A study of clay soil deformability over time

Abstract

Introduction. The study is focused on the process of clay soil deformation over time, provided that this soil, featuring varied liquidity index values, is exposed to constant load. The consolidation process is slow; it can run for years or decades in clay soils. Long-term deformations of clay soils must be taken into account in the course of design and construction of buildings and structures, on the one hand, and in the process of analyzing settlement rates and maximal settlement values for foundation beds, on the other hand.
 Materials and methods. Semi-solid, low-plasticity, high-plasticity, very high plasticity, and free-flowing clay samples were used in the study. The parameters under research encompass relative and absolute deformation of soil samples over time. These parameters are dependent on the soil liquidity index value. All laboratory tests were carried out in compression machines, and tested samples were exposed to constant load. The experimental data thus obtained were supplemented by the information provided M.A. Koltunov.
 Results. Values of absolute deformations and time-to-relative deformation ratios were obtained for clays having different liquidity index values. The analysis of the time-to-relative deformation curves shows that deformations develop over time at different rates depending on the liquidity index of clay soils. An increase in the value of the liquidity index boosts the values of initial deformations and deformation rates.
 Conclusions. The equations, derived in the course of the study, allow to analyze the deformation of semi-solid, low-plasticity, high-plasticity, very high plasticity, and free-flowing clays for various time ranges depending on the initial clay liquidity index. The accuracy of the approximation of these equations varies from 0.801 to 0.993, which makes it possible to characterize these dependences as high quality mathematical models.