UC Davis

As biocementation technologies approach field-scale implementation, systematic frameworks for anticipating and classifying the cyclic response of treated soil across a range of cementation levels and loading conditions become increasingly valuable. This paper presents a behavioral classification framework for biocemented sands, informed by the cyclic stress path responses of MICP-treated Ottawa F65 sand subjected to constant-volume monotonic and cyclic direct simple shear (DSS) loading. Four distinct types of cyclic stress path response are identified: Type I (uncemented-like response), Type II (dilative-dominant behavior), Type III (clear evidence of bond breakage), and Type IV (high-cycle fatigue behavior). The conditions under which each behavior type is observed are formalized through quantitative boundaries in terms of VsR1 and CSR, where VsR1 is a stress-normalized shear wave velocity ratio reflecting the cementation level and CSR is the applied cyclic stress ratio. As an illustrative example, the framework is applied to evaluate the element-level performance of a plasticity constitutive model for lightly to moderately cemented sands for use in earthquake engineering applications.