Abstract: A casing assembly for forming a cast-in-place pile (CIP) retaining wall based on a CIP method. The assembly comprising: a hollow elongate cylinder having a hollow cylindrical inner space defined therein; a H-beam guide received within the hollow cylindrical inner space of the hollow elongate cylinder; and a first H beam having a vertical column form and inserted into the H-beam guide, wherein the H-beam guide includes: a hollow beam-guide frame having a rectangular cross-section such that the first H beam is insertably guided in and along the hollow beam-guide frame; and an outer rounded frame coupled to an outer face of the hollow beam-guide frame, wherein an outer face of the outer rounded frame conforms to an inner face of the hollow elongate cylinder, wherein a top portion of the outer rounded frame is fixed to a top portion of the hollow elongate cylinder via a fastening flange.