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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 41117 (09)
- University: Sharif University of Technology
- Department: Civil Engineering
- Advisor(s): Haeri, Mohsen
- Abstract:
- Soil nailing is an in-situ technique of mechanically stabilizing soil masses which has been used in France, Germany, United states, and recently in Iran. A review of literature shows that Soil-Nailed walls have performed well during strong ground motions in comparison with the gravity retaining structures. After the 1989 Loma Prieta earthquake, minor signs of distress or corresponding deformation were found on the Soil-Nailed walls, indicating excellent performance of such structures during moderate and strong shakings. These observations indicate that Soil-Nailed walls have an inherent satisfactory seismic response. This has been attributed to the intrinsic flexibility of the Soil-Nailed systems and conservatism in the existing design procedures. Although the highly seismic resistance of the Soil-Nailed Walls has been proven in experimental experiment based on centrifuge and shaking table model tests, a detailed numerical study is rarely found in the literature. In this study, the seismic performance of soil-Nailed walls is numerically assessed using FLAC software. A parametric study is conducted to show the effect of design parameters of the Soil-Nailed walls such as wall height, nail length, nail diameter and nail inclination on the magnitude of critical amplitude of acceleration and critical seismic coefficient. Also the effect of soil cohesion, soil type and input load’s frequency is studied. In addition, the value of critical seismic coefficient propsed by FHWA is compared with that extracted from analysis of this study. This study shows that with an increase in the nail length, the critical amplitude of acceleration increases due to improvement of seismic resistance of the wall. Alao an insignificant increase in seismic coefficient is observed by increase in nail diameter, hole diameter and nail inclination. The critical seismic coefficient also increases when the soil cohesion increases. The result of this study indicates that the frequency of input loading significantly affects the critical amplitude of acceleration. This magnitude drastically decreases when the applied excitation frequency approaches the natural frequency of the Soil-Nailed wall. Our finding shows that the critical seismic coefficient not only depends on the lateral deformation but also relies on the wall height, natural frequency of the wall and dominant frequency of input seismic loading. The magnitude of critical seismic coefficient decreases when the height of the wall increases. The magnitude of critical seismic coefficient significantly increases when the applied excitation frequency approaches the natural frequency of the Soil-Nailed wall. The result of this study can be used by engineers for more economical seismic design of Soil-Nailed walls
- Keywords:
- Dynamic Analysis ; Seismic Response ; Soil-Naile Walls ; Acceleration Critical Amplitude ; Critical Seismic Coefficient
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