Method for preparing and preventing plug of wide-span case beam rear tension method prestress pore passage

Abstract

The invention discloses a method for preparing a prestressed duct of a large-span box girder by a post-tensioning method, and an anti-blocking method. The method adopts high-density polyethylene (HDPE) or polypropylene (PP) as a main material and a round plastic corrugated pipe formed by high temperature extrusion, utilizes U-shaped or well-shaped reinforcing steel bars to produce upper-layer andlower-layer reinforcement cages and a reinforcement positioning cage between the upper-layer and lower-layer reinforcement cages, and fixes and positions the plastic corrugated pipe in the reinforcement positioning cage. The blocking prevention of the duct is realized by adopting a technological measure that a polyethylene (PE) anti-blocking plastic mandril passes through the plastic corrugated pipe. The friction coefficient of the duct formed by the method is apparently lower than that of a duct made of metal material, and the toughness, the anti-seismic performance and the fatigue-resistantperformance are superior to those of similar products, and the unimpeded rate of the duct can reach 100 percent. The method can quickly, effectively and reliably form the prestressed duct, and is also suitable for other large-volume prestressed concrete structures.

Description

technical field [0001] The invention relates to a bridge construction method, in particular to a preparation method and an anti-blocking method for a large-span box girder post-tensioning prestressed channel used in railways, highways and urban bridges. Background technique [0002] With the rapid development of my country's national economy, the number of high-speed railway and highway construction projects is increasing, and the long-span bridge scheme has become the first choice for my country's cross-sea and cross-river passages. However, the post-tensioned prestressed tunnels of long-span bridges have the problems of making holes and ensuring the smoothness of the tunnels. This is because most of the traditional prestressed pipes are iron corrugated pipes, which are generally rolled by steel strips with a wall thickness of 0.5--0.7mm. As a result, the rolling process is usually crimped and spirally connected, and some corrugated pipe products are added with a galvanized...

AI Technical Summary

Problems solved by technology

This kind of prestressed pipeline has the following problems: 1. Due to the defects of the manufacturing process, the iron sheet connection joint runs through the entire bellows, which inevitably causes the problem of leaking; 3. The metal corrugated pipe is positioned in the steel skeleton. When the steel bar is positioned by spot welding with an electric welding machine, the spattered welding slag often burns the iron skin and forms holes; 4. Comparison of design arcs When installing large tunnels, a slight carelessness in the operation of the curved metal bellows will easily lead to loosening of the joints; 5. Bridge construction is mostly open-air operations. When the construction period is long, the metal pipes are prone to corrosion and damage, and the cost of adding galvanized coating is equivalent. Big

In addition, in the process of pouring concrete, the vibrating rod will inevitably touch the iron bellows, resulting in damage or collapse

When the corrugated pipe is damaged, the cement slurry will enter the channel when pouring concrete, causing the pipe to be blocked; if it is deformed and collapsed, it is difficult to ensure the design size of the channel, making it difficult for the steel strand to penetrate

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