Numerical modeling and optimization analysis of anti-liquefaction measures of earth rock dam under multi-objective constraints

The seismic liquefaction of the foundation of earth rock dam is a serious threat to the safety of projects. The current research of liquefaction mainly focuses on the analysis of liquefaction mechanism, while in the design and optimization of anti-liquefaction measures, the existing earth rock dam projects mainly rely on the previous experience to deal with the liquefiable foundation of the dam site. A mathematical model is built to minimize the horizontal displacement gradient of earth rock dam slope,seismic subsidence on the top of the dam and the cost of anti-liquefaction measures. An optimal design method of parameters for ballast platform and foundation replacement of earth rock dam is proposed, which is constrained by the safety factor of static and dynamic anti-sliding stability, the maximum liquefaction range of foundation, the depth of liquefaction, the average degree of liquefaction of typical points in the process of earthquake and the permanent horizontal displacement after earthquake. The fully nonlinear dynamic algorithm and multi-objective genetic algorithm are used and FLAC3D is integrated by VC ++, which realize the multi-objective optimization design considering the safety performance and economic benefits of anti-liquefaction measures of earth rock dam. This method is applied to a practical project, and nine controlling design parameters of the platform and the foundation excavation replacement are optimized by using the Archive-based Micro-Genetic Algorithm (AMGA). The results show that compared with the original scheme, the horizontal displacement gradient of upstream and downstream dam slope decreased by 16.59% and 24.33%, the seismic settlement of the dam crest is reduced by 21.03%, and the project cost reduced by 18.53%. The proposed model and method provide a new way to reduce the liquefaction of earth rock dam foundation. © 2020, China Water Power Press. All right reserved.