Speaker
Description
Fracture in porous geomaterials such as clay is governed by highly complex mechanisms involving crack initiation, branching, coalescence, and interaction over multiple length scales. In cemented or lithified clayey materials, these processes are strongly influenced by porosity, cementation level, and the associated transition from ductile to brittle behaviour. Accurately capturing such fracture evolution remains challenging, particularly when explicit resolution of the pore-scale microstructure becomes computationally expensive. In this study, the effect of porosity on fracture evolution in artificially cemented clayey materials is investigated using a mesoscale modelling strategy that avoids explicit representation of the porous matrix. An Intermediately Homogenized Peridynamics (IH-PD) framework is coupled with the Discrete Element Method (DEM) to simulate fracture initiation, propagation, and post-failure behaviour in a unified manner. Fracture evolution is governed by a novel bond-based constitutive model incorporating progressive stiffness softening, which enables a smooth transition from intact elastic response to crack nucleation and finally bond failure. This formulation is particularly suited to capturing the gradual degradation and strain-softening behaviour typical of cemented clayey materials. Following bond breakage, the mechanical response of the fractured material is handled through DEM-based non-local contact laws, allowing realistic interaction, separation, and force transmission between fragmented domains. This hybrid IH-PD-DEM approach therefore provides a consistent description of both pre-failure damage evolution and post-failure contact-dominated behaviour.
To examine the role of porosity and cementation, clay specimens with varying degrees of artificial cementation are considered, representing different levels of stiffness, brittleness, and effective porosity. Indirect tensile tests are conducted on these specimens to characterize their macroscopic tensile strength and fracture patterns. Numerical results obtained from the proposed IH-PD-DEM framework are validated against these experimental observations, demonstrating good agreement in terms of the location of crack initiation, propagation paths, and post-peak tensile response. Further, the crack opening velocity is correlated with local material heterogeneities arising from porosity variations, providing insight into the governing physics that control fracture propagation in cohesive quasi-brittle geomaterials.
| Country | India |
|---|---|
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