Three-dimensional Numerical Analysis Of The Compaction Properties Of RCC Based On DEM

Roller compacted concrete (RCC) dam achieved rapid development in recent years, the hydraulic designers and the construction staff desperately hope to build the better performance of RCC dam, and thus do a great deal of studies on the RCC materials. Most researchers regard field tests, laboratory tests and long-term monitoring of projects as the basis for analysis of the physical and mechanical properties of RCC for a long time. These methods consume time and materials, then some scholars introduce the finite element method (FEM) into the analysis of RCC materials, but this approach has many limitations. At the same time, a variety of destruction of RCC dam also arises increasingly. It is well known macroscopic mechanical properties of RCC structures are under the control of their microsco(?) structure. The evolution of RCC material micromechanical properties is the foundation of setting up the mechanical properties and macroscopic regularity of the RCC structures. Grasping the variations of internal structures can provide theoretical guidance for good construction quality.Avoiding defects of the FEM, the whole compacted process of RCC is numerically simulated using the discrete element method (DEM) based on particle flow code in3dimensions (PFC3D). Three influence factors:rolling load type, grain size distribution and particle shape are detailed studied. By analyzing the contact stress field and velocity field of particles, the RCC particles’moving law, compacted mechanism and compaction properties under compacting loads are visually researched from the micro perspective. In addition, the connectivity of mortar system in the process of rolling is analyzed. Considering rolling load type, grain size distribution and particle shape, the filling mechanism of the mortar is explored. By comparing with the measured data, it presents preliminary proof of the feasibility of the numerical simulation of DEM. Results show that fine particles continuously move to coarse particles once the compacting loads are applied. Compared with static loads, vibrating compaction stage has more significant impact on RCC’s porosity. Changing the grain size distribution with relatively low porosity, medium particles can heavily influence the compaction quality of RCC. When compared to the flat and slender particles, aggregate of spherical particles can be compacted more easily. Meanwhile, the mortar particles have successively suffered dispersing, compacting and moving stability in the process of rolling. Compared with static loads, vibrating compaction stage has more significant impact on mortar particles’ motion. Increasing the content of the medium size of aggregate particles appropriately is conducive to mortar connectivity under the conditions of this thesis. Mortar connectivity of the needle, flaky aggregate models is far worse than the spherical aggregate model.The thesis can provide a new way to study the microscopic compaction performance of RCC, accelerate the recognition of compaction properties of the RCC materials and promote the development of RCC dam.