Topology optimization method for zoning of high concrete face rockfill dam

Abstract: Concrete face rockfill dam (CFRD) is very popular in modern dam engineering applications due to its low cost, stability, adaptability and environment friendly. In CFRD engineering, many accidents are caused by the cracks of face plates. Especially, most of high CFRDs (over 100 m) have cracks in their face plates that reduce the safety of dams in operation. One of the main reasons for the cracks in face plates of a high CFRD is difference between the deformation of the face plates and dam body under gravity and upstream water pressure. Clearly, the deformation of dam body is determined by not only gravity and the water pressure, but also the distribution of filled materials. Therefore, the layout of the materials in dam body is essential to CFRD engineering. Taking TSQ-1 CFRD as an example, the best partition form of dam material within cross-section of a high CFRD was analyzed by continuum topology optimization. In traditional design, the zoning of material was given mostly according to designer's experiences and however, the intuitive method is not feasible because the height of CFRD is over 200 m. In this research, a continuum topology optimization method was proposed to find the optimal partition of the filled materials in CFRD. Considering the differences among the elasticity of materials in dam body, a material set was formed with the materials in respect to their tangential moduli. The deformation of structure was solved using finite element (FE) method and the material number of each FE was chosen within the material set. The purpose of the present research was to find the optimal material numbers in finite elements in design domain. A heuristic method was presented and similar to evolutionary structural optimization (ESO) as considering the update rule of material properties in optimization process. Here, a criterion was adopted to renew the design variables, i.e., the material numbers with respect to the tangential modulus of materials in dam body. To keep the stability of algorithm, no more than 5% of total elements' material number will be renewed in iteration. The results indicated that there were obvious differences between the layout of optimized material and that of the traditional partition. High modulus materials were located in the lower side of the upper reaches and various materials changed gradually with respect to the moduli from the upstream to downstream. And boundary slope ratios of materials were not lower than 1:0.8. Compared with the original design, deformation of panel in optimized dam was slighter and more uniform under water pressure, which helps to prevent face plate from breaking.