Time-dependence of rock salt fracture mechanics: numerical and experimental study
(English) This thesis presents an experimental and numerical study on the time-dependent behaviour of fracture propagation in rock salt. The research aims to enhance the understanding of rock salt fracture mechanics, which is crucial for applications such as underground storage of hazardous waste an...
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| Tipo de documento: | tese |
| Data de publicação: | 2026 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositório: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglês |
| OAI Identifier: | oai:dnet:upcommonspor::b59f8413432d7a5d59422abfa701c51e |
| Acesso em linha: | https://hdl.handle.net/2117/460107 https://dx.doi.org/10.5821/dissertation-2117-460107 |
| Access Level: | Acesso embargado |
| Palavra-chave: | Salt Rock Fracture Mechanics Wedge Splitting Test Creep Creep-Fracture Interaction Zero-Thickness Interface Damage Model 624 - Enginyeria civil i de la construcció en general Àrees temàtiques de la UPC::Enginyeria civil |
| Resumo: | (English) This thesis presents an experimental and numerical study on the time-dependent behaviour of fracture propagation in rock salt. The research aims to enhance the understanding of rock salt fracture mechanics, which is crucial for applications such as underground storage of hazardous waste and energy storage, whose long-term stability remains difficult to predict due to the combined effects of creep and fracture. Despite its practical significance, studies addressing the combined effects of creep and Fracture Mechanics of rock salt are scarce in the literature. To address this gap, an experimental campaign was conducted on halite specimens extracted from the Cardona Formation in Spain. Wedge Splitting Tests (WST) were performed at four loading rates spanning three orders of magnitude, complemented by uniaxial creep tests at stress levels between 2.5 and 10 MPa. The WST results reveal a clear rate dependency: peak splitting forces increase with loading rate, while the mechanical work required for fracture decreases, indicating significant contributions of creep to the fracture process at slower rates. The creep tests show non-linear viscous deformation, with approximately linear behaviour only at low stress levels. Subsequently, numerical simulations were performed using the in-house developed finite element code, which combines interface elements with an elasto-plastic constitutive law and visco-elastic continuum elements. These initial simulations partially reproduced the observed experimental trends, confirming that both bulk creep and fracture-process-zone mechanisms contribute to the observed rate dependency, but failing to match quantitatively the experimental results. To improve the modelling capabilities, two new constitutive laws for interface elements are proposed, incorporating elastic degradation, frictional behaviour, viscoelasticity and viscous dissipation processes. These formulations enhance the representation of time-dependent fracture by enabling consistent modelling of salt fracture across a wide range of loading rates. Simulations performed with the new proposed visco-elastic-damage model show improved agreement with experimental results, quantitatively reproducing the observed trends in apparent fracture energy and peak force with regard of loading rate. |
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