Depth Analysis of Slurry Diffusion in Top Pipe of PAM Polymer
As an important part of pipe jacking construction,the effect of drag reduction directly affects the quality of pipe jacking project.In order to study the diffusion mechanism of drag-reducing slurry for pipe jacking,PAM was chosen as slurry admixture,and orthogonal test and rheological prop-erty test were utilized to determine the optimal ratio and fluid properties of the slurry.Based on the gen-eralized Darcy's law and related fluid mechanics theory,the calculation formula for the penetration and diffusion depth of PAM polymer slurry for pipe jacking in sandy soil stratum is deduced.The effects of grouting pressure,formation permeability coefficient and groundwater pressure on the penetration and diffusion depth of slurry under the conditions of whether or not to consider the self-weight of slurry were comparatively analyzed in conjunction with the jacking project of 4 #～5#wells of external drain-age of the second phase of Haikou Meilan Airport.The results show that:the optimal ratio of PAM slurry for pipe jacking is:Na-bentonite:soda ash:PAM:water=9％:1.3％:0.13％:89.57％.The flow pattern of the slurry conforms to the power law fluid with yield value,the diffusion depth of slurry in sandy soil increases with the increase of initial grouting pressure,formation permeability coefficient,and decreases with the increase of groundwater pressure.
top pipe grouting mudorthogonal testflow characteristics testtheoretical deriva-tionpenetration diffusion
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