Thermal–mechanical analysis of the fracture initiation and propagation around the underground pilot LNG storage cavern

Abstract

Thermal–mechanical integrity of rock mass and lining system is a crucial factor in the construction and operation of the underground LNG storage facilities. The pilot LNG storage cavern was successfully constructed and operated for the validation of the suggested technologies. In order to simulate the fracture initiation and propagation of thermal fractures around the pilot LNG storage cavern, thermal–mechanical coupled analyses have been carried out using FRACOD and the capability of the code has been verified by a comparison of numerical results with in situ measurement data. Temperature and fracture initiations were well matched with the field data. In case of displacement, the trend was similar but the magnitude showed noticeable difference. This was partially attributed to the volume expansion during water–ice phase change because this model did not consider this phenomenon. According to the numerical analyses, the different behaviors under heating and cooling conditions must be considered in the modeling of thermal–mechanical coupled problems. More specifically, the Young's modulus obtained from the tensile test should be used in case of cooling environments.