Lattice element method for simulations of failure in bio-cemented sands

Abstract

Microbiologically induced calcite precipitation following the ureases is a bio-geo-chemical soil improvement technique in which the microorganism facilitates to create an environment for the precipitation of carbonates among the grains. It results in binding the loose granular media and prevention against mechanical failure. Although, the bio-cemented processes and media have been studied in the past in qualitative sense with experimental programs, the mathematical and numerical modelling techniques to quantify the strength parameters are rare. In this article, we propose the lattice element methodology which we applied to perform numerical computations of unconfined compression tests on bio-cemented sands. We also provide the experimental results of the unconfined compression tests on bio-cemented sands treated with a different number of cycles that we conducted in our laboratory. The experimental procedure is explained in details. The ultimate goal is to study the macroscopic response and also to quantify the process for engineering applications. The developed model with an embedded discontinuity can capture the macroscopic behaviour from meso-scale element failure, where the diagonal shear cracks which are seldom inherent to compression failure of highly cemented granular media lead the specimens to final failure. The model can capture the complex interaction of the cracks such as initiation and propagation, branching, coalescence and fingering at a nominal computation cost. The numerical and experimental results show good agreement to a large extent. The developed model is suitable to study brittle, and quasi-brittle behaviour of highly cemented granular media.