According to the "GB/T50979 Technical Specification for Rubber Dam Engineering," the design service life of rubber dam bags is generally 15 to 20 years. When the dam bags reach their design service life, systemic problems such as material aging, performance degradation, functional failure, and deterioration of supporting equipment will occur. Conventional local repairs cannot fundamentally solve these problems, indicating that the entire dam bag is due for scrapping and requires complete replacement.

1. From the perspective of external aging characteristics, the surface of over-aged dam bags will generally lose its luster, turn white, and fade. The rubber surface will show severe powdering, with rubber powder flakes off upon touch. Affected by sun exposure, alternating wet and dry conditions, and corrosion from river acidity, alkali, and salt spray, dense network cracks will appear on the water-facing side of the dam body and in the overflow vibration zone. These cracks will gradually penetrate the surface rubber material, causing moisture to seep into the interior and corrode the nylon canvas skeleton. Simultaneously, large-scale delamination, bulging, and blistering will occur between the inner and outer rubber layers and the canvas layer. Delamination is common at the seams and around the anchorages, and in severe cases, the canvas will be directly exposed. The long-term friction zone at the dam base shows significant wear and thinning, the dam body wrinkles cannot naturally rebound, the dam filling is incomplete, and the entire structure exhibits irreversible permanent deformation. Long-term water immersion also fosters microbial growth, causing the canvas to mold and rot, further reducing the overall toughness and durability of the dam.

2. In terms of material mechanical properties, the rubber used in the dam bags generally hardens, becomes brittle, and loses elasticity upon reaching maturity. It is prone to cracking at low temperatures, and its impact and vibration resistance decreases significantly. The tensile strength and tear strength of the material generally drop below 70% of the national standard requirements, the elongation at break decreases significantly, and its ability to resist impacts from floating objects and gravel is essentially lost. The dam body's density deteriorates, and its watertightness and airtightness are significantly reduced. Water-filled dams experience continuous seepage, and air-filled dams require constant depressurization, necessitating continuous water and air replenishment. Maintaining stable water levels and inflation pressures in front of the dam becomes difficult.

3. Analysis of operational performance reveals that the aging rubber dams have significantly insufficient water storage and retention capacity. Under the same inflation pressure, the dam height cannot meet design standards, resulting in a substantial weakening of their functions in river water storage, landscape regulation, and flood control. Multiple leaks occur throughout the dam body, leading to insufficient water retention stability during the flood season. Repairs in aging areas exhibit extremely poor durability, with repeated cracking and leakage at both new and old repair sites, significantly increasing the frequency of maintenance throughout the year. Increased water flow vibration within the dam body creates a vicious cycle of increased seepage, intensified vibration, and further damage, severely impacting the safe and stable operation of the project.

4. Regarding the anchoring and supporting systems, the water-stopping strips and sealing sheets have aged and cracked, and the anchoring grooves have been leaking water for a long time. The pressure plates and anchoring bolts are generally corroded and loose, and the tightening torque is insufficient, so they are prone to loosening and failure even after repeated tightening. The water pumps, air compressors, valves and pipelines and other filling and draining equipment have been operating under overload for a long time, and the failure rate and aging rate have increased significantly.

In summary, in actual engineering assessments, if a dam bag exhibits multiple characteristics such as having been in service for 15 years, large-area cracking and delamination, excessive thickness loss, abnormal leakage, frequent maintenance, and substandard material testing, it can be determined that the dam bag has reached its service life. It is recommended to replace it entirely in a timely manner to eliminate potential safety hazards during the flood season.