摘要
对某一爆破筑坝堆石料开展了试样直径1m(最大粒径为200mm)的超大型和试样直径0.3m(最大粒径为60 mm)的常规大型三轴固结排水剪切试验,研究了平行相似级配条件下最大粒径对应力–应变关系、颗粒破碎、特征应力状态、割线模量及邓肯张E-B模型参数的影响。试验结果表明:(1)大型三轴试验的峰值内摩擦角大于超大型三轴试验,并且峰值应力处的轴向应变小于超大型三轴试验;(2)大型三轴试验的相变应力比大于超大型三轴试验,并且相变处的体变及轴向应变均小于超大型三轴试验;(3)大型三轴试验的颗粒破碎率小于超大型三轴试验,但二者平行粒组的变化规律相同;(4)大型三轴试验在应力水平50%处的割线弹性模量及割线体积模量均大于超大型三轴试验。大型三轴试验的邓肯张E-B模型参数k,kb分别是超大型三轴试验的1.22倍、1.38倍。研究成果可为建立考虑缩尺效应的堆石料本构模型和分析土工构筑物变形提供重要的试验依据。
A super-large triaxial apparatus and a common large triaxial apparatus are used to conduct triaxial tests on quarried rockfill materials with the maximum particle size d_(max) of 200 and 60 mm in parallel gradation.The study mainly focuses on the effect of particle size on the stress-strain relation,particle breakage,characteristic stress state and parameters of Duncan-Chang model.The results show that the peak friction angle of d_(max)=60 mm is higher than that of the d_(max)=200 mm,and the axial stain at the peak strength of d_(max)=60 mm is smaller than that at d_(max)=200 mm.The phase transformation stress ratio of d_(max)=60 mm is higher than that at d_(max)=200 mm,and the volumetric and axial strains in phase transformation state are smaller than those at d_(max)=200 mm.The amount of particle breakage of d_(max)=200 mm is greater than that at d_(max)=60 mm.The secant elastic and bulk moduli at 50% stress level of d_(max)=60 mm are larger than those at d_(max)=200 mm.The parameters k and kb of Duncan-Changmodel for d_(max)=60 mm are 1.22 and 1.38 times those for d_(max)=200 mm,respectively.This study may provide valuable experimental references for the constitutive model considering scale effect and the deformation analysis for rockfill structures.
引文
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