Numerical Simulation of Full-Scale Testing Performed on Multi-Axial Geogrid Stabilized Pavements

Two full-scale unsurfaced pavement test sections containing multi-axial geogrids and a control test section were constructed at the US Army Engineer Research and Development Center (ERDC). Each unsurfaced pavement section consisted of 250 mm of crushed limestone aggregate base (AB) over a soft high-plasticity clay subgrade. Geogrid stabilized pavements were prepared by placing a layer of multi-axial geogrid at the interface of AB and subgrade. The test sections were instrumented to record the distribution of stress and strain at different depths. A single-axle dual wheel truck gear configuration mounted to one of ERDC's specially designed load carts was used to apply simulated truck traffic to the test sections where each pass of the truck gear was equivalent to 1.51 equivalent single axle loads (ESALs). Instrumentation response data and surface rut depth measurements were analyzed for performance evaluation of each test section. The results showed that the inclusion of geogrid contributed to minimizing the deformation of AB and subgrade. In addition to the experimental studies, numerical studies were performed using 2D Finite-Element (FE) simulation. FE models for geogrid stabilized and control test sections were developed in Plaxis using linear elastic constitutive soil models. The theoretical strain responses from the FE models were compared to the experimental dataset. The numerical results indicated that the stiffness of AB and subgrade is increased with the inclusion of geogrid. However, further numerical studies, incorporating a non-linear soil constitutive model and applying a moving wheel load with a dual tire configuration, are required to enhance the efficiency of the FE models.