Strip member for spiral pipe and rehabilitation method of existing pipe

A strip member configured to be spirally wound to form a spiral pipe, the strip member comprising:

• a strip body made of a synthetic resin, wherein the strip body includes:
• a flat strip portion that is flat;
• a first fitting portion disposed at one end portion of a cross-section orthogonal to an extending direction of the strip member, the first fitting portion integrally continuing to an end portion of the flat strip portion, wherein a fitting groove is formed in the first fitting portion, the fitting groove being open to an inner surface side of the strip member;
• and
• a second fitting portion disposed at the other end portion of the cross-section, wherein the second fitting portion has a fitting protrusion which protrudes from the flat strip portion toward an outer surface side of the strip member, the fitting protrusion of the second fitting portion being configured to be fitted with the fitting groove of the first fitting portion preceding by one turn,
• wherein the strip member has a reference width direction extending between a first point on the fitting groove and a second point on the fitting protrusion, the first and second points being in contact with each other when the protrusion is fitted into the groove;
• and
• a cross-section adjustment member, wherein the cross-section adjustment member includes:
• a pair of anchoring portions caught by the strip body;
• and
• a protruded portion laid between the pair of anchoring portions and which protrudes toward the outer surface side,
• wherein in a non-curved state of the strip member, the reference width direction is parallel to the flat strip portion, and a neutral weak axis having a minimum moment of inertia of area of the strip body is inclined toward the fitting groove and toward the outer surface side relative to the reference width direction, and a neutral weak axis having a minimum moment of inertia of an entirety of the strip member is inclined toward the fitting groove and toward the inner surface side relative to the reference width direction, and
• wherein when the strip member is spirally wound into the spiral pipe, the neutral weak axis of the entirety of the strip member becomes parallel to a pipe axis of the spiral pipe and the reference width direction becomes inclined toward the fitting groove and toward the outer surface side relative to the pipe axis such that a perimeter of the spiral pipe enlarges as the strip member is spirally wound.