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.
THRUST LINE CRITERION IN EMBANKMENT STABILITY ANALYSIS
A METHOD OF ANALYSING THE STABILITY OF EMBANKMENTS IS DESCRIBED WHICH ACCOUNTS FOR THE INTER-SLICE FORCES AND SATISFIES FORCE AND MOMENT EQUILIBRIUM CONDITIONS. THE METHOD IS APPLICABLE TO ANY SHAPE OF SLIP SURFACE WITH OR WITHOUT A TENSION CRACK. EXPRESSIONS ARE GIVEN FROM WHICH THE POSITIONS OF THE LINES OF THRUST FOR TOTAL AND EFFECTIVE STRESS CAN BE OBTAINED. SOLUTIONS ARE GIVEN TO TWO SERIES OF PROBLEMS. IN THE FIRST SERIES THERE IS NO TENSION CRACK BUT VARIOUS SHAPES ARE ASSUMED FOR THE SHAPE OF THE SLIP SURFACE AND DIFFERENT ASSUMPTIONS MADE REGARDING THE SLOPES OF THE INTER-SLICE FORCES. HOWEVER, NONE OF THESE SOLUTIONS LEADS TO A SATISFACTORY POSITION FOR THE LINE OF THRUST FOR EFFECTIVE STRESS. IN THE SECOND SERIES A TENSION CRACK WITH WATER PRESSURE ACTING IN IT IS ASSUMED PRESENT. IT IS SHOWN THAT A SATISFACTORY THRUST LINE IS OBTAINED WHEN THE DEPTH OF THE TENSION CRACK IS TAKEN TO BE THE DEPTH OF ZERO ACTIVE EFFECTIVE STRESS AND THE SLOPE OF THE INTER-SLICE FORCES IS CONSTANT, EXCEPT FOR A REDUCTION AT THE UPPER END OF THE SLIP SURFACE. THE INCLUSION OF THE TENSION CRACK WITH WATER PRESSURE ACTING IN IT DOES NOT AFFECT THE VALUE OF THE FACTOR OF SAFETY IN THIS PROBLEM. /TRRL/
The genus Pseudolithophyllum (Corallinaceae) in the Gulf of Maine
SummaryThis is the third of a series of papers covering the anatomy, morphology, systematics and ecology of the crustose corallines of the Gulf of Maine. Pseudolithophyllum orbiculatum, the only species of this genus in the region, is treated in this paper.