Study Of Mud Ratio Friction Reduction And Rock Carrying Capacity In Hard Rock Pipe Jacking

Pipe jacking technology as a non-excavation technology metho d,because of its construction speed,low cost and does not affect the traffi c and other advantages,has been widely used at home and abroad,has be come an essential technology in the construction industry.In the process of hard rock pipe jacking,the injection of bentonite slurry is particularly i mportant for reducing the frictional resistance in the jacking process,or f or discharging the rock debris generated in the jacking process to prevent the occurrence of pipe jamming accidents;however,there is a lack of the oretical research on the ratio of slurry and slurry rock carrying capacity in hard rock pipe jacking,and there is a lack of similar engineering example s to provide reference for the construction of super-long curve hard rock p ipe jacking.This paper takes Fuzhou Pingtan water allocation project as the back ground,through literature research,theoretical analysis,numerical simula tion,indoor tests,engineering verification and other methods,the bentonit e slurry ratio of friction reduction and rock-carrying capacity of the study,the main research content is as follows:(1)The main types of forces on rock debris under pressurised grouti ng are analysed by using dimensional analysis to find out the factors affec ting the rock-carrying force of the slurry,which leads to the formulation o f the rock-carrying force.(2)Through the bentonite mud ratio test,the study of different ratios and additives on the mud performance parameters of the law,found that t he polyacrylamide for the mud performance parameters have a better opti mization effect,the most suitable for this pipe jacking process in the opti mization of the mud performance.(3)A The numerical simulation method was used to simulate the flo w state of mud in the tunnel,and the changes of flow state of mud in the t unnel with different parameters were analysed.The effect of slurry consis tency factor,flow index and grouting pressure on the flow rate and pressu re distribution in the tunnel was obtained;the suitable slurry ratio(water:bentonite: polyacrylamide = 1:10.22%:0.07%)was selected by combining the ratio test results and the dynamic viscosity of the slurry.The paramet ers obtained were incorporated into the rock carrying capacity calculation equation,and a slurry pressure of 0.28 MPa was selected;the field applic ation was used to compare the discharge of rock debris particles,and it w as found that the rock debris particles could be effectively discharged fro m the tunnel.(4)The results show that the injection of mud can form a high qualit y mud jacket and reduce the jacking force;and the pressurised grouting c an discharge the rock debris generated during the jacking process,which i s very important to ensure the smooth progress of the project.There are 112 figures,12 tables and 65 references in this dissertation.