| 摘要 |
PURPOSE: A spiral tube is provided to reinforce the flexibility and pressure proof to the present corrugated tube and to improve the use of connectors. CONSTITUTION: Integrated inner and outer wall surfaces(2,3) of soft plastics are formed by fusing inner and outer protrusions(10,11) of the present corrugated tube to a projected concave groove band(5). An inner wall surface(3) formed of soft plastics and protrusion(10) integrated with a corrugated supporting band is also provided with a reinforced wall surface in a triangular sectional form. Further, a corrugated reinforcing band with a steel core being inserted therein is integrated, formed between a concave groove of a corrugated supporting band and an outer wall surface to resist earth pressure.
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