Statistical Characterization of Cone Penetration Test Variability for Ibis Hotel Soil

Abstract

Geotechnical variability is a complex attribute that results from many disparate sources of uncertainties. It is strongly dependent on the properties of the soil beneath and adjacent to the structure of interest. Probabilistic models began more realistic design compare to the old deterministic design as it can describe and take account of soil variability. Although the deterministic approach is widely used, it is well known, that almost all natural soils are spatially variable in their properties and rarely homogenous. This paper focuses on the preliminary analysis to prepare the probabilistic analysis of Pile Foundation design by characterizing the tip resistance dan sleeve friction for 6 CPTs data taken from Ibis Hotel Surakarta. It involves an extensive analysis to perform the best-fit distribution of pointwise variability of tip resistance and sleeve friction using computer program written in MATLAB and FORTRAN. Finally, the point statistics (i.e. mean, standard deviation, and coefficient of variation) across the site were derived together with the interpretation of the possibility of the existence of different materials. The results show that, there is no objection to the hypothesis of normality in the chi-square analysis, although the best fit distribution for each profile or 6 profiles which collected at once are varying (i.e.normal, log-normal, gamma, beta. When all tip resistance data are collected at once, the mean and standard deviation is 42.02 kg/cm2 and 40 kg/cm2 respectively. The mean and standard deviation of all sleeve friction data is 1.02 kg/cm2 and 0.8 kg/cm2 respectively. The coefficient of variation of tip resistance and sleeve friction tend to be skewed as its value is high (i.e. 0.95 and 0.78 respectivel).