考虑缩尺效应对颗粒破碎影响的堆石料临界状态研究

Critical State of Rockfill in Consideration of Scale Effect on Particle Breakage

堆石料缩尺后的替代料与原级配料的强度变形特性存在差异,揭示这种差异对堆石料工程运用具有重要的科学价值。采用相似级配法和混合法对弱风化灰岩料进行缩尺,缩尺后堆石料最大粒径分别为60、40、20、10 mm,通过三轴固结排水剪切试验进行缩尺后替代料的应力变形特性研究,分析了缩尺方法和试样最大粒径对堆石料临界状态及临界状态方程的影响。结果表明:最大粒径相同的条件下,混合法缩尺后试样体积变化量大于相似级配法缩尺试样,而两组试样在q-p′平面上的临界状态线几乎重合;引入分形维数描述颗粒破碎过程,颗粒破碎分维值随着围压的增大而呈幂函数增长,且与最大粒径的大小有关;在e-lgp′平面建立了考虑颗粒破碎的临界状态线方程,并给出了各参数的确定方法。研究结果为进一步构建考虑缩尺效应的堆石料临界状态本构模型提供了一种思路。

The strength and deformation characteristics of the replacement material of rockfill after scaling differ from those of the original rockfill.Studying such difference is of vital scientific value.In this paper,the influence of scaling method and maximum grain size of specimen on the critical state and the critical state equation were examined by looking into the stress and deformation characteristics of replacement material via triaxial consolidated drained shear test.The similar gradation method and the mixed method were adopted for the scale reduction of weakly-weathered limestone,and the maximum grain sizes of the designed gradations were 60 mm,40 mm,20 mm,and 10 mm respectively.Results unveiled that under the condition of the same maximum particle size,the volume change of the sample with mixed scale was larger than that of the sample with similar grading scale,and the particle breakage forms of the samples with different scales were different in the shear process,while the critical state lines of the two groups of samples on the Q-P′plane were nearly coincident.The degree of particle breakage was described by introducing fractal dimensions.The particle fractal dimension after shearing was in a power function with confining pressure and was also related with maximum particle size.In addition,the equation of critical state line in consideration of maximum particle size of particle breakage was established in e-lgp′plane,and the determination method of each parameter was also given.The research finding provides an idea for further constructing the critical state constitutive model of rockfill in consideration of scale effect.