Abstract
A parameter estimation procedure that employs a simple genetic algorithm combined with FEM calculation is developed to investigate a head loss property of nonlinear flow through rockfill. The head loss property of nonlinear flow is described by the Forchheimer equation, and two coefficients included in the equation are expressed by genetic chromosomes. In the parameter estimation, the simple genetic algorithm searches a chromosome that minimizes a squared deviation of flow discharge through rockfill between observation and FEM calculation to determine an optimal set of coefficients of nonlinear flow. Two coefficients of nonlinear flow are coded into a binary chromosome. The fitness value of the chromosome is calculated as a reciprocal of a sum of the squared deviation of fl ow discharge mentioned above. The chromosomes with large fitness are selected to reproduce a next generation of offspring. The parameter estimation procedure is applied to stage-discharge data measured in 15 embankment tests in a laboratory water flume to estimate two coefficients of nonlinear flow and to compare them with the results of one dimensional permeability tests which was conducted previously and published elsewhere. Good comparison shows a practical effectiveness of the parameter estimation procedure developed.
