the traditional time-space domain analysis to the frequency-wavenumber domain analysis. By introducing the wavenumber dimension and performing Fourier transformation in both space and frequency domains, the method enables separation and extraction of higher modes that are otherwise mixed with fundamental modes in conventional analysis approaches
2Quantity of substance
If SPAC method is used, then fewer receivers are needed, but observation array must be arranged in certain rules and shapes
Solution Approach 1:
The patent makes the observation array arrangement dynamic and flexible by removing the requirement for fixed geometric patterns. The vector wavenumber transform method can process data from arbitrarily arranged receivers by computing the wavenumber spectrum based on the actual spatial coordinates of each receiver, allowing the array configuration to adapt to various site conditions without requiring predetermined regular shapes
Solution Approach 2:
The patent creates a universal processing method that works with any receiver arrangement pattern. The vector wavenumber transform approach can handle linear arrays, circular arrays, irregular patterns, and any other configuration by using the general Fourier transform framework that does not assume any specific spatial symmetry or regularity in the receiver distribution
3Loss of information
If F-K method is used, then higher modes can be identified, but data collection requires great number of receiving points simultaneously
Solution Approach 1:
The patent extracts higher modes information from the passive source data by applying vector wavenumber transform and analyzing the energy distribution in the frequency-wavenumber domain. The method selectively extracts higher modes by identifying their characteristic wavenumber ranges and energy concentrations, separating them from fundamental modes without requiring the large number of simultaneous receivers that F-K method demands
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 approach enhances the extraction of higher modes surface wave frequency dispersion information, reduces non-uniqueness and computation time in inversion, and improves site adaptability and efficiency in surface wave prospecting.
Implementation Method 1
a phase velocity of Rayleigh wave in a layered medium is changed with frequency, and shows an obvious frequency dispersion property
Data Source
AI summary
The technical solution of the present application is applicable to the technical field of geophysical exploration, and provides a surface wave prospecting method and an acquisition equipment. This method comprises: obtaining vibration data by a vibration collecting device; calculating a dispersion graph by applying a vector wavenumber transform method to the vibration data, extracting dispersion curves from the dispersion graph, wherein the dispersion curves include fundamental mode and higher modes of dispersion curves of surface wave; establishing an initial stratigraphic model according to the dispersion graph; and performing a dispersion curves inversion based on the initial stratigraphic model and an inversion algorithm. The present technical solution can extract dispersion information of higher modes of surface wave from vibration data for reducing the non-uniqueness of inversion; computation time of the inversion algorithm can be reduced by establishing the initial stratigraphic model, and the instability of the inversion algorithm can be reduced, too. In this way, vibration collecting devices can be arranged arbitrarily, the requirement for the site layout is reduced, and the adaptability of surface wave prospecting is improved.