Preliminary Validation of a Novel Method for the Assessment of Effective Stress State in Partially Saturated Soils by Cone Penetration Tests

Diego Lo Presti,Massimiliano Bordoni,Claudia Meisina,Marco Bittelli,Stefano Stacul

doi:10.3390/geosciences8010030

Diego Lo Presti, Massimiliano Bordoni + Show 3 more

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https://doi.org/10.3390/geosciences8010030

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Abstract

A proper assessment of the soil effective stress state is crucial in many cases to identify a potential geological/geotechnical hazard as shallow landslides or failure of levees that may have a significant impact on human activities and development. This paper is aimed at validating a methodology for the expeditious and economic determination of effective stress state in the vadose zone recently proposed by Lo Presti et al. in 2016. The method is based on the interpretation of cone penetration tests (CPTu). Its validation was carried out by comparing the CPTu predicted values of suction against the measured ones in a well-documented and monitored site. The comparison also includes the prediction of suction that was obtained by using the so-called Modified Kovacs model (MK). Moreover, additional data of water content and saturation degree from another site were used to predict the suction by using the MK model. These values of suction were compared with those inferred by the CPTu.

Highlights

Traditional soil mechanics mainly considers fully saturated or dry soils
The difficulty in assessing the in situ saturation degree and/or to obtain reliable measurements of suction, as well as the continuous variation of these parameters is the main reason of the limited use in practice of the huge knowledge that has been gained in recent years on the “soil mechanics of partially saturated soils”
This paper presented a method for the determination of effective stress state in the vadose zone

Summary

Introduction

Traditional soil mechanics mainly considers fully saturated or dry soils. The interest in partially saturated soils or soils saturated by capillarity is quite recent and still under development. The difficulty in assessing the in situ saturation degree and/or to obtain reliable measurements of suction, as well as the continuous variation of these parameters is the main reason of the limited use in practice of the huge knowledge that has been gained in recent years on the “soil mechanics of partially saturated soils”. To capture the actual load-deflection curves of some lateral load tests on single pile, Stacul et al [2] developed an analysis method that considers the increase of both stiffness and resistance in partially saturated soil conditions

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