Geostructures experience repetitive load cycles, which gradually affect their long-term performance. This thesis explores the long-term response of soils subjected to mechanical load-unload, heat-cool, freeze-thaw, and atmospheric pressure oscillations. The research methodology involves new instrumented cells (oedometer, temperature-controlled triaxial chamber, and pressure-controlled drying chamber), various geophysical monitoring methods (X-ray micro-CT, NMR, S-wave, and EM-waves), and simulations using discrete element modeling. Results show that soils subjected to repetitive mechanical or environmental loading experience shear and volumetric strain accumulation and changes in saturation (during barometric pressure cycles). In all cases, soils evolve towards an asymptotic terminal void ratio; the change in void ratio is pronounced when the soil exhibits grain-displacive ice formation during freeze-thaw cycles. The initial stress obliquity defines the shear strain response, which may be either shakedown -at low stress obliquity-, or ceaseless shear strain accumulation in ratcheting mode when the maximum stress obliquity approaches failure conditions. Finally, we provide simple engineering guidelines to estimate the long-term behavior of soils subjected to repetitive mechanical or environmental loading.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/673777 |
| Date | 06 1900 |
| Creators | Cha, Wonjun |
| Contributors | Santamarina, Carlos, Physical Science and Engineering (PSE) Division, Jonsson, Sigurjon, Burns, Susan E., Finkbeiner, Thomas, McCabe, Matthew |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2022-11-25, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation will become available to the public after the expiration of the embargo on 2022-11-25. |
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