Design Highway Clearances for Highway Pavements, Volume 1

摘要

High groundwater table exerts detrimental effects on the roadway base and the whole pavement. Base clearance guidelines have been developed to prevent water from entering the pavement system in order to reduce its detrimental effects. In these guidelines a minimum height, the clearance, between a groundwater level and a particular elevation within the pavement system is specified. This report presents an experimental study to evaluate the effects of high groundwater and moisture on determining pavement base clearance for granular subgrades. Full-scale in-lab test-pit tests were conducted to simulate pavement profile and vehicle dynamic impact on the pavement. Eleven types of subgrade were tested for this study. From the test, using layer theory, the results of the resilient modulus for each layer (layer resilient modulus) can be compared with the resilient modulus results from laboratory test. The dominant factor or factors of the effect of moisture to resilient modulus will be discussed. The results showed that a 36-in. base clearance was considered adequate for the base protection of most of the A-3 and A-2-4 subgrades against high groundwater tables. The lab resilient modulus and layer resilient modulus had the same trend for each soil according to the moisture content change.