Numerical Simulation of Long-Term Stability of Irregular Underground Salt Caverns Under Alternating Loads

ABSTRACT: The proportion of green energy, such as photovoltaic and wind power, in power generation is increasing year by year. However, green energy often exhibits significant periodic fluctuations. Therefore, it is imperative to construct a large number of compressed air energy storage facilities to meet the daily demand for peak power regulation. Utilizing the dissolved cavity of salt rock layers to build underground salt cavern energy storage presents an economical and reliable solution due to the low permeability and self-repairing properties of salt rock. Nevertheless, most salt rock layers in China contain mudstone interlayers, which pose challenges in accurately controlling the shape of salt caverns during the water injection process within the dissolved cavity. This often results in irregularities, unevenness, and large curvatures near the mudstone interlayer within the cavity shape. Such irregularities on the inner wall of cavities pose a significant threat to long-term stability as they are prone to stress concentration and collapse. The present study establishes a sophisticated three-dimensional geometric model based on the geometry and geological conditions of underground salt caverns in the Hengyang area. Utilizing COMSOL, a numerical simulation is conducted to investigate the long-term creep stability of irregularly shaped salt caverns over a period of 30 years. The impact of salt cavern geometry on long-term stability is quantitatively assessed through key parameters such as volume shrinkage rate, plastic deformation, and stress concentration areas. 1. INTRODUCTION With the approaching of the carbon emissions peak date, the proportion of green energy such as photovoltaic and wind power in power generation is increasing year by year (Pan et al., 2023; Van-Tien et al., 2022). However, green energy usually has a large cyclical fluctuation (Mahdieh et al., 2023; Jean-Paul et al., 2013), and at the same time, the electricity consumption in the population gathering area itself has a daily cyclical fluctuation, so it is urgent to build a large number of compressed air energy storage to meet the daily demand for power peak regulation (Liu, X. et al., 2023). Therefore, the establishment of underground salt cavern energy storage is an economical and reliable scheme for power peak regulation (Chen et al., 2024).