Abstract
The CPG method is a method of increasing the soil density by injecting mortar, and it is applied as a liquefaction countermeasure under the existing structure of the ports and airports. However, ground upheaval often becomes a problem. The “up and down method (U/D method),” a new CPG method, was developed in our previous small-scale model tests and field tests. This new method greatly improved upheaval control and the efficacy of liquefaction mitigation compared with the conventional CPG method. The purpose of this research was (1) to increase construction efficiency (2) verify upheaval control mechanism. Consequently, it was found that the workability can be improved by using an injection pipe with a tip end tapered shape. The upheaval control mechanism was found to be explained by the cyclic elastoplastic contraction of the ground due to the up and down of the new CPG method.
