Study On The Stability Of Surrounding Rock Of Anhydrite Gas Storage In Deep Internal Pressure Environment

With the development of the economy,the demand for natural gas in the world is increasing day by day.China's current gas storage capacity is very limited,and there is still a certain gap with the world's average.Therefore,the establishment of large underground natural gas storage clusters is an important policy for China's development.The underground gas storage has the advantages of large gas storage,saving ground resources,safety and reliability,little environmental pollution and no impact by weather.At present,most of the underground gas storages in the world use depleted gas storages,and there are still a few cases of using abandoned mines as underground gas storages.China has a wide range of gypsum mine resources.Many gypsum mine goafs are a good choice for building a database.If the gypsum mine goaf can be directly used as a natural gas storage,the cost of building a gazette will be greatly saved.Therefore,the study of the stability of the surrounding rock of the cavern in the mining area is the key to the normal operation of the gas storage cavern.Supported by the general project of national natural science foundation of China(project no.41572301),this paper,based on hengtai hard gypsum mine in anhui province,combined with the engineering geological conditions of the mining area,studied the surrounding rock stability of the goaf cavern after excavation and during operation by means of laboratory tests and numerical simulation:(1)According to the research on the engineering geological conditions of the mining area,it is found that the strata of the mining area will not undergo structural activities for a long time;the thickness of the ore body in the mining area is large,the roof and floor rock layers are relatively stable,and the ore body can be considered as a water-proof layer The ore body after mining is stable.Therefore,relying on the project has good conditions for the construction of large natural gas storage groups.(2)Simulation of rock uniaxial compression test by particle flow program,based on the control variable method to establish the relationship between meso-parameters and macro-parameters,reducing the number of tests in the parameter calibration process,and combining the laboratory rock mechanics test results The meso parameters are calibrated.After that,the strength parameters of anhydrite rock mass were studied based on the generalized Hoek-Brown strength criterion,which provided the basis for the numerical simulation of the stability of the surrounding rock of gas storage caverns.(3)The FLAC / PFC coupling model is established based on the continuous-discontinuous coupling simulation idea to study the stability of the surrounding rock after excavation of the cave under different initial stress conditions;the gas storage is based on the fluid-solid coupling theory in the PFC program The stability of the surrounding rock of the cave under the high internal pressure environment during the operation period was numerically simulated,and the simulation results were analyzed and studied from the perspectives of displacement,stress and contact force chain.