Dissertation > Transportation > Road transport > Tunnel project > Tunnel construction > Construction methods > Shield Law ( full- face excavation )

Study on Grout Penetration Diffusion Mechanism and Segment Sreess Impact of Shield-driven Tunnel

Author ZhangJinLong
Tutor YeFei
School Chang'an University
Course Bridge and Tunnel Engineering
Keywords shield-driven tunnel back-filled grouting diffusion mechanism stress ofsegment numerical simulation
CLC U455.43
Type Master's thesis
Year 2013
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This paper trys to study the shield-driven tunnel’s back-filled grouting diffusionmechanism and mechanical characteristics with the method of theoretical derivation andnumerical simulation combined. At present, domestic and foreign scholars haveconducted a series of studies on the grout of mechanism, but there are still have someproblems to be solved; At the same time, the research on grouting layer effect on thestress of the tunnel lining segment is less. Based on this background, The paperresearches the problem of grout diffusion carried on the theoretical derivation andnumerical simulation.Firstly,In the generalized Darcy’s law and the spherical diffusion theory model,and the introduction of slurry viscosity time-varying, with the consideration of slurryviscosity modified Bingham fluid slurry back-filled grouting of the spherical diffusionequation was deduced. The formula shows the relationship between grout diffusionradius and diffusion time, then derived the grouting pressure on the segment andsegment pressure on unit area, finally analysis an engineering example.Secondly,This paper proposed non-uniform equivalent void ratio formula, usingnon-uniform equivalent porosity instead of shield tail gap influence within the scope ofthe original porosity of soil. Based on the generalized Darcy’s law and sphericaldiffusion theory model the formula of Bingham fluid is given.Lastly, Considering serous timeliness Bingham fluid calculation results ascalculation parameters of the instance, using ANSYS finite element software wascarried out on a ring lining segment Three-dimensional numerical simulation analysis.The paper analyzed the consideration of timeliness Bingham grout diffusion offormation stress, the influence of ground surface deformation and internal force ofsegment. Under different grouting pressure, grout diffusion on the changing laws ofsurface displacement and the influence of the segment internal force variation law wasdiscussed.

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