ESTABILIDADE E DEFORMAÇÃO DE TALUDES DE SOLO SOB CARREGAMENTO SÍSMICO / STABILITY AND DEFORMATION OF SOIL SLOPES UNDER SEISMIC LOAD
AUTOR(ES)
CARLOS HUGO SOTO MOROTE
DATA DE PUBLICAÇÃO
2006
RESUMO
The seismic stability of slopes has been a topic of considerable interest in geotechnical engineering for the past 40 years. During that period, the state of practice has moved from simples techniques to more complicated numerical procedures. The simplest approach is the pseudo-static analysis in which the earthquake load is simulated by an equivalent static horizontal acceleration acting on the mass of the landslide, according to a generally conservative limit equilibrium analysis. The ground motion parameter used in a pseudo-static analysis is referred to as the seismic coefficient k, and its selection has relied heavily on engineering judgment and local code requirements because there is no simple method for determining an appropriate value. The second main procedure is known as the Newmark displacement analysis which involves the calculation of the yield acceleration, defined as the inertial force required to cause the static factor of safety to reach 1 from the traditional limit equilibrium slope stability analysis. The procedure then uses a design earthquake strong-motion record which is numerically integrated twice for the amplitude of the acceleration above the yield acceleration to calculate the cumulative displacements. These displacements are then evaluated in light of the slope material properties and the requirements of the proposed development. The third method is referred to as the Makdisi-Seed analysis sought to define seismic embankment stability in terms of acceptable deformation instead of conventional factors of safety, using a modified Newmark analysis. Their method presents a rational means to determine yield acceleration, or the average acceleration required to produce a factor of safety of unity. Design curves were developed to estimate the permanent earthquake- induced deformations of embankments, which have since been applied to sanitary landfill and highway embankments. Finally, the most sophisticated method for seismic slope stability calculations is known as the dynamic analysis, which normally incorporates a finite element model and a rather complex stress-strain behavior for geological materials in an attempt to obtain a better representation of the behavior of soils under cyclic loading. The results of the analysis can include a time history of displacements and stresses, as well as natural frequencies, effects of damping, etc. This work presents a comparison of the results obtained by the aforementioned approaches, considering the seismic behavior of the slopes of an uranium lixiviation pad situated in Bahia, Brazil, and the South embankment of the waste landfill of the Toquepala Mine, Peru.
ASSUNTO(S)
seismic analysis terremoto deformacao de taludes de solo earthquake analise sismica elementos finitos estabilidade de taludes slope stability soil slope deformation finite elements
