Safety risk assessment of weak tunnel construction with rich groundwater using an improved weighting cloud model

Many tunnels in Western China are excavated through soft and water-rich rocks. Tunnel excavation in such regions is highly susceptible to disasters such as collapses and water and mud inrush. To control the risks associated with tunneling, this paper proposes a risk evaluation model applicable to soft and water-rich tunnels. First, geological data corresponding to typical soft and water-rich tunnels and related cases were analyzed. By analyzing the natural geology, tunnel characteristics, and construction management, ten influencing factors were selected as the risk evaluation indicators, and a risk evaluation hierarchy was established. Second, the improved combination weight method was applied to obtain the optimal weights of each indicator. A cloud model was then used to visualize the final risk level and establish an evaluation system for soft and water-rich surrounding rocks. Finally, the developed evaluation model was practically applied to a railway tunnel in Western China. The results were highly consistent with the actual situation and could play a guiding role in the construction process. This confirmed the reliability and applicability of the proposed model, which can also be used as a reference for other similar tunnels.