Substantial cost saving can be achieved if culverts are constructed with on-site marginal soils as backfill materials, rather than with imported granular soils. To increase the structural integrity of culvert good compaction by the dynamic compaction roller with big capacity is as effective as good backfill materials. However structural distress of the culvert may be induced due to the excessive earth pressure generated by applying large compaction load (Lazebnik,1998). In this study, several concrete box culverts were constructed with different compaction materials and construction methods. Three types of on-site soils - subbase, subgrade and roadbed materials - were used as backfill materials in the test program. Compaction methods were adapted based on site conditions. In most case, dynamic compaction rollers with 10 to 16 ton weights were used and vibration frequency ranged 2400 to 2500 rpm to obtain large compaction energy. The effect of EPS(Expanded Polystyrene) panels was examined at various thickness. This paper presents the characteristics of earth pressures and the vertical settlement. It was observed that subgrade and roadbed materials required more careful compaction work than subbase material and that EPS panel is efficient to mitigate dynamic earth pressure on the culvert.
The Korea Highway Corporation (KHC) manages 20 route of 2026.7 km in current. We expect the expressway up to 3700 km by 2004. In the past, culvert was traditionally considered less attention than bridge structures due to embedded structure. Poor compaction with poor quality material may cause uneven settlement over the culvert and possibly structural distress of the culvert. For this reason, the specification of KHC has designed that granular materials as backfill material to increase the structural integrity of culvert (Roh,1999). With increasing number of constructions, it is more difficult and expensive to get granular materials than before.
