Influence of plastic fines content on the liquefaction susceptibility of sands: monotonic loading

Meisam Goudarzy,Wolfgang Lieske,Torsten Wichtmann,Debdeep Sarkar

doi:10.1007/s11440-021-01283-w

Abstract

The paper presents an experimental study on the effect of plastic fines content on the undrained behavior and liquefaction susceptibility of sand–fines mixtures under monotonic loading. The results of undrained monotonic triaxial compression tests conducted on mixtures of Hostun sand with varying amount (0–20%) and type (kaolin and calcigel bentonite) of plastic fines are presented. The specimens were prepared with different initial densities using the moist tamping method and consolidated at two different isotropic effective stresses. The results demonstrate that for both types of plastic fines, an increase in the fines content leads to a more contractive response and lower values of mobilized deviatoric stress. Despite similar relative density and fines content, the sand–kaolin mixtures showed a more contractive behavior than the sand–calcigel specimens. The steady-state lines (SSLs) in e–p´ space generally move downwards with increasing clay content. While the slopes of the SSLs for the clean Hostun sand and the mixtures with 10 and 20% kaolin are quite similar, the SSL lines for the specimens containing 10% or 20% calcigel run steeper or flatter, respectively. The inclination of the SSL in the q–p′ plane was found independent of clay type and content. The sand–kaolin mixtures were observed to be more susceptible to instability and flow liquefaction than the sand–calcigel mixtures.

Highlights

The effect of various parameters on the behavior of granular soils under undrained loading conditions is of particular interest for the design of foundations or other geotechnical structures in earthquake-prone regions and has been studied by numerous researchers
A series of undrained monotonic triaxial tests was conducted on clean Hostun sand and Hostun sand mixed with different amounts of two different clays, kaolin and calcigel bentonite
The results show that for both types of clay, the response becomes more contractive and the mobilized deviatoric stresses decrease with increasing clay content

Summary

Introduction

The effect of various parameters on the behavior of granular soils under undrained loading conditions is of particular interest for the design of foundations or other geotechnical structures in earthquake-prone regions and has been studied by numerous researchers. Site inspections have shown that clayey sands are prone to liquefaction during earthquakes. The majority of the sand deposits in this region were characterized with significant amounts of low-to-medium plastic fines [12]. Similar observations for different sites and earthquakes were previously reported by Ishihara et al [25], Holzer et al [24] and Miura et al [37]. The available literature on the effect of plastic fines on the behavior of granular soils under monotonic and cyclic loading is summarized in the following, discussing the influence of the content of fines first, followed by the effect of fines plasticity

Results

Discussion

Conclusion