نوع مقاله : مقاله پژوهشی
نویسندگان
گروه معدن، دانشگاه آزاد اسلامی، واحد صفاشهر، صفاشهر، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In an actual earthquakes, the liquefaction of granular soils is generally due to seismic waves transmitted from hypocenter movement to near the field during the earthquakes. The vertical propagation of the shear wave towards the surface of the ground causes cyclic shear stress and reduces the cyclic resistance ratio (CRR) in granular soils and increases the probability of liquefaction. Large lateral deformations have been widely observed in liquefied environments during severe earthquakes, causing damage to surface structures as well as underground structures. The earthquake trigger is inherently multi-directional in nature and its amplitude and direction are always changing. This loading Characteristics creates complex patterns of stress-strain behavior when the resulting waves propagate through the soil layers. Laboratory experiments, shaking table (unit or centrifuge gravity acceleration) test and numerical methods are the proposed procedures for studying the liquefaction behavior of soil under multi-directional cyclic shear stress. In this study, a three-dimensional finite difference numerical simulation for a saturated sand column under bidirectional shear cyclic waves with different phase was performed and its results were analyzed. The numerical model was validated by comparing the results of the centrifugal shaking table experiment published by Su et al. Validation of the numerical model showed that the behavioral model and the selected numerical method are suitable for simulating the phenomenon of granular soils liquefaction created by bidirectional shear cyclic waves. The results of this study showed that the values of subsidence and excess pore water pressure in the sand column for bidirectional shaking depends on the difference in the shaking phase in the two directions, and with increasing the phase difference, the maximum amount of subsidence and excess pore water pressure decreases, and the maximum value of these parameters in the bidirectional shaking is higher than the unidirectional shaking.
کلیدواژهها [English]
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