Polymer mortar (PM) is recognized as a promising material for constructing the sealing layer of man-made caverns used in compressed air energy storage (CAES) systems, owing to its excellent airtightness, crack resistance, and deformation adaptability. This paper investigates the bonding properties and deformation adaptability of polyurethane polymer mortar (PPM) with lining concrete in man-made cavern gas storage, focusing on the effects of powder, polymer content, and mixture ratio variations on the PPM-concrete interface. Additionally, the failure characteristics and mechanisms of the interface are analyzed. The results indicate that the primary failure mode of the PPM-concrete interface is material separation on both sides. The relationship between interfacial shear stress and displacement exhibits two-stage approximate linear deformation characteristics prior to the stress peak, with a maximum shear strain of 11.05% during failure. Variations in powder and polymer content, as well as mixture ratio, significantly impact the interfacial bond strength. The maximum bond strength was about 1.21 MPa, while the lowest average bond strength was 0.237 MPa. The interfacial strength and deformability of the PPM-concrete interface satisfy the requirements for underground gas storage in CAES systems.

Compressed air energy storage (CAES) technology is a new type of physical energy storage and a kind of large-scale energy storage technology for power generation with broad development prospects. Large-scale CAES usually requires high-capacity underground air storage devices. Among the existing types of underground compressed air storage reservoir, the underground cavern with liner and air sealed layer has become a research hotspot in recent years because of its advantages such as easy site selection and minimal site constraints. Under the background of the urgent need for large-scale CAES technology in China, this paper comprehensively summarized and commented on the theoretical research results and technical development status of man-made cavern for air storage, discussed the advantages and disadvantages of the existing stability analysis theory of underground air storage cavern, sealing scheme of lined cavern and thermodynamic process analysis method. The key design points and critical issues that require attention in the development of the man-made underground lined caverns for air storage project are also discussed. Finally, the challenges affecting the industry development of compressed air energy storage with lined rock caverns were put forward.

In order to further understand the bond behavior of FRP-concrete interface in underground gas storage under combined compression and shear conditions, an indoor direct shear test was conducted to study the bond performance of the FRP-concrete interface under varying influencing factors, including normal stress, concrete surface roughness, adhesive thickness and concrete strength. The results show that the FRP-concrete interface is mainly characterized by debonding failure of the concrete surface under the combined compression and shear conditions. A significant nonlinear relationship exists between the interfacial shear stress and displacement. The strength and stiffness of the interface increase with the increase of normal stress, concrete surface roughness, adhesive thickness and concrete strength. The Mohr-Coulomb criterion can be used to describe the yield failure behavior of the interface under compression and shear conditions.

In order to make full use of the data information of all the measuring points on the landslide surface and to eliminate the misjudgment of the landslide stability state due to different evaluation methods based on displacement trend analysis, a fuzzy comprehensive evaluation method for landslide stability state was proposed, integrating the displacement information from multiple measurement points and the evaluation results of multiple indices. The validation results from case studies show that this method avoids the shortcomings of evaluating landslide stability based on the displacement trend of a single measuring point. Additionally, by considering the results from multiple evaluation methods, it also avoids the limitations of using a single evaluation method for assessing the actual landslide stability state, making the evaluation results more reasonable.

The accurate prediction on the spatial distribution of water inflow and seepage characteristics in the cavern is one of the basic tasks to ensure the safety and economy during construction and operation of the underground water-sealed oil cavern. In order to study the seepage effect of randomly distributed fractures in the surrounding rock of underground water-sealed oil storage cavern on water inflow prediction and spatial distribution of seepage field, a seepage analysis method of fractured rock mass based on embedded fracture element (EFE) is proposed to analyze the three-dimensional seepage field in Zhanjiang water-sealed oil storage caverns. The reliability of the proposed method is validated by the measured data and calculated results, and then the water inflow of the this project during the operation period is predicted. The calculation results show that the EFE model can well simulate the influence of fractures on the local seepage field of fractured rock mass, and reflect the non-uniformity of spatial distribution of the seepage field and water inflow in caverns. The research results can provide references for the precise design of seepage control measurements for water-sealed caverns and the design of sewage treatment facilities during the operation period.