Theoretical analysis of double-layer rubber dams (DRD)

A theoretical model is proposed to calculate the cross-sectional profile and tensile force of the double-layer rubber dams (DRDs). The theoretical results are further validated by those from large-scale model tests in the literature. The Runge-Kutta-Merson (RKM4) method is used to solve the proposed differential equations. The complex method is employed to search for the unknowns. Under the optimal design parameters, the anchoring force to support the Layer-2 rubber dam is larger than that of the Layer-1 rubber dam, with a maximum difference of 52.1%. The proposed theory could accurately predict the cross-section of the DRD with a maximum difference in dam height of 3.4% compared with the model test results. The properties of DRDs are compared with those of single-layer rubber dams (SRDs) to support the same water-retaining level. The cross-sectional perimeters of DRDs are larger than those of SRDs, with their magnitudes ranging from 25.7% to 49.6%. However, the tensile forces of the Layer-1 rubber dam are reduced by 40.8%–62.9% compared to conventional rubber dams, while those of Layer-2 are reduced by 51.9%–69.6%.