Abstract: In order to investigate the manifestation of the scale effect on the shear strength of coarse grains and to explore the method of eliminating the scale effect, large-scale consolidation and drainage (CD) triaxial tests were carried out on sand-cobble gravels and rock piles. Due to the size limitation of the apparatus, the equivalent substitution method and mixing method were used to scale the sand-cobble gravel and the piled stone respectively, so that the maximum particle size dM of the scaled samples reached 10, 20, 40, and 60 mm, respectively. The test results show that dM has a significant impact on the apparent cohesion c and effective internal friction angle φ′ of the c shear strength parameters of coarse-grained materials, and c and φ′ decrease gradually with the increase of dM. Moreover, the relationship curves between dM and c as well as φ′ can all be expressed as logarithmic functions. According to the relationship between dM and c as well as φ′, the relation between shear strength and dM is obtained, which can be used to predict the shear strength of the original graded coarse grains in a relatively simple way. On the other hand, an estimation formula for predicting the shear strength of the original graded coarse grains has been derived based on previous research results, and the reliability of this formula has been verified by experimental data. And it has been mutually proven with the relation between shear strength and dM that both formulas can accurately predict the shear strength of the original grade, thus proposing a method to eliminate the influence of scale effect on shear strength.

Key words: geotechnical engineering; coarse grains; shear strength; scale effect; maximum particle size; apparent cohesion; effective internal friction angle

摘要： 为研究缩尺效应对粗粒料抗剪强度的表现形式并探讨缩尺效应的消除方法，对砂卵砾石料和堆石料进行了大型固结排水（CD）三轴试验。首先，由于受仪器尺寸的限制，分别采用等效替换法和混合法将砂卵砾石料和堆石料进行缩尺，使其缩尺后试样颗粒最大粒径dM分别达到10、20、40、60 mm。试验结果表明：dM对粗粒料抗剪强度参数表观凝聚力c以及有效内摩擦角φ′有重要影响，随着dM的增加，c以及φ′逐渐减少，并且c与dM以及φ′与dM关系曲线均可用对数函数表示。然后，根据c与dM以及φ′与dM关系得到了抗剪强度与dM的关系式，该关系式可较为简单地预测原级配粗粒料抗剪强度。最后，推导了预测原级配粗粒料抗剪强度的估算公式，验证了该公式的可靠性，结合抗剪强度与dM的关系式互相证明了2个公式均能较为准确地预测原级配粗粒料抗剪强度，从而提出缩尺效应对粗粒料抗剪强度影响的消除方法。

关键词: 岩土工程；粗粒料；抗剪强度；缩尺效应；颗粒最大粒径；表观凝聚力；有效内摩擦角