Genetic Algorithm in Stability of Non-Homogeneous Slopes
In recent years, genetic algorithm search procedure has been used to locate the critical slip surface of homogeneous slopes. It has been found that genetic algorithm is a robust search technique which often gives global solution. In the present study, genetic algorithm has been used to locate the critical slip surface of non-homogeneous slope in conjunction with slope stability analysis method developed by Janbu (1973) for generalized slip surface. The results obtained from the present study have been compared with those available in the literature [Greco (1996) and Zolfaghari et al. (2005)]. The effect of various genetic algorithm parameters (population size, number of generations, crossover probability and mutation probability) on the solution has been studied. It has been found from the results that Janbu's method (1973) of stability analysis along with genetic algorithm as search procedure gives a better solution in terms of getting minimum factor of safety, compared to other methods.
Stability Analysis of Slopes Using Finite Element Method and Genetic Algorithm
A procedure to determine the factor of safety of a slope using finite element method in conjunction with genetic algorithm is proposed. The stresses in soil are obtained using finite element method whereas the critical slip surface is located using genetic algorithm, an optimization technique. The applicability of the procedure is proven by analyzing three non-homogenous slope examples and compared with those available in the literatures. It is observed from the results that the proposed technique provides better solution in terms of determining the minimum factor of safety compared to the other methods. In finite element analysis the influence of modulus of elasticity and Poisson’s ratio on factor of safety for slope 1 is studied and the effect is visible.
High‐precision U‐Pb zircon age calibration of the global Carboniferous time scale and Milankovitch band cyclicity in the Donets Basin, eastern Ukraine
High‐precision ID‐TIMS U‐Pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic, cyclostratigraphic, and biostratigraphic framework of the Carboniferous Donets Basin of eastern Europe. Chemical abrasion of zircons, use of the internationally calibrated EARTHTIME mixed U‐Pb isotope dilution tracer, and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution of <0.05%, or ∼100 ka, for these Carboniferous volcanics. This precision allows the resolution of time in the Milankovitch band and confirms the long‐standing hypothesis that individual high‐frequency Pennsylvanian cyclothems and bundles of cyclothems into fourth‐order sequences are the eustatic response to orbital eccentricity (∼100 and 400 ka) forcing. Tuning of the fourth‐order sequences in the Donets Basin to the long‐period eccentricity cycle results in a continuous age model for the Middle to Late Pennsylvanian (Moscovian‐Kasimovian‐Ghzelian) strata of the basin and their record of biological and climatic changes through the latter portion of the late Paleozoic Ice Age. Detailed fusulinid and conodont zonations allow the export of this age model to sections throughout Euramerica. Additional ages for Mississippian strata provide among the first robust radiometric calibration points within this subperiod and result in variable lowering of the base ages of its constituent stages compared to recent global time scale compilations.