Comparative Soil Liquefaction Assessment Based on Multiple Investigations Methods
Authors
Mihaela Stanciucu, Adrian Diaconu, Iuliana Dogaru, Irina Mircea
DOI
Abstract
Submerged soils like loose sands or very soft clays are sometimes hard to evaluate for geotechnical purposes with classical methods like sampling and lab testing. In such soils, evaluation of liquefaction potential became very important, especially in large projects with hard geotechnical conditions where this issue is involved in almost all stages of design. The paper presents the results of the complex geotechnical evaluation of a site situated on the alluvial plain of the Danube, where geotechnical investigations, boreholes with Standard Penetration test measurements, laboratory analyses, and Cone Penetration Tests were completed with geophysical survey (cross-hole and down-hole). To obtain local representative correlations, we apply in the first instance several well-known formulas that link shear wave velocities (Vs) and Standard Penetration Resistance (NSPT). Still, the degree of fitness was very poor. In the second stage, we developed several evolutionary polynomial regression algorithms (EPR) which is a relatively new method used to find polynomial correlations between dependent and independent variables. This algorithm represents a method of solving optimization problems, especially when the objective function is nonlinear. The new predicted values were analyzed using some statistical parameters and using residual analysis, some values were excluded. Thus, based on proposed EPR models we obtain a new series of formulas for each layer which allows more precise correlations of geotechnical and geophysical parameters inside the sedimentary alluvial structure, by reference to the relations proposed in the literature. Based on these new parameters, an assessment of the range of variation of the safety factor against liquefaction based on multiple evaluation methods and the comparison between them was the main purpose of the presented paper.