Lubrication of Pipejacking in Soft Alluvial Deposits under Impacts of Misalignment, Geology and Lubricant Injection Mode

Abstract: The impacts of the lubrication upon the pipejacking works has rarely discussed by literature. This study described a method that can be used to evaluate the lubrication performance by the reduction in the frictional coefficient μ as a function of injection type, soil and lubrication natures, and misalignment. The results of an application of the proposed method to a pipejacking project in the soft alluvial deposits of northern Taiwan were presented. The effect of misalignment increased the frictional stress τld to 12.5 kPa, reducing the reduction in the μ value to 71%. The combined effects of misalignment and varying face resistance contributed to the τ ld value of 4.0 kPa and were deemed as the main cause leading the low reduction of 84%. The misleading reduction of 60% was attributed to the inability of the occasional gravel to develop lower face resistance. The effects had greater influence on the lubrication performance than the lubricant injection mode.