Bellows material into the hole after a tensioned prestressed is an important part of prestressing system, has long prestressed works with metal bellows as a pore material, in order to overcome the metal bellows seal is poor, fragile, easily corroded, Moldova resistance big disadvantage, but also in order to provide an extra layer tendons corrosion barrier, recommended making polyethylene or polypropylene plastic bellows as bonded post-tensioned revolutionary products to improve the life of the structure. Corrugated plastic pipe performance indicators: prestressed pore system and a corrugated plastic pipe fittings composed post-tensioned grouted should meet the needs; in addition to heat welding connection, it can also provide a special seal between the pipe and the pipe connecting devices; the whole system is equipped with an exhaust into the hole, drainage, drain slurry pipe to meet the need for pressure or vacuum assisted grout filling. 2 plastic bellows, material properties comply with CJ / T3078's. 3 plastic corrugated pipe is black, inside and outside walls are not allowed to melt fracture, lumps, bubbles and other serious defects, to achieve a small plastic ring stiffness and friction coefficient should be spaced circular bellows pipe waveform. 4 plastic corrugated pipe is equipped with a sealing device with Anchorage reliable connection. Sectional area within five plastic bellows at least 2.5 to 3 times the tendons. 6 plastic corrugated pipe friction coefficient of u is 0.10 ~ 0.14, k take 0.0008 to 0.0015. 7 plastic corrugated pipe has sufficient flexibility and anti-friction properties, in order to prevent wear curve layout and beam, channel rupture tension, the spacing of steel is not recommended more than 0.8 meters, the minimum bend radius of 0.9-1.5 m.