Stochastic Calcite Morphology Effects on Discrete Element Method Shear-Wave Velocity in Sand

Abstract

The implementation of biocementation techniques, particularly microbially induced calcite precipitation, has gained significant traction in geotechnical engineering as a sustainable method for soil improvement. A critical challenge in evaluating the efficacy of this ground improvement technique lies in non-destructive monitoring, which heavily relies on the measurement of shear-wave velocity. Traditionally, computational models utilizing the discrete element method have assumed a uniform distribution of calcite precipitation at particle contacts. However, empirical microscopic observations reveal that calcite morphology is inherently stochastic, exhibiting patchy, nodular, and highly irregular distributions. This study investigates the effects of stochastic calcite morphology on shear-wave velocity in sand using a threedimensional discrete element method framework. By developing a novel contact model that incorporates random variables governing bond thickness, radius, and spatial distribution, this research provides a comprehensive analysis of wave propagation through heterogeneous cemented granular media. The computational methodology simulates bender element tests by applying dynamic excitations to representative volume elements, capturing the microscale energy dissipation and macroscale velocity dispersion. Results indicate that stochastic distributions of calcite significantly attenuate shear-wave velocity compared to uniform bond assumptions, fundamentally altering the dynamic response of the matrix. This research highlights the necessity of incorporating morphological randomness in numerical models to accurately interpret non-destructive testing data in biocemented soils.