Pub Date : 2024-09-30DOI: 10.1016/j.compgeo.2024.106797
The mechanical behavior of the sand is affected by anisotropy. This paper presents a novel constitutive model for anisotropic sand that accounts for fabric evolution. In this proposed model, a novel hardening parameter and a new state variable are introduced to capture the effects of the evolving anisotropic fabric. A universal fabric tensor evolution law, independent of specific fabric tensors, is proposed based on the characteristics of the unified hardening model and the findings from discrete element simulations. Additionally, a dilatancy anisotropy compression line (DACL) is defined to compute the state variable, ensuring the uniqueness of the critical state line (CSL). The proposed model has been validated through a large number of monotonic shear datasets obtained from experiments and DEM simulations, while parameters in this proposed model are physically meaningful and easy to be determined. Analysis of fabric evolution under different loading paths indicates that the undrained triaxial compression test is the most effective for reaching the critical state, providing a useful reference for the critical state soil mechanics.
砂的力学行为受到各向异性的影响。本文针对各向异性砂提出了一种新的结构模型，该模型考虑了砂的结构演变。在该模型中，引入了一个新的硬化参数和一个新的状态变量，以捕捉各向异性结构演变的影响。根据统一硬化模型的特点和离散元模拟的结果，提出了一种独立于特定织物张量的通用织物张量演化规律。此外，还定义了扩张各向异性压缩线（DACL）来计算状态变量，确保临界状态线（CSL）的唯一性。通过实验和 DEM 模拟获得的大量单调剪切数据集验证了所提出的模型，同时该模型中的参数具有物理意义，易于确定。对不同加载路径下织物演变的分析表明，不排水三轴压缩试验对达到临界状态最为有效，为临界状态土壤力学提供了有益的参考。
{"title":"A novel constitutive model of the anisotropic sand accounting for the fabric evolution","authors":"","doi":"10.1016/j.compgeo.2024.106797","DOIUrl":"10.1016/j.compgeo.2024.106797","url":null,"abstract":"<div><div>The mechanical behavior of the sand is affected by anisotropy. This paper presents a novel constitutive model for anisotropic sand that accounts for fabric evolution. In this proposed model, a novel hardening parameter and a new state variable are introduced to capture the effects of the evolving anisotropic fabric. A universal fabric tensor evolution law, independent of specific fabric tensors, is proposed based on the characteristics of the unified hardening model and the findings from discrete element simulations. Additionally, a dilatancy anisotropy compression line (DACL) is defined to compute the state variable, ensuring the uniqueness of the critical state line (CSL). The proposed model has been validated through a large number of monotonic shear datasets obtained from experiments and DEM simulations, while parameters in this proposed model are physically meaningful and easy to be determined. Analysis of fabric evolution under different loading paths indicates that the undrained triaxial compression test is the most effective for reaching the critical state, providing a useful reference for the critical state soil mechanics.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.compgeo.2024.106781
Partially saturated soils are ubiquitous in natural environments but still pose significant challenges for constitutive modeling. In this paper, a simple hypoplastic constitutive model incorporating a structural factor to describe the wetting-induced collapse behavior of unsaturated soils is proposed. The model features a straightforward formulation with robust prediction capacity using 10 material parameters, most of which can be calibrated through conventional laboratory tests. Comparison between numerical simulations of element tests and experimental results demonstrates that the proposed model is able to replicate the salient features of unsaturated soils, including shear dilatation, strain softening, and wetting collapse.
{"title":"A simple hypoplastic model for unsaturated soils considering wetting collapse","authors":"","doi":"10.1016/j.compgeo.2024.106781","DOIUrl":"10.1016/j.compgeo.2024.106781","url":null,"abstract":"<div><div>Partially saturated soils are ubiquitous in natural environments but still pose significant challenges for constitutive modeling. In this paper, a simple hypoplastic constitutive model incorporating a structural factor to describe the wetting-induced collapse behavior of unsaturated soils is proposed. The model features a straightforward formulation with robust prediction capacity using 10 material parameters, most of which can be calibrated through conventional laboratory tests. Comparison between numerical simulations of element tests and experimental results demonstrates that the proposed model is able to replicate the salient features of unsaturated soils, including shear dilatation, strain softening, and wetting collapse.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.compgeo.2024.106786
The reverse-consolidation caused by excavation inevitably affects the bearing capacity of basal soil to resist water pressure in confined aquifers, posing a risk to excavation stability. However, there is still a lack of efficient solutions to incorporate the layered heterogeneity into the analysis of the reverse-consolidation. This study proposes a practical approach where the spectral Galerkin method is used to capture the variation of soil properties with depth. The boundaries are characterized by time-dependent drainage boundary conditions to simulate the excavation process. The excess pore-water pressure profile is described by a single expression calculated by common matrix operations. The rationality and accuracy of the practical approach are verified by existing analytical models and field data. Subsequently, the permeability coefficient variability, relatively impervious interlayer, and sand interlayer are analyzed to illustrate their effects on the reverse-consolidation behavior of basal soil. Results indicate that the distribution of excess pore-water pressure is significantly influenced by the variability and distribution form of the permeability coefficient. The relatively impervious interlayer delays the dissipation of excess pore-water pressure and bears a large hydraulic gradient, while the sand interlayer is the opposite. These above influences become more significant as the excavation progresses due to the time effect.
{"title":"Reverse-consolidation analysis of basal soil with layered heterogeneity using the spectral Galerkin method","authors":"","doi":"10.1016/j.compgeo.2024.106786","DOIUrl":"10.1016/j.compgeo.2024.106786","url":null,"abstract":"<div><div>The reverse-consolidation caused by excavation inevitably affects the bearing capacity of basal soil to resist water pressure in confined aquifers, posing a risk to excavation stability. However, there is still a lack of efficient solutions to incorporate the layered heterogeneity into the analysis of the reverse-consolidation. This study proposes a practical approach where the spectral Galerkin method is used to capture the variation of soil properties with depth. The boundaries are characterized by time-dependent drainage boundary conditions to simulate the excavation process. The excess pore-water pressure profile is described by a single expression calculated by common matrix operations. The rationality and accuracy of the practical approach are verified by existing analytical models and field data. Subsequently, the permeability coefficient variability, relatively impervious interlayer, and sand interlayer are analyzed to illustrate their effects on the reverse-consolidation behavior of basal soil. Results indicate that the distribution of excess pore-water pressure is significantly influenced by the variability and distribution form of the permeability coefficient. The relatively impervious interlayer delays the dissipation of excess pore-water pressure and bears a large hydraulic gradient, while the sand interlayer is the opposite. These above influences become more significant as the excavation progresses due to the time effect.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.compgeo.2024.106794
Soft-rigid mixtures (SRMs) are typically pre-mixed before backfilling in engineering applications. However, the properties of soft materials make it particularly challenging to achieve uniform mixing with soils. This study is a pioneer in the exploration of non-uniform mixing in SRMs. A total of 76 quasi-static cubic compression tests were conducted with various mixing forms, mixing degrees, soft particle contents, and confining pressures under a standardized initial state. Based on the numerical results, the macroscopic responses were first quantitatively analyzed to reveal the effects of non-uniform mixing on the micromechanical behaviors of soft-rigid mixtures from compressibility, stress, and volumetric deformation perspectives. Then, the evolution of micro-scale properties, including the internal structure, stress network, internal stability, and fabric anisotropy, was investigated. It was found that the effects of non-uniform mixing on SRMs are considerably more pronounced than on traditional geotechnical binary mixtures. From a macroscopic perspective, non-uniform mixing greatly impacts the critical strength and void ratio of SRMs, with effects comparable to a 10% change in soft content. On a microscopic level, SRMs with higher uniformity exhibit a more stable internal structure, stress network, and enhanced internal stability. The results also show that layering should be avoided during construction. Additionally, the mixing index without considering stress direction is unsuitable for engineering applications. This paper underscores the paramount importance of considering the uniformity in soft-rigid mixtures, providing a robust foundation for further studies in this field.
{"title":"Investigating the effects of non-uniformity of mixing on the shear behavior of soft-rigid mixtures with DEM","authors":"","doi":"10.1016/j.compgeo.2024.106794","DOIUrl":"10.1016/j.compgeo.2024.106794","url":null,"abstract":"<div><div>Soft-rigid mixtures (SRMs) are typically pre-mixed before backfilling in engineering applications. However, the properties of soft materials make it particularly challenging to achieve uniform mixing with soils. This study is a pioneer in the exploration of non-uniform mixing in SRMs. A total of 76 quasi-static cubic compression tests were conducted with various mixing forms, mixing degrees, soft particle contents, and confining pressures under a standardized initial state. Based on the numerical results, the macroscopic responses were first quantitatively analyzed to reveal the effects of non-uniform mixing on the micromechanical behaviors of soft-rigid mixtures from compressibility, stress, and volumetric deformation perspectives. Then, the evolution of micro-scale properties, including the internal structure, stress network, internal stability, and fabric anisotropy, was investigated. It was found that the effects of non-uniform mixing on SRMs are considerably more pronounced than on traditional geotechnical binary mixtures. From a macroscopic perspective, non-uniform mixing greatly impacts the critical strength and void ratio of SRMs, with effects comparable to a 10% change in soft content. On a microscopic level, SRMs with higher uniformity exhibit a more stable internal structure, stress network, and enhanced internal stability. The results also show that layering should be avoided during construction. Additionally, the mixing index without considering stress direction is unsuitable for engineering applications. This paper underscores the paramount importance of considering the uniformity in soft-rigid mixtures, providing a robust foundation for further studies in this field.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.compgeo.2024.106773
Anisotropy is a quintessential property of granular materials, in large part stemming from the complex interparticle interactions modulated by particle shape, orientation, and contact properties. This paper delves into the microscopic underpinnings of elastic anisotropy within granular solids composed of non-spherical particles. Employing the Discrete Element Method (DEM), incremental probes have been imposed on packed configurations of ellipsoidal particles generated through a clumping strategy. The synthetic specimens were deliberately designed to prevent permanent rearrangements, thereby ensuring fully reversible granular structures. Through a comprehensive blend of analytical and numerical approaches, the study establishes scaling relationships that shed light on the intertwined influence of particle orientation and contact curvature on elastic anisotropy, effectively disentangling their individual contributions. The results enabled a clear mathematical identification of two coexisting forms of elastic anisotropy: one of microstructural type, stemming from the directional properties of the initial particle arrangement (which in an elastic context is here referred to as inherent) and another stemming from mechanical processes, such as contact interaction promoted by the imposed stress path (here referred to as induced). Specifically, it is found that each of these anisotropy contributions can be linked to distinct fabric variables, namely the shape fabric (here associated with particle orientation and aspect ratio of the particles) and the contact area fabric (here associated with the local normal force and curvature of the particles at contact points). Inherent elastic anisotropy is revealed to be predominantly governed by the microstructural characteristics of shape fabric, whereas, induced elastic anisotropy is shown to be primarily driven by the contact area fabric. By underscoring the critical role played by microstructural fabrics in determining macroscale elastic anisotropy, the DEM simulations also enabled the calibration of the fabric components of a nonlinear anisotropic hyperelastic model, thereby paving the way for enhanced predictive capabilities of constitutive laws for granular materials harnessing the profound connection between grain-scale processes and continuum-scale mechanical properties.
{"title":"Deciphering how the particle shape modulates the elastic anisotropy of granular media","authors":"","doi":"10.1016/j.compgeo.2024.106773","DOIUrl":"10.1016/j.compgeo.2024.106773","url":null,"abstract":"<div><div>Anisotropy is a quintessential property of granular materials, in large part stemming from the complex interparticle interactions modulated by particle shape, orientation, and contact properties. This paper delves into the microscopic underpinnings of elastic anisotropy within granular solids composed of non-spherical particles. Employing the Discrete Element Method (DEM), incremental probes have been imposed on packed configurations of ellipsoidal particles generated through a clumping strategy. The synthetic specimens were deliberately designed to prevent permanent rearrangements, thereby ensuring fully reversible granular structures. Through a comprehensive blend of analytical and numerical approaches, the study establishes scaling relationships that shed light on the intertwined influence of particle orientation and contact curvature on elastic anisotropy, effectively disentangling their individual contributions. The results enabled a clear mathematical identification of two coexisting forms of elastic anisotropy: one of microstructural type, stemming from the directional properties of the initial particle arrangement (which in an elastic context is here referred to as <em>inherent</em>) and another stemming from mechanical processes, such as contact interaction promoted by the imposed stress path (here referred to as <em>induced</em>). Specifically, it is found that each of these anisotropy contributions can be linked to distinct fabric variables, namely the shape fabric (here associated with particle orientation and aspect ratio of the particles) and the contact area fabric (here associated with the local normal force and curvature of the particles at contact points). Inherent elastic anisotropy is revealed to be predominantly governed by the microstructural characteristics of shape fabric, whereas, induced elastic anisotropy is shown to be primarily driven by the contact area fabric. By underscoring the critical role played by microstructural fabrics in determining macroscale elastic anisotropy, the DEM simulations also enabled the calibration of the fabric components of a nonlinear anisotropic hyperelastic model, thereby paving the way for enhanced predictive capabilities of constitutive laws for granular materials harnessing the profound connection between grain-scale processes and continuum-scale mechanical properties.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.compgeo.2024.106790
Energy shallow foundations represent an innovative technology that can simultaneously support structural loads and harvest geothermal energy. During geothermal operations, the underlying soils are subjected to structural loads and temperature fluctuations. Despite the potential, knowledge regarding the thermo-hydro-mechanical behavior of the multilayered soils beneath the energy foundations remains scarce. This study proposed an analytical approach to investigate the thermo-hydro-mechanical response of soft fine-grained soils beneath energy shallow foundations. The analysis focused on the evolutions of the temperature, pore water pressure, and vertical displacement of the underlying soils. The results indicate that the generation and development of the thermally induced excess pore pressure are controlled by thermal transfer processes and soil hydraulic properties. Furthermore, the mechanical load-induced ground settlement decreases upon heating and increases upon cooling, primarily due to the development of thermally induced pore pressure and the thermal volume changes of the soil skeleton. Under the considered conditions, ignoring the thermally induced mechanical effects could result in a settlement prediction error of nearly 120%. Therefore, the thermo-hydro-mechanical interactions within the soils should be appropriately considered in the analysis and prediction of the displacement behavior of the energy foundations.
{"title":"Thermo-hydro-mechanical behavior of soft soils beneath energy shallow foundations subjected to thermal and mechanical loads","authors":"","doi":"10.1016/j.compgeo.2024.106790","DOIUrl":"10.1016/j.compgeo.2024.106790","url":null,"abstract":"<div><div>Energy shallow foundations represent an innovative technology that can simultaneously support structural loads and harvest geothermal energy. During geothermal operations, the underlying soils are subjected to structural loads and temperature fluctuations. Despite the potential, knowledge regarding the thermo-hydro-mechanical behavior of the multilayered soils beneath the energy foundations remains scarce. This study proposed an analytical approach to investigate the thermo-hydro-mechanical response of soft fine-grained soils beneath energy shallow foundations. The analysis focused on the evolutions of the temperature, pore water pressure, and vertical displacement of the underlying soils. The results indicate that the generation and development of the thermally induced excess pore pressure are controlled by thermal transfer processes and soil hydraulic properties. Furthermore, the mechanical load-induced ground settlement decreases upon heating and increases upon cooling, primarily due to the development of thermally induced pore pressure and the thermal volume changes of the soil skeleton. Under the considered conditions, ignoring the thermally induced mechanical effects could result in a settlement prediction error of nearly 120%. Therefore, the thermo-hydro-mechanical interactions within the soils should be appropriately considered in the analysis and prediction of the displacement behavior of the energy foundations.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-29DOI: 10.1016/j.compgeo.2024.106791
Layered unsaturated soils exhibit complex mechanical and physical properties. Owing to the roughness between unsaturated soil interfaces and the presence of irregularly distributed micro-pores, this study explores the laminar flow of pore water and counter-cyclonic flow of pore air through these channels at low velocities. In response to the complex consolidation behavior of unsaturated soils influenced by the flow and air contact resistance, an improved model is developed. The model incorporates the flow contact transfer coefficient , flow partition coefficient , air contact transfer coefficient and air partition coefficient . Semi-analytical solutions for pore water pressure, pore air pressure and settlement in layered unsaturated soils are derived by employing the Laplace transform and its inverse transform. The rationality of the model is validated through comparative analysis with existing solutions. Analysis of the improved model yields critical insights: the presence of flow and air contact resistance leads to the development of relative pore pressure and air pressure gradients at interfaces, which diminishes the influence of the permeability coefficients of the water phase and air phase on the consolidation process. Moreover, neglecting the flow and air contact resistance effects may lead to an overestimation of settlement.
{"title":"One-dimensional consolidation analysis of layered unsaturated soils: An improved model integrating interfacial flow and air contact resistance effects","authors":"","doi":"10.1016/j.compgeo.2024.106791","DOIUrl":"10.1016/j.compgeo.2024.106791","url":null,"abstract":"<div><div>Layered unsaturated soils exhibit complex mechanical and physical properties. Owing to the roughness between unsaturated soil interfaces and the presence of irregularly distributed micro-pores, this study explores the laminar flow of pore water and counter-cyclonic flow of pore air through these channels at low velocities. In response to the complex consolidation behavior of unsaturated soils influenced by the flow and air contact resistance, an improved model is developed. The model incorporates the flow contact transfer coefficient <span><math><mrow><mo>(</mo><msub><mi>R</mi><mi>ω</mi></msub><mo>)</mo></mrow></math></span>, flow partition coefficient <span><math><mrow><mo>(</mo><msub><mi>η</mi><mi>ω</mi></msub><mo>)</mo></mrow></math></span>, air contact transfer coefficient <span><math><mrow><mo>(</mo><msub><mi>R</mi><mi>a</mi></msub><mo>)</mo></mrow></math></span> and air partition coefficient <span><math><mrow><mo>(</mo><msub><mi>η</mi><mi>a</mi></msub><mo>)</mo></mrow></math></span>. Semi-analytical solutions for pore water pressure, pore air pressure and settlement in layered unsaturated soils are derived by employing the Laplace transform and its inverse transform. The rationality of the model is validated through comparative analysis with existing solutions. Analysis of the improved model yields critical insights: the presence of flow and air contact resistance leads to the development of relative pore pressure and air pressure gradients at interfaces, which diminishes the influence of the permeability coefficients of the water phase <span><math><mrow><mo>(</mo><msub><mi>k</mi><mi>ω</mi></msub><mo>)</mo></mrow></math></span> and air phase <span><math><mrow><mo>(</mo><msub><mi>k</mi><mi>a</mi></msub><mo>)</mo></mrow></math></span> on the consolidation process. Moreover, neglecting the flow and air contact resistance effects may lead to an overestimation of settlement.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-28DOI: 10.1016/j.compgeo.2024.106787
The linearly bonded particle model (LBPM) and moment tensor method (MTM) have been combined and applied to simulate the progressive failure of rock and associated acoustic emission (AE). However, LBPM-MTM cannot characterize the compression-hardening response of a rock microstructure or its effect on progressive failure and AE. We propose a nonlinear bonded particle model (NBPM) to address this with MTM. Results revealed that NBPM could reproduce the compression-hardening response of Xinzhuang sandstone far better than LBPM. For the LBPM case, the proportion of the tensile force and concentration zones changed slightly during compression, while the results of the NBPM significantly increased. Microcracks in the NBPM case emerged later than in the LBPM case. Compared to the LBPM-MTM case, the NBPM-MTM case has more microcracks and AE events, and more energy is released near the peak stress. The correlation between the accumulative AE event count and magnitude via NBPM-MTM complied with the Gutenberg-Richter law much better than via LBPM-MTM. Overall, the magnitude of a single AE event with NBPM-MTM is greater than with LBPM-MTM. Our NBPM-MTM was proven to be more feasible and accurate in characterizing the progressive failure of rock and its associated AE than the traditional LBPM-MTM.
{"title":"Nonlinear distinct element modeling of the microstructural compression-hardening effect on the progressive failure and associated acoustic emission of brittle rock","authors":"","doi":"10.1016/j.compgeo.2024.106787","DOIUrl":"10.1016/j.compgeo.2024.106787","url":null,"abstract":"<div><div>The linearly bonded particle model (LBPM) and moment tensor method (MTM) have been combined and applied to simulate the progressive failure of rock and associated acoustic emission (AE). However, LBPM-MTM cannot characterize the compression-hardening response of a rock microstructure or its effect on progressive failure and AE. We propose a nonlinear bonded particle model (NBPM) to address this with MTM. Results revealed that NBPM could reproduce the compression-hardening response of Xinzhuang sandstone far better than LBPM. For the LBPM case, the proportion of the tensile force and concentration zones changed slightly during compression, while the results of the NBPM significantly increased. Microcracks in the NBPM case emerged later than in the LBPM case. Compared to the LBPM-MTM case, the NBPM-MTM case has more microcracks and AE events, and more energy is released near the peak stress. The correlation between the accumulative AE event count and magnitude via NBPM-MTM complied with the Gutenberg-Richter law much better than via LBPM-MTM. Overall, the magnitude of a single AE event with NBPM-MTM is greater than with LBPM-MTM. Our NBPM-MTM was proven to be more feasible and accurate in characterizing the progressive failure of rock and its associated AE than the traditional LBPM-MTM.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-28DOI: 10.1016/j.compgeo.2024.106765
Frost cracking is one of the primary causes of deterioration in frozen soil structures, yet few relevant numerical studies have been reported, and the simulation of frost cracking in soils remains challenging due to inadequate consideration of reasonable simulation algorithms. Numerous experimental studies have identified frost heave and desiccation shrinkage as the principal cause of frozen soil cracking. On this basis, this study presents a peridynamic (PD) model that considers the coupled effects of frost heaving and desiccation shrinkage for simulating frost cracking in soils during freezing process. The heat conduction equation is reformulated using the peridynamic differential operator (PDDO). The variation of thermal parameters for soils is addressed using the thermal enthalpy method, equivalent homogeneous method, and linear release assumption of latent heat. The frost-heaving load induced by pore water is represented using an equivalent displacement load. The multiphysics solution using PDDO and bond-based peridynamics (BBPD) considering freezing heave and desiccation shrinkage is developed for the first time. By simulating the frost cracking of a two-dimensional soil strip after model validations, the resulting crack pattern closely resembles the experimental observation. It indicates that the present model can capture the phase transition interface (PTI) and cracking behaviors of frozen soils.
{"title":"Modelling the frost cracking behavior in clayey soils: A peridynamic approach","authors":"","doi":"10.1016/j.compgeo.2024.106765","DOIUrl":"10.1016/j.compgeo.2024.106765","url":null,"abstract":"<div><div>Frost cracking is one of the primary causes of deterioration in frozen soil structures, yet few relevant numerical studies have been reported, and the simulation of frost cracking in soils remains challenging due to inadequate consideration of reasonable simulation algorithms. Numerous experimental studies have identified frost heave and desiccation shrinkage as the principal cause of frozen soil cracking. On this basis, this study presents a peridynamic (PD) model that considers the coupled effects of frost heaving and desiccation shrinkage for simulating frost cracking in soils during freezing process. The heat conduction equation is reformulated using the peridynamic differential operator (PDDO). The variation of thermal parameters for soils is addressed using the thermal enthalpy method, equivalent homogeneous method, and linear release assumption of latent heat. The frost-heaving load induced by pore water is represented using an equivalent displacement load. The multiphysics solution using PDDO and bond-based peridynamics (BBPD) considering freezing heave and desiccation shrinkage is developed for the first time. By simulating the frost cracking of a two-dimensional soil strip after model validations, the resulting crack pattern closely resembles the experimental observation. It indicates that the present model can capture the phase transition interface (PTI) and cracking behaviors of frozen soils.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":null,"pages":null},"PeriodicalIF":5.3,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-28DOI: 10.1016/j.compgeo.2024.106793
Scour is a non-negligible issue of monopiles that profoundly threatens the safety of monopile for offshore wind turbines (OWTs). Accurately predicting the scour depth is essential for the design and operation of OWTs. This study introduces a model aimed at predicting scour depth from the aspect of the natural frequency of monopile. The model is developed using uniform design samples to ensure its applicability across a wider range of OWT monopiles and soil properties. To enhance the model accuracy, a Bayesian framework is employed, incorporating prior information. The three main model coefficients are updated iteratively, allowing the predicted scour depth to converge with the observed values. The Monte Carlo Markov chain (MCMC) simulation is utilized to generate the posterior distribution. The model accuracy is validated through 48 representative samples, and the effectiveness of Bayesian updating in improving the model precision is demonstrated by comparing the results prior to and following Bayesian updating. Additionally, the numerical simulations and monitored data confirm the validity of the proposed prediction model.
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