The software allows the inversion using more modes. During the spectral processing
phase the user can view the dispersion of a customizable synthetic model and the
results are plotted directly on the velocity-frequency spectrum.
The generation of the velocity-frequency spectrum has been improved to allow a more effective
identification of modes. The user can select the points on which the inversion is performed directly
on the velocity-frequency spectrum and assign to each point the mode to
which it refers.
Importing Input Data
Data can be imported from files in SEG2, SEGY and SU standard format as well
as from text files. After importing data, the design of the geometrical
arrangement of springs and receivers will be processed. The design is a complete
report which shows the altitude of the geophones positions and the depth scales.
In addition to the geometric position are displayed field seismograms.
At this stage the user can make operations on the signals deciding to
exclude part of seismograms, move or add virtual arrays.
The analysis of Rayleigh waves using MASW technique is performed with
the spectral investigation of the signal, performing a double Fourier transform
in the time and space domain. The transformed domain (f-k) is represented in both 2D
and 3D and allows highlighting the signal produced by Rayleigh waves from other types
In the transformed domain, in fact, is well detectable the dependence of
wave velocity on the frequency and the dispersion curve is easily traceable considering,
for each frequency, the maximum amplitude of the spectrum. The experimental dispersion
curve is extracted automatically by the program and the user can choose to approximate
it to a polynomial function that can be adjusted by excluding the insignificant points.
Theoretical inversion curve
After assigning an initial geotechnical model characterized by some values as the
number and thickness of the layers, weight per unit volume, Poisson’s ratio, etc.,
it is obtained the theoretical inversion curve and is compared with the experimental one.
The process of variability of the parameters continues until is obtained the best superposition
of the theoretical curve with the experimental inversion curve, in the range established
during the picking phase. The process of matching was conducted with advanced statistical
numerical methods. A series of additional features allow to have the direct control of
the delicate inversion process: it is possible to determine the range of variability of
the speed for each layer, impose known speed on the single layer, assign special conditions
such as speed increasing with depth, etc.
For each processing it is possible to view, in addition to the fundamental mode, which is
based on the process of curves matching, even the higher modes.
Easy Masw allows to determine in addition to the speed profile, the VS30,
the soil class and some geotechnical parameters such as : Young’s Modulus,
Shear Modulus, Edometric Modulus, Compressibility Modulus, tip
resistance of the static penetrometer, Nspt correlation with dynamic penetrometer.
It is offered a detailed output report including numerical computation and graphics.
The graphics can be exported in common formats such as .DXF, .BMP, .JPG.
Exchanging data between GEOSTRU applications
The seismic test can be exported to other GeoStru software such as Slope,
Loadcap, Mp and Stratigrapher for the preparation of the stratigraphy.