Isogeometric shape optimization of high RCC gravity dams with functionally graded partition structure considering hydraulic fracturing

The seepage and cracking problems are always the key factors threatening the safety of RCC gravity dams. To improve the overall performance of the dam, a new type of high RCC gravity dam structure, functionally graded partition structure (FGPS), was proposed. The material properties including strength and impermeability were arranged in a gradient along the direction of water flow in FGPS. From the material level, the inhomogeneous numerical simulation method was applied to investigate the hydraulic fracturing of different types of concrete materials in FGPS. The influence of material properties and stress state on hydraulic fracturing was evaluated. The simulated results show that the vertical interface in FGPS is not the weak part. Gradient arrangement of materials can effectively reduce the possibility of hydraulic fracturing. From the structure level, the lowest construction cost design of FGPS was obtained by fusing isogeometric analysis and heuristic optimization algorithms (GA, MIGA, ASA) while maintaining the safety of RCC gravity dam under hydraulic fracturing. The optimization results indicated that integrating isogeometric analysis and ASA could realize faster convergence speed and reduce the computational burden of FGPS design. The proposal of FGPS in this study provides a new perspective to solve the problem of seepage and cracking. The improvement of mechanical properties and the perfection of the optimization design method probably raise the application prospect of FGPS in hydraulic engineering.