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.