Creep Behavior of Asphalt Concrete Core Materials in Embankment Dams under a Stepped Loading Path

Abstract

Understanding the long-term creep behaviors of asphalt concrete core materials is crucial to the safety of embankment dams. This study systematically analyzes the creep behavior of asphalt concrete materials under a stepped loading path. Static triaxial tests are conducted to determine the stress–strain relation of asphalt concrete core materials. Both stepped loading and separate loading paths are applied on the asphalt concrete samples to analyze the difference between them in terms of the axial strain. To simulate the realistic temperature condition during the operation of dams, the temperature is set to 22.1°C. The test samples are subjected to four confining stresses (i.e., 0.1, 0.4, 0.7, and 1.0 MPa), and the stress levels are 0.2, 0.4, 0.5, and 0.8. For processing the test data obtained under the stepped loading path, the Boltzmann superposition method and Chen’s method are applied. Then, the Burgers model is applied to estimate the stress and strain behaviors of the asphalt concrete materials. The results indicate that asphalt concrete materials characterize in primary and secondary creep stages. The data processed by Chen’s method is much closer to the data of separate loading path than those processed by the Boltzmann method. The Burgers model describes well the creep behavior of the asphalt concrete materials. Thus, it can be applied in the estimation and analysis of the creep behaviors for embankment dams under long-term operation.