周期性气体荷载作用下盐穴近场围岩强度特性及其工程应用

Compressed Air Energy Storage (CAES) is a large-scale energy storage which can be comparable to the Pumped Hydro Energy Storage (PHES). Salt caverns for CAES not only provide space for energy storage but also can avoid the geological disaster caused by salt mining. This program takes salt cavern for CAES as the research object. Considering the high injection and withdraw rates and the numerous cycles of the CAES, the strength of rock salt under high gas pressure surrounding the adjacent salt cavern will be studied. Axial compression experiments without the jacket will be conducted to analyze the effect of high-pressure gas on the rock salt. The initiation and propagation of crack caused by the gas permeation will be explored. The dilation and failure characteristic under high gas pressure will be revealed and then the strength model in the stress space which contains the compression-dilation boundary and failure criterion will be built. The loading and unloading confining pressure tests will be conducted to investigate the effect of confining pressure unloading rate on the strength. The relationships between the cyclical stresses, cycle numbers, and fatigue strength will be analyzed. The strength in the strain space will be built to describe the fatigue failure and creep failure by using the second invariant of the irreversible strain. Finally, the long-term steady numerical simulation of the salt caverns for CAES will be conducted. Based on the strength model in stress space, the minimum operating pressure criterion will be built, while based on the strength model in strain space, the maximum operating life will be predicted. The research results can be used for the design of the salt caverns for CAES.

压气蓄能是可以与抽水蓄能相媲美的大规模储能技术，利用盐穴开展压气蓄能，既可以为压气蓄能电站提供储能空间，又可以避免盐矿开采引起的地质灾害。本课题以压气蓄能电站的地下盐穴为研究对象，考虑压气蓄能注采速率高、注采循环多的特点，结合盐穴存储高压空气的工程特性，紧紧围绕盐穴近场围岩强度特征开展研究。通过气体裸三轴试验，探索气体渗透下盐岩内部裂隙的萌生、扩展过程，揭示气体荷载对扩容、破坏的影响规律，建立包含扩容方程及破坏准则的近场围岩应力型强度模型；开展围压加卸载试验，分析加卸载应力及周期与盐岩疲劳强度的相关关系，揭示应变率对疲劳强度的影响机理，以不可恢复应变的第二不变量为变量，建立描述疲劳破坏及蠕变破坏的应变型强度模型；最后，开展盐穴压气蓄能长期稳定性数值模拟，基于应力型强度模型，建立盐穴最小运行压力设计准则，基于应变型强度模型，对盐穴最长运行时间进行预测，研究成果为盐穴压气蓄能参数设计提供依据。

可再生清洁能源是我国能源可持续发展的战略需求。然而，由于风电、光伏等可再生清洁新能源具有间歇性、不确定性、随机性等特点，大规模并网将对电网的安全和稳定运行带来冲击。大规模储能装置，由于具有对功率和能量的时间迁移能力，能够为大规模风电、光伏等新能源发电并网问题提供技术解决方案。开展盐穴压气蓄能，对于优化我国能源结构，提高我国可再生清洁能源比例，减少弃风弃电，治理环境，有着重要的意义，是实现双碳战略目标的必经之路，也是我国能源安全的战略需求。压气蓄能是三种大规模储能技术之一，利用盐穴开展压气蓄能，既可以为压气蓄能电站提供储能空间，又可以避免盐矿开采引起的地质灾害。本课题以压气蓄能电站的地下盐穴为研究对象，考虑压气蓄能注采速率高、注采循环多的特点，结合盐穴存储高压空气的工程特性，紧紧围绕盐穴近场围岩强度特征开展研究。盐穴体积是压气蓄能电站选址的两大关键参数之一。现场水密封试验中发现了液体在“高压力、大体积”条件下是可压缩的，突破了“气体可压缩、液体不可压缩”的常规思想禁锢，并基于此提出了地下盐穴卤水体积的计算方法，为盐穴选址提供了基础参数；基于稳定性准则和密封性准则，结合我国盐矿地质特点和开采工艺，提出了我国压气蓄能电站地下盐穴的选址标准。研究成果在云应盐穴压气蓄能、泰安盐穴压气蓄能、淮安盐穴压气蓄能、樟树盐穴压气蓄能、平顶山盐穴压气蓄能以及榆林盐穴压气蓄能电站中得以应用。