Method for constructing cylindrical tank

A method for constructing a cylindrical tank which has a metallic inner tank and a concrete outer tank, comprising:

• a step of building up a sidewall of the concrete outer tank in an outer circumferential edge portion of a base portion of the concrete outer tank;
• a step of assembling a roof portion of the concrete outer tank on the base portion of the concrete outer tank other than the outer circumferential edge portion;
• a step of lifting the roof portion of the concrete outer tank which is on the base portion of the concrete outer tank using a jack-up unit while the sidewall of the concrete outer tank is being built up and then holding the roof portion on the sidewall of the concrete outer tank;
• and
• a step of assembling the metallic inner tank independently of the roof portion of the concrete outer tank in a space under the roof portion of the concrete outer tank which is created due to the lifting by alternately repeating lifting of an inner tank lateral plate using the jack-up unit and attachment of a next inner tank lateral plate to a lower side of the lifted inner tank lateral plate,
• wherein the method further includes installing a hanging-side jack stand in the sidewall of the concrete outer tank above the roof portion of the concrete outer tank, installing a hanged-side jack stand in the roof portion of the concrete outer tank, and installing the jack-up unit across the hanging-side jack stand and the hanged-side jack stand, and the step of lifting the roof portion of the concrete outer tank includes hoisting the roof portion of the concrete outer tank using the jack-up unit,
• wherein positions of the hanging-side jack stand and the jack-up unit in a vertical direction can be changed during the step of lifting the roof portion of the concrete outer tank, and
• wherein the lifting of the roof portion of the concrete outer tank using the jack-up unit and the lifting of the inner tank lateral plate using the jack-up unit are performed independently and in parallel with each other.