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Aiming at the problems of subjectivity and fuzziness in the traditional rock mass quality classification methods, a basic model of rock mass quality classification was established based on the fuzzy theory. According to the engineering geological characteristics of underground water sealed storage, the rock mass quality classification was determined by the method in combination of fuzzy comprehensive evaluation and neural network. A case study was carried out to an underground water-sealed storage in China, specifically, a neural network model of rock mass quality classification with good stability was built with the representative sample data measured on site, and the rock mass quality classification of Borehole ZK1 was also verified. The results show that, compared with the traditional rock mass quality classification methods, the result of rock mass quality classification determined by the fuzzy comprehensive evaluation method is more reasonable. The test results of rock mass quality classification in Borehole ZK1 are in good accuracy, which can meet the actual engineering requirement. The newly constructed rock mass quality classification method of underground water sealed storage is a quantitative analysis method, which provides a theoretical basis for the stability analysis and optimization design of underground water sealed storage.

For large-section underground water sealed oil storage, the section form of the cavern is vital to the stability, durability and sealing performance of the stored oil, but the stability at the intersection of each tunnel and oil storage cavern is still a weak link when judging from the stability of the entire storage. One underground water sealed oil storage project in Liaoning was taken as the example, and the FLAC3D numerical analysis was performed on the stability at the intersection of the water sealed oil storage from the aspect of surrounding rock stress and displacement. The intersections, between the oil storage cavern and the construction tunnel, the connecting tunnel and the vertical shaft, were analyzed by software, in which the mechanical behavior of these intersections was analyzed, and the stress distribution, deformation characteristics and structural spatial stress characteristics around the cavern were verified. It is concluded that the stress concentration at the intersection does not exceed the compressive strength of the rock, and the magnitude and area of tensile stress also meet the requirements. Finally, the weak points in the simulation were pointed out, and suggestions were put forward to increase the reinforced support in design and to strengthen monitoring and measurement in construction.