James Maina

Developing Software for Elastic Analysis of Pavement Structure Responses to Vertical and Horizontal Surface Loadings

In this research, a pavement is modeled as a multilayered elastic system composed of a subgrade that is assumed to be a semi-infinite medium. On top of the sublayer are layers of finite thickness infinitely extended horizontally. Furthermore, it is assumed that vertical loading, such as wheel load, and horizontal loading, such as brake load, are simultaneously applied at the surface of a road or runaway pavement. This load is assumed to be circular and uniformly distributed over the entire area. Expressing the displacement function of Naviers equation in a cylindrical coordinate system through harmonic and biharmonic functions, the analytical solution method is obtained by using Michell and Boussinesq functions as well as Hankel transformation and Hankel inverse transformation. In this research, a program called GAMES, which can find pavement responses to multiple vertical and shear loadings, was developed. Theoretical analysis uses the principle of superposition, and the solution is given by summing up the solutions from vertical and horizontal loads. The accuracy of this program is confirmed by comparing results for a number of worked examples with results obtained using the BISAR program. It is also possible to allow an interface slip modeled in a form of shear spring. The current version of this program allows for analysis of 10,000 measurement points with a maximum of 100 loads and 100 pavement layers.

DYNAMIC BACKCALCULATION OF PAVEMENT STRUCTURE USING MULTIPLE SETS OF TIME-SERIES DATA

Backcalculation analysis is generally greatly affected by errors in the measured deflection data. An average of multiple deflection data sets corresponding to a standard load is normally used in static backcalculation in order to reduce the effects of these errors. However, this procedure can not be applied in case of time series data. A rather time consuming procedure is used, where backcalculation is performed using each deflection data set and then an average of the backcalculated pavement layer properties is determined. This paper proposes a new method where multiple sets of time series data can be used simultaneously in dynamic backcalculation to determine an average result. Computation time is similar to the case of one data set. Domain of analysis and the number of nodes are also examined.