Study On Size Effect Of Compressive Strength Of Rockfill Concret

In recent years,with the rapid development of water conservancy projects in China,the technology of Rock-Filled Concrete(RFC)dam construction has been widely promoted and applied.As a new large-volume concrete construction technology,rock-filled concrete consists of a loadbearing framework formed by stacking large-sized stones and a matrix formed by filling with SelfCompacting Concrete(SCC).Its unique construction method also distinguishes rock-filled concrete from ordinary concrete in terms of stress characteristics.In order to test the mechanical properties of rock-filled concrete,large-sized specimens are needed to characterize the distribution of internal large-sized stones.When studying the size effect of rock-filled concrete,larger specimens are often needed for comparative testing,which is difficult due to experimental conditions.Currently,compared with rock and ordinary concrete,the study of size effect of rock-filled concrete still needs further in-depth research.In actual engineering,the particle size of the aggregate in rock-filled concrete often randomly distributed between 30 cm to 100 cm,and in some engineering projects in recent years,the particle size of aggregate used has exceeded 100 cm,and it is unknown whether the effect of particle size on the mechanical properties of rock-filled concrete is significant.Aiming at the influence of specimen size,aggregate size,rockfill rate and other factors on the mechanical properties of rock-filled concrete,this paper mainly studies the following contents:(1)Based on the Realistic Failure Process Analysis(RFPA)method and obtaining material statistical parameters,numerical models of rock-filled concrete with different sizes are established to simulate experiments and obtain corresponding size effect laws.(2)Physical and numerical experiments are conducted on rock-filled concrete with different particle sizes to study the effect of particle size on the mechanical properties and failure mode of rock-filled concrete.The results show that the particle size has an inhibitory effect on the compressive strength of rock-filled concrete,and the larger the particle size,the smaller the compressive strength,and the decreasing trend gradually slows down.The elastic modulus of rockfilled concrete is almost equal to the weighted average of the elastic modulus of the self-compacting concrete and the rock according to the volume fraction,and the effect of particle size on the elastic modulus is not significant.(3)Three-dimensional feature reconstruction of rock-filled concrete is carried out to establish a numerical model with macroscopic structure.Through numerical experiments,the effects of rock shape,rock spatial distribution,and filling rate on the mechanical properties and failure mode of rock-filled concrete are analyzed.The results show that with the increase of rockfill rate,the compressive strength of rock-filled concrete has a significant increasing trend;when the rockfill rate difference is small,the effects of rock shape and spatial distribution on strength will be reflected;when the rockfill rate difference is large,the effects of rock shape and spatial distribution on strength will be weakened,and rockfill rate will become the main factor affecting compressive strength.