To explore the influence pattern of high temperature on the crystallization amount of the waterproofing and drainage system, and to analyze the distribution characteristics of crystallization on the waterproofing and drainage board, a large-scale model test device for the crystallization of the high-temperature tunnel waterproofing system was designed and developed by replacing the circumferential drainage pipe with the waterproofing and drainage board. The gradient condition simulation of hot water temperature was realized. The test results show: (1) The crystallization adheres to the surface of the waterproofing and drainage board in two ways: strip-like and planar. The blocking degree at the lower part is more severe than that at the upper part. (2) With the increase of the circulating water temperature, the crystallization amount of the waterproofing and drainage system significantly increases. (3) In response to the high-temperature conditions and the severe blocking at the lower part of the waterproofing and drainage board, engineering suggestions are proposed to prioritize strengthening waterproofing and moderately reducing the number of convex shells at the lower part of the waterproofing and drainage board. The applicability of conventional crystallization disposal measures under high temperature is also discussed. In actual engineering, high-temperature-resistant equipment materials need to be selected, and the optimal solution should be adopted according to the time, local conditions, and segmented needs.

In water-rich geological formations, the crystallization blockage of drainage blind pipes in railway tunnels can lead to water leakage in tunnel linings and even severely impact tunnel structural safety. Laboratory model tests are conducted to investigate the crystallization patterns in drainage pipes under different flow rates. Additionally, three-dimensional numerical models are employed to analyze the water pressure distribution behind tunnel linings and the evolution of drainage volume in water-rich mountain railway tunnels equipped with different waterproof and drainage systems. The impact of the spacing between circumferential blind pipes on tunnel drainage capacity and the water pressure exerted on the lining is also explored. The results indicate that: (1) As the flow rate within the drainage pipes increases, so does the amount of crystallization within the pipes, suggesting that drainage volume is one of the primary factors influencing pipe blockage. (2) Compared to the semi-encapsulated waterproofing system, the fully encapsulated waterproofing system results in a more uniform distribution of water pressure on the lining at the arch crown and arch soles, which is more beneficial for the structural stress. (3) The water pressure distribution on the lining is closely related to the spacing between circumferential blind pipes, highlighting the critical importance of selecting an appropriate blind pipe spacing to meet lining safety requirements and ecological emission limitations. (4) Blockage in blind pipes leads to an increase in water pressure on the lining on both sides of the pipes, with the water pressure growth rate at the arch crown being greater than that at the arch soles. Special attention should be given to the arch crown area when monitoring the water pressure behind the tunnel lining. This study provides theoretical support for the design of waterproofing and drainage systems in railway tunnels located in water-rich geological formations.