To design a diaphragm wall economically and rationally.
A prestressed steel pipe 16, which is inserted into a sheathed pipe 14 and in which a lower end is fixed onto the main body 10 of a diaphragm wall, is buried beforehand into the main body 10, and tensile force is introduced to the steel material 16 after the construction of the main body 10. The internal surface side of the main body 10 is excavated primarily up to an excavating surface 17, struts 18 are installed, and secondary excavation up to a final pit excavating surface 19 is predetermined. Bending moment with excavation largely differs at the time of primary excavation and the time of secondary excavation. Approximately the same tensile force has been introduced between an anchor 30 at a lower end and anchor 31 at an upper end to such bending moment. However, prestress is effective at the time of primary excavation, but a reinforcement for coping with prestress is required at the time of secondary excavation in a section A. The steel material 16 is coated beforehand with a separation material 22 in the section of a specified section at that time, and the tensile force of the steel material 16 is released after the struts 18 are mounted after the completion of primary excavation.
CHIKAMATSU RYUICHI
AIHARA ISAO
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