A Subsurface Detection Method Based on Surface Wave Multiscale Window Analysis

Abstract

The present invention relates to an underground detection method based on multi-scale window analysis of surface waves. The method comprises the following steps: S1, laying out receiving arrays for observation and collection of surface wave data; S2, using sliding space windows of different scales to extract from surface wave data Obtain the local wave field; S3, analyze and process the local wave field to obtain the measured dispersion curves corresponding to all sliding space windows; S4, discretize the underground model into grid units, and assign initial values ​​to the elastic parameters of each grid unit; S5. Calculate the theoretical dispersion curves corresponding to all sliding space windows; S6. Calculate the fitting degree between the measured dispersion curve and the theoretical dispersion curve. If not, correct the parameters of each grid unit in the underground model and repeat step S5 ~ S6 until the set fitting accuracy is reached, and the wave velocity imaging of the underground structure is realized. Compared with the prior art, the method of the invention can not only ensure the quality of the dispersion data but also have high horizontal resolution, and improve the accuracy of the underground structure detection results.

Description

technical field [0001] The invention relates to the field of underground space development and detection, in particular to an underground detection method based on surface wave multi-scale window analysis. Background technique [0002] As a non-destructive, efficient and economical geophysical detection method, the surface wave analysis method has played a very important role in various engineering explorations on the shallow surface and the study of the earth's internal structure. Currently, the commonly used surface wave analysis methods mainly include Spectral Analysis of Surface Waves (SASW) and Multichannel Analysis of Surface Waves (MASW). [0003] In the surface wave spectrum analysis method, the surface wave dispersion curve is obtained by measuring the time difference or phase difference of two received signals. The surface wave phase velocity represented by the dispersion curve is the average phase velocity of the path. The one-dimensional shear wave velocity stru...

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Problems solved by technology

However, the accuracy of the dispersion curve extracted by surface wave spectrum analysis is easily affected by detector coupling, random noise, spatial aliasing, and high-order surface wave modes, which makes the shear wave velocity obtained by this method less reliable.

[0004] Compared with using only two received signals, the surface wave multi-channel analysis method uses wave field transformation to transform the received multi-channel surface wave signals in the time-space domain into another domain (such as the frequency-phase velocity domain) for dispersion analysis. And according to the strong energy characteristics of the surface wave, high-quality surface wave dispersion data can be extracted. However, the physical meaning of the dispersion curve extracted by the surface wave multi-channel analysis method in the transversely inhomogeneous medium is not yet clear. When the array has a certain receiving length, the horizontal layered model assumption is also used to approximate the formation below the entire array, resulting in a lower lateral resolution of the shear wave velocity obtained in the final inversion

[0005] In general, the existing surface wave analysis methods are either severely limited in data quality, or have low lateral resolution, and there is no method that can effectively solve the actual lateral inhomogeneous medium model

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