Analysis Of Critical Mechanics Of Rectangular Pipe Jacking

Rectangular pipe jacking technology is developed on the basis of circular pipejacking technology.Compared rectangular pipe with round pipe,the former has higherspace utilization. For this reason, rectangular pipetechnology possesses moreadvantages in channel engineering than traditional construction technology. With thecontinuingimprovement of underground space development and utilization in urban，the rectangular pipe jacking technology can be applied toreconstruction of electricpower tunnel and underground tunnel as well as utility tunnelpresented in recentyears,and which shows a trend of gradually popularizedwith the advance ofequipment research and construction technique. Yet the rectangular pipe jackingdesign theory is not mature, especially at the critical aspects of the pipe-soil stress,design and calculation of jacking force and design of rectangular pipe structural whichstill needs further research.The key mechanical problems of the rectangular pipe jacking technology wasmainly studied in this paper:(1) At first, the technology,equipments，technologicalprocess，advantages and requirements of rectangular pipe jacking was summarized inthis paper.Then compared with the circular pipe jacking, the particularity ofrectangular pipe jacking in technology, jacking equipment, pipes and the stressbetween pipe and soil was analyzed. Some technique problems ofwhole-section-chippush bench, lateral deviation,axisdeviation and measures to reduceresistance was researched, then some prevention and solution measures wereputforward.(2) The interaction between pipe and soil was mainly analyzed andcalculated with the unloading arch theory, thenthe calculation formula of rectangularjacking force in pipe jacking process was deducedbased on construction experience inShanghai and circular pipe jacking force calculated method.(3) The structure ofrectangular pipe was designed and calculated based on the analysis of force of it,highway box culvert design principle and specification was referenced.(4) Finally,thejacking force of a rectangular pipe jacking project case under Zhongzhou road in Zhengzhou of Henan was calculated and comparedwith the jacking force of theexperiential method. The structure of rectangular pipe in this project was alsodesigned. the applicability of the structure design method and calculation formula ofjacking force was verified.Basically the following results were achieved:The deduced rectangular pipejacking force calculation formula reflects the sectional dimension, the earthpressure,the parameters of grouting effect and the pipe jacking construction factors, itcan be used in rectangular pipe jacking force predetermination. The obtainedarithmetic of the sectionaldimension,load, internal force and steel reinforcement ofrectangular pipe can be used in rectangular pipe of pipe jacking engineering structuredesign.