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Use of Numerical Simulations To Explain Sasw Field Measurements
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 18th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, Apr 2005, cp-183-00128
Abstract
This paper uses numerical models to explain the results of two SASW field tests in the presence<br>of a void. The Fourier spectra of the field data contain a region with high energy concentration, in the<br>proximity of the void. Numerical models are constructed and the responses at the surface of the medium<br>and around voids of different sizes and embedded depths are monitored. The numerical results show that<br>part of the incident energy is trapped in the void region. The trapped energy bounces back and forth<br>between the boundaries of the void until it is attenuated by radiation. The effect of the trapped energy is<br>seen as a concentration of energy over the void region in the frequency domain. The amount of trapped<br>energy is a function of the size and embedment of the void as well as the frequency content of the<br>source. Moreover, the void absorbs part of the energy and radiates it as body waves. The numerical<br>observations conform closely with the field data. Therefore the recorded responses at the surface carry<br>valuable information about the void. The characteristics of the void can be extracted from the surface<br>responses by analyzing the responses in time, frequency and spatial domains.<br>Keywords: Rayleigh waves, finite differences method, void detection, geophysical testing<br>method, frequency domain analysis