Cemented granular materials (CGMs) are multiphase materials consisting of a skeleton of solid particles and a cohesive solid matrix filling completely or partially the voids between particles. Although, these materials are commonly used in geotechnical applications, their mechanical behavior has not yet been clearly understood. One of the most recent applications of CGMS is rock filled concrete (RFC), which is a new technology for cost-efficient construction of mass concrete structures such as dams using local materials. Peridynamics (PD) is known as an emerging numerical method to accurately simulate the damage/failure process in solid materials only based on inherent material properties. However, there are some restrictions for using Peridynamics in modelling of complicated materials...[ Read more ]

Cemented granular materials (CGMs) are multiphase materials consisting of a skeleton of solid particles and a cohesive solid matrix filling completely or partially the voids between particles. Although, these materials are commonly used in geotechnical applications, their mechanical behavior has not yet been clearly understood. One of the most recent applications of CGMS is rock filled concrete (RFC), which is a new technology for cost-efficient construction of mass concrete structures such as dams using local materials. Peridynamics (PD) is known as an emerging numerical method to accurately simulate the damage/failure process in solid materials only based on inherent material properties. However, there are some restrictions for using Peridynamics in modelling of complicated materials like CGMs. For instance, conventional PD contact model (short-range force) formulates the contact force field in such a way that leaves a large gap between particles, leading to a softer stiffness of contact and inaccurate simulation of densely packed granular materials. In this research, a new Peridynamics model is developed to remove the restrictions of PD and make it efficient to model CGMs from micromechanics to large-scale applications. The innovations of this research are listed as follows:

A non-local “touch-aware” frictional contact model for Peridynamics is developed to efficiently simulate the contact behavior between irregularly shaped particles. The developed “touch-aware” contact model initiates the contact force calculation when contacting bodies are in touch, which leaves no gap between contacting bodies and provides a stiffer contact in an accurate and efficient way. It simulates frictional contact behaviors and damping between contacting bodies with irregular shapes. Different examples are given to verify the touch-aware contact model with theoretical solutions such as Hertz theory of contact, Hertz theory of impact, Coulomb’s law, and damping formulation. The model is also compared with conventional Peridynamics contact model and the discrete element method.

A material model called “non-local PD rigid material model” is developed in this research to efficiently simulate the condensing process of aggregates, which play a key role in the study of CGMs. PD rigid material along with the touch-aware contact model is used to simulate condensation of an aggregate of irregularly shaped particles. The provided examples demonstrate excellent capacity of the “touch-aware” and “rigid” model in simulating packed granular systems.

Laboratory-scale CGMs are studied by using the developed numerical method. Three-dimensional irregularly shaped particles are created based on X-ray scanning of real rock particles. The distribution of cement matrix is created based on different schemes. Different mechanical phenomena including the bulk behavior of rock particles and cement matrix, the cohesive force field between particles and matrix, and inter-particle frictional damping contact force field between particles are considered in the model. The study demonstrates the importance of considering cement clogs and discontinuities in capturing the uniaxial compressive strength and elastic stiffness of the CGMs, when cement amount increases from 5% to 50%. Finally, the developed PD model is used to study the mechanical behavior of RFC. The numerical results agree well with field tests on large RFC samples. The novel results in this research are supported by laboratorial and field data.