Many engineering projects fall into the misconception that thicker rubber sheeting equates to stronger dam bags and longer service life. In reality, thicker rubber is not always better; blindly increasing rubber thickness can lead to numerous drawbacks.
Inflatable dam bags are fabric-rubber composite structures: tensile strength is borne by the internal nylon 66 canvas skeleton, while the rubber only provides sealing, seepage prevention, erosion resistance, and aging resistance. Rubber thickness only affects wear resistance and UV resistance; it does not increase overall tensile strength.

I. The Reasonable Role of Rubber Thickness

1. Outer Rubber Layer: Standard thickness is approximately 2.5mm, resisting sun exposure, silt erosion, and friction from floating debris.
2. Inner Rubber Layer: Approximately 2.0mm, providing a tight seal to prevent leakage of the filling medium.
3. Sandwich Rubber: Bonds the canvas and rubber together, ensuring the composite does not delaminate.
Appropriately thickening the outer rubber layer can moderately improve weather resistance and abrasion resistance in river channels with high siltation and strong ultraviolet radiation.

II. Four Major Drawbacks of Blindly Increasing Rubber Thickness

1. Significantly Increased Dam Bag Weight: Rubber has a much higher density than canvas. Excessively thick rubber layers drastically increase the overall weight of the dam bag. This requires a larger filling and discharging capacity for water and air, slows down dam collapse and erection responses, and in high dam conditions, adds extra load to the canvas, thus increasing the stress on the framework.
2. Decreased Bending Fatigue Performance: Excessive rubber thickness leads to increased rigidity during repeated inflation, deflation, and folding of the dam bag. This increases the likelihood of surface cracking and rubber-to-canvas separation at the folding points, accelerating aging and damage. Inflatable dams require flexible deformation; excessive rubber thickness sacrifices flexibility.
3. Inflated Costs and Poor Cost-Effectiveness: Simply increasing rubber material without increasing the number of canvas layers does not improve tensile strength; it only increases material costs, representing an ineffective investment. The key to truly improving the strength of high-strength dams is increasing the number of canvas layers, not simply piling on rubber thickness.
4. Increased Risk of Delamination: Excessively thick rubber layers result in uneven heating during vulcanization, easily creating internal air bubbles. This can lead to delamination and separation of the rubber and canvas during later operation.

III. Correct Selection Logic

1. Dam height determines the number of canvas layers: The higher the dam, the more nylon canvas layers are needed to improve the tensile strength safety factor (safety factor ≥ 8.5), which is the core of strength.
2. Adjust rubber thickness according to river conditions
- Urban landscape, low siltation: Standard rubber thickness is sufficient.
- Rivers with high siltation, strong ultraviolet radiation, and many floating objects: The outer rubber layer can be appropriately thickened, or additional polyurea protection can be applied, rather than increasing the overall thickness of the fabric without limit.
3. For ultra-high dams > 5m, thickening the rubber layer cannot solve the problem; special demonstration is required. New skeleton materials such as aramid can be selected.

In Summary

The right thickness is best for inflatable dams; thicker isn't always better.
Tensile strength depends on the canvas, while abrasion resistance depends on the outer rubber layer. Simply increasing the rubber thickness without adding to the canvas support is ineffective weight gain, reduces the dam's flexibility, and ultimately shortens its lifespan.