ABSTRACT
Nondestructive techniques of wave analysis can be applied for the express preliminary geotechnical soil assessment. One of these techniques is Multichannel Analysis of Surface Waves (MASW) which allows obtaining velocities profile of shear waves and the initial shear modulus for the upper section promptly and at minimal labor costs. The soil deformation properties assessment requires the deformation modulus that is obtained by the direct technique of plate load test (PLT). The purpose of the study is to assess the correlation between the PLT deformation modulus and the initial shear modulus determined with MASW.
Plate load tests (PLT) were carried out for various plates and moduli of deformation were calculated. Deformation modulus adjustment factors were applied to bring values of different size plates to the 5000 cm2 plate one in order to perform a comparative analysis. Wave analysis was carried out by the active method of MASW.
During the comparative analysis a correlation coefficient was evaluated for the deformation modulus determined strictly according to the Russian State Standard (GOST 20276-2012). In this case “correlation coefficient - unit weight” indicative dependence was observed. The regression equation is presented.
Correlation between the two types of tests was established by in-situ tests. The proposed empirical regression equation allows us to obtain the deformation modulus on the basis of MASW data and to perform an express soil foundation geotechnical assessment for the future construction.
Preliminary assessment of the geotechnical situation on the site enables carrying out a technical and economic analysis of the object of reconstruction or new construction. Preliminary geotechnical evaluation includes: determination of the geotechnical category of the object of construction or reconstruction, analysis of nearby structures, assignment of the survey work scope, and determination of arrangement options for the underground part of the object and their economic comparison. To correctly choose the variants of constructive solution of the future construction underground part, it is necessary to know the existing layering of soils on the construction site, their physical and mechanical characteristics, and the presence of anomalous inclusions (mines, pipeline cavity, other underground structures, etc.) that will allow performing the feasibility study as correctly as possible. Modern non-destructive research methods enable rapid and cost-effective construction of ground layer sections and estimation of physical and mechanical characteristics of soils. One of such methods is MASW.
The MASW technique was first introduced in (Park et al. 1999) and continues to develop and improve up to now (Park & Carnevale 2010). The authors of this study also conducted a number of natural and numerical experiments to determine the possibility of using the wave analysis for geotechnical calculations (Ofrikhter & Ofrikhter 2015, Antipov & Ofrikhter 2019). The MASW technique is applied to measure the surface wave velocities in layered soil thicknesses. From the received velocities it is possible to pass to the initial shear modulus at small deformations by the known dependence (Foti et al. 2015). For practical purposes, it is very useful to establish the relationship between the surface wave velocity, the initial shear modulus, and the soil deformation modulus from the plate tests. The purpose of the researches is to establish the correlation between the initial shear modulus determined with MASW and the soil deformation modulus determined with PLTs.
