APPLICATION OF RADON TRANSFORMATION METHODS ON RAYLEIGH WAVE AND INVERSION OF GENETIC ALGORITHM AND DIFFERENTIAL EVOLUTION ALGORITHM FOR ESTIMATION OF SHEAR WAVE VELOCITY PROFILE, CASE STUDY: TANI KOTA

• Main Author: Cahyo Syamsu, Agung
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/37209
• Institution: Institut Teknologi Bandung

One of the method which use surface wave to determine the S wave velocity of subsurface is active MASW method. This method consists of three stages: acquisition, dispersion curve analysis, and inversion. Dispersion curve extraction stage plays a big role in producing a good Shear wave velocity model. Therefore, in this study the application of Radon transformation method has advantages in terms of good resolution and the continuation of the dispersion curve trend over a longer frequency range. These two advantages affect the accuracy and resolution of a good Shear wave velocity model. Genetic algorithm (GA), Differential Evolution (DE), and Joint Inversion (GA and DE) techniques are used in inversion stage. There are three data used, synthetic data and Tani Kota. Synthetic data is used to determine the accuracy level of dispersion curve extraction algorithm. In addition, synthetic data is also used at the inversion stage to measure the accuracy of the inversion method. The results of the synthetic data test at the dispersion curve extraction stage shows that the radon transformation method can produce good resolution and a fairly good curve continuity. From the results of dispersion images and dispersion curves picking at 1m and 3m spaces, the dispersion images have good resolution, results from inversion of field data, there are three layers and these results are similar to results of field observationin, first layer (vs =120.8867516m/s and thickness = 1.085572437m interpreted as soil, layer 2 (vs = 575.4901698m/s) and (thickness =2.707651195m) interpreted as soft rock / very dense soil, layer 3 (vs=897.6049617m/s) interpreted as sedimentary rocks in the depths of more than 2,7m. This result is similar to the results of observations in the field.