The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interes...The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interest(ROI)is used to analyze the cracking characteristics.Also,the mathematical morphology method based on the image threshold segmentation is used to obtain characteristic parameters of cracks to describe the cracking evolution of RSA.Results show that the elastic mismatch between rock blocks and soil matrix is the primary reason for RSA cracking.The mean CT value for the RSA specimen,rock block inclusions,and their adjacent soil regions decreases with the increasing stress level.However,it is more sensitive for block inclusions than soil regions.Using the image segmentation method,length,area and mean width of cracks obey to power function distribution.Crack statistical characteristics are closely related to the rock block’s distribution and morphology.These results may be useful to reveal the mesoscopic cracking mechanism,establish meso-damage evolution equation,and constitutive relation for RSA.展开更多
基于考虑含石量、含水率、块石岩性、初始孔隙比、法向压力5个影响因素的土石混合体室内大型直剪试验,利用剪切面在分形几何学上的统计规律和颗粒流数值模拟方法得到的直剪试验中颗粒的相互作用规律,对土石混合体的抗剪强度产生机制进...基于考虑含石量、含水率、块石岩性、初始孔隙比、法向压力5个影响因素的土石混合体室内大型直剪试验,利用剪切面在分形几何学上的统计规律和颗粒流数值模拟方法得到的直剪试验中颗粒的相互作用规律,对土石混合体的抗剪强度产生机制进行研究。结果表明:(1)土石混合体的剪切面呈不规则的起伏形态与块石的存在关系密切,且具有较好的分形特征,分形维数随着含石量和块石强度的增大、含水率和法向压力的减小均呈增大趋势;(2)含石量高于40%时,黏聚力小于30 k Pa;(3)内摩擦角随着含石量的增大、块石强度的增大、含水率的降低、初始孔隙比的降低、法向压力的降低均呈增大规律,且与分形维数满足正相关函数关系;(4)块石附近应力集中较明显,剪切过程中,颗粒间的接触力主要通过迎着剪切方向的接触面传递,而背着剪切方向的颗粒接触面基本不传递力;(5)内摩擦角φ等于剪切面上与颗粒本身接触性质有关的接触面内摩擦角θ0和与剪切面分形维数有关的接触面倾角θi之和,利用此机制可解释直剪试验中强度参数的变化规律。展开更多
基金supported by the National Natural Science Foundation of China(Grants Nos.41227901,41027001,and 41027001)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants Nos.XDB10030000,XDB10030300 and XDB10050400)
文摘The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interest(ROI)is used to analyze the cracking characteristics.Also,the mathematical morphology method based on the image threshold segmentation is used to obtain characteristic parameters of cracks to describe the cracking evolution of RSA.Results show that the elastic mismatch between rock blocks and soil matrix is the primary reason for RSA cracking.The mean CT value for the RSA specimen,rock block inclusions,and their adjacent soil regions decreases with the increasing stress level.However,it is more sensitive for block inclusions than soil regions.Using the image segmentation method,length,area and mean width of cracks obey to power function distribution.Crack statistical characteristics are closely related to the rock block’s distribution and morphology.These results may be useful to reveal the mesoscopic cracking mechanism,establish meso-damage evolution equation,and constitutive relation for RSA.
文摘基于考虑含石量、含水率、块石岩性、初始孔隙比、法向压力5个影响因素的土石混合体室内大型直剪试验,利用剪切面在分形几何学上的统计规律和颗粒流数值模拟方法得到的直剪试验中颗粒的相互作用规律,对土石混合体的抗剪强度产生机制进行研究。结果表明:(1)土石混合体的剪切面呈不规则的起伏形态与块石的存在关系密切,且具有较好的分形特征,分形维数随着含石量和块石强度的增大、含水率和法向压力的减小均呈增大趋势;(2)含石量高于40%时,黏聚力小于30 k Pa;(3)内摩擦角随着含石量的增大、块石强度的增大、含水率的降低、初始孔隙比的降低、法向压力的降低均呈增大规律,且与分形维数满足正相关函数关系;(4)块石附近应力集中较明显,剪切过程中,颗粒间的接触力主要通过迎着剪切方向的接触面传递,而背着剪切方向的颗粒接触面基本不传递力;(5)内摩擦角φ等于剪切面上与颗粒本身接触性质有关的接触面内摩擦角θ0和与剪切面分形维数有关的接触面倾角θi之和,利用此机制可解释直剪试验中强度参数的变化规律。