In classical continuum constitutive models, the loss of ellipticity of the governing rate equilibrium equations entails localizing deformations and mesh sensitivity in finite element simulations. Extensions of such models, rooted in the micromorphic continuum, aim at remedying mesh sensitivity by introducing length scales into the constitutive formulation. The micropolar continuum constitutes a special case of the micromorphic continuum and is commonly employed for remedying mesh sensitivity accompanying shear band failure. However, localizing deformations in the micropolar continuum remains largely unexplored. This study aims to investigate the conditions for localizing deformations in the micropolar continuum and to highlight their implications for 2D and 3D finite element simulations. To this end, we propose a micropolar extension of the modified Cam‐clay model formulated in a three‐dimensional infinitesimal elastoplastic framework and establish its localization characteristics following a method recently presented for the classical Cauchy–Boltzmann continuum. Investigations at the constitutive level highlight the stabilizing effect of the micropolar extension, which is increased both by the presence of couple stresses as well as by increasing the Cosserat couple modulus. Simulations at the structural level exhibit good agreement with the results obtained at the constitutive level and indicate that the Cosserat couple modulus required for adequately regularizing the structural response depends on the level of modal dilatancy. Even though localized failure is commonly regarded to be restricted to opening modes, we find mesh‐sensitive structural behavior also in cases where the expected maximum modal dilatancy is far from unity.
{"title":"Localized Deformation Analysis of a 3D Micropolar Modified Cam‐Clay Model","authors":"Paul Hofer, Matthias Neuner, Günter Hofstetter","doi":"10.1002/nag.3941","DOIUrl":"https://doi.org/10.1002/nag.3941","url":null,"abstract":"In classical continuum constitutive models, the loss of ellipticity of the governing rate equilibrium equations entails localizing deformations and mesh sensitivity in finite element simulations. Extensions of such models, rooted in the micromorphic continuum, aim at remedying mesh sensitivity by introducing length scales into the constitutive formulation. The micropolar continuum constitutes a special case of the micromorphic continuum and is commonly employed for remedying mesh sensitivity accompanying shear band failure. However, localizing deformations in the micropolar continuum remains largely unexplored. This study aims to investigate the conditions for localizing deformations in the micropolar continuum and to highlight their implications for 2D and 3D finite element simulations. To this end, we propose a micropolar extension of the modified Cam‐clay model formulated in a three‐dimensional infinitesimal elastoplastic framework and establish its localization characteristics following a method recently presented for the classical Cauchy–Boltzmann continuum. Investigations at the constitutive level highlight the stabilizing effect of the micropolar extension, which is increased both by the presence of couple stresses as well as by increasing the Cosserat couple modulus. Simulations at the structural level exhibit good agreement with the results obtained at the constitutive level and indicate that the Cosserat couple modulus required for adequately regularizing the structural response depends on the level of modal dilatancy. Even though localized failure is commonly regarded to be restricted to opening modes, we find mesh‐sensitive structural behavior also in cases where the expected maximum modal dilatancy is far from unity.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"27 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thanh‐Trung Vo, Nhu H. T. Nguyen, Trung‐Kien Nguyen, Thanh‐Hai Nguyen
The granular column collapse is a simple model to study natural disasters such as landslides, rock avalanches, and debris flows because of its potential to provide solid links of physical and mechanical properties to these catastrophic flows. Such flows are commonly composed of different grain‐size distributions, namely, polydispersity. Owing to the complexity of different particle‐size phases, explanations of the collapse dynamics, run out distance, and size‐segregation behavior of granular flows remain elusive. A binary‐size mixture of granular materials is well‐known as a simplified version of particle‐size distribution. This paper explores the effects of the large‐particle content on the collapse mobility, deposition morphology, and size segregation of binary‐size mixtures composed in each column geometry. Although the kinetic energy and deposition morphology are nearly insensitive to the content of large particles for each column geometry, the large and small particle‐size phases govern differently on total kinetic energy. Remarkably, the contribution of these two particle phases to the kinetic energy is similar when the large‐particle content reaches around 10% for all column geometries. By quantifying the difference of the apparent friction coefficient of small and large particle phases, the size‐segregation degree of binary‐size mixtures is evaluated. The results noted that the segregation degree increases exponentially with increasing the large‐particle content, but it is nearly independent of the column geometry. These findings complement insights into the flow properties of geological hazards, leading to offering valuable evidence for the management of natural disasters such as landslides and debris flows.
{"title":"Granular Columns of Binary‐Size Mixtures Collapse on a Horizontal Plane","authors":"Thanh‐Trung Vo, Nhu H. T. Nguyen, Trung‐Kien Nguyen, Thanh‐Hai Nguyen","doi":"10.1002/nag.3948","DOIUrl":"https://doi.org/10.1002/nag.3948","url":null,"abstract":"The granular column collapse is a simple model to study natural disasters such as landslides, rock avalanches, and debris flows because of its potential to provide solid links of physical and mechanical properties to these catastrophic flows. Such flows are commonly composed of different grain‐size distributions, namely, polydispersity. Owing to the complexity of different particle‐size phases, explanations of the collapse dynamics, run out distance, and size‐segregation behavior of granular flows remain elusive. A binary‐size mixture of granular materials is well‐known as a simplified version of particle‐size distribution. This paper explores the effects of the large‐particle content on the collapse mobility, deposition morphology, and size segregation of binary‐size mixtures composed in each column geometry. Although the kinetic energy and deposition morphology are nearly insensitive to the content of large particles for each column geometry, the large and small particle‐size phases govern differently on total kinetic energy. Remarkably, the contribution of these two particle phases to the kinetic energy is similar when the large‐particle content reaches around 10% for all column geometries. By quantifying the difference of the apparent friction coefficient of small and large particle phases, the size‐segregation degree of binary‐size mixtures is evaluated. The results noted that the segregation degree increases exponentially with increasing the large‐particle content, but it is nearly independent of the column geometry. These findings complement insights into the flow properties of geological hazards, leading to offering valuable evidence for the management of natural disasters such as landslides and debris flows.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"50 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pile‐plate road foundation (PRF) is a new type of road foundation arising in recent years. As the seismic wave is an important kind of dynamic loads, the dynamic analysis of the PRF under seismic wave is thus necessary for its dynamic design. To simplify the analysis of the PRF under seismic waves, the PRF is simplified as the periodic pile‐plate road foundation (PPRF) in this study. To establish the dynamic model for this PPRF, the PPRF is divided into two regions first, namely, the regions I and II. Region I is the region of interest of the PPRF, containing the bedrock, soil layers, embankment, pile rows, and plate, while the region II is the surrounding domain for the region I, including the soil layers and bedrock. In this study, the region I is treated by the periodic 2.5D finite element method (P2.5D FEM) and corresponding P2.5D FEM equations are obtained. For the region II, the periodic thin layer method (PTLM) is established and is used to establish the traction‐displacement relation at the regions I–II interface. With the obtained traction‐displacement relation, the transmitting boundary condition is imposed on the region I, and the incident seismic wave is input to the region I, yielding the P2.5D FE‐TLM model for the PPRF. Based on the established P2.5D FE‐TLM model, some results for the response of the PPRF to the incident surface waves are presented.
桩板道路基础是近年来兴起的一种新型道路基础。由于地震波是一种重要的动力载荷，因此对其进行地震波作用下的动力分析是其动力设计的必要条件。为了简化地震波作用下的周期桩基的分析，本文将周期桩基简化为周期桩板路基（PPRF）。为了建立该PPRF的动态模型，首先将PPRF划分为两个区域，即区域I和区域II。区域I是PPRF感兴趣的区域，包括基岩、土层、路堤、桩排和板块，而区域II是区域I的周边区域，包括土层和基岩。本研究采用周期2.5D有限元法（P2.5D FEM）对区域I进行处理，得到相应的P2.5D有限元方程。对于II区，建立了周期薄层法（PTLM），并用于建立I-II区界面处的牵引-位移关系。根据得到的牵引力-位移关系，在I区施加传输边界条件，将入射地震波输入到I区，得到PPRF的P2.5D FE - TLM模型。基于所建立的P2.5D FE‐TLM模型，给出了PPRF对入射表面波响应的一些结果。
{"title":"A Seismic Model for the Periodic Pile‐Plate Road Foundation Based on the P2.5D Finite Element Method","authors":"Jian‐Fei Lu, Qiang‐Jun Fan, Yang Liu","doi":"10.1002/nag.3945","DOIUrl":"https://doi.org/10.1002/nag.3945","url":null,"abstract":"Pile‐plate road foundation (PRF) is a new type of road foundation arising in recent years. As the seismic wave is an important kind of dynamic loads, the dynamic analysis of the PRF under seismic wave is thus necessary for its dynamic design. To simplify the analysis of the PRF under seismic waves, the PRF is simplified as the periodic pile‐plate road foundation (PPRF) in this study. To establish the dynamic model for this PPRF, the PPRF is divided into two regions first, namely, the regions I and II. Region I is the region of interest of the PPRF, containing the bedrock, soil layers, embankment, pile rows, and plate, while the region II is the surrounding domain for the region I, including the soil layers and bedrock. In this study, the region I is treated by the periodic 2.5D finite element method (P2.5D FEM) and corresponding P2.5D FEM equations are obtained. For the region II, the periodic thin layer method (PTLM) is established and is used to establish the traction‐displacement relation at the regions I–II interface. With the obtained traction‐displacement relation, the transmitting boundary condition is imposed on the region I, and the incident seismic wave is input to the region I, yielding the P2.5D FE‐TLM model for the PPRF. Based on the established P2.5D FE‐TLM model, some results for the response of the PPRF to the incident surface waves are presented.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jinwei Fu, Hadi Haeri, Vahab Sarfarazi, Negin Rafiei, Amir Abbas Amiri, Mohammad Fatehi Marji
Experimental tests were conducted in the laboratory to investigate the shear behavior of interfaces in grout‐gypsum specimens. Various specimens were created to produce different interface configurations for testing and modeling. The tensile strength measurements indicated that grout has a strength of 1.2 MPa, while gypsum measures 0.52 MPa. For Young's modulus, grout was found to be 9 GPa, in contrast to gypsum's 4 GPa. Furthermore, the compressive strength values recorded were 13 MPa for grout and 7.9 MPa for gypsum. The fracture toughness values were found to be 0.09 MPa for grout and 0.01 MPa for gypsum. The rate of loading during the experimental tests was set at 0.05 mm/s, which was considered too low to satisfy the static loading criteria. Additionally, the laboratory tests helped calibrate the PFC modeling results, allowing for a detailed study of the shear behavior of the grout‐gypsum interfaces. The number of channels in the specimens created suitable interfaces, which influenced the shear failure mechanisms and fracturing patterns for both sample types. Tensile cracking can occur at these interfaces and may propagate throughout the channels. As the number of channels increases, the volume of injected gypsum in the specimens also rises. This increase raises the crack initiation stress, failure stress, shear stiffness, and the number of fractures. Moreover, the shear stiffness and shear strength of the grout injection channels were found to be greater than those of the gypsum channels. Overall, there was a strong correlation between the experimental and numerical results.
{"title":"Investigation of the Shear Mechanism at the Interface Between Grout and Brittle Rock: Physical Testing and PFC3D Simulation","authors":"Jinwei Fu, Hadi Haeri, Vahab Sarfarazi, Negin Rafiei, Amir Abbas Amiri, Mohammad Fatehi Marji","doi":"10.1002/nag.3944","DOIUrl":"https://doi.org/10.1002/nag.3944","url":null,"abstract":"Experimental tests were conducted in the laboratory to investigate the shear behavior of interfaces in grout‐gypsum specimens. Various specimens were created to produce different interface configurations for testing and modeling. The tensile strength measurements indicated that grout has a strength of 1.2 MPa, while gypsum measures 0.52 MPa. For Young's modulus, grout was found to be 9 GPa, in contrast to gypsum's 4 GPa. Furthermore, the compressive strength values recorded were 13 MPa for grout and 7.9 MPa for gypsum. The fracture toughness values were found to be 0.09 MPa for grout and 0.01 MPa for gypsum. The rate of loading during the experimental tests was set at 0.05 mm/s, which was considered too low to satisfy the static loading criteria. Additionally, the laboratory tests helped calibrate the PFC modeling results, allowing for a detailed study of the shear behavior of the grout‐gypsum interfaces. The number of channels in the specimens created suitable interfaces, which influenced the shear failure mechanisms and fracturing patterns for both sample types. Tensile cracking can occur at these interfaces and may propagate throughout the channels. As the number of channels increases, the volume of injected gypsum in the specimens also rises. This increase raises the crack initiation stress, failure stress, shear stiffness, and the number of fractures. Moreover, the shear stiffness and shear strength of the grout injection channels were found to be greater than those of the gypsum channels. Overall, there was a strong correlation between the experimental and numerical results.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"40 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bing Bai, Haiyan Wu, Qingke Nie, Jingjing Liu, Xiangxin Jia
A theoretical model of the migration process of high‐alkalinity red mud particles in porous media was derived from granular thermodynamics, complying with the complementary motion process of two‐phase flows (i.e., hydroxide ions and red mud powder). From the perspective of energy dissipation provoked by particle migration and molecular thermal motion, a migration model of hydroxide ions and suspended particles under mixed conditions was established. This model naturally considers the complex adsorption/desorption process between hydroxide ions (or red mud particles) and a porous medium solid matrix, as well as between hydroxide ions and red mud particles. Moreover, the model reveals the dynamic process and deposition effect of suspended powder under multiphase interactions during temporal and spatial variations. The migration progression of suspended substances in the process of transient injection of red mud filtrate with different pH values and the continuous change in red mud particle injection were verified by experiments.
{"title":"Granular Thermodynamic Migration Model Suitable for High‐Alkalinity Red Mud Filtrates and Test Verification","authors":"Bing Bai, Haiyan Wu, Qingke Nie, Jingjing Liu, Xiangxin Jia","doi":"10.1002/nag.3946","DOIUrl":"https://doi.org/10.1002/nag.3946","url":null,"abstract":"A theoretical model of the migration process of high‐alkalinity red mud particles in porous media was derived from granular thermodynamics, complying with the complementary motion process of two‐phase flows (i.e., hydroxide ions and red mud powder). From the perspective of energy dissipation provoked by particle migration and molecular thermal motion, a migration model of hydroxide ions and suspended particles under mixed conditions was established. This model naturally considers the complex adsorption/desorption process between hydroxide ions (or red mud particles) and a porous medium solid matrix, as well as between hydroxide ions and red mud particles. Moreover, the model reveals the dynamic process and deposition effect of suspended powder under multiphase interactions during temporal and spatial variations. The migration progression of suspended substances in the process of transient injection of red mud filtrate with different pH values and the continuous change in red mud particle injection were verified by experiments.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"36 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To characterize the rate‐dependency and frictional behavior of quasi‐brittle interface material, a coupling rate‐dependent and friction interface model improved from the Park‐Paulino‐Roesler (PPR) cohesive model, is proposed and validated in this paper. Based on the potential function, this novel coupling model forms the basic relationship of traction‐displacement within the interfaces, in which rate effect and friction behavior are considered by constructing a rate‐sensitive item and smooth friction term, respectively. Specifically, governing equations for typical mode I and mode II crack formation, as well as for normal and tangential directions, are established, and the model includes a complete unloading/reloading mode for the complex loading situations. To validate this model, the 3D simplified shear test of the anchor rod and mortar block model and a three‐point bend test of the composite concrete‐FRP beam with different loading rates are established to verify the engineering availability, considering different loading rates and friction coefficients. The results show that shear and tensile behaviors of brittle material in numerical models and laboratory tests are similar in the fracture initiation and propagation characteristics. The proposed model can reflect not only the elastic, softening, and residual stages, but also the strength rate‐related effects and friction effects of interface materials. This provides a comprehensive solution for describing the complex mechanical behavior of quasi‐brittle materials subjected to tensile and shear loads.
{"title":"An Improved Park‐Paulino‐Roesler (PPR) Cohesive Model Considering Rate‐Dependent Characteristics and Frictional Behavior of Brittle Materials","authors":"Jiang Yu, Tingting Wang, Kai Liu, Chun'an Tang","doi":"10.1002/nag.3938","DOIUrl":"https://doi.org/10.1002/nag.3938","url":null,"abstract":"To characterize the rate‐dependency and frictional behavior of quasi‐brittle interface material, a coupling rate‐dependent and friction interface model improved from the Park‐Paulino‐Roesler (PPR) cohesive model, is proposed and validated in this paper. Based on the potential function, this novel coupling model forms the basic relationship of traction‐displacement within the interfaces, in which rate effect and friction behavior are considered by constructing a rate‐sensitive item and smooth friction term, respectively. Specifically, governing equations for typical mode I and mode II crack formation, as well as for normal and tangential directions, are established, and the model includes a complete unloading/reloading mode for the complex loading situations. To validate this model, the 3D simplified shear test of the anchor rod and mortar block model and a three‐point bend test of the composite concrete‐FRP beam with different loading rates are established to verify the engineering availability, considering different loading rates and friction coefficients. The results show that shear and tensile behaviors of brittle material in numerical models and laboratory tests are similar in the fracture initiation and propagation characteristics. The proposed model can reflect not only the elastic, softening, and residual stages, but also the strength rate‐related effects and friction effects of interface materials. This provides a comprehensive solution for describing the complex mechanical behavior of quasi‐brittle materials subjected to tensile and shear loads.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"14 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel theoretical model is proposed to investigate the torsional response of a pile in fractional‐order viscoelastic unsaturated transversely isotropic soil with imperfect contact. This model employs Biot's framework for three‐phase porous media along with the theory of fractional derivatives. Unlike previous models that assume continuous displacement at the pile–soil interface, this study uses the Kelvin model to simulate relative slippage between pile–soil contact surfaces (imperfect contact). Incorporating fractional‐order viscoelastic and transversely isotropic models to describe the stress‐strain relationship, comprehensive dynamic governing equations are derived. Using the separation of variables method, inverse Fourier transform, and convolution theory, analytical solutions for the frequency domain response and semi‐analytical solutions for the time domain response of the pile head under semi‐sine pulse excitation are obtained. Using numerical examples, the effects of model parameters in the fractional‐order viscoelastic constitutive model, pile–soil relative slip and continuity model, and soil anisotropy on the torsional complex impedance, twist angle, and torque are presented.
{"title":"Dynamic Torsional Response of Pile in Fractional‐Order Viscoelastic Unsaturated Transversely Isotropic Soil With Imperfect Contact","authors":"Wenjie Ma, Eng‐Choon Leong, Xu Wang, Binglong Wang, Changdan Wang, Bolin Wang","doi":"10.1002/nag.3943","DOIUrl":"https://doi.org/10.1002/nag.3943","url":null,"abstract":"A novel theoretical model is proposed to investigate the torsional response of a pile in fractional‐order viscoelastic unsaturated transversely isotropic soil with imperfect contact. This model employs Biot's framework for three‐phase porous media along with the theory of fractional derivatives. Unlike previous models that assume continuous displacement at the pile–soil interface, this study uses the Kelvin model to simulate relative slippage between pile–soil contact surfaces (imperfect contact). Incorporating fractional‐order viscoelastic and transversely isotropic models to describe the stress‐strain relationship, comprehensive dynamic governing equations are derived. Using the separation of variables method, inverse Fourier transform, and convolution theory, analytical solutions for the frequency domain response and semi‐analytical solutions for the time domain response of the pile head under semi‐sine pulse excitation are obtained. Using numerical examples, the effects of model parameters in the fractional‐order viscoelastic constitutive model, pile–soil relative slip and continuity model, and soil anisotropy on the torsional complex impedance, twist angle, and torque are presented.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"38 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zengchun Sun, Yang Xiao, Qingyun Fang, Xiang Jiang, Xiang He, Hanlong Liu
In geo‐energy engineering projects, temperature is an essential environmental variable, and accurately predicting its effect on the thermomechanical properties of geomaterials remains a challenge. Similar to fine‐grained soils, temperature variation is also a crucial factor that affects the stress‐strain response and critical state behavior of coarse‐grained soils. In this study, a thermomechanical model is established for coarse‐grained soils using theories from the critical state and fractional plasticity. The evolution of the critical state line with increasing temperature can be well characterized by introducing a thermal‐dependent parameter, then the state void‐ratio‐pressure parameter that incorporates the effect of temperature can be derived according to the temperature‐dependent critical state. The plastic flow direction and dilatancy function are obtained directly from the fractional derivation of the modified elliptical yield function to describe the nonassociated flow characteristics. Furthermore, the thermal state parameter is introduced into the non‐orthogonal dilatancy function and hardening modulus to reflect the state‐ and temperature‐dependent behaviors. Comparative analysis of experimental data and predictions indicates that the established thermomechanical model can reasonably predict the drained shear characteristics of coarse‐grained soils under different temperatures, including strain‐hardening, strain‐softening, dilatancy, contraction, and thermal softening.
{"title":"A Thermomechanical Model of Coarse‐Grained Soils With Non‐Orthogonal Flow Rule","authors":"Zengchun Sun, Yang Xiao, Qingyun Fang, Xiang Jiang, Xiang He, Hanlong Liu","doi":"10.1002/nag.3942","DOIUrl":"https://doi.org/10.1002/nag.3942","url":null,"abstract":"In geo‐energy engineering projects, temperature is an essential environmental variable, and accurately predicting its effect on the thermomechanical properties of geomaterials remains a challenge. Similar to fine‐grained soils, temperature variation is also a crucial factor that affects the stress‐strain response and critical state behavior of coarse‐grained soils. In this study, a thermomechanical model is established for coarse‐grained soils using theories from the critical state and fractional plasticity. The evolution of the critical state line with increasing temperature can be well characterized by introducing a thermal‐dependent parameter, then the state void‐ratio‐pressure parameter that incorporates the effect of temperature can be derived according to the temperature‐dependent critical state. The plastic flow direction and dilatancy function are obtained directly from the fractional derivation of the modified elliptical yield function to describe the nonassociated flow characteristics. Furthermore, the thermal state parameter is introduced into the non‐orthogonal dilatancy function and hardening modulus to reflect the state‐ and temperature‐dependent behaviors. Comparative analysis of experimental data and predictions indicates that the established thermomechanical model can reasonably predict the drained shear characteristics of coarse‐grained soils under different temperatures, including strain‐hardening, strain‐softening, dilatancy, contraction, and thermal softening.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"25 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lei Ma, Georg Koval, Cyrille Chazallon, Yannick Descantes
In this work, a fatigue crack propagation model is proposed using the two‐dimensional discrete element method (DEM). The challenge lies in describing the small progressive fatigue crack growth within a single cycle, which is typically much smaller than the size of the smallest particles, making it difficult to continuously capture the loss of contact stiffness. To accurately represent crack increments in DEM, a reduction in contact stiffness is directly linked to the length of the propagated crack, based on the local energy release in a contact. This allows for a precise description of crack increments at scales much smaller than particle size. Building on this, and utilizing the local evaluation of the energy release rate, Paris' law is applied to describe the fatigue behaviour of the contact under cyclic loading. An efficient approach is introduced that replaces the full cycle analysis with equivalent quasi‐static monotonic simulations, leading to significant gains in computational time. The resultant DEM simulations adopt the same parameters as in continuum mechanics, eliminating the need for calibration, and demonstrate good agreement with theoretical and experimental results from the literature.
{"title":"A Discrete Element Method–Based Energetic Approach to Model Two‐Dimensional Fatigue Crack Propagation","authors":"Lei Ma, Georg Koval, Cyrille Chazallon, Yannick Descantes","doi":"10.1002/nag.3928","DOIUrl":"https://doi.org/10.1002/nag.3928","url":null,"abstract":"In this work, a fatigue crack propagation model is proposed using the two‐dimensional discrete element method (DEM). The challenge lies in describing the small progressive fatigue crack growth within a single cycle, which is typically much smaller than the size of the smallest particles, making it difficult to continuously capture the loss of contact stiffness. To accurately represent crack increments in DEM, a reduction in contact stiffness is directly linked to the length of the propagated crack, based on the local energy release in a contact. This allows for a precise description of crack increments at scales much smaller than particle size. Building on this, and utilizing the local evaluation of the energy release rate, Paris' law is applied to describe the fatigue behaviour of the contact under cyclic loading. An efficient approach is introduced that replaces the full cycle analysis with equivalent quasi‐static monotonic simulations, leading to significant gains in computational time. The resultant DEM simulations adopt the same parameters as in continuum mechanics, eliminating the need for calibration, and demonstrate good agreement with theoretical and experimental results from the literature.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"45 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yada Tesfaye Boru, Joanna Pieczyńska‐Kozłowska, Wojciech Puła
The study presents a comprehensive study on the assessment of the bearing capacity of closely spaced strip footings on c‐ø soil, considering spatial variability in soil properties. A linear elastic model is employed for footings and elastic–perfect plastic soil behaviour via the Mohr–Coulomb yield criterion. Soil properties obtained from extensive field investigations of Taranto Blue Clay (TBC) in Italy are modelled as stationary random fields (RFs) generated using the Fourier series method. The cohesion and friction angle RFs are integrated with the Z‐soil FE code. The final results are obtained according to the random finite element method (RFEM). The study investigates the influence of spacing distances between footings and spatial correlation lengths of soil parameters on the bearing capacity. Results show how spacing distance affects bearing capacity. Moreover, it indicates that neighbouring footing bearing capacity is strongly correlated with investigated parameters. In the case of small spatial correlation lengths, the patterns were obtained as non‐symmetrical, transitioning to more symmetrical patterns at larger lengths. The manuscript concludes by presenting reliability‐based design considerations for the ultimate bearing capacity, considering the horizontal spatial scale of fluctuation (SOF). The findings emphasize the importance of evaluating allowable design bearing capacity for proximity structures using RFEM and provide valuable insights into the interplay between spacing distances and spatial variability in soil properties. To this end, the study underscores the critical interplay between spacing distance, spatial correlation lengths, and random soil properties in assessing neighbouring footing‐bearing capacities.
{"title":"Effects of Random Field Heterogeneity of Spatial Soil Properties on the Bearing Capacity of Neighbouring Footing","authors":"Yada Tesfaye Boru, Joanna Pieczyńska‐Kozłowska, Wojciech Puła","doi":"10.1002/nag.3932","DOIUrl":"https://doi.org/10.1002/nag.3932","url":null,"abstract":"The study presents a comprehensive study on the assessment of the bearing capacity of closely spaced strip footings on c‐ø soil, considering spatial variability in soil properties. A linear elastic model is employed for footings and elastic–perfect plastic soil behaviour via the Mohr–Coulomb yield criterion. Soil properties obtained from extensive field investigations of Taranto Blue Clay (TBC) in Italy are modelled as stationary random fields (RFs) generated using the Fourier series method. The cohesion and friction angle RFs are integrated with the Z‐soil FE code. The final results are obtained according to the random finite element method (RFEM). The study investigates the influence of spacing distances between footings and spatial correlation lengths of soil parameters on the bearing capacity. Results show how spacing distance affects bearing capacity. Moreover, it indicates that neighbouring footing bearing capacity is strongly correlated with investigated parameters. In the case of small spatial correlation lengths, the patterns were obtained as non‐symmetrical, transitioning to more symmetrical patterns at larger lengths. The manuscript concludes by presenting reliability‐based design considerations for the ultimate bearing capacity, considering the horizontal spatial scale of fluctuation (SOF). The findings emphasize the importance of evaluating allowable design bearing capacity for proximity structures using RFEM and provide valuable insights into the interplay between spacing distances and spatial variability in soil properties. To this end, the study underscores the critical interplay between spacing distance, spatial correlation lengths, and random soil properties in assessing neighbouring footing‐bearing capacities.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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