Estimating Hydraulic Conductivity of Overconsolidated Soils Based on Piezocone Penetration Test (PCPT)

Overconsolidated (OC) soils may develop a low or negative pore pressure during PCPT. Thus, it is challenging to develop an “on-the-fly” estimation of hydraulic conductivity from PCPT results. This study presents a method to estimate the hydraulic conductivity of OC soils from PCPT results based on a previously developed method for normally consolidated (NC) soils. To apply the existing method, PCPT pore pressure in OC soils is adjusted by using a correction factor. An equation for the correction factor is derived based on the concepts of critical state soil mechanics, cavity expansion, and consolidation theories. Then, it was reformulated so that traditional cone indices could be used as input parameters. It is shown that the correction factor is mainly influenced by the cone tip resistance, pore pressure, and the rigidity index. The comparison of predicted, which is based on corrected pore pressure and measured hydraulic conductivity showed a good match for four well documented data sets. With the findings of the study, it is expected that an “on-the-fly” estimation of hydraulic conductivity of overconsolidated soils is possible.

Calculation of foundation settlement on a overconsolidated base

The article presents experimental and theoretical bases of overconsolidated soils deformation. The effect of preliminary soil compaction on its deformation under conditions of compression is shown. Based on this dependence, a method is proposed for calculating the foundation settlement on a overconsolidated base, taking into account the pre overburden pressure. The obtained method is compared with the results of the problem solution by the finite element method.

EXPERIMENTAL AND THEORETICAL BASES OF CALCULATIONS OF THE DEFORMATIONS OF DEEP FOUNDATIONS IN OVERCONSOLIDATED SOILS

The paper presents the formulation and solution of the problem by quantifying precipitation of deep foundations (DF) considering the initial stress state of the soil base and state compaction, the history of its formation – taking into account nonlinear properties of soil deformation. It is shown that the inclusion of these factors has a significant impact on the SSC base of deep foundations, including sediment DF, i.e. to decrease it. Also shown that on SSC and on the quantity of foundation displacements of deep foundations is significantly affected by the ratio of the width and depth of the b/h.