Risk analysis of mechanical cross-passage construction using work breakdown and fault tree

A subway cross-passage is a connecting aisle between main tunnels. Owing to its narrow construction site, it is difficult to implement safety measures, and intensive construction techniques are often required. With the development of technology, the mechanical cross-passage technology has emerged. In order to address the risk problem of mechanical cross-passage construction, the construction process was systematically decomposed based on the work breakdown structure, and a fault tree of each construction process was established for qualitative analysis. Various factors leading to construction risks have been identified, such as head sinking of the excavation machine, spiral machine gushing, excavation deviation from axis, excavation surface soil instability, and ground deformation, and corresponding risk response measures have been proposed. The targeted measures were applied to the mechanical construction of Qingdao Subway Line 8, and the successful completion of the cross-passage verified the applicability of the risk analysis and the effectiveness of the response measures.