Accession Number : ADA309077

Title :   Green's Function Analysis of Pavement Deflections Due to Moving Wheel Loads.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Thuma, Richard G.

PDF Url : ADA309077

Report Date : DEC 1995

Pagination or Media Count : 197

Abstract : Nondestructive pavement deflection testing is commonly used to evaluate the structural capacity of flexible pavements. Different types of tests, characterized by their loading mechanism -- static or dynamic, stationary or moving -- are used for this purpose. For all tests, a pavement deflection model is used to interpret the measured deflections. This thesis presents the conceptual development, validation, and parametric study of a flexible pavement model for predicting deflections caused by a rolling wheel. The model uses a Green's function approach to compute deflections. The Green's function computes the deflections at a known distance from a disk that is loaded harmonically at a known frequency. The deflections caused by an impulse load are computed using Fourier superposition analysis. The rolling wheel load is modeled as a sequence of impulse loads and the model combines the responses from each impulse to predict a deflection basin that would be seen by an observer moving with the wheel. This process assumes that all materials in the pavement stmcture behave linear-elastically. The model was validated by predicting deflections caused by falling weight deflectometer (FWD) tests. Predicted deflections were reasonably close to measured deflections; however, the pavement layer moduli used in the validation were backcalculated using static rather than dynamic models. The sensitivity of the computed deflection basin to three categories of input parameters -- algorithm, material, and loading -- was investigated by a detailed parametric study. Algorithm variables were studied to determine the values that produced the most accurate solution in the minimum time. The sensitivity of the basin shape to layer material variables provided insight into which variables can be potentially backcalculated with this model. Loading variables were studied to determine the effect t

Descriptors :   *DEFLECTION, *PAVEMENTS, *GREENS FUNCTIONS, COMPUTER PROGRAMS, ALGORITHMS, DENSITY, THICKNESS, LOAD DISTRIBUTION, NONDESTRUCTIVE TESTING, ELASTIC PROPERTIES, THESES, ASPHALT, CONCRETE, SUBGRADES, SATURATED SOILS, GROUND WATER, CLAY, ROADS, TIRES, FREQUENCY DOMAIN, SOIL STRUCTURE INTERACTIONS, FLEXIBLE MATERIALS, POISSON RATIO, IMPULSE LOADING, BEARING CAPACITY.

Subject Categories : Civil Engineering
      Soil Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE