Study On Grouting Behind Shield Tunnel Wall Under Different Diffusion Modes

Grouting in the shield is a key process to protect tunnel construction safety and reduce surface settlement.It has been the focus of many scholars.In actual engineering,there are generally theoretical studies after actual cases,as well as in grouting.Grouting theory lags behind on-site construction.At present,some scholars have studied the law of the diffusion of slurry,but with the continuous development of processes and materials,there are still many problems to be solved.Based on this background,the paper combines shield construction and theoretically deduces the problem of grouting diffusion.Under the filling and diffusion model,in the process of Bingham fluid analysis,the study considers the difference between the grouting slurry pressure in the fluid flow process and the negligible flow core region,and points out the necessity of considering the nuclear region.The pressure distribution law of the grouting slurry densified by the Bingham fluid in the circumferential direction when considering and neglecting the viscosity of the slurry is derived.The two main factors affecting the circumferential pressure distribution are the slurry's own weight and viscosity coefficient.In the osmotic diffusion model,the hemispherical and cylindrical diffusion laws of the grouting wall after the shield wall is considered to be uneven.It mainly analyzes the range of slurry diffusion and the expression of the pressure of the slurry in the two diffusion modes,and analyzes the influence of relevant parameters on the diffusion range and the pressure of the tube by case,and points out that the model is suitable for the shield injection in sandy soil.Pulp calculation.In the compaction diffusion model,the hemispherical and cylindrical diffusion laws of the grouting wall after considering the osmotic effect are derived.It mainly analyzes the law of segmental pressure in hemispherical mode and the maximum displacement of surface in cylindrical diffusion mode,and analyzes the influence of relevant parameters on the pressure of the segment and the maximum displacement of the surface by case,and points out the viscosity in the poor permeability.The necessity of considering the osmotic effect in the soil.Finally,combined with the above analysis,it is pointed out that the influence of each grouting parameter on the final grouting effect in the actual project providessome theoretical support for the selection of the final parameters.At the end,a brief discussion of unresolved issues and further research is available.