| The main work of this paper includes two independent parts.The first part is conducted in view of the fact that granular materials are widely used in civil and hydraulic engineering practice and particle breakage may be mobilized under high compression and shear loads.This part is focused on the progressive compression breakage of a single particle and particle layers by laboratory tests and three-dimensional refined numerical simulation,so as to probe into the influencing factors and appearance functions of granular crushing,and to incorporate it into a macro-meso multi-scale model,which can be applied to investigate the mechanical properties of concrete faced rockfill dams considering rockfill breakage.The second part,based on field measurements and numerical simulation,presents an in-depth investigation into the deformation mechanisms of dam-valley deformation due to reservoir impounding.The main research contents and innovations are as follows:1.Effects of single particle compression breakage.Fragmentation behavior and influencing factors of quasi-brittle spherical particles under uniaxial compression were studied by analytical solution and numerical simulation,and the main fragmentation mechanisms were revealed.Considering the meso-heterogeneities of rock blocks,a random field generation algorithm with given spatial correlation length is proposed.The progressive fragmentation characteristics of randomly heterogeneous rock blocks under rolling compression are studied by FE-SPH coupling method.2.Theoretical modeling of compression fragmentation effect of particle layers.The general evolution rules of breakage characteristic index considering the variation of particle materials,feed size and gradations are studied.A theoretical Es-t10-tn model for predicting product size distribution based on input energy is established,which has been verified by experimental and numerical results.3.Numerical simulation of confined compression tests and triaxial compression tests considering fragmentation effects.A deformable discrete particle model considering fragmentation effects is established.The fragmentation characteristics of particle layers and its influence on macro-scale mechanical properties are studied.The numerical simulation results are in agreement with the experimental results.4.Multi-scale simulation of rockfill dam settlements considering particle breakage effects.A macro-and meso-scale coupling numerical model is established.Taking Shuibuya RFC project as an instance,the effects of rockfill fragmentation on dam settlements and concrete face deformation are studied.Simulation results show that settlements considering fragmentation effects can give a better prediction as compared to the field measurements.5.Deformation mechanisms of dam-valley system due to reservoir impounding.Main characteristics of deformation responses and mechanisms of Xiluodu dam-valley are discussed based on field monitoring data.It is discovered that large-scale cooling of the bedrock upstream and downstream on the dam site give rise to the uniform valley contractions,while the seepage pressure increase of the limestone roof caused by impounding bring about the uplift of dam base and downstream basin.A numerical model of impounding-cooling-seepage pressure is established and the simulation results approve the proposed valley deformation mechanism. |
