WSASW Application for Soil Dynamic Properties in Soft Soil Investigation at Kelang, Malaysia

In seismic wave measurements, soil dynamic parameters, i.e., shear wave velocity and shear modulus are determined from a dispersion curve of phase velocity with employing the theory of elasticity of soils. In this paper, a developed technique from Spectral Analysis of Surface Waves (SASW), namely as the Wavelet Spectrogram Analysis of Surface Waves (WSASW) is introduced for measurement of the soil dynamic properties at soft marine clay soils sites. This technique has capability to localize the interested response spectrum of surface waves, to reconstructed spectrograms of noisy seismic waves and produces the enhanced phase data to develop the phase velocity dispersion curve. A filtration procedure is also proposed in order to remove the noisy signals from the seismic records received during field measurement. The identification, denoising and reconstruction of the wave response spectrum from seismic surface wave propagation on a soft soil were carried out by using time-frequency analysis of continuous wavelet transforms. The wavelet analysis was used for providing good resolution of spectrogram at low frequency and their spectrograms could be used to clearly identify the various events of interest of the seismic surface waves and noisy signals. Good agreements were obtained between the measured shear wave velocities and the corresponding dynamic shear modulus by the WSASW technique compared to Continuous Surface Wave (CSW), SASW and conventional soil testing method that performed in the same site location. Some good empirical correlations were also obtained as study case for soft soil site

An Integration Of The Seismic Methods In Characterization Of An Unsaturated Granitic Residual Soil Site

A comprehensive seismic survey encompassing the seismic refraction and the downhole method have been carried out in order to characterize a site of granitic residual soil.  The seismic refraction was found to be useful in the initial modeling of the subsurface and has managed to identify the water table, a bolder and the bedrock level satisfactorily.  From the downhole seismic, P-wave velocity was found to be responsived to lithology and the water table, while the S-wave velocity was found to be able to characterise the residual soil in terms of their weathering grades.  Correlations between the S-wave velocity (Vs) and dynamic shear modulus (Gseis)  were established with the SPT (N) and the static unload reload shear modulus (Gur)of the pressuremeter tests. The relationship of Vs = 2.89N + 167.84 and Gseis (MPa) = 2.39Gur + 36.03 were obtained in this study. 

Analisis Arus Jenuh dan Panjang Antrian pada Simpang Bersinyal: Studi Kasus di Jalan Dr. Sutomo-Suryopranoto, Yogyakarta

The aim of this paper is to analyse the delay length based on MKJI (1997). A case study was conducted on a signalized junction of Dr.Sutomo-Suryopranoto road, Yogyakarta. The correction was carried out on coefficient of basic saturation flow in ranging from 600 to 2200. Therefore, the predicted (from MKJI 1997) and measured delay length was compared. The results show that the coefficient on basic saturation flow calculation needs to be modified in the range of 600 to 2200 in order to find the similar length of the delay between prediction and field measurement. Passenger car unit (PCU) unit for motorcycle from MKJI (1997) was also corrected from 0.2 to 0.15.

Coupled CWT Spectrogram Analysis and Filtration: New Approach for Surface Wave Analysis (A Case Study on Soft Clay Site)

Surface wave analysis consists of generation, measurement and processing of the dispersive Rayleigh waves recorded from two or more vertical transducers. However, in case of soft clay soil, the reliable dispersion curve is difficult to be produced particularly at the frequency below 20 Hz. Some noises from nature and other human-made sources may disturb the generated surface wave data. In this paper, coupled analysis of continuous wavelet transform (CWT) spectrogram analysis based on Gaussian Derivative function was used to analyze the seismic waves in different frequency and time. First analysis is time-frequency wavelet spectrogram which was employed to localize the interested seismic response spectrum of generated surface waves. Second analysis is a time-frequency wavelet filtering approach which was used to remove noisy distortions in the spectrogram. Based on the generated spectrogram, the thresholds for wavelet filtering could be easily obtained. Consequently, the denoised signals of the seismic surface waves were able to be reconstructed by inverse wavelet transform considering the thresholds of the interested spectrum. Results showed that the CWT spectrogram analysis is able to determine and identify reliable surface wave spectrum and phase velocity dispersion curve of soft clay residual soil. This technique can be applied to problems related to non-stationary seismic wave