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Prediction of water inflow in caverns has been a big problem for a long time, and the predication during construction has not been effectively combined with the water sealing by grouting, resulting in excessive grouting cost and difficulty in acceptance of storages during construction, which have caused great problems to the design, construction and operation of underground storages. Herein, a seepage field model was firstly established by FEFLOW software based on the actual geological conditions and the layout of underground works of a underground water-sealed storage, the water inflow of the storage during its operation without water-sealing by grouting was calculated by simulation, and the recommended water inflow value was finally determined to be 10 115 m3/d through the mutual verification with the calculation results of the empirical formula. Further, the permeability coefficient was calculated according to the requirements of relevant specifications. Definitely, the average permeability coefficient of the whole storage area needed to be reduced from 1.1×10-5 cm/s to 1.09×10-6 cm/s, which could guide the grouting design in a targeted way. The calculation of water inflow and seepage control were correlated in the research for the first time, capable of accurately estimating the quantity of pre-grouting and guiding the construction organization design, thus effectively overcoming the common difficulty in acceptance and commissioning of similar projects due to excessive water inflow.

With the continuous expansion of national strategic reserve scale, less massive crystalline rock mass is available in China due to the limitation of various factors. Therefore, making a breakthrough in the construction technology of an underground water-sealed cavern in sandstone area can greatly broaden the site available for the underground caverns. In order to study the feasibility of cavern construction in sandstone area, the seepage field models of underground caverns in sandstone area under three working conditions of horizontal bedding, inclined 10° bedding and inclined 50° bedding were established with the FEFLOW software under the background of site selection for cavern construction in a sandstone area in southwest China. It is assumed that 2 to 3 layers of thick mudstone exist in the sandstone to amplify the damage degree of low-permeability mudstone layers to the water-sealed environment, so as to better study the design technology of water seal for the underground caverns in sandstone area. The simulation results show that the thick mudstone layers have the least influence on the inclined 50° bedding and the greatest influence on the horizontal bedding. The thick mudstone layers, as the water barrier in the groundwater environment, seriously affect or even destroy the water-sealed environment. By adjusting the model in a targeted way such as setting horizontal water curtain holes and a vertical or oblique water curtain system, the water-sealed effect is improved obviously. In the actual project, water seal can be realized by moving down the horizontal water curtain system, or setting a vertical or oblique water curtain system in specific areas. The results can provide theoretical reference for the design and site selection of underground water-sealed caverns in sandstone area.