Reevaluation of the design and excavation of underground oil storage cavern groups using numerical and monitoring approaches

The bench method is widely used in the construction of underground oil storage caverns. From the perspective of single caverns, a large amount of work has been performed on the cavern stability, assuming that the influence of the auxiliary tunnels can be ignored. This paper reevaluates the necessity of auxiliary tunnels for the stability analysis. First, the equivalent continuum model is established based on a cavern group that includes auxiliary tunnels, and the space-time evolution of the displacement field after excavation in a practical sequence is studied. Then, the field monitoring time series are collected to compare the differences in deformation characteristics between the intersection and non-intersection of auxiliary tunnels and caverns. The results show that the crown settlement is significantly increased at the intersection of the caverns affected by the auxiliary tunnels. When the three-cavern group design is adopted, the stability of the middle cavern is worse, and these intersections must be reinforced. The crown settlement before excavation accounts for approximately 40%–50% of the total. As different construction stages proceed, the convergence characteristics of different feature points in a whole section are different, which is helpful for improving the understanding of the deformation space-time evolution of the excavation.