Structural behavior and soil arching state of underground corrugated steel utility tunnel

Underground corrugated steel utility tunnel (UCSUT) is an optional alternative to traditional concrete utility tunnel. However, the structural mechanical behavior and surrounding soil arching state of UCSUT, as a typical flexible structure, depend on the soil-structure interaction between the structure body and surrounding soil, and are not clear currently. Thus, a case study on a real multi-compartment UCSUT project was reported in this paper. The field test and finite element simulation using ABAQUS software were conducted to investigate the mechanical behavior of the pipe-arched main compartment of the UCSUT. After that, the equilibrium equations were established based on the plane strain theoretical model to present the forces' balance of UCSUT and then an algorithm to convert the internal forces into external interface pressure was proposed. Based on the results from the field test and finite element simulation as well as the algorithm mentioned above, the soil arching state around the structure body was also analyzed. The results show that the UCSUT coordinates the external soil load through its own deformation, which in turn affects the surrounding soil arching state. After the soil covers the crown, the soil arching state outside the crown transitions from "negative" to "positive". The horizontal arching factor near the spring line always greater than the coefficient of earth pressure at-rest, showing a "passive arching state". In addition, the bending moment is closely related to the structural deformation as well, while the axial force is mainly affected by the cover height above the crown.