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| 1 | 现代土力学研究的新视野——宏微观土力学显示文摘随着岩土工程领域的不断拓展,特别是在深地、深海、深空工程('三深工程')方面需要面对更多复杂的岩土材料和环境条件。基于连续介质和唯象的常规土力学理论与方法在描述岩土材料的非连续性、大变形和破坏等复杂特性以及复杂环境影响上有许多缺陷。宏微观土力学力图从本质上探求岩土材料复杂宏观特性的微细观机理,建立其多尺度分析理论与方法,解决岩土力学与工程中的疑难与关键问题,从而帮助提高工程设计水平。本文回顾了宏微观土力学近40 a的发展历程,从宏微观土力学的研究方法、理论和应用等方面综述了国内外学者的主要研究成果,包括典型土体的微观特性、微观本构理论、宏微观关联、基于微观机制的宏观本构理论等。研究土体包括陆地上黏土、结构性砂土、黄土、深海能源土和太空土(月壤)。重点阐述了宏微观土力学的重要研究手段之一的离散单元法在模拟陆、海、空疑难岩土力学与工程中的应用与拓展,探讨了宏微观土力学研究所面临的各种挑战和重大机遇。通过系统介绍上述研究成果,勾勒了宏微观土力学的基本框架,以期推动该研究方向的加速发展。 | 蒋明镜 | 2019 | 岩土工程学报2019，41，2： | 94 |
| 2 | 粒料固有各向异性的离散元模拟与细观分析显示文摘粒料在摊铺后形成的颗粒定向排列将导致其力学性质的固有各向异性.依据粒料的实际不规则形状,构建了可模拟粒间咬合嵌挤作用的三维离散元复杂形状颗粒;生成了5种不同沉积方向的各向异性试件和1种各向同性试件,对比了各试件在三轴压缩试验中的宏观力学特性差异;引入组构张量以量化各向异性程度,利用玫瑰图表达接触法向与接触力的分布特征,探究了粒料各向异性的细观发展规律.结果表明:颗粒长轴愈趋向水平排布,峰值应力比愈大,剪缩与剪胀程度愈明显;相较于各向同性试件,沉积角θ为0?时,峰值应力比和最大体积压缩应变分别提高了12.6%和18.8%,其原因在于加载过程中颗粒旋转和滑动百分比更小,内部调整时间更短、更易被剪密;固有各向异性对颗粒法向接触力分布的影响不大,但显著影响接触法向分布特征;剪切过程中,θ为90?时的接触法向各向异性系数先快速减小后逐渐增大,而θ为0?到60?时则呈现出增大后稍有回落或趋于稳定的趋势,且θ愈小的试件各向异性系数增大愈快. | 钱劲松 陈康为 张磊 | 2018 | 力学学报2018，50，5： | 15 |
| 3 | 往复荷载下铁路道砟沉降特性的扩展多面体离散元分析显示文摘基于Minkowski Sum方法,采用扩展多面体单元构造非规则的道砟颗粒,对道砟材料在往复荷载作用下的动力特性进行离散元分析,研究其沉降量和形变刚度的演变过程。结果表明,在往复荷载作用下道砟材料的累计沉降量在变形初期增加显著,随着往复荷载次数的增加趋于稳定,其有效刚度在累计变形过程中不断增大并最终趋于平稳。本文研究表明,扩展多面体单元可有效模拟道砟材料的力学行为,研究其在列车往复荷载下的动力特性。 | 孙珊珊 严颖 赵春发 季顺迎 | 2015 | 铁道学报2015，37，11： | 11 |
| 4 | 低围压下颗粒形态对软黏土抗剪强度影响的离散元分析显示文摘黏土颗粒形态不仅反映黏土的矿物组分,更是影响其物理力学性质的重要因素之一。为了研究物质组成对软黏土微宏观性质的影响,采用离散元方法对不同颗粒形态的软黏土试样进行三轴压缩模拟试验。首先,基于扫描电镜图像量化颗粒形态,对天然状态下黏土颗粒的方向角和凹凸度进行统计,引入球度和凹凸度作为颗粒形态的特征参数;然后,基于原生矿物的单粒结构和黏土矿物的片状结构特征,构造球体单粒及圆柱体、正方体、长方体的片状簇体;最后,基于三轴试验离散元模拟方法,分析软黏土颗粒形态对其宏观力学及微观特性的影响。结果表明:片状颗粒试样比球体颗粒试样的初始模量高,抗剪强度大,随加载其排列趋于水平向分布;加载初期,颗粒球度对初始弹性模量影响较明显,初始弹性模量随着球度增大而逐渐减小;加载后期,颗粒凹凸度对抗剪强度指标影响作用逐渐凸显,试样内摩擦角和黏聚力随着凹凸度增大而逐渐减小;微观结构上,颗粒形状对颗粒位移和旋转也有较大影响。 | 赵洲 张鹏 宋晶 李学 李志杰 黄伟标 | 2019 | 工程地质学报2019，27，5： | 9 |
| 5 | Quantified evaluation of particle shape effects from micro-to-macro scales for non-convex grains显示文摘 | Y. Yang J.F. Wang Y.M. Cheng | 2016 | Particuology2016，14，2： | 8 |
| 6 | DEM investigation of angle of repose for super-ellipsoidal particles显示文摘We explore the effect of particle shape on the angle of repose (AoR) in granular packing using a three-dimensional discrete element method.Non-spherical particles were modeled using super-ellipsoids characterized by aspect ratio and blockiness.The relationship between AoR and particle shape was examined,followed by a series of analyses on the origin of AoR from a microscopic perspective.Results show that,with blockiness deviating from unity,AoR has an approximate 'M' shape that exhibits a strong to weak trend with aspect ratio,matching results of previous reports.Another finding suggests a parabolic relationship between normalized AoR and normalized coordination number,AoR increases with anisotropy related more with the anisotropy of particle orientation than with the anisotropy of contact normal.Particle shape is more likely to affect AoR by affecting the tangential force than the normal contact force.An analysis based on traction indicates that dips in stress associated with the tangential force (compared with the normal force) and non-spherical particles (compared with spheres) are more significant.For various particle shapes,AoR is positively correlated with friction mobilization but is negatively correlated with friction mobilization for various coefficient of friction. | Hao Chen Shiwei Zhao Xiaowen Zhou | 2020 | Particuology2020，18，3： | 6 |
| 7 | 颗粒形状对粗砂直剪特性影响研究显示文摘岩土材料物理力学性质变化的本质是其细观结构发生改变,颗粒形状作为砂土细观结构的重要参数,必然会对其力学性质产生影响。借助颗粒形貌扫描设备对3种不同形状的粗砂进行测试,并通过室内直剪试验探究颗粒形状对粗砂抗剪强度的影响。结果表明:4种颗粒形状参数敏感性由大到小依次为:长宽比>扁平度>磨圆度>球度;粗砂颗粒形状愈规则,其颗粒重排列所主导的峰值内摩擦角就愈小,所以峰值内摩擦角随颗粒形状规则程度的提高而减小;颗粒形状愈规则,剪切后期颗粒间的滑动摩擦力就愈小,相应的残余内摩擦角就愈小。 | 赵书辉 魏厚振 吴永洁 王睿 | 2020 | 土工基础2020，34，6： | 5 |
| 8 | 模拟月壤颗粒形状特征及其对抗剪强度影响分析显示文摘为研究颗粒形状特征对抗剪强度的影响,对模拟月壤颗粒进行体视显微镜扫描拍照,并利用图形处理软件对各粒径组颗粒的形状特征进行量化统计.结果表明:模拟月壤颗粒的主要形状有圆形、类椭圆形、类三角形和类正方形等.利用PFC 3D软件中的'Clump'命令构造出不同形状的模拟月壤颗粒并通过三轴试验数值模型研究其抗剪强度指标值,模拟结果表明:颗粒形状对模拟月壤的抗剪强度指标值有着明显的影响,其中构造出的类椭圆体颗粒试样抗剪强度最大,而规则的球体颗粒试样的抗剪强度最小;当颗粒形状都是类三角体时,凹凸度越大,试样的抗剪强度指标值也越大. | 林呈祥 钟世英 凌道盛 | 2016 | 东北大学学报(自然科学版)2016，37，11： | 4 |
| 9 | 各向异性对软土力学特性影响的离散元模拟显示文摘软土预压工程中,初始和诱发各向异性对软土力学性质的影响十分显著,而现有研究缺乏对初始和诱发各向异性的统一研究方法。采用离散单元法,以颗粒长宽比作为定量评价指标,构建真实形态的颗粒模型,生成5组不同沉积角的初始各向异性试样,并进行竖直和水平两方向加载的双轴模拟实验,研究了初始各向异性和诱发各向异性对软土力学特性影响;在细观层面,以颗粒为对象研究了颗粒接触形式和转动角度的变化规律,以接触为对象研究了配位数和接触法向各向异性的发展趋势,在此基础上探究抗剪强度指标与各向异性关系。结果表明:初始和诱发各向异性共同影响试样力学性质,当加载方向和软土沉积方向垂直时,土体有最大的峰值强度。颗粒接触形式中面面接触的比例随加载的进行逐渐增大,并影响着试样初始模量和抗剪强度,配位数和接触法向各向异性受颗粒接触形式的影响有不同的演化规律,并在加载后期趋于稳定;同时,初始各向异性试样相较各向同性试样有更大的黏聚力,诱发各向异性主要影响试样内摩擦角,进而影响试样抗剪强度。 | 赵洲 宋晶 刘锐鸿 杨守颖 李志杰 | 2021 | 水文地质工程地质2021，48，2： | 3 |
| 10 | FWD动载下的横观各向同性路基动力响应分析显示文摘利用有限元分析原理,建立基于横观各向同性路基的三维仿真模型,分析在落锤式弯沉仪(falling weight deflectometer,FWD)脉冲动载作用下路基表面的弯沉,及不同深度处力学指标的变化,讨论土基材料横观各向同性对力学指标的动力响应影响.结果表明,路基弯沉峰值随距荷载中心点距离的增大而滞后,荷载中心点与距荷载中心200 mm处传感器点的滞后幅度最大(为60%);弯沉值随水平模量的增大而减小,最大减小幅度为21%;路基所受应力随深度的增加而减小,最大减小幅度为67%;水平模量的增大也会减小应力值,最大减小幅度为28%.落锤式弯沉仪能较好模拟车辆移动荷载状况,反映实际路面受力情况,基于横观各向同性的土质路基,能有效地预测路基的使用性能. | 栗振锋 张敏 | 2013 | 深圳大学学报(理工版)2013，30，2： | 1 |
| 11 | Impulse force reductions and their effects on WBV exposures in high impact shovel loading operations显示文摘When shovels load the dump trucks with over 100-ton passes under gravity dumping conditions, they will create a large impact force on the dump truck body which generates high frequency shock waves which expose the operators to whole body vibrations(WBV). The main cause of such truck vibrations is the large impact force due to the gravity dumping of large tonnage passes. Therefore a rigorous mathematical model has been developed for the impact force containing all the necessary factors upon which it depends. Latter, a thorough analysis shows that percentage reduction of 7.19%, 9.40%, 13.27%, 14.8%,17.30% and 18.13% can be achieved by reducing the dumping distance to 6.33 m, 6.0 m, 5.5 m, 5.33 m,5.0 m and 4.9 m, respectively, as compared to when the dumping distance was 7.33 m. Even more reduction in the magnitude of impact force can be observed if the shovel pass gets divided into more than two sub-passes. Therefore, these models can be used to figure out the number of sub-passes into which a single ore pass can be divided and/or the extent to which the dumping distance can be reduced which would reduce the impact force significantly enough to obtain safer yet economic operations. | Danish Ali Samuel Frimpong | 2018 | International Journal of Mining Science and Technology2018，28，3： | 1 |
| 12 | Cyclic behavior of reinforced sand under principal stress rotation显示文摘Although the cyclic rotation of the principal stress direction is important,its effect on the deformation behavior and dynamic properties of the reinforced soil has not been reported to date.Tests carried out on large-scale hollow cylinder samples reveal that the cyclic rotation of the principal stress direction results in significant variations of strain components(ε_z,ε_r,ε_θ and γ_(zθ)) with periodic characteristics despite the deviatoric stress being constant during tests.This oscillation can be related to the corresponding variations in the stress components and the anisotropic fabric that rotate continuously along the principal stress direction.Sand under rotation appears to develop a plastic strain.Similar trends are observed for reinforced sand,but the shear interaction,the interlocking between particles and reinforcement layer,and the confinement result in significant reductions in the induced strains and associated irrecoverable plastic strains.Most of the strains occur in the first cycle,and as the number of cycles increases,the presence of strains becomes very small,which is almost insignificant.This indicates that the soil has reached anisotropic critical state(ACS),where a stable structure is formed after continuous orientation,realignment and rearrangement of the particles accompanied with increasing cyclic rotation.Rotation in the range of 60°-135° produces more induced strains even in the presence of the reinforcement,when compared with other ranges.This relates to the extension mode of the test in this range in which σ_θ>σ_z and to the relative approach between the mobilized plane and the weakest horizontal plane.Reinforcement results in an increase in shear modulus while it appears to have no effect on the damping ratio.Continuous cycles of rotation result in an increase in shear modulus and lower damping ratio due to the densification that causes a decrease in shear strain and less dissipation of energy. | Alaa H.J. Al-rkaby A. Chegenizadeh H.R. Nikraz | 2017 | Journal of Rock Mechanics and Geotechnical Engineering2017，9，4： | 0 |
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