EARTHQUAKE RESISTING PIPE JACKING METHOD, PIPE JOINT FOR USE IN EARTHQUAKE RESISTING PIPE JACKING METHOD, AND WATER-SOLUBLE POLYMER

摘要

PROBLEM TO BE SOLVED: To solve a problem of insufficient earthquake resistance of a conduit, i.e., insufficient stretchability of the same in both directions, the conduits being laid under the ground by pressing the rear thereof. SOLUTION: There is provided a joint for use in an earthquake resisting pipe jacking method, which is constructed by interposing a propelling force transmitting ring 3 between a pressing flange 11 sheathing an insertion port 1 of a pipe 10A to be fitted, and a side end face 21 of an opening of a receptacle 2 of the other pipe 10B, whereby propelling force is transmitted by the ring 3 to form the conduit. After completion of the propulsion, the ring 3 swells and melts to lose the compressive strength thereof, and the joint have an annular dissolved layer R which allows expansion and contraction over a peripheral surface thereof. Alternatively, the ring 3 is dissolved and disappeared to thereby form a void over the peripheral surface thereof. The ring 3 may be formed of any of a water-soluble polymer, an alkaline water-soluble polymer, an acid water-soluble polymer, especially poly(vinyl alcohol) and its derivative, poly(N-vinyl pyrrolidone) and its copolymer, copolymers of various vinyl monomers containing a carboxyl radical, a sulfonic acid radical, an amino group and their salts, and combinations between any of these materials, other polymers, and fillers. The materials thus prepared are of high practical value.