Proposal of Control Criteria for Embankment Compaction in Hokkaido

As the quality of embankments is correlated to their strength and density, which can be determined easily at low cost, methods based on the degree of compaction are widely used in quality control. In light of recent increased demand for a safe, secure social infrastructure, there is growing interest in road embankment and riverbank structures that have sufficient strength to withstand earthquakes and severe storms brought by abnormal weather conditions. The authors studied the relationship between the degree of compaction and the strength of the embankment type mainly used in Hokkaido, and determined variations in density and materials at execution sites. The results showed that: (1) as the degree of compaction decreases, shear strength is reduced; (2) embankment quality control methods involving impact acceleration provide favorable results; (3) the materials used for quality control may be different from the actual materials used for embankments; (4) since the characteristics of embankments vary significantly, quality control methods that take such variations into account should be used; and (5) the reference values specified by the Hokkaido Regional Development Bureau may not match the actual values of materials for which the maximum dry density cannot be determined from compaction curves. The authors therefore believe that the current criteria should be reviewed, and propose control criteria that match the actual situations of the embankment type adopted by the Hokkaido Regional Development Bureau.