CONSTRUCTION METHOD FOR EXTENDING BULB OF THE GROUND ANCHOR BY POST GROUTING AND BULB EXTENDING APPARATUS BEING USED FOR THE SAME

摘要

The present invention relates to a method for expanding a bulb of an underground anchor pile, which generates crack on a grout bulb through a post-grouting process which repeatedly injects high pressure grout before the solidification of the bulb is developed after a first bulb is formed by using a gravity or a pressing method to inject the grout in a bored hole and which makes a high pressure grout material penetrate a crack gap to expand the bulb; and to a bulb expanding device used for the same. The method comprises a first step for performing pre-grouting after forming an anchor hole by boring the ground; a second step for inserting an anchor into the anchor hole, and filling and curing grout; a third step for causing random cracks in the filled grout by sprouting the high pressure grout through an outlet of a grout hose that is inserted together with the anchor into the anchor hole, and for making the high pressure grout penetrate gaps of the cracks; and a fourth step for expanding the bulb by repeatedly performing the third step.