大型地下石油洞库自然水封性应力-渗流耦合分析

根据地质条件，地下水封石油洞库可以选择自然水封或人工水封方式。以中国首个大型地下水封石油洞库为背景，开展了岩石三轴压缩试验和现场水文试验，获得了洞库围岩变形特征和渗透特性，采用应力-渗流耦合理论，分析了该地下石油洞库的自然水封性与稳定性。岩石三轴实验表明，岩体受剪作用下体积变化情况与剪胀性密不可分。现场水文试验表明，洞库渗透系数存在一定的不确定性。通过数值分析得出如下结论：自然水封条件下，洞库水位将不满足水封要求；地下水封洞库实现水封条件的水头受水力梯度和岩体渗透性影响；洞库施工期涌水量与渗透系数存在着分形关系；施工期各洞室拱顶沉降为19～32 mm，水平收敛为16～35 mm。研究成果为中国首个大型地下水封石油洞库工程建设提供了科学依据。

Assessment of natural containment properties of an underground crude oil storage cavern using fluid flow-stress coupling method

For the construction of underground crude oil storage caverns, natural groundwater table or artificial curtain system is employed in the cases of different geological conditions. In this study, the containment and stability properties of an underground crude oil storage cavern facility with natural groundwater table are investigated using the stress-fluid flow coupling theory. It is one of the first crude oil storage caverns being built in granite in China. The laboratory and field tests are performed to determine the volumetric deformation characteristics and seepage properties. It is indicated that the volumetric deformation characteristics are related to the shear dilatancy in laboratory tests, while there is uncertainty for the permeability in field tests. It is found that the groundwater table dissatisfies the containment requirements for the caverns under natural containment. The groundwater head required for the storage is influenced by the hydraulic gradient of underground water and the permeable properties of rock mass. There is a fractal relation between the groundwater inflow volume during construction period and the permeability of the rock mass around the caverns. During the construction period, the crown settlement ranges from 19 to 32 mm, while the horizontal convergence ranges from 16 to 35 mm. The results may benefit the construction of underground crude oil storage caverns.