Effect of excavation shield conicality on displacement and stress on the pipeline in layered areas during pipe jacking operations

Recently, most underground structures are mechanized using excavation shields. Moreover, one of the major challenges in underground structures is the ground deformation. So, the analysis of this mechanism is necessary for safety purposes and project design. One of the effective parameters in the ground displacement is the geometry of the excavation shield. Since the pipes are connected to the excavation shield, the initial stress relaxation and displacement are not allowed. In this regard, having a cone excavation shield can solve this problem. In this research the effect of excavation shield conicality on the ground is investigated. The Plaxis finite element software is utilized for numerical modeling. Moreover, in order to validation, the results are verified with the field data and analytical analysis. Furthermore, the effect of stress on the pipeline is also investigated in this research. Finally, it is found that the relationship between conical excavation shield and ground surface displacement is linear. The load on the pipeline almost doubles with increasing the percentage of conicality of the shield from 0.3% to 0.9%. One of the most important applications of this research is the possibility of controlling the ground movement with respect to the effective parameters.