International Journal for Numerical and Analytical Methods in Geomechanics最新文献_第6页

A Stress‐Driven Double‐Phase–Field Framework for Tensile Fracturing Processes in Transversely Isotropic Rocks 横向各向同性岩石拉伸压裂过程的应力驱动双相场框架

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-19 DOI: 10.1002/nag.3830

Weihong Yuan, Yang Zhao, Bingyin Zhang

We present a double‐phase–field framework for tensile fracturing processes in transversely isotropic rocks. Two distinct phase‐field variables are introduced to represent smeared approximations of tensile fractures along the weak bedding planes and through the anisotropic rock matrix, respectively. Driving forces that control fracture propagation in the phase‐field framework are constructed as a stress‐based formula with a recently developed tensile failure criterion that distinguishes the two failure modes in transversely isotropic rocks. For numerical implementation, we adopt a staggered integration scheme and decouple the governing equations so that the displacement field and phase‐field variables can be updated in sequence for a given loading step. The finite element formulation of the proposed framework is introduced in detail in this paper and is implemented in an in‐house finite element code. The numerical implementation is then validated by reproducing the uniaxial tension test results of Lyons sandstone. After that, we conduct simulations on a pre‐notched square plate loaded in tension to demonstrate the features of the proposed framework. Finally, we conduct simulations of three‐point bending tests of Pengshui shale and show that the proposed model can reproduce the force–displacement curves and failure patterns of specimens with different bedding plane orientations observed in laboratory experiments.

我们提出了横向各向同性岩石拉伸断裂过程的双相场框架。我们引入了两个不同的相场变量，分别代表沿弱基底面和穿过各向异性岩石基质的拉伸断裂的涂抹近似值。相场框架中控制断裂扩展的驱动力被构建为一个基于应力的公式，该公式采用了最新开发的拉伸破坏准则，可区分横向各向同性岩石中的两种破坏模式。在数值实现方面，我们采用了交错积分方案，并将控制方程解耦，从而可以在给定加载步骤中依次更新位移场和相场变量。本文详细介绍了拟议框架的有限元公式，并在内部有限元代码中实施。然后，通过再现里昂砂岩的单轴拉伸试验结果，对数值实现进行了验证。之后，我们对一块预缺口方形板进行了模拟拉伸加载，以展示所提框架的特点。最后，我们对彭水页岩的三点弯曲试验进行了模拟，结果表明所提出的模型可以再现实验室实验中观察到的不同基底面方向试样的力-位移曲线和破坏模式。

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引用次数: 0

Semi‐Analytical Solution for One‐Dimensional Nonlinear Consolidation of Multilayered Soil Considering Self‐Weight and Boundary Time Effect 考虑自重和边界时间效应的多层土一维非线性固结的半解析解

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-19 DOI: 10.1002/nag.3839

Mengfan Zong, Jing Zhang, Wenbing Wu, Ziye Yu, Yi Zhang, Guoxiong Mei

The self‐weight stress in multilayered soil varies with depth, and traditional consolidation research seldom takes into account the actual distribution of self‐weight stress, resulting in inaccurate calculations of soil consolidation and settlement. This paper presents a semi‐analytical solution for the one‐dimensional nonlinear consolidation of multilayered soil, considering self‐weight, time‐dependent loading, and boundary time effect. The validity of the proposed solution is confirmed through comparison with existing analytical solutions and finite difference solution. Based on the proposed semi‐analytical solution, this study investigates the influence of self‐weight, interface parameter, soil properties, and nonlinear parameters on the consolidation characteristics of multilayered soil. The results indicate that factoring in the true distribution of self‐weight leads to a faster dissipation rate of excess pore water pressure and larger settlement and settlement rate, compared to not considering self‐weight. Both boundary drainage performance and soil nonlinearity have an impact on consolidation. If the boundary drainage capacity is inadequate, the influence of soil nonlinearity on consolidation diminishes.

多层土中的自重应力随深度变化而变化，传统的固结研究很少考虑自重应力的实际分布，导致土壤固结和沉降计算不准确。本文提出了多层土一维非线性固结的半解析解，考虑了自重、随时间变化的荷载和边界时间效应。通过与现有的分析解法和有限差分解法进行比较，证实了所提解法的有效性。基于所提出的半解析解，本研究探讨了自重、界面参数、土壤特性和非线性参数对多层土壤固结特性的影响。结果表明，与不考虑自重相比，考虑自重的真实分布会导致过剩孔隙水压力消散速度加快，沉降量和沉降速度增大。边界排水性能和土壤非线性对固结都有影响。如果边界排水能力不足，土壤非线性对固结的影响就会减弱。

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引用次数: 0

Modeling of Drain Consolidation in the Quick Triaxial Test and Its Analytical Solution 快速三轴试验中的排水固结模型及其分析方法

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-17 DOI: 10.1002/nag.3842

Zhibo Chen, Jungao Zhu, Xinjiang Zheng, Lei Wang

Sand columns have been widely used to accelerate drainage and then improving the mechanical properties of soft soil foundations. The sand column has also been introduced into the triaxial test by researchers, in the center of the cylindrical specimen, to greatly accelerate drainage and consolidation process. The objective of this paper is to evaluate the consolidation properties of the triaxial cylindrical specimen considering the presence of a sand column, and then to propose a consolidation model that simulates the consolidation process of the triaxial test. The consolidation equations were derived considering the drainage of the specimen with a sand column composed of both vertical and double‐radial flows. Then the analytical solution of the model was obtained based on specific initial and boundary conditions. The comparison between the consolidation model and the laboratory tests yielded highly consistent. The case study demonstrated that the proposed consolidation model accurately simulates the evolution of average pore pressure and degree of consolidation in triaxial specimens containing a sand column. The studies on the consolidation parameters showed that there were different effects on the drainage rate for the diameter of specimen, the permeability coefficients of specimen and sand column, as well as the radius of the sand column.

砂柱已被广泛用于加速排水，进而改善软土地基的力学性能。研究人员还在三轴试验中引入了砂柱，将其置于圆柱形试样的中心，以大大加速排水和固结过程。本文旨在评估考虑到砂柱存在的三轴圆柱试样的固结特性，然后提出一个模拟三轴试验固结过程的固结模型。考虑到试样排水时砂柱由垂直流和双径向流组成，推导出了固结方程。然后根据特定的初始条件和边界条件得到了模型的解析解。固结模型与实验室试验的对比结果高度一致。案例研究表明，所提出的固结模型能够准确模拟含有砂柱的三轴试样中平均孔隙压力和固结程度的演变。对固结参数的研究表明，试样直径、试样和砂柱的渗透系数以及砂柱半径对排水率有不同的影响。

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引用次数: 0

Micro‐Mechanical Analysis for Residual Stresses and Shakedown of Cohesionless‐Frictional Particulate Materials Under Moving Surface Loads 移动表面载荷下无内聚摩擦颗粒材料残余应力和抖动的微观力学分析

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-17 DOI: 10.1002/nag.3837

Wei Cai, Ping Xu, Runhua Zhang

Residual stresses and shakedown have been successfully presented by two‐dimensional numerical experiments based on the discrete element method (DEM), wherein a cohesionless‐frictional material under moving surface loads was replicated through irregular‐shaped particles. With surface loads below the shakedown limit, both permanent deformations and residual stresses cease to accumulate and the numerical structure shakes down after a number of load passes. Corresponding micro‐mechanical analyses indicate that strong forces and normal forces make a dominant contribution to residual stresses. Besides, averaged magnitudes of interparticle forces and corresponding total contact numbers initially change with load passes, and their final variation trends will differ as the structure shakes down or not. Furthermore, polar distributions of interparticle forces and contacts have been presented, and variations of their preferential orientations were emphasised. Lastly, the fabric tensor and anisotropy of resultant forces were studied, presenting the anisotropy weakening of macro‐stress fields, induced by developments of residual stresses.

基于离散元法（DEM）的二维数值实验成功地展示了残余应力和抖动，通过不规则形状的颗粒复制了移动表面载荷下的无内聚摩擦材料。当表面载荷低于晃动极限时，永久变形和残余应力都不再累积，数值结构在经过若干次载荷后发生晃动。相应的微观力学分析表明，强力和法向力对残余应力起着主导作用。此外，粒子间力的平均值和相应的总接触数最初会随着加载次数的增加而变化，其最终变化趋势也会随着结构的抖动与否而不同。此外，还介绍了粒子间作用力和接触的极性分布，并强调了其优先方向的变化。最后，研究了结构张量和结果力的各向异性，展示了残余应力发展所引起的宏观应力场的各向异性削弱。

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引用次数: 0

Analytical Solution for Longitudinal Seismic Responses of Circular Tunnel Crossing Fault Zone 穿越断层带的圆形隧道纵向地震响应的解析解

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-17 DOI: 10.1002/nag.3841

Jie Tang, Manchao He, Hanbing Bian, Yafei Qiao

This paper proposes a simplified analytical solution for longitudinal seismic responses of a circular tunnel crossing a fault zone under longitudinally propagating shear waves. The transmissions and reflections of shear waves at two geological interfaces between the fault zone and intact rock are considered when calculating the free‐field displacement. An improved elastic foundation beam model considering different tangential contact conditions at the tunnel‒rock interface is also adopted. According to the continuous conditions at the two geological interfaces, explicit expressions for the tunnel displacement, bending moment, and shearing force are given. The effectiveness of the proposed analytical solution is validated via numerical simulations, and the importance of accounting for tangential contact conditions at the tunnel‒rock interface is emphasized. Moreover, parametric studies are performed to investigate the effects of the fault zone width, rock conditions, tunnel lining stiffness, tangential contact conditions, and earthquake frequency on the deformation and internal forces of tunnels subjected to seismic waves. This novel analytical solution can be utilized to quickly estimate the longitudinal seismic responses of circular tunnels crossing fault zones subjected to longitudinally propagating shear waves, particularly in the preliminary engineering design, and can be extended to geological conditions with multiple interfaces.

本文提出了在纵向传播的剪切波作用下，穿越断层带的圆形隧道纵向地震反应的简化分析方案。在计算自由场位移时，考虑了剪切波在断层带和完整岩石之间两个地质界面的传递和反射。此外，还采用了一种改进的弹性地基梁模型，考虑了隧道与岩石界面的不同切向接触条件。根据两个地质界面的连续条件，给出了隧道位移、弯矩和剪力的明确表达式。通过数值模拟验证了所提分析方案的有效性，并强调了考虑隧道与岩石界面切向接触条件的重要性。此外，还进行了参数研究，以探讨断层带宽度、岩石条件、隧道衬砌刚度、切向接触条件和地震频率对地震波作用下隧道变形和内力的影响。这种新颖的分析方案可用于快速估算穿越断层带的圆形隧道在纵向传播剪切波作用下的纵向地震响应，特别是在初步工程设计中，并可扩展到具有多个界面的地质条件。

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引用次数: 0

Analytical Solutions for a Fully Coupled Hydraulic‐Mechanical‐Chemical Model With Nonlinear Adsorption 具有非线性吸附作用的全耦合水力-机械-化学模型的分析解决方案

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-17 DOI: 10.1002/nag.3829

Lin Han, Zhihong Zhang, Jiashu Zhou

Adsorption characteristics play a crucial role in solute transport processes, serving as a fundamental factor for evaluating the performance of clay liners. Nonlinear adsorption isotherms are commonly found with metal ions and organic compounds, which introduce challenges in obtaining analytical solutions for solute transport models. In this study, analytical solutions are proposed for a fully coupled hydraulic‐mechanical‐chemical (HMC) model that accounts for both the Freundlich and Langmuir isotherms. To mitigate the difficulties arising from the variable coefficients, the system of second‐order partial differential equations involving three variables is linearized. The method of separation of variables, theory of integration, and Fourier series are utilized to derive analytical solutions. The analytical method presented can potentially be extended to a broad spectrum of nonlinear adsorption isotherms. The results reveal a 56.5% reduction in solute breakthrough time under the Freundlich isotherm and a remarkable 2.6‐fold extension under the Langmuir isotherm when compared to the linear isotherm. The adsorption constants of the Freundlich and Langmuir isotherms exhibit a positive correlation with breakthrough time, while the exponent of the Freundlich isotherm and the maximal adsorption capacity in the Langmuir isotherm demonstrate a negative association with breakthrough time. This study enhances the precision of solute transport prediction and provides a more scientific assessment of clay liner performance.

吸附特性在溶质迁移过程中起着至关重要的作用，是评估粘土衬里性能的基本因素。非线性吸附等温线常见于金属离子和有机化合物，这给获取溶质迁移模型的分析解决方案带来了挑战。在本研究中，我们提出了一个完全耦合的水力-机械-化学（HMC）模型的分析解决方案，该模型同时考虑了 Freundlich 和 Langmuir 等温线。为了减轻可变系数带来的困难，对涉及三个变量的二阶偏微分方程系统进行了线性化处理。利用变量分离法、积分理论和傅立叶级数求出分析解。所提出的分析方法可以扩展到多种非线性吸附等温线。结果显示，与线性吸附等温线相比，Freundlich 等温线下的溶质突破时间缩短了 56.5%，Langmuir 等温线下的溶质突破时间显著延长了 2.6 倍。Freundlich 和 Langmuir 等温线的吸附常数与突破时间呈正相关，而 Freundlich 等温线的指数和 Langmuir 等温线的最大吸附容量与突破时间呈负相关。这项研究提高了溶质迁移预测的精度，并为粘土衬垫性能的评估提供了更科学的依据。

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引用次数: 0

Investigation on the Instability Mechanism of Expansive Soil Slope With Weak Interlayer Based on Strain Softening 基于应变软化的弱夹层膨胀土边坡失稳机理研究

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-17 DOI: 10.1002/nag.3834

Shuai Xu, Hanjing Jiang, Yongfu Xu, Aoxun Wang, Shunchao Qi

Expansive soils are widespread in the world and coincide with areas of high human activity. The main cause of deep instability of expansive soil slopes is due to their softening caused by excavation and seepage. By developing a comprehensive numerical model based on the theory of unsaturated soil, this study examines the characteristics of stress and displacement distribution of expansive soil slopes through hydraulic‐mechanical coupled numerical simulation. This study analyzes the evolution patterns of slopes with excavation unloading and seepage of water storage to reveal the mechanisms of deep‐seated instability of expansive soil slopes. The findings demonstrate that: The instability of expansive soil slopes begins at the foot of the slope and propagates along the interlayer, affecting the entire slope. Excavation leads to the softening of the expansive soil interlayer and the transfer of shear stress. During water storage, the weakening of the soil strength results in slope instability along the weak interlayer slip. Softening of the expansive soil interlayer facilitates the redistribution of shear forces in the slope and alters the distribution law of the plastic zone in the deep layer. Overly slowing down the slope leads to significant excavation unloading, which is detrimental to the slope's stability.

膨胀土在世界范围内广泛存在，并且与人类活动频繁的地区相吻合。膨胀土边坡深层失稳的主要原因是开挖和渗流造成的软化。本研究以非饱和土理论为基础建立了一个综合数值模型，通过水力机械耦合数值模拟研究了膨胀土边坡的应力和位移分布特征。研究分析了边坡在开挖卸荷和蓄水渗流作用下的演变规律，揭示了膨胀土边坡深层失稳的机理。研究结果表明膨胀土边坡的失稳始于坡脚，并沿夹层传播，影响整个边坡。开挖导致膨胀土夹层软化和剪应力传递。在蓄水期间，土壤强度的减弱会导致沿薄弱夹层滑动的斜坡失稳。膨胀土夹层的软化促进了斜坡剪力的重新分布，并改变了深层塑性区的分布规律。过度放缓斜坡会导致大量开挖卸荷，不利于斜坡的稳定。

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引用次数: 0

Cover Image, Volume 48, Issue 14 封面图片，第 48 卷第 14 期

IF 3.4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-10 DOI: 10.1002/nag.3840

Kehao Chen, Rui Pang, Bin Xu, Xingliang Wang

The cover image is based on the article Elastoplastic constitutive model for overconsolidated clays with an advanced dilatancy relation by Kehao Chen et al., https://doi.org/10.1002/nag.3803.

封面图片来自 Kehao Chen 等人撰写的文章《具有高级膨胀关系的过固结粘土弹塑性构造模型》（Elastoplastic constitutive model for overconsolidated clays with an advanced dilatancy relation），https://doi.org/10.1002/nag.3803。

引用次数: 0

Extended B-spline-based implicit material point method for saturated porous media 饱和多孔介质的基于 B 样条的扩展隐式材料点法

IF 3.4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-03 DOI: 10.1002/nag.3827

Yuya Yamaguchi, Shuji Moriguchi, Kenjiro Terada

The large deformation and fluidization process of a solid–fluid mixture includes significant changes to the temporal scale of the phenomena and the shape and properties of the mixed material. This paper presents an extended B-spline (EBS)-based implicit material point method (EBS-MPM) for the coupled hydromechanical analysis of saturated porous media to enhance the overall versatility of MPM in addressing such diverse phenomena. The proposed method accurately represents phenomena such as high-speed motion in both the quasi-static and dynamic states by employing a full formulation of coupled hydromechanical modeling. The weak imposition of boundary conditions based on Nitsche's method allows representing the boundary conditions independent of the relative position of the particles and computational grid. In addition, it enables dynamic changes in the boundary domain based on the deformation. The robustness of this boundary representation is reinforced using EBS basis functions, which prevent the degradation of the condition number of the system matrices regardless of the position of the boundary domain with respect to the computational grid. Furthermore, a stabilization method based on a variational multiscale method (VMS) approach is employed to provide the flexibility in choosing arbitrary basis functions for spatial discretization, facilitating the effective construction of EBS. Numerical examples including comparisons between a full formulation and a simplified formulation are presented to demonstrate the performance of the developed method under various boundary conditions and loading states across different time scales.

固液混合物的大变形和流化过程包括现象的时间尺度以及混合材料的形状和性质的显著变化。本文提出了一种基于扩展 B-样条曲线（EBS）的隐式材料点方法（EBS-MPM），用于饱和多孔介质的耦合水力学分析，以增强 MPM 在处理此类不同现象时的整体通用性。所提出的方法通过采用完整的耦合水力学建模公式，准确地表示了准静态和动态状态下的高速运动等现象。基于 Nitsche 方法的弱边界条件强加，使得边界条件的表示不受粒子和计算网格相对位置的影响。此外，它还能根据变形情况动态改变边界域。使用 EBS 基函数加强了这种边界表示法的稳健性，无论边界域相对于计算网格的位置如何，它都能防止系统矩阵的条件数下降。此外，基于变异多尺度方法（VMS）的稳定方法为空间离散化提供了选择任意基函数的灵活性，从而促进了 EBS 的有效构建。研究还给出了一些数值示例，包括完整公式和简化公式之间的比较，以展示所开发的方法在不同边界条件和不同时间尺度的加载状态下的性能。

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引用次数: 0

Development of improved finite element formulations for pile group behavior analysis under cyclic loading 开发循环加载下桩群行为分析的改进型有限元公式

IF 4 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

International Journal for Numerical and Analytical Methods in Geomechanics

Pub Date : 2024-09-03 DOI: 10.1002/nag.3828

Jian‐Hong Wan, Shui‐Hua Jiang, Xue‐You Li, Zhilu Chang

The effect of cyclic loading is an essential factor leading to progressive soil strength degradation. Therefore, a comprehensive analysis of the pile‐soil system behavior under cyclic loading is required to ensure the stability of pile group. There is room for improvement in the inherent constraint of the conventional numerical model in terms of approximating the soil resistance distribution along the pile by point loads at element nodes, necessitating a specific element that integrates considerations of pile group effect and cyclic loading within a unified framework. This study aims to develop a newly specific type of element for efficiently predicting nonlinear behavior within the pile‐soil system, addressing simulations involving nonlinear pile‐soil interaction, pile group effect, and cyclic loading. Modified element formulations based on soil stiffness matrices and soil resistance vectors specifically address pile group effect and consider parameters that influence pile behavior under cyclic lateral loading. The numerical solution procedure with Newton‐Raphson iteration allows the calculation of pile responses in geometric and material nonlinear analyses. The validation of the proposed method includes several examples, comparing it with existing numerical solutions and experimental tests of single piles and pile groups under cyclic loading. These comparisons further support the consistency of the proposed method with measured data and validate its accuracy in considering group effect and cyclic loading. The parametric study illustrates the ability of the proposed method to capture cyclic loading parameters while considering the influence of the number and magnitude of load cycles, the cyclic load direction, and the installation methods.

循环荷载的影响是导致土壤强度逐渐降低的一个重要因素。因此，需要对循环荷载下的桩土系统行为进行全面分析，以确保桩群的稳定性。传统数值模型的固有约束条件有待改进，即通过元素节点上的点荷载来近似沿桩的土体阻力分布，这就需要一种特定的元素，在统一的框架内综合考虑桩群效应和循环荷载。本研究旨在开发一种新的特定元素类型，用于有效预测桩土系统内的非线性行为，解决涉及非线性桩土相互作用、桩群效应和循环加载的模拟问题。基于土体刚度矩阵和土体阻力矢量的修正元素公式专门针对桩群效应，并考虑了在循环侧向加载下影响桩行为的参数。采用牛顿-拉夫逊迭代的数值求解程序可以计算几何和材料非线性分析中的桩响应。对所提方法的验证包括几个实例，将其与现有的数值解法以及循环荷载下单桩和桩群的实验测试进行比较。这些比较进一步证明了所提方法与测量数据的一致性，并验证了其在考虑群体效应和循环荷载时的准确性。参数研究表明，在考虑荷载循环次数和幅度、循环荷载方向以及安装方法的影响时，所提出的方法能够捕捉循环荷载参数。

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引用次数: 0