مقاله انگلیسی رایگان در مورد ظرفیت باربری لرزه ای فونداسیون سطحی در زمین شیبدار – الزویر 2018

Design of shallow foundations requires the consideration of safety and serviceability. Safety check generally requires bearing capacity calculations, whereas serviceability calculations are done to keep the expected settlements within tolerable limits. However, a design that satisfies the serviceability criteria almost always satisfies the safety requirements. Then, the bearing capacity calculations are generally done for procedural purposes since they are compulsory in most design codes. But sometimes the combined influences of prevailing loading conditions and topography might reduce the bearing capacity of shallow foundations to critical levels and safety checks control geotechnical design. This is especially correct for the foundations of retaining structures, bridge abutments and transmission towers that rest on or near slopes within seismic zones. Under the influences of structural loads and earthquake accelerations, bearing capacity mechanism can induce slope instability which reduces the allowable bearing pressure in design. For projects that cover large distances, such as power transmission lines, many such foundations that support pylons and towers need to be designed. Thus, it is the goal of this study to develop simple design charts that allow the calculation of bearing capacity for different combinations of foundation dimensions, positions, soil properties, slope inclinations, crest heights and seismic accelerations. This study limits its scope to surficial shallow foundations resting on cohesive soils. The underlying reason for this preference is that sloping grounds generally have cohesive properties and the foundations of structures that are frequently built on sloping ground, such as retaining walls and transmission towers, are surficial shallow foundations. Accordingly, undrained behavior will be assumed as this corresponds to the most critical condition. Seismic loading will be defined using pseudo-static accelerations. Since there is no exact solution of the considered problem, it is essential to develop approximate solutions. For this purpose in this study, two-dimensional finite element method (FEM) is used for investigating the problem. As a shortcoming of the two-dimensional approach, modelled surficial foundations are always strip foundations. However, the applicability of the obtained results will be increased as the use of shape factors is adapted to seismic bearing capacity problems. The problem of shallow foundations resting on or near slopes has attracted the attention of many researchers since late 1950s. These studies resulted in the development of several empirical equations and design charts [1–17,19,20]. Adopted methodologies of research are various and include limit equilibrium methods [6,7,15], upper bound [4,5,9,10,12,17,19] and lower bound analyses [20], method of stress characteristic [10,16], and finite elements method [8,10,16].