Dynamic Analysis of Infinite Beam on Modified Vlasov Subgrade

Abstract

A static method, such as multilayer elastic theory, is commonly used to analyze pavement-subgrade systems under traffic loads. While the static analysis method is sufficient and conservative for daily practice, in some instances, a truly dynamic analysis is necessary for special cases, such as shallow bedrock with high vehicle speed. Furthermore, interpretation of nondestructive testing data from falling-weight deflectometer and Dynaflect tests requires the use of more rigorous dynamic back-calculation techniques. This paper presents an efficient dynamic analysis procedure for the interaction behavior of an infinite beam on a modified Vlasov subgrade. A complete description of the technique is given, followed by a detailed parametric study to examine the effects of subgrade depth, the material stiffness and damping ratio, and vehicle speed on the calculated beam response. Results of analysis indicate that the subgrade depth exerts significant influence on the beam response. Increasing vehicle speed, however, only causes a small increase in dynamic displacement under the load. The paper also offers an efficient back-calculation algorithm based on the derived dynamic compliance function. Two case studies illustrate the accuracy and convergence rate of the developed back-calculation algorithm. The two analysis procedures (forward and back-calculation) are implemented into personal computer based computer program for field application.