Ground deformation as a result of the foundation of a new module in the Spanish Antarctic Base Gabriel de Castilla, Deception Island, Antarctica

Since its inauguration in the 1989/90 campaign, the Spanish Antarctic Base Gabriel de Castilla (BAEGC) has supported an increasing volume of scientific projects, stimulating the expansion of its facilities. The permafrost soil on which they are located is affected by changing thermal and periglacial conditions that disturb its mechanical and physical characteristics. This paper analyzes the foundation behavior of a building (18.5x6.5x2.7 m long – wide – height, around 104 kg in operation supported on 16 posts) through the geomechanical study (stresses and deformations) of the ground during the winter and southern summer seasons, supported by three types of foundations: piles, footings and slabs. These are commonly recommended as support elements in periglacial soils affected by thermal-seasonal variations. The geotechnical properties have been obtained from stress-tests on soil samples collected in the surroundings of the BAEGC, General Marvá Army Engineers Laboratory (INTA). Considering the thermal variations in the tests on frozen and unfrozen samples, the geotechnical column type has been established and extended along the profile of the 2D domain. The stationary stress-strain equations with a constitutive Mohr-Coulomb rupture model have been solved using finite elements in MIDAS GTS-NX, for each season and each foundation, discretizing with a triangular or quadrangular mesh adapted to the 2D domain geometry with the foundation. The numerical results show that, in any tested case, there is no critical ground failure, and the foundation with the smallest displacement (about 0.036 m), both in summer and winter, is the 1.2 m foundation placed at 0.5 m depth on permafrost.