نوع مقاله : مقاله تحقیقی (پژوهشی)
1 دانشیار، دانشکده مهندسی عمران، دانشگاه تربیت دبیر شهید رجایی، تهران، ایران
2 دانش آموخته کارشناسی ارشد مهندسی ژئوتکنیک، دانشگاه تربیت دبیر شهید رجایی، تهران، ایران
عنوان مقاله [English]
Today, many earthquakes occur in most parts of the world that are very different in terms of intensity, duration, energy and other seismic characteristics, so the amount and extent of damage to different structures are also affected by the characteristics of the earthquake. In this regard, the study of the effects of earthquake frequency content on the behavior and response of reinforced soil walls is also important.
In this research, using numerical simulation with two-dimensional modeling of geocell-reinforced soil in Flac-2D finite difference software and seismic analysis with nonlinear dynamic time history of earthquake, the effect of earthquake frequency content on the behavior and seismic response of reinforced soil and also the role of various factors such as embankment geometry and reinforcement characteristics were investigated. The most important results can be summarized as follows:
In seismic conditions, lateral displacement is significant compared to vertical displacement and its maximum value is above the wall.
By increasing the frequency range of the earthquake around the natural frequency range of the structure, the strain energy in the embankment increases and the reliability and stability decrease consequently.
By increasing the frequency range and strain energy, the amount of unbalanced internal forces of the embankment is increased. It creates a large deformation and displacement during the earthquake by creating a cumulative plastic strain and will lead to rupture and instability of the embankment.
With increasing altitude and subsequent geometric dimensions of the embankment, the weight of the mass increases and the seismic acceleration leads to large and permanent displacement during the earthquake, which is a significant increase in earthquakes with wide frequency content (around the natural frequency range of the structure).
As the length of the reinforcement increases, the displacement of the embankment during the earthquake decreases due to the increase in internal capacity. It is a tangible improvement in earthquake behavior with wide frequency content. The minimum length of the reinforcement in proportion to the height of the embankment and the frequency range of the earthquake is recommended.
As the geocell height and reinforcement thickness increase, the axial and flexural stiffness increase and the embankment displacement during the earthquake decreases in proportion to this. It improves the behavior in proportion to the frequency content of the earthquake. The proposed height and thickness of the geocell is proportional to the frequency content of the earthquake and to the average dimension of soil particles (D50).
The effect of earthquake frequency content on embankment behavior depends on the natural frequency of the embankment, in which various factors such as embankment geometry, arrangement and reinforcement geometry, as well as the physical and mechanical characteristics of the embankment are involved and cannot be easily calculated.