PURPOSE: To enable holding of frames more reliably and safely in comparision with a conventional method in which a separator is coupled to a sheet pile and to prevent coming off of the separator from a retaining side when placing concrete.

CONSTITUTION: A holding metal 5 for inner end of a separator is secured by means of a clamping system 6 on a flange 4 of a H-steel in a sheathing 3 in which a sheet pile 2 is held by mating it between H-steels driven-in vertically. A separator 7, coupled to said metal 8, and a frame clamping metal 8, coupled to the separator 7, hold a concrete frame 9, keeping a proper distance away from the retaining wall 3.