含泥盐岩的扩容特性与剪胀角模型

Dilation behavior and dilation angle model of salt rock with mudstone

深部地层中的盐岩层是储气库的重要目标层,在储气库运行条件下盐岩的扩容损伤特性是储气库运行稳定分析的重要指标。取自地下储气库典型含泥盐岩实验样品,通过不同围压下的三轴压缩试验,分析了含泥盐岩试样压缩过程的扩容特性及剪胀角模型。试验结果显示,含泥盐岩三轴压缩曲线表现出应变硬化特性,且伴随着明显的扩容特征。通过摩尔-库仑塑性势函数分析可知,含泥盐岩剪胀角随着塑性剪应变增加而逐步增大,最终剪胀角在7o^10o之间,并建立了考虑塑性剪应变和围压影响的含泥盐岩剪胀角模型。数值模拟方法验证所获得的剪胀角模型能很好地模拟含泥盐岩扩容过程中的体应变。

The salt layer in the deep stratum is usually used to form cavern for natural gas storage. The behavior of dilation of salt rock is the important criterion for the safety of storage. In this paper, the volumetric dilation behavior and the dilation angle model of salt rock with mudstone is analyzed from the compressed test under different confining pressures. Experimental results show that strain-hardening law and obvious volumetric dilation during the test. From Mohr-Coulomb plastic potential function, the dilation angle of samples increases with the increase of plastic shear strain. And the dilation angle can approach 7o-10o at last. Finally, the dilation angle model with plastic shear strain and confining pressure is constructed. The dilation angle model that simulates perfectly the volumetric strain of salt rock with mudstone is verified by the numerical simulation.