Reliability-Based Design Analysis of Cohesive Soil as an Embankment Material Amended Using Hydrophobic Biopolymers.

The advent of biopolymers in the ground improvement industry has made significant contributions by reducing the carbon footprint and tremendous improvement in soil engineering properties at par with chemical stabilizers. The current study investigates the effect of two biopolymers, chitosan, and casein on the unconfined compressive strength (UCS) behavior of high-plasticity clay at varying dosages of 0.5%, 1%, 2%, and 4%. The study also evaluates the effect of curing periods up to 90 days on the untreated and biopolymer-treated clay. Chitosan and casein bring a 1428% increase and a 989% increase in UCS at the highest dosage of 4% and the highest curing period of 90 days. The nonlinear multivariate regression models establish a link between the experimental and best-fit data with the coefficient of multiple determination (<italic>R</italic><italic>2</italic>) > 0.98. Additionally, the reliability analysis assesses the efficacy of biopolymer-treated soils as an alternate embankment material. With an increase in curing period of up to 28 days, the chitosan-treated samples exhibit higher factors of safety compared to casein-treated samples. The modified embankment attains a target reliability index of more than 3.0 with minimum Chitosan content (<italic>D</italic>ch) of 2.25% and Casein content (<italic>D</italic>ca) of 1.85% at Coefficient of Variation (COV\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{COV}}$$\end{document}) of UCSmin\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{UCS}}_{\min }$$\end{document}<bold> = </bold>10% for 28-day cured samples. Thus, the reliability analysis presents a rational approach for using biopolymer-treated soils in embankment construction by considering the effect of dosage, curing period, and the variability associated with the UCS. [ABSTRACT FROM AUTHOR]