Study On The Through Cracks Grouting Diffusion Law Of Tunnel Lining Straight Wall

It can be seen that ignoring the effect of void in the structure on the safety and usability of the structure will cause serious consequences.The grouting technology,by using solidifiable pulp,can seal and reinforce the void of the original structure without damaging the original structure,which has unique advantages.Since the birth of grouting technology,it has started its pace of self-improvement.After 200 years of development,it has been applied in many aspects of civil engineering,and has long been applied in tunnel grouting water plugging.By studying the stone rate and rheological characteristics of the slurry with ultrafine cement as the main agent,and establishing the corresponding diffusion model,the diffusion pattern of the slurry in the through-hole crack was finally simulated through model experiment,and the diffusion law of the slurry in the crack was explored.The main discussion was as follows:? In ultra-fine cement slurry,in different water-cement ratios,bentonite incorporation and fly ash incorporation in various proportions,the change of stone body volume of 200 ml slurry is the change of slurry stability.The results show that the stone rate of slurry is inversely correlated with water-cement ratio,positively correlated with bentonite content,and negatively correlated with fly ash content.Finally,through orthogonal test,it is found that the main factors affecting the stone rate of grouting slurry are water-cement ratio and bentonite content.At last,the serous mixture with good stability was found by orthogonal test.? MCR102 rheometer was used to test the shear rate and shear strain of a series of ultrafine cement grout with different proportions.It was found that the shear rate-shear force curve of ultrafine cement grout with different proportions was consistent with the mathematical description form of bingham fluid,and it was bingham fluid without flow pattern change due to the change of proportion.In different proportions,the water-cement ratio of ultrafine cement increases and the viscosity of ultrafine cement decreases.With the increase of bentonite content,the viscosity of ultrafine cement paste increases gradually.With the increase of fly ash content,the viscosity of ultrafine cement slurry decreases continuously.In the case of double mixing,the change of water-cement ratio has a more significant effect on the initial shear force and plastic viscosity of ultra-fine cement paste than that of other factors.The slurry viscosity can be controlled by adjusting water-cement ratio,bentonite admixture and fly ash admixture,so as to save materials and ensure the injectability of slurry.? Based on fluid mechanics tables describe the Navier-Stokes equations of viscous fluid,probes into the slurry is given priority to with superfine cement slurry agent such as bingham fluid in the tunnel lining two straight wall through crack spread in the form of pipe flow,such as crack width,grouting materials,grouting time grouting parameters,such as viscosity and the relationship between the slurry eventually spread distance.Finally,the diffusion model of bingham fluid in the crack of tunnel lining straight wall was established,and the slurry diffusion model to some extent was obtained.It can be seen from the model that the diffusion radius of slurry is related to crack width,viscosity of bingham fluid,initial shear force,grouting time and other factors.? By means of two adjacent cast-in-place concrete made by ourselves and the middle crack formed by them,the penetrating crack of the existing tunnel lining straight wall is simulated,and the diffusion path of ultra-fine cement grouting slurry in the penetrating crack is explored.In the experiment,different crack width,slurry ratio and grouting speed all show the influence characteristics on the slurry diffusion trajectory,among which the same is that the diffusion shape of ultra-fine cement slurry is ellipse,and different influencing factors reflect the difference in the ratio of the major and minor axes of the ellipse.With the increase of grouting time,the boundary of slurry diffusion becomes larger.As can be seen from the slurry diffusion morphology,the initial diffusion rate is larger,and then the diffusion rate is slower.Finally,the maximum distance of slurry diffusion in x axis direction at the slurry diffusion boundary has an extreme value.At the same time,the difference with x axis direction is that the positive slurry diffusion boundary of y axis is hindered by the gravitational field,and the limit value of slurry diffusion boundary appears faster.The negative slurry diffusion in the Y-axis is enhanced by the gravity field,and the slurry diffusion velocity slope still increases at a certain rate at 25 s.