Large-scale model test studies on the double-layer rubber dam

A new rubber dam with two layers of dam bodies anchored together into a rigid concrete base was proposed to improve the water-retaining capacity of the traditional rubber dam. A series of large-scale model tests are conducted to evaluate the static behavior of the double-layer rubber dam under conditions of different internal and external water heads, anchorage distances, and cross-sectional perimeters. It is found that the maximum tensile force of the Layer-1 dam is located at the anchoring point but that the Layer-2 dam is located at the extruded free section. The optimum cross-sectional perimeter ratio is concluded as 0.8 with the optimal anchoring distance of 0.06 L1, the internal water head in the upstream dam, and that in the downstream dam of 0.40 L1 and 0.36 L1 where L1 is the cross-sectional perimeter of the upstream dam.