Estimation of the shear strength of heterogeneous granular soils with matrix

TL;DR

This paper evaluates methods to estimate the shear strength of heterogeneous granular soils with fines, highlighting the effects of fines content on the accuracy of parallel gradation and scalping techniques.

Contribution

It investigates how fines content influences the accuracy of existing estimation methods for shear strength in heterogeneous soils.

Findings

Parallel gradation predicts the friction angle well despite high fines.

Cohesion is overestimated by both methods with increasing fines.

Scalping underestimates the friction angle with higher fines.

Abstract

The determination of the mechanical properties of soils containing particles larger than the allowable size by standard laboratory equipment is problematic. It is indeed necessary to eliminate the coarsest fraction to carry out the tests, which poses a problem of representativeness of the results at the scale of the structure. Parallel gradation and scalping methods are presented as a means of estimating the shear strength of heterogeneous granular soils from tests on their finer fraction. This study focuses on the effect of fines content on the estimation by these methods, which is not well known. The results showed that the parallel gradation method can predict the angle of friction of the initial material despite a high percentage of fines. However, the cohesion of the initial material was overestimated. As for the scalping method proposed by Fragaszy et al., the higher fines content in the modelled material resulted in an overestimation of the cohesion and an underestimation of the friction angle of the initial material.