| 摘要 |
PURPOSE: A reinforcing spiral tube for synthetic resin is provided to form a melted reinforcing layer by melting upper and lower surfaces of each superposed hollow and to reinforce weakness of the hollow by filling hard foaming agent. CONSTITUTION: A reinforcing spiral tube for synthetic resin is formed as a two-layer structure by forming a melted reinforcing layer. Each hollow(11,11') is divided to an upper layer and a lower layer. The melted reinforcing layer is formed by attaching a lower surface(16) with an upper surface(15') of the hollow. A hard foaming agent(14) fills each hollow. Therein, the reinforcing spiral tube is supplied. Therefore, weakness of the hollow like underground settlement is reinforced.
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