Villarreal-Arango, Andrés F.

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    Proyecto piloto para microzonificación sísmica en Puerto Rico: el caso de Mayagüez
    (2015) Villarreal-Arango, Andrés F.; Suárez, Luis E.; College of Engineering; Ramos, Ricardo; Huerta, Carlos I.; Department of Civil Engineering; Huérfano, Víctor
    In this study a seismic microzonation of the city of Mayaguez, Puerto Rico was developed, starting from the design spectrum of the IBC-09 code for rock B. A conventional microzonation project requires substantial funds to carry out the geophysical tests needed, for this reason, a simplified methodology was proposed based on the use of equivalents soil layers. The proposed methodology consists on defining a soil deposit with multiple layers through other with just one equivalent soil layer, using the formula of fundamental natural period of a uniform soil deposit. With the natural periods from an isoperiod map and the shear wave velocity obtained indirectly from a soil type map, the thickness of the equivalent soil layer is calculated. A site response analysis with the program EERA© was performed to propose the response spectra. Analyzing the spectra obtained for each site, for seven historical earthquakes, the design spectra were proposed. Using the program ArcGIS© the design spectra are presented in interactive form.
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    Geotechnical resiliency in the tectonically active tropics: Liquefaction and earthdam vulnerability case studies in Puerto Rico
    (2019-05-14) Villarreal-Arango, Andrés F.; Morales-Vélez, Alesandra C.; College of Engineering; Hughes, Stephen; Ramos Cabeza, Ricardo; Camacho Padrón, Beatriz I.; Suárez Colche, Luis E.; Department of Civil Engineering; Vásquez Urbano, Pedro
    This dissertation is comprised of four manuscripts developed from different topics of geotechnical and earthquake engineering. Puerto Rico is selected as the study area because is an island located in a high tectonic active area and threaten by atmospheric phenomena. The first topic investigates a link between resilience, liquefaction, and natural hazards. An extensive literature review is performed in order to apply a conceptual definition of resilience in the field of geotechnical engineering to establish a framework to evaluate liquefaction potential in Puerto Rico. The second topic deals with site response analysis and liquefaction evaluation of a unique calcareous sand soil from southwest Puerto Rico. Liquefaction potential was evaluated as the factor of safety (FS) between the soil resistance (CRR) and the earthquake demand (CSR). For the earthquakes considered, the FS indicates that the CRR-CSR profiles for the calcareous sand are susceptible to liquefaction. Also, a seismic design spectrum is proposed that area using the site response analysis that considers soil site effects. The third topic compares the results of a liquefaction analysis using simplified procedures and specific site stress-based approaches. An alluvium sand deposit from Mayaguez, Puerto Rico is used as case of study. The principal difference between the two methods is the calculation of the CSR. General results indicate that the coastal area of Mayagüez has a high liquefaction potential (FS < 1). The comparison of the two procedures demonstrates that at the majority of the CRR-CSR soil profiles, the factor of safety against liquefaction using the simplified method is less than the one obtain using the specific stress-based approach. The four and final topic presents a multi-decadal earth dam monitoring using airborne LiDAR and structure from motion (SfM) of Lago Guajataca (northwest Puerto Rico). As Hurricane María crossed Puerto Rico, the dam spillway of Lago Guajataca suffered major damages, caused by overtopping due to extreme precipitation and other factors. The complete temporal analysis includes; SfM analysis from aerial images from 1930; airborne LiDAR datasets from 2004 to 2016; SfM from photos taken by the Air Patrol days after Hurricane María (September and October 2017); and our 2018 UAV survey. General deformations of the dam were identified. In addition, changes in volume from the structure were quantified before and after Hurricane María.