Research On Scale Effect Of Rockfill Partical Strength

The deformation of rockfill dam is the key to the design of high earth-rock dam because it's related to anti-leakage.As the main supporting material of dam,rockfill is prone to particle breakage,due to the large size and limited size of indoor test equipment,the deformation of dam body can only be calculated from the test results of scaled coarse particle.A large number of studies have shown that there exists scale-effect between the deformation characteristics of small size specimen and the prototype specimen,in the estimation of dam deformation,there often appear that the high dam is small amd the low dam is large.Therefore,it is significant to study the crushing of rockfill particle and the scale-effect of the strength of rockfill particle.As the smallest unit of rockfill,rockfill particle exists scale-effect and is easy to be broken.The main reason is that there are original cracks,joints and defects inside the rockfill particles,which lead to the heterogeneous particle.Dalian limestone particles within the range of 20-240 mm were selected for single particle strength test,and the distribution law of particle strength with different particle sizes was analyzed.The main content is as follows:(1)The statistical analysis of the crushing strength of 13 groups with 20-240 mm size of dalian limestone was carried out,which was used frequency statistical histogram.The distribution of rockfill particle strength is illustrated by three kinds of math ematical statistics.(2)The Weibull distribution and Logistic distribution were used to fit the particle strength of different particle groups,and the particle strength formula considering scale-effect was established based on Weibull and Logistic respectively.Compared with the Weibull scale-effect formula,Logistic scale-effect formula can not only describe the distribution law of particle strength better,but also predict the strength of large-diameter particles accurately.(3)According to the characteristics of particle breakage and the curve of force and displacement,four kinds of breakage models were put forward.In this paper,the fractal dimension was obtained by screening the crushed particles and studying the distribution of the fragments.(4)Based on Hertz-Minlin contact model,experimental model was established to analyze the law of the elastic modulus of dalian limestone with the change of particle size,and the approximate range of the elastic modulus of dalian limestone rockfill was calculated.