Temperature effect on gypsum-bearing soil and supported (building) foundations: The case of the Central Storage Facility of Villar de Cañas, Spain

Abstract

Thermal load imposed on the ground by the foundations of some singular buildings may produce variations in geochemistry conditions. In soils containing soluble salts, such as gypsum, their dissolution/precipitation rates may be modified, triggering ground settlement as well as angular distortion of building foundations. This paper examines these processes for the case of the Central Storage Facility for high-level radioactive waste planned in Spain. This facility would impose a thermal load over a long period of time due to the disposal of spent nuclear fuel. A numerical model, including the equations for describing the dissolution/precipitation process, as well as the hydrogeological, thermal, chemical, and geomechanical changes in the ground caused by the construction and operation of the facilities, is proposed. The model focuses on the response of the building foundation under different hypothesis of thermal loading underneath the building. Comsol Multiphysics software was used for solving the resulting partial differential equations by the finite element method. This analysis concludes that moderate thermal loading of the ground would develop in the Case Study, with negligible mechanical effect on the foundation. • Thermal load imposed by some buildings may produce variations in ground chemistry conditions. • A temperature dependency occurs on the dissolution processes of calcium sulfated phases. • Thermal load is expected over a long period of time due to the disposal of spent nuclear fuel. • With moderate thermal loading of the ground, negligible mechanical effect on the foundation develop.