摘要: |
Compaction of embankment, subgrade, and base materials is a significant portion of state highway construction budgets and is critical to the performance of highway pavements. Heterogeneity of earth materials, variability in equipment and operators, and difficulty in maintaining uniform lift thickness and prescribed moisture content combine to make desired earthwork compaction difficult to achieve. Current quality-control and quality-assurance testing devices--such as the nuclear gage, the dynamic cone penetrometer, the stiffness gauge, and the lightweight falling weight deflectometer--are typically used to assess less than one percent of the actual compacted area. In addition each of these testing devices measures values unique to the device. Intelligent soil compaction has the potential to improve infrastructure performance, reduce costs, reduce construction duration, and improve safety. Intelligent soil compaction involves: (a) continuous assessment of mechanistic soil properties (e.g., stiffness, modulus) through compaction-roller vibration monitoring; (b) continuous modification of roller vibration amplitude and frequency, and (c) an integrated global positioning system to provide a complete GIS-based record of the earthwork site. Research findings in Europe and in the United States have shown that soil stiffness and modulus can be assessed through vibration of the compaction roller drum and that continuous monitoring, feedback, and automatic adjustment of the compaction equipment can significantly improve the quality of the compaction process. Standard specifications for the application of intelligent compaction systems in the United States are needed. Such specifications should build on existing specifications and experience gained in Germany, Switzerland, Finland, Sweden, Japan, and other countries. The objectives of this research are to determine the reliability of intelligent compaction systems and to develop recommended construction specifications for the application of intelligent compaction systems in soils and aggregate base materials. |