PCa UNDERGROUND STEEL COLUMN INSERTION METHOD FOR CAST- IN-PLACE PILE

PROBLEM TO BE SOLVED: To provide a PCa underground steel column insertion method for cast-in-place pile which enables early commencement of construction of above- ground stories, improves the efficiency of the construction, shortens a construction period, and reduces construction costs. SOLUTION: According to the method, PCa underground steel columns 7 are erected on the ground 1, and PCa girders 12 are erected on head portions of the PCa underground steel columns 7, followed by placing concrete into an area forming a first-story floor 15, to thereby form the first-story floor 15. Then, earth retaining walls 10 are set outside the first-story floor 15, and horizontal struts 16 are set between both the earth retaining walls 10 and the first-story floor 15. Next, excavation for a basement is carried out by using the first-story floor 15 as a work floor, and at the same time skeleton construction of the above-ground stories is started. Further, mat slab bars 20 are arranged on the basement, and concrete is placed, to thereby form a basement mat slab 22 on a basement bottom portion. In this manner, skeleton construction of the basement and the skeleton construction of the above-ground stories can be carried out at the same time.