Optimizing Method of Main Caverns in Large Underground Water-Sealed Storage Cavern

Underground water-sealed storage cavern is an important way for petroleum strategic reserve in China, which owns lots of outstanding advantages, such as low operating costs, high safety, and land resource conservation. As the major structure in underground water-sealed storage cavern, its layout parameters and excavation scheme will have significant impact on rock stability and overall project quality. A method is put forward to optimize layout and excavation scheme of main caverns. In this method, the Q system and Hoek–Brown strength criterion is utilized to estimate equivalent mechanical parameters of rock mass based on field survey data. Numerical test analysis is carried out by 3 Dimensions Distinct Element Code (3DEC). Displacement, maximum displacement and plastic zone volume are selected as three indicators for quantitative assessment. Besides, it is applied into a proposed large-scale underground water-sealed storage cavern project in China. Results show that axial direction should adopt NW325°, buried depth of cavern crown should locate at − 100 m, and spacing should be 1.5 times the span (36 m). Scheme two and “jump excavation” mode is recommended in construction, which can effectively reduce the interaction effect between adjacent caverns. This method has the characteristics of easy data acquisition, strong operability and common applicability. The achieved results can not only provide reference for related projects, but also further enrich the research content in this field, which has a certain engineering value and theoretical significance.