堆石料的颗粒破碎规律研究

粗颗粒土剪切过程中的颗粒破碎现象已被广泛认识,并且在试验和理论方面进行了大量研究。利用大型三轴仪开展了一系列不同级配、不同密度、不同围压条件下堆石料的排水剪切试验,并对试验前后的试样分别进行了颗粒分析,以探讨堆石料的颗粒破碎规律及其影响因素。试验结果表明:密度对颗粒破碎影响较小,而级配和围压的影响较大,围压越高则颗粒破碎越严重。对比试验前后的粒径分布曲线发现,颗粒破碎主要集中在粒径20 mm以上的颗粒范围内,粒径变化幅度随粒径的减小呈减小趋势。基于分形理论,建立了颗粒破碎分形维数与围压和颗粒级配之间的关系表达式,为进一步研究堆石料的强度、变形及剪胀特性提供依据。

Particle breakage rules of rockfill materials

The particle breakage phenomenon of coarse-grained soils during shearing has been widely known, and a lot of researches have been performed in the fields of experiments and theories. A series of drained shear tests on rockfill materials with different gradations and densities under different confining pressures are carried out by using large-scale triaxial apparatus, and the particles of rockfill samples before and after tests are analyzed to discuss the particle breakage rules of rockfill materials as well as their influencing factors. The test results indicate that the density has small influence on the particle breakage, while the gradation and confining pressure have great influence on the particle breakage. The larger the confining pressure, the severer the particle breakage. A comparison of grain-size distribution curves of rockfill specimens before and after tests shows that the particle breakage mainly occurs within the range of particles with grain size larger than 20 mm, and the variation amplitude of grain size has a decreasing tendency with the decrease of the grain size. Based on the fractal theory, an expression of relationship between the fractal dimension of particle breakage and the confining pressure and particle gradation is proposed so as to provide a basis for further researches on strength, deformation and dilatancy of rockfill materials.