Analysis On Displacement Regularity Of Large Diameter Pipe Jacking In Gravel Clay

Pipe jacking technology is a trenchless construction technique,and it is widely used in municipal underground engineering construction such as long distance water diversion tunnel,underground power pipe gallery,water supply pipeline,drainage pipeline and gas pipeline.Considering the size effect of large diameter concrete pipe,a wide range of soil is disturbed in the semi-infinite space,which results in the larger settlement deformation of the surface and the destruction of the environment.In this thesis,the disturbance effect on the surround soil,the stress characteristic and settlement deformation law are analysized in 4.14 m large dameter circular pipe jacking construction in gravel clay,based on large diameter concrete pipe jacking project of the diversion tunnel in Rizhao.Terchaki theory,finite element analysis method and the Peck settling tank theoretical formula are ultilized in analysis.The main research content is as follows:1)The traditional deformation band width calculation expression is revised,and deformation band width calculation expression for circular pipe jacking construction is given,based on Terchaki theory.The revised expression can be applied to circular pipe jacking.2)Three dimensional numerical dynamic analysis of 4.14 m circular diameter pipe jacking construction is carried out relying on the construction in gravel layer of the diversion tunnel project in RiZhao.Reasearch indicate that subsidence value of the soil at the top of the pipe is maximum in the part that has been excavated,and the farther the distance to axis of pipe jacking,the small the soil settlement of longitudinal section.In addition,the soil settlement due to jacking construction is relatively large in the range of 2 times the pipe diameter in the horizontal of pipe.3)Land subsidence due to jacking construction in gravel clay is calculated and analyzed,based on traditional Peck settling tank theory formula and revised expression.Failure mechanism of soil andland subsidence regularity considering different soil loss rate are given,as well.4)Deformation zone width values calculated by the revised expression and the ground settlement curve are compared with three dimensionalsimulation results,respectively.The analysis results are consistent with each other,the analysis conclusion is proved to be reasonable.