Risk Assessment of Shield Tunneling in a Subway Project in Beijing Using the P=R×C Method

The shield construction is used from Xitieying staiton to You'anmen outside station in a subway project in Beijing (hereafter, the Project). The risk identification revealed 10 major types of hazards that may arise from shield tunneling in the Project. The P=R×C  risk assessment method is adopted to carry out the risk grading of engineering, and the main factors of risk are the four Class 4 hazards, i.e. underground pipeline damage (u2), surface subsidence (u3) and shield spewing out water (u4), as well as one Class 5 hazard, i.e. damage to surrounding buildings or structures (u1). The method combines the qualification with quantification, localizes every rick factor and then guild the risk control and management.