Control Of The Key Technology Links In Pipe-jacking Project Construction

Pipe jacking is a modern construction method in laying pipes. Recently in the construction of sewage, industrial underground pipe, underground walkways, underground passage crossing the highway and railway , the pipe jacking method has been widely used home and abroad, in order to avoid the destruction of underground structure, especially in the scenic spot, and to reduce traffic impact, even considering from the economic effect , pipe jacking method is superior to laying pipe through cut and cover.Theoretically, the jacking force can be enhanced arbitrarily, so the jacking distance can reach arbitrary length. But the jacking force is supported by the pipe, and the bearing capacity of pipe is limited, meanwhile the supporting pit is aim at economic saving. Oversize jacking force need bigger bearing capacity of the pipe and pits, so the investment and technology cost is enlarged.To reduce resistance of the pipe jacking, fort Benton from USA discovered bentonite in 1890. the main component of bentonite is montmorillonite, it is a clay mineral which has the dual property of supporting and lubrication.Large numbers of researches and constructions have proved that using the bentonite and modified slurry in the pipe jacking construction can form the slurry sleeves: this slurry sleeve is required to have the physical properties that when it is subjected to shear, the consistence becomes smaller, and motion flow limits is decreasing, but the consistence becomes bigger and static flow limits is increasing after stopping shear. So the use of slurry is helpful to reduce jacking force and beneficial to the successful accomplishment of the pipe jacking construction.Based on actual engineering, and combining with the friction law,hydraulic transmission knowledge and the application of earth pressure analysis; this thesis discusses the research and application of thixotropic slurry during pipe-jacking. It is great benefit for the jacking force calculation ,the thixotropic slurry using and the jacking force decreasing, and this thesis also hopes to improve the application of pipe jacking resistance reducing theory to a high level.