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Integrated Multiphysics Modeling of Environmentally Assisted Brittle Fracture

Rimsza, Jessica R.; Jones, Reese E.; Trageser, Jeremy T.; Hogancamp, Joshua H.; Torrence, Christa E.; Mitts, Cody A.; Mitchell, Chven A.; Taha, Mahmoud R.; Raby, Patience R.; Regueiro, Richard R.; Jadaan, Dhafer J.

Brittle materials, such as cement, compose major portions of built infrastructure and are vulnerable to degradation and fracture from chemo-mechanical effects. Currently, methods of modeling infrastructure do not account for the presence of a reactive environment, such as water, on the acceleration of failure. Here, we have developed methodologies and models of concrete and cement fracture that account for varying material properties, such as strength, shrinkage, and fracture toughness due to degradation or hydration. The models have been incorporated into peridynamics, non-local continuum mechanics methodology, that can model intersecting and branching brittle fracture that occurs in multicomponent brittle materials, such as concrete. Through development of new peridynamic capabilities, decalcification of cement and differential shrinkage in clay-cement composites have been evaluated, along with exemplar problems in nuclear waste cannisters and wellbores. We have developed methods to simulate multiphase phenomena in cement and cement-composite materials for energy and infrastructure applications.

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TYPE SAND Report YEAR 2021
OSTIDOI

Initial Simulations of Empty Room Collapse and Reconsolidation at the Waste Isolation Pilot Plant

Reedlunn, Benjamin R.; Moutsanidis, Georgios M.; Baek, Jonghyuk B.; Huang, Tsung-Hui H.; Koester, Jacob K.; Matteo, Edward N.; He, Xiaolong H.; Taneja, Karan T.; Wei, Haoyan W.; Bazilevs, Yuri B.; Chen, Jiun-Shyan C.; Mitchell, Chven A.; Lander, Robert L.; Dewers, Thomas D.

The Waste Isolation Pilot Plant (WIPP) is a geologic repository for defense-related nuclear waste. If left undisturbed, the virtually impermeable rock salt surrounding the repository will isolate the nuclear waste from the biosphere. If humans accidentally intrude into the repository in the future, then the likelihood of a radionuclide release to the biosphere will depend significantly on the porosity and permeability of the repository itself. Room ceilings and walls at the WIPP tend to collapse over time, causing rubble piles to form on floors of empty rooms. The surrounding rock formation will gradually compact these rubble piles until they eventually become solid salt, but the length of time for a rubble pile to reach a certain porosity and permeability is unknown. This report details the first efforts to build models to predict the porosity and permeability evolution of an empty room as it closes. Conventional geomechanical numerical methods would struggle to model empty room collapse and rubble pile consolidation, so three different meshless methods, the Immersed Isogeometric Analysis Meshfree, Reproducing Kernel Particle Method (RKPM), and the Conformal Reproducing Kernel method, were assessed. First, the meshless methods and the finite element method each simulated gradual room closure, without ceiling or wall collapse. All three methods produced equivalent room closure predictions with comparable computational speed. Second, the Immersed Isogeometric Analysis Meshfree method and RKPM simulated two-dimensional empty room collapse and rubble pile consolidation. Both methods successfully simulated large viscoplastic deformations, fracture, and rubble pile rearrangement to produce qualitatively realistic results. In addition to geomechanical simulations, the flow channels in damaged salt and crushed salt were measured using micro-computed tomography, and input into a computational fluid dynamics simulation to predict the salt's permeability. Although room for improvement exists, the current simulation approaches appear promising.

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TYPE SAND Report YEAR 2019
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12 Results
12 Results