Abstract Summary
In the near future, geothermal energy is bound to play a critical role in the transition to sustainable energy sources. Micro-earthquakes may be induced by the underground operations performed at the geothermal power plants. In most cases, these vibrations are considered a general nuisance similar to the vibrations resulting from railway track operations. However, given the heightened public concern regarding induced seismicity, it is crucial to identify and analyze the effects of these micro-seismic events on the built environment. In this contribution, we present a numerical technique for the simulation of buildings subjected to geothermal induced seismicity. We apply a substructure method, where the soil is represented as a continuum using the integral transform method (ITM) and the building as a discrete structure using the finite element method (FEM). The soil is assumed to be horizontally layered and the coupled system linear. The structure model represents a low-rise residential building. The focus lies on the computation of the three-dimensional seismic free field displacements, which represents a preliminary step of the whole simulation workflow. The seismic excitation of soil-structure-interaction (SSI) systems is more baffling than the case of external loads applied to the structure: the dynamic response of the coupled system results from the transfer of vibrational energy from the seismic source to the foundation, after the wave propagates through the soil. Therefore, the form and the location of the load application can be open to more than one interpretation. It can be demonstrated that, for the semi-analytical elastodynamical solution, as in the ITM case, the seismic excitation can be converted to an equivalent load acting at the interaction nodes between soil and structure. To compute these equivalent loads, one has to compute the free field displacements at these interaction nodes. Here, we showcase the computation of the three-dimensional free field displacements caused by the induced far-field wave field. The latter is defined at a certain depth of the soil and can be arbitrarily distributed in space and time and is generated with a different technique, where the model encompasses the source and the far field.
