Abstract: Serious problems, i.e. bad crushing effect, cutterhead twined by flexible sundries and mucking pipe blocking, are often encountered during pipe jacking machine boring in complex stratum with steel bar and other flexible sundries. Hence, the crushing characteristics of steel bars and characteristics of complex backfill stratum are analyzed, and the cutting and crushing mechanism of shell knife is studied firstly. And then the structure of pipe jacking machine is improved and innovative structural design is carried out for the complex strata containing hard materials such as concrete and stone and flexible sundry materials such as steel bars. Meanwhile, the mucking equipment of pipe jacking machine and the structure of soil chamber are improved. Finally, special control system and assistant construction methods are adopted. The innovative technology is applied to the Shenzhen Heisby pipe jacking project, which successfully passed through the backfill soil layer containing a large number of flexible sundries such as steel bars.

Key words: flexible sundries, steel bars, backfill soil, pipe jacking machine, pipe jacking construction