The Asphalt Core Embankment Dam:A Very Competitive Alternative

摘要

The asphalt core embankment dam is gaining in popularity as the advantages of this design become more apparent.Countries like Austria,Germany,China and Norway,among others,have built many of this type of dam over the last 50 years,and now new countries like Brazil and Canada are building their first ones. A summary of recent research results and case studies is presented.Laboratory tests have demonstrated the high resistance of asphalt concrete to earthquake shaking and to tensile strains without cracking even at very low temperatures. The selfhealing (self-sealing) of any cracks that may occur due to accidental loads takes place very quickly. The requirements to asphalt aggregate quality do not have to be as strict as those practiced for asphalt concrete in pavement construction. This opens up the possibility for using aggregates available locally,and there is no need to transport aggregates over long distances to meet the strict pavement criteria.Field experience and special field tests have demonstrated that the rate of construction of an asphalt core can be increased considerably compared to previous practice without reducing the core quality. The core may be built in rainy and cold weather,and the core construction will not slow down the construction of other zones of the embankment.Field case studies also confirm that asphalt core dams may be successfully built with lower grade compacted rockfill than that usually required in earlier dams of this type. The dam may be built over compressible foundations as the core,due to its ductile and viscous behavior,-can accommodate differential foundation settlements without cracking. The difference between the stress-strain behavior of laboratory-and field compacted specimens,even with the same air porosity,must be recognized and accounted for in the quality assurance and control program during core construction. The differences are discussed,and a method of laboratory compaction has been developed that best simulates the field roller compaction for an asphalt core. A comparison is made among embankment dams designed with earth core,asphalt core,reinforced concrete facing,and geomembrane facing,respectively,pointing out relative advantages and disadvantages.