Computers and Geotechnics最新文献_第4页

Microscopic investigation of shape effect on local scour around the monopile using CFD-DEM 利用 CFD-DEM 对单桩周围局部冲刷的形状效应进行微观研究

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-11-03 DOI: 10.1016/j.compgeo.2024.106872

Dong Li , Ziying Zheng , Zheng Hu , Huihuan Ma

Local scour refers to the erosion or migration of sedimental particles around bridge piers or abutments under the action of water flow. It can potentially undermine the hydraulic structures, resulting in catastrophic damage or even collapse. Under various hydraulic conditions, monopiles with diverse cross-sectional shapes have increasingly been applied to marine foundations. This study aims to investigate the effect of monopile shapes on scour development, and to establish a cross-scale connection between the macroscopic evolution of scour pits and the microscopic characteristics of sediments. The scour processes around monopiles are simulated using a coupled computational fluid dynamics and discrete element method (CFD-DEM). Four monopile shapes are examined, including circular, square, square with rounded corners, and diamond. Macroscopic characteristics such as seabed morphology, maximum scouring depth, and scour areas are analyzed, along with the microscopic characteristics such as the kinetic energy, drag force, and mechanical coordination number. The outcomes highlight that the diamond-shaped pile results in the greatest scour depth and widest scour areas compared to the other shapes. The incorporation of rounded pile corners improves flow characteristics and mitigate scour pit development. Furthermore, the local scour at different areas around the monopiles varies under the influence of different flow features.

局部冲刷是指在水流作用下，桥墩或桥台周围的沉积颗粒被侵蚀或迁移。它有可能破坏水力结构，造成灾难性的破坏甚至坍塌。在各种水力条件下，截面形状各异的单桩越来越多地应用于海洋地基。本研究旨在探讨单桩形状对冲刷发展的影响，并建立冲刷坑宏观演变与沉积物微观特征之间的跨尺度联系。采用计算流体动力学和离散元耦合方法（CFD-DEM）模拟了单桩周围的冲刷过程。研究了四种单桩形状，包括圆形、方形、带圆角的方形和菱形。分析了海底形态、最大冲刷深度和冲刷面积等宏观特征，以及动能、阻力和机械配合数等微观特征。结果表明，与其他形状的桩相比，菱形桩的冲刷深度最大，冲刷面积最广。圆角桩的加入改善了水流特性，减缓了冲刷坑的形成。此外，在不同水流特征的影响下，单桩周围不同区域的局部冲刷也各不相同。

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引用次数: 0

MatGBM: A Computer Vision-Aided Triangular Mesh Generator for High-Fidelity Grain-Based Model MatGBM：用于高保真纹理模型的计算机视觉辅助三角网格生成器

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-11-02 DOI: 10.1016/j.compgeo.2024.106871

Louis Ngai Yuen Wong, Zihan Liu

The grain-based model (GBM) stands as a renowned model for polycrystalline simulations in computational mechanics. Despite its popularity, there remains a critical need for a more advanced and user-friendly tool to generate high-fidelity microstructures with specified grain size distributions. Addressing this need, this paper introduces ’MatGBM’, an innovative modeling tool that aspires to enhance numerical simulations of polycrystalline materials. MatGBM seamlessly integrates three modules: a computer vision-aided mineral grain distribution detection, Voronoi tessellation processing, and triangular mesh generation. To accurately capture the two-dimensional structural characteristics of polycrystalline materials, the mineral grain distribution detection module employs computer vision functions to pinpoint particle coordinates and areas. The weighted Voronoi tessellation is generated and processed based on the original grain distribution features, resembling the original image of the polycrystalline material more closely than basic Voronoi tessellation. Finally, MatGBM directly outputs triangular mesh using two optional meshing tools based on the Voronoi polygons. Our rigorous testing via uniaxial compressive tests, Brazilian splitting tests, and three-point bending tests in crystalline rocks and metals, using the combined finite-discrete element method, validates that MatGBM can reliably reproduce the key deformation, damage, and failure characteristics of polycrystalline materials. Overall, MatGBM emerges not only as a promising tool for numerical simulations of rock, metallurgic, and ceramic materials, but also as a potent pre-processing tool for multiple numerical methods.

基于晶粒的模型（GBM）是计算力学中多晶体模拟的著名模型。尽管该模型广受欢迎，但仍迫切需要一种更先进、更方便用户使用的工具，以生成具有指定晶粒尺寸分布的高保真微结构。为了满足这一需求，本文介绍了 "MatGBM"，这是一种创新的建模工具，旨在增强多晶材料的数值模拟。MatGBM 无缝集成了三个模块：计算机视觉辅助矿物晶粒分布检测、Voronoi 镶嵌处理和三角网格生成。为了准确捕捉多晶材料的二维结构特征，矿物晶粒分布检测模块利用计算机视觉功能精确定位颗粒坐标和区域。根据原始晶粒分布特征生成并处理加权 Voronoi 网格，与基本 Voronoi 网格相比，加权 Voronoi 网格更接近多晶材料的原始图像。最后，MatGBM 使用两个基于 Voronoi 多边形的可选网格工具直接输出三角形网格。我们使用有限元和离散元相结合的方法，对晶体岩石和金属进行了单轴压缩试验、巴西劈裂试验和三点弯曲试验等严格测试，验证了 MatGBM 能够可靠地再现多晶材料的关键变形、损伤和破坏特征。总之，MatGBM 不仅是岩石、冶金和陶瓷材料数值模拟的理想工具，也是多种数值方法的有效预处理工具。

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引用次数: 0

Three-dimensional dynamic responses of a layered transversely isotropic half-space with irregular interfaces using the thin layer method 使用薄层法测量具有不规则界面的分层横向各向同性半空间的三维动态响应

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-11-02 DOI: 10.1016/j.compgeo.2024.106851

Chao He , Xiaoxin Li , Shunhua Zhou , Hui Li , Xiaoqing Dong

This paper proposes a thin layer method (TLM) for computing 3D dynamic responses in a layered transversely isotropic (TI) half-space with irregular interfaces. Utilizing Fourier transforms and modal superposition, stiffness matrices for semi-infinite and finite-length thin layer elements are derived, enabling the simulation of wave propagation in the finite-depth domain with irregular interfaces. The complex frequency shifted perfectly matched layer (CFSPML) within the TLM framework is developed to simulate wave attenuation in the underlying TI half-space, addressing the instability issues of the classical PML in the TI medium. The finite-length thin layer element can be of arbitrary length and is independent of the frequency, thus enhancing computational efficiency compared to discrete numerical methods like the FEM. The accuracy of the proposed method is verified with existing methodologies. The dynamic responses of a two-layered TI half-space with a Gaussian-shaped interface induced by either surface or buried dynamic point loads are investigated. The influences of the position and size of the irregular interface, as well as the transversely isotropy, are analyzed. Numerical results demonstrate that the presence of the irregular interface significantly changes the distribution of displacement fields. The influence of the irregular interface is highly dependent on the loading frequency and observation position.

本文提出了一种薄层法（TLM），用于计算具有不规则界面的分层横向各向同性（TI）半空间的三维动态响应。利用傅立叶变换和模态叠加，推导出半无限和有限长度薄层元素的刚度矩阵，从而能够模拟具有不规则界面的波在有限深度域中的传播。在 TLM 框架内开发了复杂频率偏移完全匹配层 (CFSPML)，用于模拟底层 TI 半空间中的波衰减，解决了经典 PML 在 TI 介质中的不稳定性问题。有限长度薄层元素可以是任意长度，并且与频率无关，因此与有限元等离散数值方法相比，提高了计算效率。所提方法的准确性与现有方法进行了验证。研究了具有高斯形状界面的双层 TI 半空间在表面或埋入式动点载荷诱导下的动态响应。分析了不规则界面的位置和大小以及横向各向同性的影响。数值结果表明，不规则界面的存在极大地改变了位移场的分布。不规则界面的影响与加载频率和观测位置密切相关。

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引用次数: 0

The combined effect of particle angularity and inter-particle friction on micro- and macroscopic properties of granular assemblies 颗粒角度和颗粒间摩擦对颗粒集合体微观和宏观特性的综合影响

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-31 DOI: 10.1016/j.compgeo.2024.106850

Dominik Krengel , Haoran Jiang , Jian Chen , Takashi Matsushima

Both inter-particle friction and particle shape are known to influence the micro- and macroscopic properties of granular assemblies individually. However their combined influence is still poorly understood. In this work we perform a series of Discrete Element Simulations to systematically study the combined effect of particle angularity and friction on the shear resistance of granular aggregates. We find that for angular particles the residual shear resistance as a function of inter-particle friction shows a local maximum, while for round particles it increases monotonically until it saturates. In contrast, no such effect is observed in the packing structure of the aggregates. The non-monotonic behaviour of angular particles is mirrored by the critical state directional and normal force fabric anisotropies, while the tangential normal force anisotropy shows more similarity to the bulk porosity and the mobilization of friction at the individual particle contacts. Our results now provide a much clearer picture on the origin of the non-monotonic behaviour of the critical state shear resistance on the inter-particle friction, as a competition between sliding and rolling in two different rolling regimes.

众所周知，颗粒间摩擦和颗粒形状都会单独影响颗粒集合体的微观和宏观特性。然而，人们对它们的综合影响还知之甚少。在这项工作中，我们进行了一系列离散元素模拟，系统地研究了颗粒角度和摩擦力对颗粒集合体抗剪性能的综合影响。我们发现，对于棱角分明的颗粒，残余剪切阻力与颗粒间摩擦力的函数关系显示出局部最大值，而对于圆形颗粒，残余剪切阻力单调增加直至饱和。相反，在聚合体的堆积结构中没有观察到这种效应。角形颗粒的非单调行为反映在临界状态的方向力和法向力结构各向异性上，而切向法向力各向异性则显示出与块体孔隙率和单个颗粒接触处的摩擦动员更为相似。现在，我们的结果更清楚地说明了临界状态剪切阻力对颗粒间摩擦力的非单调行为的起源，即滑动和滚动在两种不同滚动状态下的竞争。

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引用次数: 0

Ultimate lateral bearing capacity of rigid pile in clay considering soil stress history and scour-hole dimension 考虑土壤应力历史和冲孔尺寸的粘土中刚性桩的极限侧向承载力

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-30 DOI: 10.1016/j.compgeo.2024.106848

Mingke Lin , Changbing Qin , Siyu Li , Jiangtao Yi

Rigid monopiles in a marine environment are frequently subjected to severe lateral loads and scour effects, which complicates the stability assessment of monopiles. This paper proposes a ‘double failure mechanism’ that integrates the meniscus-conical failure wedge and rotational failure model to evaluate the ultimate lateral bearing capacity of a rigid pile in clay under scour conditions. Considering the influence of scour-hole, three distinct failure modes are introduced based on the possible ranges of failure. The critical ‘double failure mechanism’ can satisfy both the force balance and the moment balance of the pile-soil system. Based on this framework, an analytical solution for the ultimate lateral bearing capacity of a rigid monopile with considerations of these three failure modes is derived using the limit equilibrium method. Additionally, the combined effects of additional stress and stress history on soil properties are accurately analyzed. The FEM results and existing theoretical solutions are employed to validate the derived limit equilibrium solution. Finally, the effects of scour-hole dimensions and load eccentricity on the ultimate lateral bearing capacity of a rigid monopile, wedge failure and rotational failure are investigated.

海洋环境中的刚性单桩经常受到严重的侧向荷载和冲刷影响，这使得单桩的稳定性评估变得复杂。本文提出了一种 "双重破坏机制"，综合了半月板-锥形破坏楔和旋转破坏模型，用于评估冲刷条件下粘土中刚性桩的极限侧向承载力。考虑到冲刷孔的影响，根据可能的破坏范围引入了三种不同的破坏模式。临界 "双重破坏机制 "可同时满足桩-土系统的力平衡和力矩平衡。在此框架基础上，使用极限平衡法得出了考虑这三种破坏模式的刚性单桩最终侧向承载力的分析解决方案。此外，还精确分析了附加应力和应力历史对土壤性质的综合影响。利用有限元结果和现有的理论解决方案来验证推导出的极限平衡解决方案。最后，研究了冲孔尺寸和荷载偏心对刚性单桩极限侧向承载力、楔形破坏和旋转破坏的影响。

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引用次数: 0

Numerical investigations of the mechanical properties and energy characteristics of sandy cobble strata considering its internal stochastic structures 考虑内部随机结构的砂卵石地层力学性能和能量特征的数值研究

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-30 DOI: 10.1016/j.compgeo.2024.106867

Fan Wang , Pengfei Li , Xiuli Du , Jianjun Ma , Lin Wang

Investigating the mechanical properties of sandy cobble strata is essential for optimizing the design and construction of urban tunnels, thereby controlling ground deformation and ensuring tunnel stability. This paper aims to comprehensively investigate the mechanical properties and energy characteristics of heterogeneous sandy cobble strata. Numerical simulations are employed to examine the stress–strain behavior and energy evolution mechanism in scenarios with and without interfaces between the soil matrix and blocks. Subsequent analysis focuses on elucidating the effects of the internal stochastic structures, which characterize heterogeneity, on the overall strength and energy characteristics. The results indicate that the presence of interfaces significantly compromises the overall strength, while exacerbating the occurrence of a tortuous plastic zone around blocks. The volumetric block proportion (VBP), which represents the volumetric content of cobbles, has a significant impact on the overall mechanical behaviour. In the context of high VBP, block sizes, counts and orientations play substantial roles. Finally, the discussion reveals that when blocks are modelled using the elastic model, the overall strength is significantly overestimated compared to the strain-softening and Mohr-Counlomb models, especially in scenarios with high VBP and in-situ stress. It provides an unsafe evaluation (i.e., overestimation) of tunnel stability.

研究砂卵石地层的力学特性对于优化城市隧道的设计和施工，从而控制地面变形和确保隧道稳定性至关重要。本文旨在全面研究异质砂卵石地层的力学特性和能量特征。本文采用数值模拟的方法，研究了土体基质与砌块之间有界面和无界面情况下的应力应变行为和能量演化机制。随后的分析侧重于阐明内部随机结构对整体强度和能量特征的影响，而内部随机结构正是异质性的特征。结果表明，界面的存在极大地影响了整体强度，同时加剧了砌块周围迂回塑性区的出现。体积块比例（VBP）代表鹅卵石的体积含量，对整体机械性能有显著影响。在 VBP 较高的情况下，砌块的尺寸、数量和取向都起着重要作用。最后，讨论表明，与应变软化模型和莫尔-库伦模型相比，使用弹性模型对鹅卵石进行建模时，整体强度被明显高估，尤其是在高 VBP 和原位应力的情况下。这提供了对隧道稳定性的不安全评估（即高估）。

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引用次数: 0

Calibration and intelligent optimization for DEM numerical parameters in heterogeneous rock mass 校准和智能优化异质岩体中的 DEM 数值参数

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-30 DOI: 10.1016/j.compgeo.2024.106863

Runpeng Shang , Yugui Yang , Bingxiang Huang , Yong Chen , Chao Qiu , Wang Liu

Calibrating meso parameters is a crucial step in modeling rock materials using the Distinct Element Method (DEM). Improved calibration methods integrating machine learning and optimization algorithms have been proposed to revise the time-consuming conventional trial-and-error approach. This study introduces an innovative calibration method for heterogeneous DEM numerical parameters, optimized with the improved DBO algorithm (IDBO) utilizing Latin Hypercube Sampling combined with Gaussian Processes (GP-LHS) for initialization and hybrid strategies for iteration. Findings suggest the proposed enhanced heterogeneous DEM calibration method can accurately reproduce laboratory results and similar material experiments. Additionally, this method performs better than the DBO-DEM, PSO-DEM, and GA-DEM calibration methods in heterogeneous DEM parameters calibration speed with the same accuracy requirement during unconfined compression tests. The findings affirm the potential of the method for heterogeneous DEM numerical parameters calibration.

校准中观参数是使用独立元素法（DEM）对岩石材料进行建模的关键步骤。有人提出了集成机器学习和优化算法的改进校准方法，以修正耗时的传统试错法。本研究介绍了一种创新的异质 DEM 数值参数校准方法，该方法采用改进的 DBO 算法（IDBO）进行优化，利用拉丁超立方采样结合高斯过程（GP-LHS）进行初始化，并采用混合策略进行迭代。研究结果表明，所提出的增强型异质 DEM 校准方法能够准确再现实验室结果和类似材料实验。此外，在无约束压缩试验中，在相同精度要求下，该方法的异质 DEM 参数校准速度优于 DBO-DEM、PSO-DEM 和 GA-DEM 校准方法。研究结果肯定了该方法在异质 DEM 数值参数校准方面的潜力。

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引用次数: 0

A plastic-damage cohesive zone model for shear rupture band in geomaterials under mixed-mode and cyclic loading 混合模式和循环加载下土工材料剪切断裂带的塑性破坏内聚区模型

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-30 DOI: 10.1016/j.compgeo.2024.106829

Xiao Miao, Daosheng Ling, Anhao Pan, Hai Wang

The characterization of the mechanical behavior of the shear rupture band is essential to the analysis of the strain localization failure of geotechnical structures, with a key focus on describing the plastic-damage behavior and dilatancy of the geomaterial. A novel plastic-damage cohesive zone model is presented based on the unified plastic-damage modeling framework, in which an enhanced dilatancy angle evolution law is put forward to capture the dilatancy, and the yield function and the dissipation potential function are proposed to account for the tension/compression-shear coupling effect. The capability of the proposed model is demonstrated by its constitutive responses under several typical monotonic and cyclic loading paths, and further validated by simulating three laboratory tests of rock joint and silt-steel interface. The notable agreement between the simulation results and their experimental counterparts illustrates the effectiveness of the proposed model in characterizing the mechanical behavior of the shear rupture band under mixed-mode and cyclic loading conditions, including post-peak hardening/softening, plastic-damage behavior, and hysteresis.

剪切断裂带力学行为的表征对于岩土结构应变局部破坏的分析至关重要，重点是描述岩土材料的塑性破坏行为和扩张性。本文基于统一的塑性破坏建模框架，提出了一种新的塑性破坏内聚带模型，其中提出了一种增强的扩张角演化规律来捕捉扩张性，并提出了屈服函数和耗散势函数来解释拉伸/压缩-剪切耦合效应。该模型在几种典型的单调和循环加载路径下的构成响应证明了其能力，并通过模拟岩石节理和淤泥-钢界面的三次实验室试验进一步验证了其能力。模拟结果与实验结果之间的显著一致性说明了所提出的模型在描述混合模式和循环加载条件下剪切断裂带的力学行为（包括峰后硬化/软化、塑性破坏行为和滞后）方面的有效性。

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引用次数: 0

Upper bound stability analysis of single-layered slurry trenches in clay using the perturbation method 采用扰动法对粘土中的单层泥浆沟进行上限稳定性分析

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-30 DOI: 10.1016/j.compgeo.2024.106864

Tingzhen Tan , Maosong Huang , Zhenhao Shi

This study systematically analyzed the stability of slurry trenches in clayey soils. The analysis focused on non-homogeneous clays with a linear increase in undrained shear strength. The perturbation procedures based on three-dimensional rigid translational moving elements are established and employed in the analysis. The findings of this study provide lower upper-bound solutions than the existing solutions and demonstrate the potential of the perturbation method in delivering precise upper-bound solutions. The study offers a comprehensive understanding of the factors affecting trench stability, including the dimensions of the trench (width, length, and depth), the properties of the slurry (unit weight and filling level), and the properties of the clay (unit weight, the undrained shear strength at the ground, and undrained strength gradient). The analysis is investigated by considering the dimensionless quantities associated with previous factors. Finally, a novel design equation is presented through nonlinear regression analysis of computed upper-bound solutions.

本研究系统分析了粘性土中泥浆沟的稳定性。分析的重点是非均质粘土，其排水剪切强度呈线性增长。在分析中建立并采用了基于三维刚性平移移动元素的扰动程序。研究结果提供了比现有解决方案更低的上限值解决方案，并证明了扰动法在提供精确上限值解决方案方面的潜力。该研究全面了解了影响沟槽稳定性的因素，包括沟槽的尺寸（宽度、长度和深度）、泥浆的特性（单位重量和填充水平）以及粘土的特性（单位重量、地面排水剪切强度和排水强度梯度）。通过考虑与前述因素相关的无量纲量，对分析进行了研究。最后，通过对计算出的上限解进行非线性回归分析，提出了一个新的设计方程。

引用次数: 0

Efficient simulation of 3D conditional random field using kriging with Gaussian-process trend 利用具有高斯过程趋势的克里金法高效模拟三维条件随机场

IF 5.3 1区工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computers and Geotechnics

Pub Date : 2024-10-30 DOI: 10.1016/j.compgeo.2024.106862

Jianye Ching , Ikumasa Yoshida

Previous investigations have shown that for the modeling the soil spatial variability, the Gaussian process regression (GPR) provides a more plausible trend model than the linear combination of basis functions. However, the effectiveness of the conditional random (CRF) simulation based on the GPR trend model (denoted by the t-GPR kriging) has not been investigated. This study first addresses the high computational cost issue of the t-GPR kriging for realisic 3D problems by deriving the Kronecker-product algorithms. Then, this study further investigates the effectiveness of the t-GPR kriging in CRF simulation using real case studies. It is shown that with the Kronecker-product derivations, the computational time can be dramatically reduced such that the t-GPR kriging can conduct CRF simulation for full-scale 3D problems.

以往的研究表明，对于土壤空间变异性建模，高斯过程回归（GPR）提供了比基函数线性组合更可信的趋势模型。然而，基于 GPR 趋势模型的条件随机（CRF）模拟（表示为 t-GPR 克里金）的有效性尚未得到研究。本研究首先通过推导 Kronecker-product（克朗克积）算法，解决了三维实际问题中 t-GPR 克里格计算成本高的问题。然后，本研究利用实际案例进一步研究了 t-GPR 克里金法在 CRF 仿真中的有效性。结果表明，通过 Kronecker-product推导，计算时间可以大大缩短，因此 t-GPR 克里金法可以对全尺度三维问题进行 CRF 仿真。

引用次数: 0