Multiscale risk assessment for subway station construction: safety management and sensitivity analysis

With the increasing complexity and multilayered characteristics of projects in the modern engineering field, project risks are becoming increasingly uncertain. As a result, more comprehensive and systematic risk assessment methods are in greater demand. Multiscale risk assessment, as an important method for analysing the evolution of safety risk behaviours, can accurately capture the complexity and variability of risks over time and space. It has become an indispensable tool in risk management research. This study focuses on the A1 foundation pit of a Ningbo metro station. By comparing the measured data with FLAC3D numerical simulations, the accuracy of the model was validated. Deformation sensitivity analyses of two risk factors were conducted. Based on numerical simulations and multiscale risk assessment methods, this study revealed the significant amplifying effects of risk factors on foundation pit deformation and overall project risk. When the risk factors included a soil elastic modulus at 0.6E and overexcavation at 2.0 m that acted simultaneously, foundation pit deformation intensified, and the system-level project risk value reached 78.7594, leading to a sharp increase in project risk. These findings hold important theoretical and practical significance for effectively controlling construction safety accidents in metro station projects in soft soil areas.