Case History of a Geosynthetic-Stabilized Base Roadway Founded over Expansive Clay Subgrade

摘要

Performance of a geosynthetic-stabilized base roadway founded over an expansive clay subgrade in Texas was evaluated over a period of 4 years. The construction involved three test sections. Two test sections were stabilized using two triangular geogrids of different characteristics and one test section was constructed without geogrid (control section). The geogrid layer was installed between a chemically-treated subbase and a flexible base layer. A comprehensive monitoring program was conducted to evaluate the performance of the roadway under environmental loads. Specifically, vertical movement of the roadway over time induced by recurring heave and settlement of the expansive clay subgrade was monitored. In addition, severity and extent of the environmental longitudinal cracks, identified as the main damage results from the expansive clay subgrade, were documented in each test section using data collected through rigorous visual condition surveys. Environmental conditions of the site, in form of changes in temperature and precipitation, was also closely monitored. Evaluation of the data collected on this roadway provided evidence for mechanisms that result in the development of environmental longitudinal cracks. In addition, comparison of the performance of the geogrid-stabilized test sections with the control section underscored the benefits from geosynthetic stabilization in mitigation of damages induced by the expansive clay subgrade. Furthermore, the observed difference between the performances of the two test sections stabilized with geogrids of different characteristics underscored the impact of geosynthetic characteristics on the benefits result from geosynthetic stabilization.