The time-space prediction model of surface settlement for above underground gas storage cavern in salt rock based on Gaussian function

Abstract

Research shows that the volume shrinkage of the underground storage cavern in salt rock is the basic reason why surface settlement appears above storage caverns. In order to further study the quantitative relationship between cavity volume shrinkage and surface settlement, this paper starts from the form of the reservoir surface settlement curve, selects Gaussian function to match the profile curve of the surface settlement basin above the single cavity gas storage, proposes a settlement prediction method that is similar to the Peck curve of tunnel surface settlement and establishes a space prediction model of surface settlement for storage cavern which can reflect directly the relationship between cavity shrinkage of storage cavern and surface deformation. Then with the consideration of surface settlement changing over time, and through introducing the analytical formula of volume shrinkage of the cavern in the stage of steady creep, the predicting analytical formula of annual subsidence rate in the reservoir is obtained and the time-space prediction model of surface settlement above gas storage cavern in salt rock is established. Finally, the paper takes a storage cavern in Yunying salt mine as an example, compares the result of prediction model with the result of numerical simulation to verify the accuracy of this prediction model and proves its feasibility. This research provides a simple and reliable prediction method for the surface settlement prediction during the operation of underground storage cavern in salt rock and has an important guiding significance for the long-term safe operation of underground storage caverns and environmental protection in mining areas.