Development of an In situ Method for Continuous Evaluation of the Resilient Modulus of Pavement Subgrade.

摘要

Pavement designs, materials and uses vary around the world, but engineers typically employ the resilient moduli of pavement materials as the primary means of evaluating those materials. Unfortunately, the majority of tests used to determine the resilient modulus of materials are performed in the laboratory where the material either has been removed from the in-situ conditions or has been reconstituted. Soil samples which are removed from the ground using various techniques are at best moderately disturbed. Typically the testing of these samples is performed in a triaxial device equipped for repetitive axial loading. The strain used to calculate the resilient modulus is the recoverable portion of the deformation response. The fact that this response varies with state of stress is widely accepted, but the laboratory test results continue to be used for lack of a more useful and convenient method of determining resilient moduli (Yoder and Witczak, 1975). The purpose of this study is to develop a method for continuous, in-situ evaluation of the resilient modulus of subgrade material under a highway pavement using seismic waves. Although this technique is not mobile and the equipment is fully embedded in the soil under the pavement, it provides a more accurate means of evaluating resilient modulus. This approach can then be used as a benchmark with which to compare the laboratory results to improve design methods as well as our fundamental understanding of the behavior of pavement materials in the field.