| Summary: | 碩士 === 國立交通大學 === 土木工程系所 === 93 === Presently, by adjusting the survey line parameters, such as near offset, receiver spacing, and offset range, surface wave testing can provide reasonable results even though tradeoffs are involved when determining the field configuration parameters. However, we still have problems with the tradeoffs. We use numerical simulation to study the application of pseudo-section concept, which is introduced to provide a solution of the tradeoffs, in surface wave testing.
Forth-order velocity-stress finite difference method is used to simulate the surface wave testing data based on conventional and pseudo-section survey line in earth models with different lateral heterogeneity. According to the results, false dispersion and interference zone exist when surface wave propagating in the earth with lateral heterogeneity. Furthermore, comparing the results based on conventional survey line and pseudo-section concept with no backward reflecting waves or well separation of the backward reflecting and forward propagating waves, the performance of pseudo-section survey line is the same or even better. When pseudo-section survey is interfered by backward reflecting wave, it is necessarily to develop a new signal processing to filter out the backward reflecting wave to achieve better performance. In its current form, pseudo-section survey is still a good way to detect the existence of lateral heterogeneity.
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