Thesis Type: Postgraduate
Institution Of The Thesis: Gazi University, Turkey
Approval Date: 2016
Thesis Language: Turkish
Student: Ayşe Selin Keserli
Supervisor: SAMİ OĞUZHAN AKBAŞ
Open Archive Collection: AVESIS Open Access Collection
Abstract:Soil nails are the construction technique that stabilizes excavation and slopes by increasing the stability. This technique is done by placing long bolts or nails on the ground in order to increase the shear strength of the soil. The aim of the design is to transfer the tensile forces in the nails to the ground by means of friction. In this study, a number of factors that are thought to affect the mechanical behavior of nailed soil have been investigated parametrically in order to obtain a more cost effective design. Two-dimensional elastoplastic finite element analysis program Phase2 was used in the studies. First, two case studies were modeled in Phase2 software. Displacement values measured in the field and the displacement values obtained from the program were compared. It has been researched how close the program outputs are to actual values. Stability analyzes of these models of the two case studies were also performed in Phase2 software. The calculated results were compared with the results of different software used in previous studies. The safety coefficients and displacements calculated in Phase2 software are very compatible to those obtained by measured and other methods. After proving that the Phase2 software used in the study successfully represented the nailed wall behavior, the factors affecting the soiled wall mechanism were investigated parametrically. These factors are nail inclination, nail length pattern, nail yield strength, nail diameter, horizontal and vertical spacing of nails and shot-crete thickness. The parametric factors investigated were evaluated by considering lateral displacement values and safety factors. The results generally show that nail inclination, diameter and horizontal and vertical spacing provide the optimum design by using of the values recommended by FHWA. Analyzes show that the recommended nail lengths in the same reference sources remain on the safe side in case studies. The changes in the mechanical properties of nails produced in the market are so small that there is no effect on system performance. In addition to parametric investigations, risk analysis of the soil nailed wall system was performed and the reliability level of the system was evaluated as probabilistic. Finally, the risks were found to be within acceptable limits.