为解决压缩空气储能（compressed air energy storage，CAES）地下硐室由于普通混凝土衬砌开裂导致的柔性密封层陷裂问题，提出高韧性工程水泥基复合材料（engineered cementitious composites，ECC）与纤维增强复合材料（fiber reinforced polymer，FRP）筋混凝土组成的复合衬砌结构。通过试验研究适用于CAES地下硐室国产聚乙烯醇纤维ECC的力学性能，采用数字图像相关技术（digital image correlation，DIC）分析ECC的应变分布和破坏特征，获取应力-应变曲线，建立相应的ECC塑性损伤本构模型。在此基础上，建立ECC-FRP筋混凝土复合衬砌CAES地下硐室的有限元模型，对比分析复合衬砌CAES地下硐室与普通混凝土衬砌CAES地下硐室的衬砌应力分布、开裂损伤分布及围岩变形分布，并开展ECC厚度、FRP筋配筋率的参数分析。结果表明： 1）ECC具有良好的变形性能和多缝开裂能力，达到极限应变时的最大裂缝宽度为0.12~0.15 mm，能有效解决柔性密封层陷裂问题。2）在围岩条件较差的情况下，相较于普通混凝土衬砌，ECC-FRP筋混凝土复合衬砌具有更优的变形性能，能减小衬砌应力集中与缩小围岩塑性变形区域，更好地传递硐室内压，从而发挥围岩的承载能力。3）复合衬砌中FRP筋的最大应力随ECC层厚度和FRP筋配筋率的增大而降低，围岩最大变形随ECC层厚度的增大而增大，ECC层最大应力随其厚度的增大呈先减小后增大的趋势，随FRP筋配筋率的增大逐渐降低。
The cracking of conventional concrete linings in underground compressed air energy storage (CAES) caverns fractures the flexible sealing layer. To address this challenge, a composite lining structure composed of high-toughness engineered cementitious composite (ECC) and fiber-reinforced polymer (FRP)-filled concrete is proposed. Experimental investigations were conducted on the mechanical properties of Chinese-produced polyvinyl alcohol fiber-reinforced ECC suitable for underground CAES caverns. Digital image correlation technology was used to analyze the strain distribution and failure characteristics of ECC, yielding stress-strain curves that were used to establish corresponding parameters for a plastic damage constitutive model of ECC. Subsequently, a finite element model of a CAES cavern with a composite lining was developed. A comparative analysis was performed on the stress distribution within the lining, the distribution of cracking damage, and the deformation of the surrounding rock between the CAES cavern with the composite lining and that with a conventional concrete lining. Furthermore, a parametric sensitivity analysis was conducted on the ECC layer thickness and the FRP reinforcement ratio. The results indicate that ECC exhibits excellent deformation capacity and multiple microcracking capability, with a maximum crack width of 0.12－0.15 mm at ultimate strain, effectively mitigating the fracture risk of the flexible sealing layer. Furthermore, under poor surrounding rock conditions, the ECC-FRP-reinforced concrete composite lining demonstrates superior deformation performance compared to the conventional concrete lining. The composite reduces stress concentration in the lining and minimizes the plastic deformation zone in the surrounding rock while more effectively transferring the internal cavern pressure to mobilize the bearing capacity of the surrounding rock. In addition, the maximum stress in the FRP bars decreases with increasing ECC layer thickness and FRP reinforcement ratio in the composite lining. The maximum deformation of the surrounding rock increases with increasing ECC layer thickness. The maximum stress in the ECC layer initially decreases and then increases with increasing thickness, and gradually decreases with increasing FRP reinforcement ratio.
