Water Intrusion in Base/Subgrade Materials at Bridge Ends
Departments of transportation spend considerable time and money repairing pavement failures that occur in the base or subgrade materials near bridge ends. Investigation of these failures often reveal saturated base/subgrade materials. The objectives of this research were to determine all possible sources for water intrusion, develop methods to recognize in-the-field causes of water collection at bridge approaches, and to develop new repair methods that can be economically implemented in the field to minimize water intrusion or remove water from soils. Research focused on existing bridge approaches, concentrated on maintenance techniques to prevent water intrusion at bridge ends, and included an extensive literature review. Several state transportation agencies were contacted for information on design features such as drainage systems and repair techniques. Researchers surveyed the 25 Texas Department of Transportation (TxDOT) districts to gather observations about major factors contributing to water intrusion and settlement at bridge ends. Four TxDOT districts were visited for field investigations of specific bridges, and one bridge was selected for field testing to determine sources of water intrusion for a recurring seepage problem. Based upon information collected, researchers developed a site assessment technique to evaluate the potential of a particular site to incur water intrusion, and methods to develop optimum repair strategies. Several recommendations resulted including an implementation project plan to examine repair techniques in field trials for comparison.