Study On The Lubricating And Resistance-reducing Wall-protecting Slurry System Used For Ultra-long Pipe Jacking

The pipe jacking construction method is used for laying pipe underground with trenchless technology,which is widely applied in domestic,and the long-distance,large-diameter pipe jacking is also more and more accepted.The grouting and friction reducing is an important measure for reducing the resistance of pipe jacking,increasing the distance of each jacking,especially for ultra-long pipe jacking,it is the key step which decide the success of jacking.When the pipe jacking jacks,some resistance-reducing slurry have been injected to pipe exine through the reserving the grouting hole of tool pipe and pipe section,which forms a slurry suite to reduce the friction of pipe section exine and soil layer,and finally to reduce the jacking force.The quality of the formation of slurry suite is directly related to the effect of resistance-reducing,if the intact slurry suite is formed around the pipe by the grouting slurry,the effect of resistance-reducing is satisfactory,but the regular grouting method usually cause the situations of slurry migration and uneven grouting,which lead to excessive increase of jacking force,and even cause the pipe broken.So ultra-long pipe jacking have some new demands for grouting materials and grouting process.Based on lots of constructions techniques of pipe jacking and analytical data of lubricating and resistance-reducing wall-protecting slurry system,with combination of the domestic and overseas advanced techniques,and through comprehensive consideration of the construction characteristics and experiences of pipe jacking,this paper have developed a lubricating and resistance-reducing wall-protecting slurry system used for ultra-long pipe jacking in complex strata and the grouting process,solving the technical problem of ultra-long pipe jacking using for complex strata.And based on this,a ubricating and resistance-reducing wall-protecting slurry system that achieve international advanced level,which can solve the problems such as strata collapse when constructed in sand and gravel layer or other complex strata,jacking failure caused by excessive increase of pipe jacking resisance,have been developed,and applied widely in sorts of pipe jacking projects. The bentonite-polymer slurry system takes the high-quality bentonite slurry as basic slurry,and conducts a laboratory test with addition of polyacrylamide and water-reducing agent,to analyse the optimal mixing amount of the slurry components,which are used for preparing the slurry that have the comprehensive properties of turbulence and resistance-reducing,lubricating and wall protecting.This slurry can solve the problems of turbulence and resistance-reducing for long-distance transport,decreasing loss of pump pressure,lubricating and resistance-reducing of pipe,reduce the resistance of pipe jacking,wall protecting for complex strata,preventing the strata collapse,ensuring the process of constructions of pipe jacking,and can meet the technical demands of ultra-long pipe jacking constructed in complex strata.The solid-free slurry takes the plant gum slurry as basic slurry,the polymer as treatment agent,and through the laboratory test,preparing the lubricating and resistance-reducing wall-protecting solid-free flushing fluid,the comprehensive property of which reach or exceed the bentonite-polymer lubricating and resistance-reducing wall-protecting polymer slurry.