Study On Damage And Stability Of Salt Rock Gas Storage Under Earthquake

Salt rock has many advantages such as good creep property,low porosity and self-recovery of damage.It is recognized as the ideal medium for energy storage.The salt rock deposit in China is mainly distributed in layered structures.Therefore,the deformation and mechanical properties of the salt rock deposit are different from those of foreign homogeneous and massive salt caverns.Salt rock caverns built or under construction in China are mainly located in seismic fortification areas,and the bedded salt caverns will be subjected to strong earthquake action during the construction and operation.So it is necessary to study the dynamic response of cavern in bedded salt rock under seismic action.The main content of this article is as follows:Firstly,the dynamic characteristics and deformation characteristics of salt rock under cyclic and impact loads are summarized,and the research results of seismic disaster of underground caverns are analyzed,and the dynamic response analysis method of salt rock gas storage under seismic is defined.Secondly,based on the theory of damage mechanics,the dynamic damage constitutive model of salt rock(EDD model)is established by considering the strain rate effect and damage weakening factor.The parameters in the constitutive model are obtained by fitting with the experimental data.At the same time,the dynamic development library function of the user-defined constitutive model was written using VC++language which was developed on the secondary development function in FLAC~3DD software.The numerical simulation of Small cylindrical specimen shows that the simulated value is in good agreement with the experimental value,which verifies the correctness of the EDD model.Finally,the dynamic response of the salt rock gas storage under seismic action is numerically simulated by adopting the EDD model.The deformation,stress and damage development of surrounding rock in salt caverns are analyzed.The study shows that the seismic acceleration will have a magnification effect during the propagation of salt rock gas storage.The surrounding rock of the salt rock storage has obvious stress redistribution.The surrounding rock is subjected to the shear force,and it is easy to produce tensile damage in the mudstone interlayer.The damage variable increases with the increase of earthquake intensity,and the damage depth of mudstone interlayer is larger than that of salt rock,and shear damage will occur between mudstone interlayer and salt-rock interface.In a certain range,the seismic performance can be improved by increasing the working pressure and burying depth of the cavern.