Determination of Structural Benefits of PennDOT-Approved Geogrids in Pavement Design

摘要

The research was undertaken to evaluate and determine structural benefits of three Pennsylvania Department of Transportation approved geogrids for reinforcing weak pavement subgrade. A mechanistic-empirical approach was adopted to develop subgrade permanent deformation models for geogrid-reinforced flexible pavements. Multi-scale tests were conducted for the three geogrids. Mechanical and index properties of the geogrids were tested before the geogrids were subjected to bench-scale testing, namely pullout and direct shear tests. Two sets of accelerated pavement tests were carried out to investigate the effectiveness of geogrids in improving pavement performance. For each APT, four pavement sections were constructed in a pit with concrete walls, among which one was control and the others were reinforced with different geogrids. Two different types of soil were involved for the subgrade construction through the two sets of accelerated testing. Various instruments were installed in the pavement system to measure both static and dynhamic response of the pavements. Finite element models were created to simulate the pavement sections in the pit. Subgrade permanent deformation models were developed for pavement sections on the basis of the model adopted by the mechanistic-Empirical Pavement Design Guide. The MEPDG model was modified to accommodate the test conditions in the study.