Case study on pressure filled karst cave detection, tunnel construction simulation, and disaster risk assessment in karst development areas

During the construction of tunnels in karst areas, it is crucial to accurately detect the condition of karst caves and evaluate the impact of pressurized and water filled karst caves on the stability of surrounding rock. Taking the Mangshan Taikong Tunnel as a case study, this paper combines the three-dimensional geological prediction technology with numerical simulation to investigate the influences of seepage field, plastic zone change, water pressure, size and distance on the stability of surrounding rock through numerical simulation. The results indicate that the plastic zone becomes partially connected at a distance of 3.5 m, forming a potential water inrush channel, and becomes fully connected at 3 m. The increase in water pressure leads to a significant increase in horizontal displacement at the haunch and induces stress concentration at the arch foot and arch bottom. As the cave radius increases, the crown settlement significantly increases and stress concentration at the arch foot intensifies.The safety distance threshold for tunnel excavation is 3.5 m and the sensitivity of tunnel stability to various karst cave factors is ranked as follows: cave scale > distance > water pressure. This study provides a theoretical basis for avoiding water inrush and collapse risks in karst tunnel construction.