Research On Physical And Mechanical Characteristics Of Rockfill And Its Engineering Applications

Rockfill is a cohesionless frictional aggregate material with certain gradation, high seepage velocity and has particular physical and mechanical characteristics since rockfill is mainly composed of particles and void. Its properties are related to particle's size, shape and distributing character. These particle's parameters will change when force is put on, and the characteristics of rockfill change too. The strength and deformation mechanism are studied in this thesis on the base of discrete mechanics and granular material mechanics considering the change of microstructure of rockfill.The adaptive mechanical model is established combining characteristic parameters of microstructure with macro mechanical parameters. The thesis enriches the research of rockfill, and the main achievements are as follows: A more integrated fundamental theory system for rockfill is built up upon synthetically compare, analysis, study and summarization of the research achievements about physical and mechanical characteristics of rockfill through introducing related theories of discrete mechanics, granular material mechanics and statistical mechanics.The Log-normal distribution model of rockfill particle is established based on rock fragmentation mechanism. It well forecast the gradation distribution of blasted rockfill.Comprehensive experimental research is carried out in this thesis to study the particle gradation, shear strength, seepage ability, compress ability and settlement of rockfill including in situ test and analysis, large scale roll test, in situ shear test, seepage test, compaction test, compress test, triaxial shear test and so on. The results are helpful to further research and provide necessary data for engineering project.Probability density of contact force is acquired through research contact force, contact force normal and fabric characteristics of rockfill by statistical mechanics to study the relationship between physical and mechanical characteristics of rockfill and packing style of particles, void and its dimensional distribution.Relationship between local micro contact force of particle and macro stress of rockfill is studied through discrete mechanics and statistical theory by analyzing of contact relation and contact force from dimensional packing of particle. Put forward rigid contact model that can connect contact force with local stress and establish local constitutive model based on micro structure of rockfill particle. Two dimensional and three dimensional constitutive models for rockfill are built up on the base of local constitutive relation. It connects particle micro fabric with macro mechanical response and can be the base for further research.Through theoretically analysis, in situ monitor and numerical analysis to study thesoil force distributing status and investigate the arching action of rockfill and analyze the influence of rockfill on its inner structures. Engineering examples approve that rockfill has excellent engineering characteristics, such as good compactness, strong seepage ability, high density, low sedimentation, high bearing capacity, good stability and so on. It shows well safe benefit, economic benefit, social benefit and environmental benefit. So rockfill is a safe and economical engineering material with well social benefit and environmental benefit.