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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. [ABSTRACT FROM AUTHOR]

Assessing the hydromechanical behavior of collapsible soils is always a challenging topic in an unsaturated soil mechanics context. Although numerous efforts have been made thus far to establish frameworks for explaining the stress-strain behavior of collapsible soils, many of them are developed based on the results from conventional tests without controlling or measuring the unsaturated state variables. Furthermore, modeling the hydromechanical behavior of chemical-stabilized collapsible soils has been rarely studied. To establish a constitutive model for predicting the behavior of a lime-stabilized collapsible soil, the results obtained from filter paper and unsaturated odometer tests on a lime-treated loessial soil (which are presented in a companion paper) have been analyzed by considering the effective stress approach for unsaturated soils. An empirical model for explaining the load-collapse behavior of lime-stabilized tested soil is presented. Moreover, by implementing the disturbed state concept (DSC) method, a coupled semiempirical hydromechanical model is developed to predict the disturbance level and calculate the soil strain due to application of the vertical stress in Ko condition. Both presented models in this research are introduced as functions of two important governing state and material variables, namely matric suction and lime content. Results show excellent conformance between the laboratory test results and model predictions. [ABSTRACT FROM AUTHOR]