STUDY ON MESOSTRUCTURAL CHARACTERISTICS OF SHEAR SURFACES FOR ALLUVIAL-DILUVIAL SUBGRADE FILLERS BASED ON THE N-METHOD
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摘要: 为研究不同级配条件下冲洪积体填料的力学和结构特性,以陕西洛南冲洪积体填料为对象,基于最大密实度理论中的N法设计了五种不同路基的填料级配,并进行大型直剪试验,分析级配对抗剪强度的影响;应用高清数码相机采集不同级配的试件剪切面图像,利用图像处理软件从细观尺度对填料剪切面细观结构特征进行分析;从宏、细观相结合的角度分析了级配对其力学特性的影响。结果表明:当形状系数n为0.55时,冲洪积体填料抗剪强度最高;剪切面上填料的孔隙形态以扁圆形为主,近等轴状次之,长条状最少;块石形态则从扁圆向近等轴形发展;剪切面孔隙面积百分含量、块石破碎率和块石轮廓分维数随着n的增大先减小后增大,在n=0.55时达到极值。Abstract: In order to study the mechanical and structural characteristics of alluvial-diluvial subgrade fillers with different gradations, the alluvial-diluvial deposits in Luonan, Shaanxi were researched. Based on the N-method in the theory of the maximum density, five different subgrade filler gradations were designed. A large-scale direct shear test was designed to analyze the effects of gradations on the shear strength. A HD digital camera was used to collect the shear plane images of specimens different with gradations. The mesostructure characteristics of the shear plane for specimens were analyzed from the mesoscale by the software of lmage-Pro Plus. The effects of gradations on mechanical properties of fillers were analyzed from the perspective of macro and meso. The results showed that the effect of pore forms in the shear planes on shear characteristics were significant, when the pore form was oblate mainly, the shear strength of fillers was the highest and the form coefficient was 0.55; then it was equiaxed and finally was bar-type. The pore forms of fillers developed from the oblate to the equiaxed, the percentage of the pore areas, fragmentation ratios and fractal dimension values of fillers decreased first and then increased with the increase of n, and finally reached the extreme value when n was 0.55.
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Key words:
- alluvial-diluvial deposit /
- subgrade filler /
- N-method /
- meso-structure /
- digital image processing
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[1] 田海,孔令伟,李波.降雨条件下松散堆积体边坡稳定性离心模型试验研究[J].岩土力学,2015,36(11):3180-3186. [2] 油新华.土石混合体的随机结构模型及其应用研究[D].北京:北方交通大学,2001. [3] 徐文杰,胡瑞林,岳中琦.基于数字图像处理的土石混合体细观结构[J].辽宁工程技术大学学报(自然科学版),2008(1):51-53. [4] 徐文杰,胡瑞林,岳中琦,等.土石混合体细观结构及力学特性数值模拟研究[J].岩石力学与工程学报,2007,26(2):300-311. [5] 徐文杰,胡瑞林,岳中琦,等.基于数字图像分析及大型直剪试验的土石混合体块石含量与抗剪强度关系研究[J].岩石力学与工程学报,2008,27(5):996-1007. [6] 丁秀丽,张宏明,黄书岭,等.基于细观数值试验的非饱和土石混合体力学特性研究[J].岩石力学与工程学报,2012,31(8):1553-1566. [7] 丁秀丽,李耀旭,王新.基于数字图像的土石混合体力学性质的颗粒流模拟[J].岩石力学与工程学报,2010,29(3):477-484. [8] 金磊,曾亚武,叶阳,等.基于不规则颗粒离散元的土石混合体三维随机模型及其数值试验[J].长江科学院院报,2016,33(5):94-101. [9] 金磊,曾亚武,李欢,等.基于不规则颗粒离散元的土石混合体大三轴数值模拟[J].岩土工程学报,2015,37(5):829-838. [10] 高文伟,高玮,胡瑞林,等.块石空间定向性对土石混合体力学性质的影响[J].防灾减灾工程学报,2019,39(1):89-97. [11] 张佩,杜修力,金浏,等.块石长轴倾角对土石混合体宏观力学性能的影响研究[J].工程力学,2018,35(9):64-72. [12] 刘新荣,涂义亮,王林枫,等.土石混合体的剪切面分形特征及强度产生机制[J].岩石力学与工程学报,2017,36(9):2260-2274. [13] 罗伟,王优,张帅浩,等.土石混合体随机结构模型生成与直剪强度数值试验研究[J].铁道科学与工程学报,2019,16(7):1681-1689. [14] 杨呈刚.基于数字图像处理技术的土石混合体数值模拟试验[J].土工基础,2019,33(1):49-53. [15] 赵新坡.密级配沥青稳定碎石基层材料与性能研究[D].西安:长安大学,2006. [16] 章毅.沥青稳定碎石基层技术性能研究[D].西安:长安大学,2007. [17] 申爱琴.道路工程材料[M].北京:人民交通出版社,2010. [18] DENG J X, ZHOU X D, HUANG Y T, et al. Discrete Element Simulation and Analysis for Max Density Curve Theory of Mineral Aggregate Mixtures[J]. Applied Mechanics and Materials, 2014(668/669):12-16. [19] 刘新荣,涂义亮,王林枫,等.土石混合体的剪切面分形特征及强度产生机制[J].岩石力学与工程学报,2017,36(9):2260-2274. [20] TYLER S W, WHEATCRAFT S W. Fractal Scaling of Soil Particle-Size Distributions:Analysis and Limitations[J]. Soil Science Society of America Journal, 1992(56):362-369. -

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