Wednesday, 27 March 2013

The Application of Genetic Algorithm in Backcalculating Pavement Moduli of Three-Layered System Structures Using Database Approach

By Mirza Adrian NP*
Pavement structural evaluation plays an important role in road maintenance. One method to perform pavement structural evaluation is by performing Non-Destructive Test, such as Falling Weight Deflectometer, on pavement structures and performs backcalculation to calculate the pavement’s layer moduli using the acquired FWD deflection data. One approach to perform backcalculation is by using a database of pavement deflection. Using this approach, the calculation of pavement moduli is done by interpolating between enveloping moduli saved within the database. Thus, the accuracy of the results from this approach greatly depends on the data and the method of interpolation. Also, the problem of backcalculation is a complex multi-dimensional problem that has many local minima within the solution space. To avoid that, Genetic Algorithm is used because of its ability to perform global search within the solution domain.
This report studies the database approach for backcalculation and found that backcalculation can be done accurately using a database containing 37.240 pavement deflection data. This database is acquired from combining 49 asphalt moduli (E1), 40 sub-base moduli (E2), and 19 subgrade moduli (E3). This report also found that the semi-logarithmic method of interpolation is a better method to interpolate pavement deflection compared to the linear method of interpolation. The database and the interpolation method are then used to develop Genetic Algorithm based software to perform backcalculation on pavement deflection. Comparison with programme GA BackCalc for 27 real deflection data shows that the results compares favourably well even though the calculation time is quite lengthy.

Keywords: genetic algorithm, backcalculation, pavement evaluation, database

* This is an abstract for my undergraduate thesis. If you would like to see the complete text, you can contact me through my email

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