Avalanches and Fractures in Biotreated Calcareous Sands

Biotreatment is an emerging reinforcement technology. Avalanche dynamics has recently been used to analyze the fracture behavior of biotreated specimens under unconfined conditions. However, the avalanche dynamics along with fractures in biotreated specimens under confined conditions have not yet been investigated. In this study, we aimed to determine the basic laws of the avalanche dynamics for biotreated calcareous sand specimens through a series of triaxial compression tests under various confining pressures. We found that the probability density distributions of acoustic emission signal (AES) energy, the AES amplitude, and the AES duration of the biotreated specimens under confined conditions obeyed the damped power law, and the AES waiting-time distribution followed the prediction by the gamma function. However, the confining pressure had no significant influence on the relative magnitude, the aftershock-sequence distribution, the AES energy-versus-amplitude distribution, or the AES amplitude-versus-duration distribution. More importantly, the maximum-likelihood estimation of the AES energy could be used to predict the occurrence of catastrophic damage in the biotreated soils.