## 1 Introduction
[12] studied the direct shear stress and stress-sharing ability of the double shell lining during the bending process, and proved that the sprayed waterproof film can transfer stress between the concrete linings loaded in the direct shear test. According to the composition of waterproof materials, [PERSON] [18] divided them into three categories: water-based ethylene vinyl acetate (EVA), resin-based methacrylate reactive and polymer-based styrene-butadiene rubber (SBR), and investigated the characteristics of each waterproof film. [PERSON] et al. [7] summarized the material properties of various spray waterproof films, and the results show that there are great differences in the reaction and curing rate, sensitivity to water, water absorption, and expansion of various waterproof film products. Among these waterproof materials, polyurea materials exhibit advantages such as low permeability, high tensile strength, good ductility, strong environmental resistance, and eco-friendliness. Since their introduction to China in the early 21 st century, they have been widely adopted in numerous water conservancy and hydropower engineering projects. [PERSON] et al. [19], [PERSON] et al. [20],and [PERSON] et al. [21] conducted extensive experimental studies on the mechanical properties of polyurea materials under quasi-static loading rates at ambient temperature. Their findings revealed that polyurea materials demonstrate rubber-like mechanical characteristics, including significant ductility and strain-hardening non-linear viscoelastic deformation behavior, with quasi-static tensile strengths typically ranging between 6 MPa and 15 MPa. Based on experimental observations, [PERSON] et al. [22] and [PERSON] et al. [23] proposed hyperelastic constitutive models for polyurea materials, respectively. [PERSON] et al. [24] investigated the durability of polyurea materials through experimental studies. [PERSON] et al. [25] examined the puncture resistance of polyurea materials under various loading conditions, discovering that higher loading rates enhance their anti-penetration performance. Owing to their exceptional impermeability and mechanical properties, polyurea materials have proven highly valuable in seepage prevention applications, such as joint sealing in high-face slab dams and segmental linings, as well as crack repair in hydraulic structures. In addition, epoxy materials and silicone materials have been widely utilized for impermeability and durability protection in hydraulic and coastal engineering structures, benefiting from their stable physicochemical properties and reliable anti-seepage performance. As a new type of advanced interface protection material, modified polydimethylsiloxane has good flexible mechanical properties, transparency, and hydrophobicity [26]. Our research group has applied a coating composed of modified polydimethylsiloxane to concrete surfaces and found that this coating can effectively improve the impermeability of concrete under high-pressure water, even after concrete cracking [27]. The modified polydimethylsiloxane was compared with the sodium silicate commonly used in the current construction, and it was found that the modified material had better impermeability. However, the application of modified polydimethylsiloxane, polyurea, epoxy, and similar materials as anti-seepage coatings in the lining of high-pressure water conveyance tunnels remains exploratory and experimental, with only limited practical implementations similar to the Guangzhou Pumped Storage Power Plant's water diversion tunnel [28]. During the operation of ultra-high-pressure water conveyance tunnels, the composite lining structure--composed of concrete and anti-seepage coatings--is subjected to extreme internal water pressure and surrounding rock pressure. Critical questions arise: How does the anti-seepage layer function after cracking occurs in the concrete lining? Could ultra-high internal water pressure lead to catastrophic failure of the composite lining structure? What mechanisms govern the failure of anti-seepage systems?