Case Studies of Earthquake Resistance Measures and Analyses by Compaction Method for River Embankments

Abstract

The "Guide to Measures against Liquefaction of River Embankments" lists "compaction method" as one of the liquefaction countermeasures. Among compaction methods, the sand compaction pile (SCP) method is the most typical method and can be classified into three types: the "SCP method for vibratory type (vibratory SCP)”, the "Static compaction sand pile method for non-vibratory type (non-vibratory SCP)”, and the "Static compaction method for sand injection type with small machine (sand- injection type SCP). In this paper, we report on examples of river embankments where the SCP method was used for restoration work and seismic countermeasures improved just below and at the bottom of slope, and on the improvement effects of the method. In recent years, it has become possible to apply the slanting improvement method using a small machine, and the influence and factors of the improvement location (just below, at the bottom of the slope, or at an angle) on the amount of settlement of the embankment top are discussed based on the results of static deformation analysis (ALID) when the compaction improvement is applied to liquefaction countermeasures for embankments.