| Summary: | 碩士 === 淡江大學 === 土木工程學系 === 91 === Particle media frictional strength is influenced by space characters of particles graded degree and packing. Traditional particle size analysis only can indicates condition of graded degree; it can’t be used to describe the state of relative stuffing among particles.However, particles with the same graded degree may have different mechanical properties because of different packing .This study make the sample of the same graded degree and different packing degree to do direct shear test. After shearing, take pictures which present sizes and position of graded on failure surface to do image technology. Furthermore, taking advantage of box dimension(Db) and two-point correlation dimension(DC) in fractal thesis to describe graded degree and arranging characters of particle media; then can realize the relationship between graded space characters and its shear strength.
The main conclusion of this study are draw as follows. (1) To use the same one sample on 2D and 3D, although their particle diameter distribution of graded is different, the trend parallel mutually. Besides, the fit line slope of double log is close; thus, their Db shows no difference. (2) DC can be used to indicate packing degree of particle concentrated degree. When particles distribute more concentrated, the DC is higher; on the contrary, DC become lower when they distribute more dispersed.(3) When size of graded particle diameter distribute more widely, the Db is higher. At this time, graded with large particle would be stuffed by that with small particle. Meanwhile, particles would closer through this step; so that DC increase. The increase of interlock effect makes frictional angle raise. On the contrary, the range of graded particle diameter distribution become more narrow, Db become smaller and inside samples are large-particle with same size and it distribute more dispersed. So that DC decrease, interlock effect reduce and frictional angle become smaller. (4) Compare the coefficientratio of Db and DC,the coefficients of DC is approximately 2.6 times as the coefficients of Db.
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