Dynamic Risk Assessment of the Subsea Tunnel Construction Process: Analytical Model
Daohong Qiu, Jiuhua Cui, Yiguo Xue, Yang Liu and Kang Fu
The geological conditions of subsea tunnels are highly complex, and there are considerable risks involved in the construction process. A method to dynamically evaluate the risk in the tunnel construction process is a practical problem that should be immediately addressed. Taking the Jiaozhou Bay subsea tunnel in Qingdao, China, as the object of this study, a risk analysis and construction measurement system are combined to identify the risk factors. Convergence displacement, arch crown settlement, internal forces of the steel grid, intactness index, rock uniaxial compressive strength, groundwater, and surrounding rock pressure were selected as the evaluation indices. According to the rough set theory, an attribute reduction operation was used to analyze the evaluation index, and five primary control influencing factors were obtained. An attribute importance analysis was then conducted to obtain the weight coefficient of each evaluation index. Finally, a dynamic risk assessment model for the subsea tunnel construction process with new Austrian tunneling methods (NATM) was established, based on the basic principles of the cloud model. This model can quantify the measurement data into a single dynamic risk index, and dynamically evaluate the construction risk as the tunnel excavation and measurements are conducted. The actual engineering applications verify the evaluation results of this method, indicating that the proposed method can be used for future design and construction.
Keywords: subsea tunnel, NATM, dynamic risk assessment, rough set, cloud model