## 1 Introduction  
Arch dams find widespread application globally, offering substantial economic benefits alongside inherent risks. The complexity of stress distribution, particularly evident in super-high arch dams with heights around 300 m, complicates crack assessment within the dam heel. Subsequent to impoundment, the emergence of surface cracks can lead to hydraulic fracturing failures due to high water pressure, entailing intricate and costly repairs [1; 2; 3]. Illustrating this, the Sayano-Shushenskaya arched gravity dam (H = 245 m) encountered numerous cracks during construction due to temperature control oversights. In its seventh operational year, the No. 35 dam section witnessed an abrupt escalation in crack propagation upon impoundment to design water levels. The ensuing breach, reaching depths of 50 m with a width of 2.5 mm, triggered significant seepage at approximately 483 L/s. A two-year effort to lower water levels successfully halted hydraulic fracturing [4]. Similarly, Austria's Kolnbrein arch dam (H = 200 m) faced analogous challenges. Cracks emerged in the dam heel upon its 1978 commissioning, resulting in substantial leakage (200 L/s) at reservoir water levels reaching 158 m. Diverse measures, including freezing, grouting, and innovative anti-seepage interventions, failed to mitigate the issue. As a result, a downstream multifaceted support arch was introduced to enhance stress distribution and restore operational stability [5]. Drawing insights from the Kolnbrein experience, Austria's Zillergrundl arch dam (182 m high) incorporated a bottom joint and pre-dam heel apron in its design. In addition, post-impoundment, hydraulic fracturing persisted just above the bottom joint. Mitigation necessitated reservoir drainage, transforming the dry bottom joint into a wet joint, coupled with controlled water pressure moderation [6]. The Xiaowan arch dam, towering at 294.5 m, boasts a parabolic double-curvature design and a substantial water thrust of approximately 19 million tons. The reservoir's formidable water flow, however, poses maintenance challenges due to its river's robust discharge [7]. The safety evaluation of the Xiaowan high arch dam has been explored through geomechanical model tests and numerical simulations. Model tests effectively replicate water pressure using jacks and facilitate continuous load addition until failure occurs, enabling the attainment of overload safety factors across diverse ultimate states [8]. [PERSON]'s approach [9; 10] combines overloading and strength reduction analysis, encompassing a 20% weakening of structural surfaces. Results indicate that dam heel cracks manifest at safety factors ranging from 1.2 to 1.4, with maximum overload safety factors of 3.96 to 4.20. References [11; 12] underscore safety factors of 1.2 to 2.5 during upstream surface and dam heel initiation cracking, with overload failure safety factors ranging from 5 to 6.5. [PERSON]'s assessment highlights substantial upstream surface cracking risk for the Xiaowan arch dam [13]. Meanwhile, [PERSON] and [PERSON] prognosticate the dam's cracking stability by juxtaposing it with the Ertan and Kolnbrein arch dams listed in Table 1[14; 15]. Outcomes reveal a dam heel cracking safety factor of 1.1 for the Xiaowan arch dam, surpassing Kolnbrein's unreinforced dam yet trailing Ertan and Kolnbrein's reinforced states. Diverse strategies were implemented to ensure the safety of the Xiaowan arch dam. These encompassed the utilization of C\({}_{180}\)45 concrete in high tensile stress zones above the dam foundation and the establishment of induced dry joints near the dam heel foundation to optimize stress conditions [16; 17]. However, considering the pronounced risk of cracking and its potential to culminate in hydraulic fracturing, the efficacy of these measures in ensuring safety remains insufficient. Consequently, a hydraulic fracturing model test was conducted to investigate the post-crack anti-hydrofracturing capability of concrete.