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通过试验模拟盐岩储气库建腔期腔体围岩围压动态降低过程,开展单轴压缩和三轴卸荷扩容试验,并分析温度对盐岩试件卸荷扩容特征的影响。试验结果表明:由于都是应力增加的过程,卸荷试验的扩容特征与常规单轴试验相比,在扩容阶段划分上具有一些共同点,都存在体积压缩段、稳定扩容段和加速扩容段。卸荷试验和单轴试验的压缩极限基本相同。但由于加载方式不同,卸荷试验的稳定扩容段在整体扩容中所占比例更小,扩容速率和扩容幅度也较单轴试验小。在相同的偏应力作用下,卸荷试验产生更大的扩容。温度升高能够促进盐岩的扩容,表现为加速扩容点前移、初始稳定扩容段缩短、加速扩容段变长、扩容速度加快、扩容幅度增大等。
The dynamic reduction process of cavity confining pressure in cavity during the construction of salt rock gas storage reservoir was simulated through experiments, and the uniaxial compression and triaxial unloading expansion tests were carried out. The influence of temperature on unloading and expansion of salt rock samples was analyzed. The experimental results show that both of them have some commonalities in the division of the expansion stage compared with the conventional uniaxial tests due to the stress increasing process. Both the volumetric compression section, the stable expansion section and the accelerated expansion section exist. Unloading test and uniaxial compression test limit is basically the same. However, due to different loading methods, the steady expansion of unloading test in the overall expansion of the proportion of smaller, expansion rate and expansion rate is also smaller than the uniaxial test. Under the same deviatoric stress, the unloading test produces greater expansion. The increase of temperature can promote the expansion of salt rock, which shows that the point of accelerated expansion is advanced, the initial stable expansion is shortened, the accelerated expansion is longer, the expansion is faster and the expansion rate is larger.