Numerical analysis of a double layer rubber dam

Abstract

A new rubber dam with two layers of dam bodies anchored closely into a rigid base is proposed to improve the water-retaining ability of the conventional rubber dam. Numerical studies using FLAC2D software are conducted to analyze the behavior of the proposed double layer rubber dam. Laboratory model tests are also carried out to verify the accuracy of the numerical model. It is found that the optimal internal water head in the upstream dam normalized by its cross-sectional perimeter ranges from 0.35 to 0.45, and that in the downstream dam ranges from 0.32 to 0.40. The double layer rubber dam has optimal perimeter ratio of 0.8 and optimal anchoring distance normalized by cross-sectional perimeter of upstream dam of 0.08. For same ultimate external water head, the cross-sectional perimeter of the double layer rubber dam increased by 25.7%–49.6% than that of conventional rubber dam in different design parameters. However, the requirements of the maximum circumferential tensile strength of the upstream and downstream dams decreased by 40.8%–62.9% and 51.9%–69.6%, respectively. Assuming the material cost is determined by length and maximum circumferential tensile strength of membrane materials, the total material costs of the proposed double layer rubber dam reduce at most 82.2% than those of the conventional rubber dam in different design parameters.