## 1 Introduction
This pursuit aimed to identify the requisite engineering interventions essential for averting hydraulic fracturing within the Xiaowan arch dam. Leakage issues arising from surface cracks in concrete dams are typically averted through the application of polymer geomembranes or coating materials onto the dam's surface [18; 19; 20]. As per ICOLD Bulletin 135, approximately 400 dams worldwide have incorporated PVC geomembranes to mitigate seepage concerns [21]. Coating materials encompass impregnated silicone, fluorocarbon resin, epoxy resin, and polyurea, et al. Silane impregnation treatment on concrete surfaces for global and domestic projects, meticulously elucidating mechanisms, was summarized by [PERSON] [22]. Meanwhile, [PERSON] examined the utility of fluorocarbon resin coating on the Guandi Hydropower Station dam surface [23]. Additionally, [PERSON]'s work focused on repairing cracks and voids on the Xinanjiang spillway's concrete surface using epoxy mortar [24]. Innovatively, polyurea emerged as a novel dam surface protection material in China around 2008. Notably, [PERSON] et al. [25] and [PERSON] et al. [26] developed GB plastic sealing material from IGAS plastic filler for CFRD in 1995, exhibiting commendable fluidity, water \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Arch Dam**} & \multicolumn{2}{c}{**The Safety Factor of**} & \multicolumn{2}{c}{**The Safety Factor of**} & \multicolumn{2}{c}{**The Safety Factor of**} \\  & **Initiation Cracking** & **Crack Propagation** & **Overall Instability** \\  & **in Dam Heel** & **\(K_{2}\)** & \(K_{3}\) \\ \hline Xiaowan & 1.1 & 2.0 & 3.5–4.0 \\ Ertan & 1.3 & 2.0 & 4.5–5.0 \\ Kolnbrein (before & 0.9 & 1.65 & 2.56 \\ reinforcement) & 1.2 & 2.0 & 3.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The ultimate safety factors of analogy engineering [14; 15]. resistance, and extended freeze-thaw cycles. The GB material, heralded for its robust concrete adhesion, found extensive application in China and abroad, effectively replacing traditional water stops for concrete joints [27; 28]. In light of the imperatives of economic safety and temperature-humidity stability near the dam heel, the synergy between polyurea and GB plastic material is being explored as a countermeasure against surface hydrofracturing for the Xiaowan arch dam. This study delves into hydraulic fracturing in a 300-m super-high concrete arch dam, specifically focusing on tensile cracks on the dam surface and near the dam heel when subjected to high-pressure water. Using the Xiaowan arch dam as a foundation, a simulation test method for hydraulic fracturing in full-graded concrete structure specimens with cracks under tensile and compressive stress is designed. The results from hydraulic fracturing model tests led to the proposal of a novel dam surface anti-hydrofracturing technology. A pioneering flexible anti-hydrofracturing system, combining GB plastic body and polyurea elastomer, is introduced for super-high arch dams. This system's reliability is verified using specialized large-scale indoor test equipment, confirming its efficacy under 3 MPa water pressure and 8-millimeter crack openings. These measures significantly mitigate hydraulic fracturing risks and bolster dam safety, offering crucial support for similar endeavors such as the Liyuan concrete face rockfill dam and the Fengning Pumped-storage Power Station. Following this research, recommendations have been adopted by the Xiaowan arch dam, leading to improvements since its impoundment in 2008.