Pub Date : 2026-02-04DOI: 10.1016/j.compgeo.2026.107952
Xinyi Wu, Jialin Xu, Chengshun Xu, Zhuolin Su
Solid-liquid two-phase flows with particles of a wide size range are widespread in geotechnical engineering. The CFD-DEM method is valid for solid–fluid coupling analysis, but traditional methods are limited in size applicability. This study proposes an improved semi-resolved CFD-DEM method capable of simulating systems with wide mesh/particle size ratios (L/d). In the method, a dynamic coupling strategy is adopted for different L/d: when the mesh size is much larger than the particle diameter, a gradient-based interpolation method is used to reconstruct the fluid velocity around the particles; when the mesh size is comparable to or smaller than the particle diameter, inter-phase forces are corrected through an extended domain. The proposed method is validated through the simulation of two typical cases, including single particle settling and collapse of granular piles, and is applied to upward seepage in sandy soils. Simulation results show that the method not only accurately reflects macroscopic phenomena, but also effectively captures the characteristics of the local flow field around particles in wide L/d systems, thereby revealing the mesoscopic mechanisms of particle–fluid interactions. Furthermore, the simulation of upward seepage indicated that the non-uniformity of the flow field drives the preferential migration of fine particles, which subsequently induces piping in gap-graded soils.
{"title":"An improved semi-resolved CFD-DEM method for particle systems with wide mesh/particle size ratios","authors":"Xinyi Wu, Jialin Xu, Chengshun Xu, Zhuolin Su","doi":"10.1016/j.compgeo.2026.107952","DOIUrl":"10.1016/j.compgeo.2026.107952","url":null,"abstract":"<div><div>Solid-liquid two-phase flows with particles of a wide size range are widespread in geotechnical engineering. The CFD-DEM method is valid for solid–fluid coupling analysis, but traditional methods are limited in size applicability. This study proposes an improved semi-resolved CFD-DEM method capable of simulating systems with wide mesh/particle size ratios (<em>L</em>/<em>d</em>). In the method, a dynamic coupling strategy is adopted for different <em>L</em>/<em>d</em>: when the mesh size is much larger than the particle diameter, a gradient-based interpolation method is used to reconstruct the fluid velocity around the particles; when the mesh size is comparable to or smaller than the particle diameter, inter-phase forces are corrected through an extended domain. The proposed method is validated through the simulation of two typical cases, including single particle settling and collapse of granular piles, and is applied to upward seepage in sandy soils. Simulation results show that the method not only accurately reflects macroscopic phenomena, but also effectively captures the characteristics of the local flow field around particles in wide <em>L</em>/<em>d</em> systems, thereby revealing the mesoscopic mechanisms of particle–fluid interactions. Furthermore, the simulation of upward seepage indicated that the non-uniformity of the flow field drives the preferential migration of fine particles, which subsequently induces piping in gap-graded soils.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107952"},"PeriodicalIF":6.2,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174382","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 : 2026-02-03DOI: 10.1016/j.compgeo.2026.107943
Qiuxin Gu , Qiang Zhang , Kai Zhang , Hui Liu , Yihan Du , Bo Huang , Wei Han
The hydraulic fracturing and low-temperature thermal stimulation are commonly adopted for the construction of geothermal reservoirs in hot dry rock (HDR). However, it is hardly involved in the existing research on the variation law of the temperature and stress fields in the surrounding rock and the crack initiation propagation mechanism when the cooling fluid flows through the borehole. In this study, the unsteady temperature and stress field of the borehole surrounding rock during the cooling process was derived and solved firstly using the heat transfer and elasticity mechanics theories. Then, the crack initiation and propagation criteria for the borehole surrounding rock are proposed according to the fracture mechanics theory. Finally, the initiation and propagation laws of thermal cracks in the borehole surrounding rock under cyclic thermal shock are investigated through the discrete element method. The results reveal that when the cooling fluid is injected into the borehole, the temperature of the rock around the borehole drops the fastest. As the distance from the borehole increases, the temperature gradually rises and gets closer to the initial rock temperature. The temperature variation of the surrounding rock is closely related to the duration of thermal shock. During the initial stage of liquid nitrogen injection, the temperature drop is the most obvious. With the increase in thermal shock time, the tangential stress transitions from compressive stress to tensile stress. The tensile stress is the largest at the edge of the borehole, which is the location most prone to cracking. The mesoscopic cracking characteristics of the borehole surrounding rock are influenced by multiple factors, including buried depth, initial temperature, cooling method, thermal cycles, and the mesoscopic composition features of HDR. These research findings provide significant theoretical reference for EGS reservoir construction and high-efficiency stable operation
{"title":"Crack initiation and propagation mechanism of borehole surrounding rock subjected to cyclic thermal loading: insights from theoretical solution and DEM simulation","authors":"Qiuxin Gu , Qiang Zhang , Kai Zhang , Hui Liu , Yihan Du , Bo Huang , Wei Han","doi":"10.1016/j.compgeo.2026.107943","DOIUrl":"10.1016/j.compgeo.2026.107943","url":null,"abstract":"<div><div>The hydraulic fracturing and low-temperature thermal stimulation are commonly adopted for the construction of geothermal reservoirs in hot dry rock (HDR). However, it is hardly involved in the existing research on the variation law of the temperature and stress fields in the surrounding rock and the crack initiation propagation mechanism when the cooling fluid flows through the borehole. In this study, the unsteady temperature and stress field of the borehole surrounding rock during the cooling process was derived and solved firstly using the heat transfer and elasticity mechanics theories. Then, the crack initiation and propagation criteria for the borehole surrounding rock are proposed according to the fracture mechanics theory. Finally, the initiation and propagation laws of thermal cracks in the borehole surrounding rock under cyclic thermal shock are investigated through the discrete element method. The results reveal that when the cooling fluid is injected into the borehole, the temperature of the rock around the borehole drops the fastest. As the distance from the borehole increases, the temperature gradually rises and gets closer to the initial rock temperature. The temperature variation of the surrounding rock is closely related to the duration of thermal shock. During the initial stage of liquid nitrogen injection, the temperature drop is the most obvious. With the increase in thermal shock time, the tangential stress transitions from compressive stress to tensile stress. The tensile stress is the largest at the edge of the borehole, which is the location most prone to cracking. The mesoscopic cracking characteristics of the borehole surrounding rock are influenced by multiple factors, including buried depth, initial temperature, cooling method, thermal cycles, and the mesoscopic composition features of HDR. These research findings provide significant theoretical reference for EGS reservoir construction and high-efficiency stable operation</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107943"},"PeriodicalIF":6.2,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174472","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 : 2026-02-03DOI: 10.1016/j.compgeo.2026.107949
Tingfang Liu , Gang Wang , Changsheng Wang , Yujing Jiang , Xuezhen Wu , Wen Zheng , Feng Jiang , Weimin Yang , Jinglong Li
The shear behavior and failure mechanisms of non-persistent joints are key to the stability of jointed rock masses, whose shear responses are jointly governed by geometric parameters such as joint aperture and joint persistence. In this study, direct shear tests were performed on specimens containing coplanar non-persistent joints, and the shear-failure process was simulated using the finite element method–cohesive zone model (FEM–CZM) method. The combined effects of joint aperture and joint persistence on shear behavior were investigated from both macroscopic and mesoscopic perspectives, and an improved Jennings shear strength criterion incorporating the weakening effect of joint aperture was derived. The tests revealed two typical post-peak failure patterns: a “sudden drop followed by arcuate recovery” and a “stepwise decline”. Increases in both the joint aperture and joint persistence reduce the peak shear strength, with joint persistence exerting a more pronounced influence. Larger joint apertures increase the degrees of rock bridge fracture surface undulation and specimen surface spalling, whereas higher joint persistence flattens the fracture surface and mitigates surface spalling. Simulations indicate that stress initially concentrates at the rock bridge ends and extends towards the middle during shearing. The number of cracks increases sharply at the peak shear stress, with tensile cracks consistently dominating. Larger joint apertures intensify the stress concentration at the rock bridge ends, leading to earlier crack initiation, a more vigorous crack propagation trend, and more dispersed crack paths, whereas higher joint persistence narrows the stress concentration zone and accelerates crack coalescence across the rock bridge. Finally, based on the test and simulation results, an improved Jennings shear strength criterion is proposed by introducing a cohesion reduction coefficient η(d) that decays exponentially with joint aperture. The validation results demonstrate that the predicted peak shear strengths agree well with the measured values and external data.
{"title":"Effects of the joint aperture and persistence on the shear behavior of coplanar non-persistent jointed rock masses and an improved Jennings shear strength criterion","authors":"Tingfang Liu , Gang Wang , Changsheng Wang , Yujing Jiang , Xuezhen Wu , Wen Zheng , Feng Jiang , Weimin Yang , Jinglong Li","doi":"10.1016/j.compgeo.2026.107949","DOIUrl":"10.1016/j.compgeo.2026.107949","url":null,"abstract":"<div><div>The shear behavior and failure mechanisms of non-persistent joints are key to the stability of jointed rock masses, whose shear responses are jointly governed by geometric parameters such as joint aperture and joint persistence. In this study, direct shear tests were performed on specimens containing coplanar non-persistent joints, and the shear-failure process was simulated using the finite element method–cohesive zone model (FEM–CZM) method. The combined effects of joint aperture and joint persistence on shear behavior were investigated from both macroscopic and mesoscopic perspectives, and an improved Jennings shear strength criterion incorporating the weakening effect of joint aperture was derived. The tests revealed two typical post-peak failure patterns: a “sudden drop followed by arcuate recovery” and a “stepwise decline”. Increases in both the joint aperture and joint persistence reduce the peak shear strength, with joint persistence exerting a more pronounced influence. Larger joint apertures increase the degrees of rock bridge fracture surface undulation and specimen surface spalling, whereas higher joint persistence flattens the fracture surface and mitigates surface spalling. Simulations indicate that stress initially concentrates at the rock bridge ends and extends towards the middle during shearing. The number of cracks increases sharply at the peak shear stress, with tensile cracks consistently dominating. Larger joint apertures intensify the stress concentration at the rock bridge ends, leading to earlier crack initiation, a more vigorous crack propagation trend, and more dispersed crack paths, whereas higher joint persistence narrows the stress concentration zone and accelerates crack coalescence across the rock bridge. Finally, based on the test and simulation results, an improved Jennings shear strength criterion is proposed by introducing a cohesion reduction coefficient <em>η</em>(<em>d</em>) that decays exponentially with joint aperture. The validation results demonstrate that the predicted peak shear strengths agree well with the measured values and external data.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107949"},"PeriodicalIF":6.2,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174473","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 : 2026-02-02DOI: 10.1016/j.compgeo.2026.107955
Pei Zhang , Chengru Yang , Chao Ma , Jie Yang , Xiuli Du
Sandy cobble strata exhibit pronounced heterogeneity and a discrete nature. Clarifying the ground failure mechanism during shield tunneling in such strata has great theoretical significance and practical values. In this paper, based on the cohesive zone element, a numerical analysis method for simulating tunnel excavation under dynamic explicit algorithm is established. In the approach, the dissipation of ground energy, the implementation of tunnel excavation and the establishment of the initial stress field under the explicit algorithm are three crucial points. For the first point, the Rayleigh damping was used to achieve the input or output of ground energy. For the second point, a user-defined field variable subroutine was compiled to simulate tunnel excavation by reducing the element stiffness of excavation zone. For the third point, the “trial and error” method was used to determine the required analysis time for the geostatic step. Then, through simulating a physical model test on tunnel excavation in boulder-cobble mixed formations, the applicability of the proposed method was verified. The results show that the proposed method can effectively capture the progressive failure process and instability range of ground. Subsequently, the proposed method was extended to investigate the ground failure mechanism for deep circular tunnel in sandy cobble strata. The progressive failure process of ground was reproduced, and the stages of instability evolution was clarified. Combined with the distribution density of failed cohesive zone elements, the development of the collapse arching and the soil pressure arching were clarified. It was found that the outer boundary of collapse arching can be described by a parabolic curve, and the outer boundary of soil pressure arching can be described by an elliptical curve. Furthermore, a detailed parametric analysis was carried out to explore the influence of ground conditions on the failure zones.
{"title":"Ground failure mechanism for deep tunnel in sandy cobble strata based on the cohesive zone element","authors":"Pei Zhang , Chengru Yang , Chao Ma , Jie Yang , Xiuli Du","doi":"10.1016/j.compgeo.2026.107955","DOIUrl":"10.1016/j.compgeo.2026.107955","url":null,"abstract":"<div><div>Sandy cobble strata exhibit pronounced heterogeneity and a discrete nature. Clarifying the ground failure mechanism during shield tunneling in such strata has great theoretical significance and practical values. In this paper, based on the cohesive zone element, a numerical analysis method for simulating tunnel excavation under dynamic explicit algorithm is established. In the approach, the dissipation of ground energy, the implementation of tunnel excavation and the establishment of the initial stress field under the explicit algorithm are three crucial points. For the first point, the Rayleigh damping was used to achieve the input or output of ground energy. For the second point, a user-defined field variable subroutine was compiled to simulate tunnel excavation by reducing the element stiffness of excavation zone. For the third point, the “trial and error” method was used to determine the required analysis time for the geostatic step. Then, through simulating a physical model test on tunnel excavation in boulder-cobble mixed formations, the applicability of the proposed method was verified. The results show that the proposed method can effectively capture the progressive failure process and instability range of ground. Subsequently, the proposed method was extended to investigate the ground failure mechanism for deep circular tunnel in sandy cobble strata. The progressive failure process of ground was reproduced, and the stages of instability evolution was clarified. Combined with the distribution density of failed cohesive zone elements, the development of the collapse arching and the soil pressure arching were clarified. It was found that the outer boundary of collapse arching can be described by a parabolic curve, and the outer boundary of soil pressure arching can be described by an elliptical curve. Furthermore, a detailed parametric analysis was carried out to explore the influence of ground conditions on the failure zones.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107955"},"PeriodicalIF":6.2,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174471","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 : 2026-02-02DOI: 10.1016/j.compgeo.2026.107954
S. Akhyani, B. Shahbodagh, N. Khalili
A physics-informed neural networks (PINNs) framework is presented for the fully coupled hydro-mechanical analysis of saturated poroelastic materials. Continuous-time PINNs are developed that simultaneously solve the coupled momentum balance and mass conservation equations with no training data or spatial and time discretisation. The framework is validated against three benchmark hydro-mechanical problems with known analytical solutions: one-dimensional Terzaghi’s consolidation (linear and nonlinear elasticity, with a stress-dependent bulk modulus), De Leeuw’s cylindrical problem, and Cryer’s spherical problem. A key contribution is the implementation of a simultaneous optimisation strategy to capture the strong coupling between the mechanical and hydraulic fields, enabling accurate modelling of the Mandel–Cryer effect. Parametric studies are presented to demonstrate the robustness of the proposed approach across varying Poisson’s ratios and fluid bulk moduli.
{"title":"Fully coupled physics-informed neural networks for hydro-mechanical analysis of saturated poroelastic media","authors":"S. Akhyani, B. Shahbodagh, N. Khalili","doi":"10.1016/j.compgeo.2026.107954","DOIUrl":"10.1016/j.compgeo.2026.107954","url":null,"abstract":"<div><div>A physics-informed neural networks (PINNs) framework is presented for the fully coupled hydro-mechanical analysis of saturated poroelastic materials. Continuous-time PINNs are developed that simultaneously solve the coupled momentum balance and mass conservation equations with no training data or spatial and time discretisation. The framework is validated against three benchmark hydro-mechanical problems with known analytical solutions: one-dimensional Terzaghi’s consolidation (linear and nonlinear elasticity, with a stress-dependent bulk modulus), De Leeuw’s cylindrical problem, and Cryer’s spherical problem. A key contribution is the implementation of a simultaneous optimisation strategy to capture the strong coupling between the mechanical and hydraulic fields, enabling accurate modelling of the Mandel–Cryer effect. Parametric studies are presented to demonstrate the robustness of the proposed approach across varying Poisson’s ratios and fluid bulk moduli.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107954"},"PeriodicalIF":6.2,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174470","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 : 2026-02-01DOI: 10.1016/j.compgeo.2026.107948
Xu Gao , Tian-Chyi Jim Yeh , E-Chuan Yan , Guo-qing Chen
Traditional displacement back analysis of the spatial distribution of hillslope mechanics parameters relies on costly and inefficient collections of displacement data from boreholes. This paper proposes a method that fuses monitored displacements at the hillslope surface after excavation and the vibration velocities after applying impact-loading to invert (back analysis) the spatial distribution of elastic modulus. Via numerical experiments, we demonstrate the effectiveness of the method and draw the following conclusion: if only excavation displacement at the hillslope surface is available for the back analysis, the resolution of the estimated elastic modulus field is too smooth. The inversion resolution of the elastic modulus field using the fusion of vibration velocities and excavation displacements on the hillslope surface is comparable to that of inversion using borehole displacement data. Moreover, the results of fusion back analysis also lead to accurate slope stability predictions. Further, the cross-correlation analysis reveals that the vibration velocity data contain more spatial heterogeneity characteristics of elastic modulus at different locations of the hillslope than the excavation displacement data. As the monitoring density of vibration velocity increases, the inversion resolution of the elastic modulus field initially improves and then stabilizes, suggesting that deploying monitoring points with a horizontal spacing of half of the horizontal spatial correlation scale is sufficient.
{"title":"Fusion of vibration velocity and excavation displacements for inversion of mechanical parameters of heterogeneous hillslope","authors":"Xu Gao , Tian-Chyi Jim Yeh , E-Chuan Yan , Guo-qing Chen","doi":"10.1016/j.compgeo.2026.107948","DOIUrl":"10.1016/j.compgeo.2026.107948","url":null,"abstract":"<div><div>Traditional displacement back analysis of the spatial distribution of hillslope mechanics parameters relies on costly and inefficient collections of displacement data from boreholes. This paper proposes a method that fuses monitored displacements at the hillslope surface after excavation and the vibration velocities after applying impact-loading to invert (back analysis) the spatial distribution of elastic modulus. Via numerical experiments, we demonstrate the effectiveness of the method and draw the following conclusion: if only excavation displacement at the hillslope surface is available for the back analysis, the resolution of the estimated elastic modulus field is too smooth. The inversion resolution of the elastic modulus field using the fusion of vibration velocities and excavation displacements on the hillslope surface is comparable to that of inversion using borehole displacement data. Moreover, the results of fusion back analysis also lead to accurate slope stability predictions. Further, the cross-correlation analysis reveals that the vibration velocity data contain more spatial heterogeneity characteristics of elastic modulus at different locations of the hillslope than the excavation displacement data. As the monitoring density of vibration velocity increases, the inversion resolution of the elastic modulus field initially improves and then stabilizes, suggesting that deploying monitoring points with a horizontal spacing of half of the horizontal spatial correlation scale is sufficient.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107948"},"PeriodicalIF":6.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174287","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 : 2026-01-31DOI: 10.1016/j.compgeo.2026.107929
Hongmei Gao , Wenhao Xu , Yinqiang Liu , Zhifu Shen , Xinlei Zhang , Zhihua Wang
The evaluation of sand liquefaction has long faced two major technical bottlenecks. Firstly, conventional centrifuge tests and finite element numerical simulations struggle to precisely control granular deposition anisotropy (e.g., deposition angle) and accurately characterize the interactions between fluid and non-spherical particles. Secondly, due to insufficient control of dynamic similarity, the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupled methods encounter significant computational efficiency challenges in the large-scale site simulations. To address these issues, this study innovatively proposes an improved CFD-DEM coupling framework, achieving methodological integration and parameter optimization in two key aspects: (1) incorporation of a non-spherical particle model to accurately characterize the directional effects of particle shape on fluid resistance; and (2) through refined adjustment of key parameter matching relationships including fluid viscosity, coupling forces, and particle Reynolds number, enabling equivalent simulation of high-gravity models while strictly maintaining physical consistency, thereby significantly improving computational efficiency. Within this framework, periodic boundary conditions were effectively employed to eliminate rigid boundary interference and achieve high-precision control of initial fabric anisotropy. Using this methodological system, the study successfully reproduced the liquefaction response differences in the sand layers with three deposition angles (0°, 45°, and 90°). It reveals that deposition angle exerts significant control on the soil liquefaction resistance: horizontally deposited (0°) sand layers demonstrate the optimal anti-liquefaction capacity due to their stable force chain network structure, while vertically deposited (90°) sand layers exhibit the highest liquefaction susceptibility owing to rapid particle suspension (suspension coefficient βt→1.0) and pronounced pore compression effects. The findings offer some micro-mechanistic insights for seismic liquefaction risk assessment in the sites with natural deposition anisotropy.
{"title":"CFD-DEM simulation of sand liquefaction with non-spherical particles and inherent anisotropic effects","authors":"Hongmei Gao , Wenhao Xu , Yinqiang Liu , Zhifu Shen , Xinlei Zhang , Zhihua Wang","doi":"10.1016/j.compgeo.2026.107929","DOIUrl":"10.1016/j.compgeo.2026.107929","url":null,"abstract":"<div><div>The evaluation of sand liquefaction has long faced two major technical bottlenecks. Firstly, conventional centrifuge tests and finite element numerical simulations struggle to precisely control granular deposition anisotropy (e.g., deposition angle) and accurately characterize the interactions between fluid and non-spherical particles. Secondly, due to insufficient control of dynamic similarity, the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupled methods encounter significant computational efficiency challenges in the large-scale site simulations. To address these issues, this study innovatively proposes an improved CFD-DEM coupling framework, achieving methodological integration and parameter optimization in two key aspects: (1) incorporation of a non-spherical particle model to accurately characterize the directional effects of particle shape on fluid resistance; and (2) through refined adjustment of key parameter matching relationships including fluid viscosity, coupling forces, and particle Reynolds number, enabling equivalent simulation of high-gravity models while strictly maintaining physical consistency, thereby significantly improving computational efficiency. Within this framework, periodic boundary conditions were effectively employed to eliminate rigid boundary interference and achieve high-precision control of initial fabric anisotropy. Using this methodological system, the study successfully reproduced the liquefaction response differences in the sand layers with three deposition angles (0°, 45°, and 90°). It reveals that deposition angle exerts significant control on the soil liquefaction resistance: horizontally deposited (0°) sand layers demonstrate the optimal anti-liquefaction capacity due to their stable force chain network structure, while vertically deposited (90°) sand layers exhibit the highest liquefaction susceptibility owing to rapid particle suspension (suspension coefficient <em>β<sub>t</sub></em>→1.0) and pronounced pore compression effects. The findings offer some micro-mechanistic insights for seismic liquefaction risk assessment in the sites with natural deposition anisotropy.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107929"},"PeriodicalIF":6.2,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080664","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 : 2026-01-31DOI: 10.1016/j.compgeo.2026.107930
Yaoru Liu , Songyu Yue , Rujiu Zhang , Yuequn Huang , Muwu Xie , Qiang Yang
During TBM tunneling, timely and effective prediction of energy evolution of surrounding rock is critical for forecasting potential hazards like rockburst, serving as a fundamental safeguard for deep underground construction. So far, most researchers often underestimate the importance of rapid prediction of the energy evolution of tunnel surrounding rock, resulting in the inability to predict specific information such as the location and time of rock bursts. In this study, a surrogate model for predicting the evolution of energy dissipation rate of tunnel surrounding rock based on the static TFT model is proposed to achieve fast time series prediction. Building upon the Temporal Fusion Transformer (TFT) framework, the static TFT model which considers the time invariant nature of tunnel surrounding rock data is proposed. 4373 numerical samples containing 9 surrounding rock energy influencing factors and 12 output features are established and trained on the model guided by the proposed mixed data and physical loss function. The model’s performance is evaluated through sample size impact, and ablation feature experiments, as well as comparing the predictive accuracy and fitting effectiveness with baseline models. It is found that the proposed model achieves superior performance across all metrics in predicting surrounding rock energy evolution without redundant features. Specifically, it attains an MAE of , an R2 of 0.9201, and an MSE of for energy dissipation rate prediction. These outcomes signify a substantive advancement in rapid energy evolution forecasting for tunnel surrounding rock and provide an early-warning basis for related geohazards.
{"title":"Prediction of rock mass energy evolution during deep tunnel construction using static temporal fusion transformer and numerical surrogate model","authors":"Yaoru Liu , Songyu Yue , Rujiu Zhang , Yuequn Huang , Muwu Xie , Qiang Yang","doi":"10.1016/j.compgeo.2026.107930","DOIUrl":"10.1016/j.compgeo.2026.107930","url":null,"abstract":"<div><div>During TBM tunneling, timely and effective prediction of energy evolution of surrounding rock is critical for forecasting potential hazards like rockburst, serving as a fundamental safeguard for deep underground construction. So far, most researchers often underestimate the importance of rapid prediction of the energy evolution of tunnel surrounding rock, resulting in the inability to predict specific information such as the location and time of rock bursts. In this study, a surrogate model for predicting the evolution of energy dissipation rate of tunnel surrounding rock based on the static TFT model is proposed to achieve fast time series prediction. Building upon the Temporal Fusion Transformer (TFT) framework, the static TFT model which considers the time invariant nature of tunnel surrounding rock data is proposed. 4373 numerical samples containing 9 surrounding rock energy influencing factors and 12 output features are established and trained on the model guided by the proposed mixed data and physical loss function. The model’s performance is evaluated through sample size impact, and ablation feature experiments, as well as comparing the predictive accuracy and fitting effectiveness with baseline models. It is found that the proposed model achieves superior performance across all metrics in predicting surrounding rock energy evolution without redundant features. Specifically, it attains an <em>MAE</em> of <span><math><mrow><mn>0.0447</mn><mi>J</mi><mo>·</mo><msup><mi>m</mi><mrow><mo>-</mo><mn>3</mn></mrow></msup><mo>·</mo><msup><mi>s</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></math></span>, an <em>R</em><sup>2</sup> of 0.9201, and an <em>MSE</em> of <span><math><mrow><mn>0.0148</mn><msup><mi>J</mi><mn>2</mn></msup><mo>·</mo><msup><mi>m</mi><mrow><mo>-</mo><mn>6</mn></mrow></msup><mo>·</mo><msup><mi>s</mi><mrow><mo>-</mo><mn>2</mn></mrow></msup></mrow></math></span> for energy dissipation rate prediction. These outcomes signify a substantive advancement in rapid energy evolution forecasting for tunnel surrounding rock and provide an early-warning basis for related geohazards.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107930"},"PeriodicalIF":6.2,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174387","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}
The uncertainty in determining rock mass properties significantly impacts tunnel stability. Additionally, squeezing conditions worsen tunnel stability, causing the tunnel to gradually converge over time. This paper addresses this issue and investigates the long-term behavior of deep tunnels using both visco-elastic and visco-elasto-plastic models. This study also includes risk-based analyses to offer a quantitative tool for engineering decision-making. Initially, an analytical method is introduced to calculate tunnel convergence in a visco-elastic rock mass. The uncertainty of key parameters that significantly affect tunnel behavior is also considered. Using MATLAB, the probability distributions of tunnel wall deformations over time are determined. The results indicate that, except in one case, the long-term tunnel convergence follows a right-skewed Gamma distribution, especially with a low GSI in both visco-elastic and visco-elasto-plastic models. This suggests that deterministic methods may not be reliable for ensuring the safety of long-term tunnel designs.
{"title":"Time-dependent deformations in deep tunnels: Insights into uncertainty and variability of rheological behavior","authors":"Milad Zaheri , Pierpaolo Oreste , Masoud Ranjbarnia , Elham Mahmoudi","doi":"10.1016/j.compgeo.2026.107942","DOIUrl":"10.1016/j.compgeo.2026.107942","url":null,"abstract":"<div><div>The uncertainty in determining rock mass properties significantly impacts tunnel stability. Additionally, squeezing conditions worsen tunnel stability, causing the tunnel to gradually converge over time. This paper addresses this issue and investigates the long-term behavior of deep tunnels using both visco-elastic and visco-elasto-plastic models. This study also includes risk-based analyses to offer a quantitative tool for engineering decision-making. Initially, an analytical method is introduced to calculate tunnel convergence in a visco-elastic rock mass. The uncertainty of key parameters that significantly affect tunnel behavior is also considered. Using MATLAB, the probability distributions of tunnel wall deformations over time are determined. The results indicate that, except in one case, the long-term tunnel convergence follows a right-skewed Gamma distribution, especially with a low GSI in both visco-elastic and visco-elasto-plastic models. This suggests that deterministic methods may not be reliable for ensuring the safety of long-term tunnel designs.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107942"},"PeriodicalIF":6.2,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080663","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 : 2026-01-30DOI: 10.1016/j.compgeo.2026.107956
Keitaro Hoshi, Shotaro Yamada, Yuta Abe, Takashi Kyoya
Swelling of smectite-bearing bedrock can cause severe tunnel deformation, depending on the type of exchangeable cation present in the interlayer structure. This study proposes an extended expansive bedrock model capable of capturing distinct swelling behaviors induced by different cation species. The model incorporates a double-layer repulsive force, formulated based on Stern theory, into a previously developed finite elastoplastic framework. Finite element analyses of tunnel excavation and subsequent swelling were performed using the proposed model. The results indicate that yielding of the bedrock skeleton acts as a trigger for accelerated swelling deformation, and that the swelling behavior is strongly influenced by the type of exchangeable cation: in sodium-type smectite, pronounced swelling occurred primarily at the tunnel invert, whereas calcium- and potassium-type smectites exhibited only minor expansion. The analysis also investigated the mechanical interaction between the expansive bedrock and an invert concrete layer. Under the assumed conditions, compressive axial stresses exceeding 20 MPa developed in the invert, suggesting that the swelling pressure can surpass the compressive strength of ordinary unreinforced concrete. These findings elucidate the fundamental mechanism of tunnel invert deformation, highlighting the distinct swelling behaviors associated with various exchangeable cation species, clarifying the multiscale and multiphysics interactions between electrochemical processes in the interlaminar region and the elastoplastic response of the surrounding rock mass, and quantitatively demonstrating the mitigating effect of the invert on swelling-induced tunnel deformation.
{"title":"Tunnel excavation and swelling analysis of expansive bedrock with multiphysics elasto-plastic model capable of describing different swelling behavior due to exchangeable cation species","authors":"Keitaro Hoshi, Shotaro Yamada, Yuta Abe, Takashi Kyoya","doi":"10.1016/j.compgeo.2026.107956","DOIUrl":"10.1016/j.compgeo.2026.107956","url":null,"abstract":"<div><div>Swelling of smectite-bearing bedrock can cause severe tunnel deformation, depending on the type of exchangeable cation present in the interlayer structure. This study proposes an extended expansive bedrock model capable of capturing distinct swelling behaviors induced by different cation species. The model incorporates a double-layer repulsive force, formulated based on Stern theory, into a previously developed finite elastoplastic framework. Finite element analyses of tunnel excavation and subsequent swelling were performed using the proposed model. The results indicate that yielding of the bedrock skeleton acts as a trigger for accelerated swelling deformation, and that the swelling behavior is strongly influenced by the type of exchangeable cation: in sodium-type smectite, pronounced swelling occurred primarily at the tunnel invert, whereas calcium- and potassium-type smectites exhibited only minor expansion. The analysis also investigated the mechanical interaction between the expansive bedrock and an invert concrete layer. Under the assumed conditions, compressive axial stresses exceeding 20 MPa developed in the invert, suggesting that the swelling pressure can surpass the compressive strength of ordinary unreinforced concrete. These findings elucidate the fundamental mechanism of tunnel invert deformation, highlighting the distinct swelling behaviors associated with various exchangeable cation species, clarifying the multiscale and multiphysics interactions between electrochemical processes in the interlaminar region and the elastoplastic response of the surrounding rock mass, and quantitatively demonstrating the mitigating effect of the invert on swelling-induced tunnel deformation.</div></div>","PeriodicalId":55217,"journal":{"name":"Computers and Geotechnics","volume":"193 ","pages":"Article 107956"},"PeriodicalIF":6.2,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080666","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}
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