نوع مقاله : پژوهشی
نویسندگان
1 پژوهشگاه بینالمللی زلزلهشناسی و مهندسی زلزله
2 دانشگاه آزاد اسلامی، واحد اراک
3 پژوهشکدهی حمل و نقل وزارت راه و ترابری
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Structures, such as buildings, walls and towers, are often located on sloping ground, which may involve the construction of shallow foundations adjacent to the top of the slope. The literature concerned with evaluation of the bearing capacity factors of foundations is mostly limited to horizontal ground surfaces, as well as static cases. Assessment of the seismic bearing capacity of strip foundations has been the concern of few researchers in the field of geotechnical earthquake engineering during recent decades. This paper presents the seismic bearing capacity factors, ${bf N_{gamma}}$,${bf N_{q}}$ and ${bf N_{c}}$, of a rigid strip foundation resting adjacent to the top of a slope, obtained by the stress characteristic method, commonly referred to as the slip-line method.
The effects of earthquakes on body forces, as well as on overburdened surcharges are incorporated. It is assumed that the soil behaves as rigid perfectly plastic and obeys the well known Mohr-Coulomb failure criteria under plane strain conditions. It is assumed that the state of stress everywhere in the neighborhood of the foundation is at failure. It is also assumed that everywhere along the surface of the foundation, the ratio of shear to normal stress is equal to the horizontal earthquake acceleration coefficient (${bf k_{h}}$). The
${bf N_{gamma}}$ parameter was calculated based on the both-sides failure mechanism,
whereas the ${bf N_{q}}$ and ${bf N_{c}}$ parameters were calculated based on the single-side
failure mechanism. The ${bf N_{c}}$ parameter for cohesive media was calculated using the
rule of equivalent states.
Some graphs and tables are presented that could be used in order to assess the seismic bearing capacity factors of foundations resting adjacent to the top of a slope, evaluated by the stress characteristic method. It is shown that all seismic bearing capacity factors reduce considerably with an increase in either
ground inclination or in ${bf k_{h}}$.
It is also shown that in weighty media, the seismic bearing capacity of a foundation adjacent to the top of a slope is less compared to the one resting on a similar infinite slope, whereas, in weight-less media, it is equal. The values of the seismic bearing capacity factors calculated by the stress characteristic method are compared with those obtained by the upper bound theorem reported in the literature. It is observed that the stress characteristic method gives lower values of seismic bearing capacity factors than those estimated by the upper bound theorem.
کلیدواژهها [English]
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