Stability analysis of salt caverns is a very complicated subject due to the coupled time-dependent thermo-mechanical behavior of salt during leaching and operational phase of the gas storage subjected to the cyclic loading. Because of purely plastic behavior of salt and the relevant convergence during injection and withdrawal, investigation of the salt cavern stability becomes more challenging. The objective of this study is stability analysis of Nasrabad salt cavern by numerical method using a comprehensive software entitled LOCAS having capability to model the complex time-dependent thermo-mechanical behavior of salt under cyclic loading of natural gas pressure. Measurement of geomechanical properties of salt is also the important requirement for modelling. First, geomechanical properties of Nasrabad salt including uniaxial and tri-axial compressive strength, tensile strength, uniaxial and tri-axial creep under different temperatures were measured. Thereafter, time-dependent behaviors and parameters of dilatancy criterion of the test results were analyzed by the advanced constitutive models for rock salt to obtain accurate parameters for modeling. Then, long-term stability was analyzed for Nasrabad salt cavern having different shapes, sizes, and depths under cyclic loading 3–8 MPa as minimum and maximum gas pressures. The results showed that an ellipsoidal cavern having initial volume of 100,000 m³ at 450 m depth by 0.3% creep closure rate per year and volume loss of 0.8% of the initial volume per year as ideal conditions can store 8,000,000 m³ natural gas with working capacity of about 6,000,000 m³.

盐洞的稳定性分析是一个非常复杂的主题，因为盐在储气库的浸出和运行阶段的循环时间过程中，盐分随时间变化而具有热机械行为。由于盐的纯塑性行为以及注射和抽出过程中的相关收敛性，因此对盐穴稳定性的研究变得更具挑战性。这项研究的目的是使用名为LOCAS的综合软件，通过数值方法对Nasrabad盐洞进行稳定性分析，该软件具有对天然气循环压力下盐的复杂时变热力学行为进行建模的能力。盐的地质力学性质的测量也是建模的重要要求。第一的，测量了Nasrabad盐在不同温度下的单轴和三轴抗压强度，抗拉强度，单轴和三轴蠕变的地球力学性质。此后，通过先进的岩盐本构模型分析了随时间变化的行为和测试结果的膨胀准则参数，从而获得了准确的建模参数。然后，分析了在3–8 MPa作为最小和最大气压的循环载荷下具有不同形状，大小和深度的Nasrabad盐洞的长期稳定性。结果表明，一个椭圆形洞穴的初始体积为100,000 m 通过先进的岩盐本构模型分析了随时间变化的行为和测试结果的膨胀准则参数，从而获得了准确的建模参数。然后，分析了在3–8 MPa作为最小和最大气压的循环载荷下具有不同形状，大小和深度的Nasrabad盐洞的长期稳定性。结果表明，一个椭圆形洞穴的初始体积为100,000 m 通过先进的岩盐本构模型分析了随时间变化的行为和测试结果的膨胀准则参数，从而获得了准确的建模参数。然后，分析了在3–8 MPa作为最小和最大气压的循环载荷下具有不同形状，大小和深度的Nasrabad盐洞的长期稳定性。结果表明，一个椭圆形洞穴的初始体积为100,000 m³在450 m的深度以每年0.3％的蠕变封闭率和每年0.8％的初始体积的体积损失作为理想条件，可以存储8,000,000 m ^3的天然气，工作能力约为6,000,000 m ³。