Further investigation into the progression of soil arching under the impact of noncentered tunnel is warranted. This study addresses this need by examining trapdoor models with varying vertical and horizontal spacings between the tunnel and the trapdoor through the discrete element method. The numerical model underwent calibration utilizing data from previous experiments. The results indicated that the soil arching ratio under the impact of noncentered tunnel exhibits four distinct stages: initial soil arching, maximum soil arching, load recovery, and ultimate stage, aligning with observations unaffected by tunnel presence. The minimal disparity in stress ratio within the stationary region was observed when the vertical spacing between the tunnel and the trapdoor ranges between 150 and 200 mm. Moreover, the disturbed area on the left part of the trapdoor extended significantly beyond the trapdoor width, with notably higher disturbance height compared to the right side. When the tunnel deviated from the centerline of the trapdoor, the stress enhancement on the right side was considerably greater compared to the left. Additionally, the displacement of the trapdoor resulted in a reduction of contact force anisotropy in the soil on the side more distant from the tunnel, while increasing it on the side closer to the tunnel.
{"title":"Macro‐ and Microscopic Mechanisms of Soil Arching Evolution Under the Impact of Noncentered Tunnel","authors":"Rui‐Xiao Zhang, Dong Su, Xiang‐Sheng Chen, Xing‐Tao Lin, Hao Xiong, De‐Jin Zhang","doi":"10.1002/nag.3962","DOIUrl":"https://doi.org/10.1002/nag.3962","url":null,"abstract":"Further investigation into the progression of soil arching under the impact of noncentered tunnel is warranted. This study addresses this need by examining trapdoor models with varying vertical and horizontal spacings between the tunnel and the trapdoor through the discrete element method. The numerical model underwent calibration utilizing data from previous experiments. The results indicated that the soil arching ratio under the impact of noncentered tunnel exhibits four distinct stages: initial soil arching, maximum soil arching, load recovery, and ultimate stage, aligning with observations unaffected by tunnel presence. The minimal disparity in stress ratio within the stationary region was observed when the vertical spacing between the tunnel and the trapdoor ranges between 150 and 200 mm. Moreover, the disturbed area on the left part of the trapdoor extended significantly beyond the trapdoor width, with notably higher disturbance height compared to the right side. When the tunnel deviated from the centerline of the trapdoor, the stress enhancement on the right side was considerably greater compared to the left. Additionally, the displacement of the trapdoor resulted in a reduction of contact force anisotropy in the soil on the side more distant from the tunnel, while increasing it on the side closer to the tunnel.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"35 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143473555","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}
Zhigang Ye, Lujun Wang, Bin Zhu, Simin Yuan, Bingfa Yan, Ronghan Guo, Yunmin Chen
Natural gas hydrates are the preferred alternative to traditional fossil fuels, estimated to store twice as much carbon. The gas hydrate‐bearing sediment (GHBS) is a representative degradable soil. During gas hydrate production, solid mass loss and pore liquid/gas generation occur, including both decomposition and consolidation processes of GHBS. These potentially trigger reservoir collapse, severely affecting production safety. This study develops a decomposition–consolidation model for GHBS, quantifying the solid hydrate loss by the kinetic decomposition equation and describing skeleton deformation via both modified elasticity and volumetric strain relationships. By linking hydrate saturation with the representative parameters of hydrate decomposition, mass migration, heat transfer, and skeleton deformation, decomposition degree and consolidation degree are respectively introduced to assess these processes. The decomposing and mechanical parameters are calibrated through triaxial/modeling tests. Results show that consolidation degree and decomposition degree are not synchronized in sandy hydrate‐bearing sediments, where depressurization‐induced variation of consolidation degree predominates in the early stage, while the evolution of consolidation degree lags behind decomposition degree for temperature recovery after complete hydrate decomposition; hydrate decomposition‐induced skeleton deformation, significant compared to pore pressure dissipation, remains crucial long after complete depressurization. These findings provide insights into optimizing safety of long‐term gas hydrate production.
{"title":"A Decomposition–Consolidation Model for the Production Behavior of Gas Hydrate‐Bearing Sediments","authors":"Zhigang Ye, Lujun Wang, Bin Zhu, Simin Yuan, Bingfa Yan, Ronghan Guo, Yunmin Chen","doi":"10.1002/nag.3965","DOIUrl":"https://doi.org/10.1002/nag.3965","url":null,"abstract":"Natural gas hydrates are the preferred alternative to traditional fossil fuels, estimated to store twice as much carbon. The gas hydrate‐bearing sediment (GHBS) is a representative degradable soil. During gas hydrate production, solid mass loss and pore liquid/gas generation occur, including both decomposition and consolidation processes of GHBS. These potentially trigger reservoir collapse, severely affecting production safety. This study develops a decomposition–consolidation model for GHBS, quantifying the solid hydrate loss by the kinetic decomposition equation and describing skeleton deformation via both modified elasticity and volumetric strain relationships. By linking hydrate saturation with the representative parameters of hydrate decomposition, mass migration, heat transfer, and skeleton deformation, decomposition degree and consolidation degree are respectively introduced to assess these processes. The decomposing and mechanical parameters are calibrated through triaxial/modeling tests. Results show that consolidation degree and decomposition degree are not synchronized in sandy hydrate‐bearing sediments, where depressurization‐induced variation of consolidation degree predominates in the early stage, while the evolution of consolidation degree lags behind decomposition degree for temperature recovery after complete hydrate decomposition; hydrate decomposition‐induced skeleton deformation, significant compared to pore pressure dissipation, remains crucial long after complete depressurization. These findings provide insights into optimizing safety of long‐term gas hydrate production.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"179 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470739","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}
Zixin Wang, Jun Peng, Chuanhua Xu, Linfei Wang, Bibo Dai
In the field of geomechanics and geotechnical engineering, joint is crucial as a common structure or flaw in rock material. The shear deformation, strength, and failure behavior of rock are significantly influenced by the structural properties of joints, which include arrangement, persistency, dip angle, and length. The shear strength and deformation behavior, as well as the related micro‐cracking process of a collection of 2D jointed rock masses with varying joint persistency and joint apertures under various normal stresses, are numerically investigated in this study using an improved grain‐based model (GBM) considering feldspar shape. The results show that joint persistency and normal stress have a larger influence on the shear strength and micro‐cracking behavior of rock when compared with joint aperture. In particular, the crack initiation stress (CIS) is not greatly affected by joint aperture, while the direct shear strength (DSS) and the shear modulus (G) slightly decrease with the increase of joint aperture. The developed micro‐cracks initiate primarily at both ends and the center of the rock bridge at the initial loading stage. The results from quantitative analysis of vertical stress of the numerical model reveal that higher joint persistency and lower normal stress result in a more uniform stress distribution. The influence of joint aperture, joint persistency, and normal stress on shear mechanical behavior and the micro‐cracking mechanism of rock is theoretically explained through macroscopic and microscopic force analysis.
{"title":"Influence of Aperture on Shear Behavior of Non‐Persistent Joint: Insights from Grain‐Based Modeling","authors":"Zixin Wang, Jun Peng, Chuanhua Xu, Linfei Wang, Bibo Dai","doi":"10.1002/nag.3964","DOIUrl":"https://doi.org/10.1002/nag.3964","url":null,"abstract":"In the field of geomechanics and geotechnical engineering, joint is crucial as a common structure or flaw in rock material. The shear deformation, strength, and failure behavior of rock are significantly influenced by the structural properties of joints, which include arrangement, persistency, dip angle, and length. The shear strength and deformation behavior, as well as the related micro‐cracking process of a collection of 2D jointed rock masses with varying joint persistency and joint apertures under various normal stresses, are numerically investigated in this study using an improved grain‐based model (GBM) considering feldspar shape. The results show that joint persistency and normal stress have a larger influence on the shear strength and micro‐cracking behavior of rock when compared with joint aperture. In particular, the crack initiation stress (CIS) is not greatly affected by joint aperture, while the direct shear strength (DSS) and the shear modulus (<jats:italic>G</jats:italic>) slightly decrease with the increase of joint aperture. The developed micro‐cracks initiate primarily at both ends and the center of the rock bridge at the initial loading stage. The results from quantitative analysis of vertical stress of the numerical model reveal that higher joint persistency and lower normal stress result in a more uniform stress distribution. The influence of joint aperture, joint persistency, and normal stress on shear mechanical behavior and the micro‐cracking mechanism of rock is theoretically explained through macroscopic and microscopic force analysis.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"31 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143462922","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}
Rigid pile composite foundation (RPCF) has been widely used in Yellow River Alluvial Plain (YRAP) due to remarkable reinforcement and economical effects. However, current design of RPCF in this area are typically based on saturated soil mechanic principles assuming drained condition, despite the fact that the soil is typically in unsaturated condition. Due to long time water scouring, the silt in YRAP generally exhibits high particle sphericity and poor particle gradation. Even after standard compaction, it is still in a relatively loose state with developed capillary pores. Water content increment induced by infiltration can lead to considerable soil mechanical properties degradations due to matric suction reduction associated with soil micro‐structure rearrangement. Consequently, the RPCF will suffer serious bearing characteristic deteriorations, exhibiting additional settlement. In this study, extending unsaturated soil mechanics, initially the influences of matric suction on mechanical properties of YRAP silt were demonstrated. Then total RPCF settlement was calculated as the sum of the compression deformation of the soil between piles in the reinforcement zone and the underlying soil stratum. The former one was estimated through the modified load transfer curve method considering the pile‐soil interface behaviors deteriorations with matric suction reduction, while the later one was estimated through the traditional stress diffusion method. The feasibility of the proposed method was validated through a model RPCF test subjected to ground water level fluctuations. Good comparisons on RPCF mechanical behaviors indicate the proposed method can be a valuable tool in the design of RPCF in YRAP under extreme weather conditions.
{"title":"Mechanical Behaviors of Rigid Pile Composite Foundation in Yellow River Alluvial Plain Subjected to Soil Water Content Variations","authors":"Yunlong Liu, Yanyan Xia, Jingwei Zhang, Bantayehu Uba Uge","doi":"10.1002/nag.3959","DOIUrl":"https://doi.org/10.1002/nag.3959","url":null,"abstract":"Rigid pile composite foundation (RPCF) has been widely used in Yellow River Alluvial Plain (YRAP) due to remarkable reinforcement and economical effects. However, current design of RPCF in this area are typically based on saturated soil mechanic principles assuming drained condition, despite the fact that the soil is typically in unsaturated condition. Due to long time water scouring, the silt in YRAP generally exhibits high particle sphericity and poor particle gradation. Even after standard compaction, it is still in a relatively loose state with developed capillary pores. Water content increment induced by infiltration can lead to considerable soil mechanical properties degradations due to matric suction reduction associated with soil micro‐structure rearrangement. Consequently, the RPCF will suffer serious bearing characteristic deteriorations, exhibiting additional settlement. In this study, extending unsaturated soil mechanics, initially the influences of matric suction on mechanical properties of YRAP silt were demonstrated. Then total RPCF settlement was calculated as the sum of the compression deformation of the soil between piles in the reinforcement zone and the underlying soil stratum. The former one was estimated through the modified load transfer curve method considering the pile‐soil interface behaviors deteriorations with matric suction reduction, while the later one was estimated through the traditional stress diffusion method. The feasibility of the proposed method was validated through a model RPCF test subjected to ground water level fluctuations. Good comparisons on RPCF mechanical behaviors indicate the proposed method can be a valuable tool in the design of RPCF in YRAP under extreme weather conditions.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"36 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443317","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}
Failure criteria are crucial in numerical methods for effectively resolving material failures, especially in geomaterials such as rock and concrete. A wide array of criteria, designed for different rock types and complex stress conditions, has been developed. Although Artificial Neural Network (ANN)‐based failure criteria present a unified solution for incorporating these diverse criteria into numerical models, their opaque nature and heavy data demands frequently curtail their practical utility and computational efficiency. To address these issues, this paper introduces a geometric‐based method for reconstructing existing failure criteria. This novel approach not only simulates the functionality of ANNs but also offers greater interpretability, simpler visualization, and reduced data requirements. The effectiveness of this reconstruction method in representing established failure criteria is validated, and its utility in a four‐dimensional lattice spring model (4D‐LSM) for modeling true triaxial conditions is showcased through multiple numerical examples.
{"title":"General Geometric Reconstruction Method of Failure Criteria for Lattice Spring Model","authors":"Zhen‐Qi Yang, Xin‐Dong Wei, Zhe Li, Gao‐Feng Zhao","doi":"10.1002/nag.3960","DOIUrl":"https://doi.org/10.1002/nag.3960","url":null,"abstract":"Failure criteria are crucial in numerical methods for effectively resolving material failures, especially in geomaterials such as rock and concrete. A wide array of criteria, designed for different rock types and complex stress conditions, has been developed. Although Artificial Neural Network (ANN)‐based failure criteria present a unified solution for incorporating these diverse criteria into numerical models, their opaque nature and heavy data demands frequently curtail their practical utility and computational efficiency. To address these issues, this paper introduces a geometric‐based method for reconstructing existing failure criteria. This novel approach not only simulates the functionality of ANNs but also offers greater interpretability, simpler visualization, and reduced data requirements. The effectiveness of this reconstruction method in representing established failure criteria is validated, and its utility in a four‐dimensional lattice spring model (4D‐LSM) for modeling true triaxial conditions is showcased through multiple numerical examples.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"63 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417490","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}
The framework of poromechanics is generalized to simulate the multiscale behavior of porous media subjected to internal loadings stemming from the growth of solid inclusions. This generalization is designed to enable the study of anisotropic internal stress generation from solid growth within the pores, while recovering isotropic fluid‐induced loading as a particular case. For this purpose, a mathematical strategy to define constitutive tensors in a thermodynamically consistent form is proposed, thus offering new opportunities for determining the poromechanical properties of a porous solid through advanced experimentation or micromechanical models. The framework is specialized by means of established elastic solutions for single pore–matrix interaction, as well as through homogenization schemes considering the interaction among congruent pores. In particular, the second Eshelby solution and the Tanaka–Mori–Benveniste homogenization scheme are used to derive a microporoelastic model. At an elemental scale, the model is tested under mixed control conditions by replicating different scenarios of geomaterial testing. In addition, the model characteristics are outlined with reference to inelastic microscopic loadings replicating chemo‐mechanical forcing, such as expansive crystal formation. Through a series of parametric analyses, it is shown that the microstructure of the pores significantly influences the properties of porous media. Most notably, it is shown that the effects of a solid forming within the pores depend in a highly nonlinear fashion on the constitutive characteristics of the inhomogeneities and can therefore not be readily quantified or predicted without models capturing the diverse multiscale interactions among pores, inhomogeneities, and matrix.
{"title":"A Poromechanical Framework for Internal Interactions Induced by Solid Inclusions","authors":"Yifan Yang, Giuseppe Buscarnera","doi":"10.1002/nag.3952","DOIUrl":"https://doi.org/10.1002/nag.3952","url":null,"abstract":"The framework of poromechanics is generalized to simulate the multiscale behavior of porous media subjected to internal loadings stemming from the growth of solid inclusions. This generalization is designed to enable the study of anisotropic internal stress generation from solid growth within the pores, while recovering isotropic fluid‐induced loading as a particular case. For this purpose, a mathematical strategy to define constitutive tensors in a thermodynamically consistent form is proposed, thus offering new opportunities for determining the poromechanical properties of a porous solid through advanced experimentation or micromechanical models. The framework is specialized by means of established elastic solutions for single pore–matrix interaction, as well as through homogenization schemes considering the interaction among congruent pores. In particular, the second Eshelby solution and the Tanaka–Mori–Benveniste homogenization scheme are used to derive a microporoelastic model. At an elemental scale, the model is tested under mixed control conditions by replicating different scenarios of geomaterial testing. In addition, the model characteristics are outlined with reference to inelastic microscopic loadings replicating chemo‐mechanical forcing, such as expansive crystal formation. Through a series of parametric analyses, it is shown that the microstructure of the pores significantly influences the properties of porous media. Most notably, it is shown that the effects of a solid forming within the pores depend in a highly nonlinear fashion on the constitutive characteristics of the inhomogeneities and can therefore not be readily quantified or predicted without models capturing the diverse multiscale interactions among pores, inhomogeneities, and matrix.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"29 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417544","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}
The maintenance effort for a ballast bed is determined by the combination of tamping and stabilizing, which have always been separated in previous researches. In this study, a tamping‐stabilizing‐ballasted track was established, and a dynamic domain was innovatively developed to improve calculation efficiency. This model was verified through a comparison with field test results. Using this model, the mechanical properties of ballast bed in tamping and stabilizing under different combination modes were firstly analyzed. The results indicate that the mechanical characteristics of rock ballast in tamping are much more intense than those in stabilizing, and repeated tamping may aggravate ballast degradation, but is beneficial for ballast rotation. Repeated tamping and stabilizing operations are conducive to the coordination number of rock ballast and contact density on the sleeper but have opposite effects on the compactness of rock ballast and pressure on the sleeper. The optimal combination model is determined to be T2S1, and this is followed by T1T1S1, according to a comprehensive evaluation of the mechanical state of ballast bed. This study can provide practical guidance for the combination of tamping and stabilizing operations in railway maintenance.
{"title":"Mechanical Properties of Rock Ballast in Combined Tamping and Stabilizing Operations Using Numerical Dynamic Domain","authors":"Shunwei Shi, Yixiong Xiao, Yang Xu, Xichong Ren, Chunyu Wang, Yanan Zhang, Liang Gao","doi":"10.1002/nag.3961","DOIUrl":"https://doi.org/10.1002/nag.3961","url":null,"abstract":"The maintenance effort for a ballast bed is determined by the combination of tamping and stabilizing, which have always been separated in previous researches. In this study, a tamping‐stabilizing‐ballasted track was established, and a dynamic domain was innovatively developed to improve calculation efficiency. This model was verified through a comparison with field test results. Using this model, the mechanical properties of ballast bed in tamping and stabilizing under different combination modes were firstly analyzed. The results indicate that the mechanical characteristics of rock ballast in tamping are much more intense than those in stabilizing, and repeated tamping may aggravate ballast degradation, but is beneficial for ballast rotation. Repeated tamping and stabilizing operations are conducive to the coordination number of rock ballast and contact density on the sleeper but have opposite effects on the compactness of rock ballast and pressure on the sleeper. The optimal combination model is determined to be T2S1, and this is followed by T1T1S1, according to a comprehensive evaluation of the mechanical state of ballast bed. This study can provide practical guidance for the combination of tamping and stabilizing operations in railway maintenance.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"78 5 Pt 1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401290","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}
Microbially induced carbonate precipitation (MICP) has been extensively studied through experiments as a potential solution for ground improvement. However, the investigation and optimization of the MICP grouting process remain incomplete due to various experimental limitations, such as budget constraints, equipment availability, time limit, and suitable sites. As a result, the numerical method could be a practical approach, providing a clearer understanding of the hydrological‐biological‐chemical processes involved, which could help improve the performance of MICP. In this study, a hydrological‐biological‐chemical coupling model was developed to simulate MICP grouting in both homogeneous and layered heterogeneous soils, which is often found in nature. The model effectively captures the impact of carbonate precipitation on critical aspects of the grouting process, such as flow field, bacterial adsorption, bacterial activity, and soil properties. Additionally, the Péclet and Damköhler numbers were introduced to comprehensively describe the impact of various grouting factors on the distribution of precipitates and the average CaCO3 increment in homogeneous soils. In layered heterogeneous soils, it was observed that some solutions migrate across the interface between the two soil layers, leading to an accumulation of precipitates near the interface and forming a wedge‐shaped CaCO3 increment zone in the lower‐permeability soil layer. Beyond this wedge‐shaped zone, the distribution of CaCO3 is comparable to that in homogeneous soils. These findings suggest that in layered heterogeneous soils, special attention should be given to the area adjacent to the soil interface in the less permeable layer, as the precipitate distribution in other regions mirrors that in corresponding homogeneous soils.
{"title":"Numerical Modeling of MICP Grouting in Homogeneous and Layered Heterogeneous Soils","authors":"Guo‐Liang Ma, Zhen‐Yu Yin, Yang Xiao","doi":"10.1002/nag.3957","DOIUrl":"https://doi.org/10.1002/nag.3957","url":null,"abstract":"Microbially induced carbonate precipitation (MICP) has been extensively studied through experiments as a potential solution for ground improvement. However, the investigation and optimization of the MICP grouting process remain incomplete due to various experimental limitations, such as budget constraints, equipment availability, time limit, and suitable sites. As a result, the numerical method could be a practical approach, providing a clearer understanding of the hydrological‐biological‐chemical processes involved, which could help improve the performance of MICP. In this study, a hydrological‐biological‐chemical coupling model was developed to simulate MICP grouting in both homogeneous and layered heterogeneous soils, which is often found in nature. The model effectively captures the impact of carbonate precipitation on critical aspects of the grouting process, such as flow field, bacterial adsorption, bacterial activity, and soil properties. Additionally, the Péclet and Damköhler numbers were introduced to comprehensively describe the impact of various grouting factors on the distribution of precipitates and the average CaCO<jats:sub>3</jats:sub> increment in homogeneous soils. In layered heterogeneous soils, it was observed that some solutions migrate across the interface between the two soil layers, leading to an accumulation of precipitates near the interface and forming a wedge‐shaped CaCO<jats:sub>3</jats:sub> increment zone in the lower‐permeability soil layer. Beyond this wedge‐shaped zone, the distribution of CaCO<jats:sub>3</jats:sub> is comparable to that in homogeneous soils. These findings suggest that in layered heterogeneous soils, special attention should be given to the area adjacent to the soil interface in the less permeable layer, as the precipitate distribution in other regions mirrors that in corresponding homogeneous soils.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"132 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393171","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}
Mualem's approach has been widely used to predict hydraulic conductivity functions (HCFs) of bare soils if a soil water retention curve (SWRC) model is available. The assumption that Mualem's approach holds is that the distribution of soil pores is spatially completely random. Under this assumption, relative hydraulic conductivity (Kr) is determined by the continuance probability of water‐filled pores. However, this assumption is not valid for rooted soils, as root growth causes soil particle rearrangement, and thus soil pore rearrangement, altering the probability of pore connectivity. After reconsidering Mualem's assumption, this study attempts to develop a new approach for predicting HCF of rooted soils by modeling the root‐induced pore rearrangement and the resultant change in the continuance probability of water‐filled pores. Two approaches mentioned were incorporated with a root‐dependent SWRC model to express HCF as a function of matric suction. The proposed model was validated against nine sets of measured HCFs from published studies. It was found that the proposed model reduced the root mean square error (RMSE) of Kr and lg Kr by 33% and 53%, respectively, as compared to traditional Mualem's model. Physically, the model's effectiveness depended on soil texture and root type. In fine‐textured soils, roots were capable of displacing soil particles, thereby causing soil pore rearrangement. Also, coarse roots with high strength tend to alter pore distribution. After considering the effects of pore‐level root‐soil interaction on pore rearrangement, the proposed model provided a significant improvement in the prediction of HCF of unsaturated rooted soils.
{"title":"Pore‐Based Modeling of Hydraulic Conductivity Function of Unsaturated Rooted Soils","authors":"Hao Wang, Rui Chen, Anthony Kwan Leung, Ankit Garg, Zhenliang Jiang","doi":"10.1002/nag.3958","DOIUrl":"https://doi.org/10.1002/nag.3958","url":null,"abstract":"Mualem's approach has been widely used to predict hydraulic conductivity functions (HCFs) of bare soils if a soil water retention curve (SWRC) model is available. The assumption that Mualem's approach holds is that the distribution of soil pores is spatially completely random. Under this assumption, relative hydraulic conductivity (<jats:italic>K<jats:sub>r</jats:sub></jats:italic>) is determined by the continuance probability of water‐filled pores. However, this assumption is not valid for rooted soils, as root growth causes soil particle rearrangement, and thus soil pore rearrangement, altering the probability of pore connectivity. After reconsidering Mualem's assumption, this study attempts to develop a new approach for predicting HCF of rooted soils by modeling the root‐induced pore rearrangement and the resultant change in the continuance probability of water‐filled pores. Two approaches mentioned were incorporated with a root‐dependent SWRC model to express HCF as a function of matric suction. The proposed model was validated against nine sets of measured HCFs from published studies. It was found that the proposed model reduced the root mean square error (RMSE) of <jats:italic>K<jats:sub>r</jats:sub></jats:italic> and lg <jats:italic>K<jats:sub>r</jats:sub></jats:italic> by 33% and 53%, respectively, as compared to traditional Mualem's model. Physically, the model's effectiveness depended on soil texture and root type. In fine‐textured soils, roots were capable of displacing soil particles, thereby causing soil pore rearrangement. Also, coarse roots with high strength tend to alter pore distribution. After considering the effects of pore‐level root‐soil interaction on pore rearrangement, the proposed model provided a significant improvement in the prediction of HCF of unsaturated rooted soils.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"84 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385013","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}
This study assesses the capability of ChatGPT to generate finite element code for geotechnical engineering applications from a set of prompts. We tested three different initial boundary value problems using a hydro‐mechanically coupled formulation for unsaturated soils, including the dissipation of excess pore water pressure through fluid mass diffusion in one‐dimensional space, time‐dependent differential settlement of a strip footing, and gravity‐driven seepage. For each case, initial prompting involved providing ChatGPT with necessary information for finite element implementation, such as balance and constitutive equations, problem geometry, initial and boundary conditions, material properties, and spatiotemporal discretization and solution strategies. Any errors and unexpected results were further addressed through prompt augmentation processes until the ChatGPT‐generated finite element code passed the verification/validation test. Our results demonstrate that ChatGPT required minimal code revisions when using the FEniCS finite element library, owing to its high‐level interfaces that enable efficient programming. In contrast, the MATLAB code generated by ChatGPT necessitated extensive prompt augmentations and/or direct human intervention, as it involves a significant amount of low‐level programming required for finite element analysis, such as constructing shape functions or assembling global matrices. Given that prompt engineering for this task requires an understanding of the mathematical formulation and numerical techniques, this study suggests that while a large language model may not yet replace human programmers, it can greatly assist in the implementation of numerical models.
{"title":"Can ChatGPT Implement Finite Element Models for Geotechnical Engineering Applications?","authors":"Taegu Kim, Tae Sup Yun, Hyoung Suk Suh","doi":"10.1002/nag.3956","DOIUrl":"https://doi.org/10.1002/nag.3956","url":null,"abstract":"This study assesses the capability of ChatGPT to generate finite element code for geotechnical engineering applications from a set of prompts. We tested three different initial boundary value problems using a hydro‐mechanically coupled formulation for unsaturated soils, including the dissipation of excess pore water pressure through fluid mass diffusion in one‐dimensional space, time‐dependent differential settlement of a strip footing, and gravity‐driven seepage. For each case, initial prompting involved providing ChatGPT with necessary information for finite element implementation, such as balance and constitutive equations, problem geometry, initial and boundary conditions, material properties, and spatiotemporal discretization and solution strategies. Any errors and unexpected results were further addressed through prompt augmentation processes until the ChatGPT‐generated finite element code passed the verification/validation test. Our results demonstrate that ChatGPT required minimal code revisions when using the FEniCS finite element library, owing to its high‐level interfaces that enable efficient programming. In contrast, the MATLAB code generated by ChatGPT necessitated extensive prompt augmentations and/or direct human intervention, as it involves a significant amount of low‐level programming required for finite element analysis, such as constructing shape functions or assembling global matrices. Given that prompt engineering for this task requires an understanding of the mathematical formulation and numerical techniques, this study suggests that while a large language model may not yet replace human programmers, it can greatly assist in the implementation of numerical models.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"163 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258241","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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