摘要
Ordinary columns of jet grouting are circular or fan-shaped. But in recent years, such shapes as candy-shaped columns were put to practical use. They are constructed by switching the rotational speed of the stem in one rotation. We applied this method to swing jet grouting. That is, we changed the rotational speeds in the swing jet grouting to make elongated columns near rectangle. The test construction was succeeded and the columns’ shapes conformed to those designed. In addition, the quality was confirmed to be as good as ordinary columns. Radii （distances from center to outer ends） were 1.03 to 1.21 times as large as those designed. Improvement ratios were 95% or more in any position. Strengths were varied by location, but they satisfied design strength 1.5 kN/m2 at any position. We concluded that this new column can be applied to practice in the same way as ordinary columns.
