地下储库岩体施工过程及套管与岩石相互作用数值模拟

NUMERICAL SIMULATION OF CONSTRUCTION PROCESS OF ROCK MASS OF AN UNDERGROUND STORAGE AND INTERACTION OF ROCK-CASING

采用ABAQUS有限元分析软件,对某天然气储藏基地的一个储藏库进行三维黏弹塑性有限元模拟,分析了整个围岩体系在岩石溶解开挖阶段的应力与变形,以及套管相应的变形。主要内容包括:(1)给出施工引起的溶腔上部岩体的应力场和位移场,并给出套管周围岩体随深度的变化曲线;(2)结合ABAQUS软件要求的形式,给出一条合理实用的岩石蠕变曲线;(3)结合应力分析数值结果,确定岩石和套管中可能存在的塑性区,并对施工完成后岩体的稳定性做出评价。数值结果表明,经过3a的溶解开挖施工后,围岩能够形成以"压力拱"为特征的稳定的上覆岩体自承体系,说明储藏洞室的设计是合理可行的。但是有必要采取特殊措施,增强套管下端的强度。同时还应采取措施削减管段受到的来自围岩的向下牵拉作用。

With finite element software ABAQUS,a three-dimensional viscoelasto-plastic finite element analysis was performed for the excavation of rock mass of a natural gas underground storage. The stress variation and deformation during the excavation process were calculated and analyzed. The deformation of the casing with which water is pumped in and out was calculated. The main researchs include:(1) the stress field and displacement distribution of rockmass caused by solution mining were presented,as well as a curve of rock mass displacement versus z-direction for the rock around casing;(2) a practical curve of viscoplastic constitutive model of rock mass with reference to the form requirements of software ABAQUS was given out;(3) the possible plastic area was predicted,and the estimation of the stability of the storage rock mass structure was given out. The numerical results indicate that the self-bearing system which is characterized by 'compressive arch' has been formed around the storage space after 3 years solution mining construction. The design of the underground storage is reasonable and practical. However,it is necessary to adopt reasonable measure to enhance the lower section of casing as well as to reduce the pulling effect of rock mass acting on the casing.