Pub Date : 2025-07-09DOI: 10.1016/j.undsp.2025.04.002
Xu Song , Chang-Wei Miao , Ren-Peng Chen , Xiao-Ning Deng , Yu Zhang , Jun-Qing Wang , Xiao-Fei Chen
The soil arching effect induced by deep-buried shield tunneling strongly influenced the ground stress and displacement. Therefore, revealing the evolution mechanism of the soil arching effect is a prerequisite for accurately predicting the tunnel load, which has not been understood in deep-buried conditions. Three model tests and eight numerical simulations were carried out to enhance the understanding of the soil arching evolution, in which the stress field, displacement field, and strain field were analysed. The experimental and numerical results indicated that the ground reaction curve presented a two-stage development process of an initially linear decrease followed by a gradual decrease. Compared with the theoretical tunnel loads, the measured and numerical values are relatively larger due to the loosening earth pressure theory ignoring the evolution process of the soil arching effect. The soil arching height decreases with the increase in stress level, measuring 1.75D (the initial diameter of the model tunnel), 1.65D, and 1.61D, respectively, which results from the lagging evolution of the soil arching effect under high-stress conditions. The formation of the shear band was affected by the stress-dependent dilatancy of the soil. At low stress levels, the shear band develops vertically upward. In contrast, at higher stress levels, the shear bands tilt towards the lateral side.
{"title":"Experimental and numerical study on the soil arching effect caused by deep-buried shield tunneling","authors":"Xu Song , Chang-Wei Miao , Ren-Peng Chen , Xiao-Ning Deng , Yu Zhang , Jun-Qing Wang , Xiao-Fei Chen","doi":"10.1016/j.undsp.2025.04.002","DOIUrl":"10.1016/j.undsp.2025.04.002","url":null,"abstract":"<div><div>The soil arching effect induced by deep-buried shield tunneling strongly influenced the ground stress and displacement. Therefore, revealing the evolution mechanism of the soil arching effect is a prerequisite for accurately predicting the tunnel load, which has not been understood in deep-buried conditions. Three model tests and eight numerical simulations were carried out to enhance the understanding of the soil arching evolution, in which the stress field, displacement field, and strain field were analysed. The experimental and numerical results indicated that the ground reaction curve presented a two-stage development process of an initially linear decrease followed by a gradual decrease. Compared with the theoretical tunnel loads, the measured and numerical values are relatively larger due to the loosening earth pressure theory ignoring the evolution process of the soil arching effect. The soil arching height decreases with the increase in stress level, measuring 1.75<em>D</em> (the initial diameter of the model tunnel), 1.65<em>D</em>, and 1.61<em>D</em>, respectively, which results from the lagging evolution of the soil arching effect under high-stress conditions. The formation of the shear band was affected by the stress-dependent dilatancy of the soil. At low stress levels, the shear band develops vertically upward. In contrast, at higher stress levels, the shear bands tilt towards the lateral side.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 129-141"},"PeriodicalIF":8.2,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144713827","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 : 2025-07-04DOI: 10.1016/j.undsp.2025.03.005
Zhenning Ba , Yao Wang , Zhiwei Fang , Dongqiao Li
In recent decades, there have been numerous reports of damage cases involving tunnels crossing active faults. The mechanical response and failure mechanisms of cross-fault tunnels have become a key issue in the field of tunnel engineering. This study established a continuum-discrete coupling model comprising intact rock mass, fault zones, and tunnel. In this model, the tunnel and intact rock are modeled as continuous media, while the fault zone is modeled as a discrete medium. The non-uniform fault displacement is adopted to simulate the mechanical response and damage patterns of tunnels crossing active faults under reverse faulting. The simulation results are validated by comparison with the damage of Longchi tunnel observed from 2008 Wenchuan earthquake in China, as well as the experimental phenomenon from the model test. The results demonstrate that the proposed coupling model effectively reproduces the tunnel failure modes caused by reverse faulting. In addition, the high consistency between the simulation results and experimental data further confirms computational accuracy and reliability of the coupling model. A parametric analysis based on the Xianglushan tunnel in China is carried out to investigate the effects of fault displacements, fault widths, dip angles and fault zone rock mass qualities on damage patterns of crossing-fault tunnels. This study provides a valuable reference for seismic fortification of the tunnel crossing reverse faults.
{"title":"Continuum-discrete coupling model for mechanical response analysis of tunnels subjected to non-uniform reverse faulting","authors":"Zhenning Ba , Yao Wang , Zhiwei Fang , Dongqiao Li","doi":"10.1016/j.undsp.2025.03.005","DOIUrl":"10.1016/j.undsp.2025.03.005","url":null,"abstract":"<div><div>In recent decades, there have been numerous reports of damage cases involving tunnels crossing active faults. The mechanical response and failure mechanisms of cross-fault tunnels have become a key issue in the field of tunnel engineering. This study established a continuum-discrete coupling model comprising intact rock mass, fault zones, and tunnel. In this model, the tunnel and intact rock are modeled as continuous media, while the fault zone is modeled as a discrete medium. The non-uniform fault displacement is adopted to simulate the mechanical response and damage patterns of tunnels crossing active faults under reverse faulting. The simulation results are validated by comparison with the damage of Longchi tunnel observed from 2008 Wenchuan earthquake in China, as well as the experimental phenomenon from the model test. The results demonstrate that the proposed coupling model effectively reproduces the tunnel failure modes caused by reverse faulting. In addition, the high consistency between the simulation results and experimental data further confirms computational accuracy and reliability of the coupling model. A parametric analysis based on the Xianglushan tunnel in China is carried out to investigate the effects of fault displacements, fault widths, dip angles and fault zone rock mass qualities on damage patterns of crossing-fault tunnels. This study provides a valuable reference for seismic fortification of the tunnel crossing reverse faults.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 44-59"},"PeriodicalIF":8.2,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696420","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 : 2025-07-03DOI: 10.1016/j.undsp.2025.03.004
Fengqiang Gong , Lei Xu , Shuren Wang , Qinghe Zhang , Yong Huang
Rockburst is an engineering phenomenon characterized by the release of elastic strain energy due to the dynamic failure of deep surrounding rock. The existing rockburst proneness indexes primarily focus on rock materials, failing to encompass rock mass quality and engineering excavation disturbance. On the basis of the potential elastic strain energy released by rock failure, five kinds of rockburst proneness indexes of surrounding rock are established considering the rock mass quality and excavation disturbance factor. Firstly, the linear relationship between elastic modulus and residual elastic energy of rock materials (AEF), the relationships between elastic and deformation moduli, as well as the link with rock mass quality evaluation indexes (i.e., rock mass rating (RMR), basic quality index of rock mass (BQ), and geological strength index (GSI)) and deformation modulus, were used to derive five assessment model of rockburst proneness for surrounding rock. Secondly, the rockburst proneness degree for three grades of surrounding rock (I: excellent rock, II: good rock, and III: fair rock) was assessed utilizing the RMR89, BQ, and GSI indices, and the influence of excavation disturbances on the residual elastic energy of surrounding rock () was analysed. In general, the higher the quality of rock mass and the lesser the disturbance factor, the greater the rockburst proneness degree of surrounding rock. The accuracy of proposed rockburst proneness indexes was validated by using the field data from 27 rockburst cases. The results demonstrate that the discriminant grade of rockburst index based on GSI is basically consistent with the actual occurrence grade of rockburst cases, with an accuracy of 93%, which can be used as a recommended method for evaluating the rockburst proneness degree of surrounding rock. Finally, the shortcomings of rockburst proneness assessment model are discussed, and the improvement direction is elucidated.
{"title":"Rockburst proneness index of surrounding rock considering rock mass quality and excavation disturbance factor","authors":"Fengqiang Gong , Lei Xu , Shuren Wang , Qinghe Zhang , Yong Huang","doi":"10.1016/j.undsp.2025.03.004","DOIUrl":"10.1016/j.undsp.2025.03.004","url":null,"abstract":"<div><div>Rockburst is an engineering phenomenon characterized by the release of elastic strain energy due to the dynamic failure of deep surrounding rock. The existing rockburst proneness indexes primarily focus on rock materials, failing to encompass rock mass quality and engineering excavation disturbance. On the basis of the potential elastic strain energy released by rock failure, five kinds of rockburst proneness indexes of surrounding rock are established considering the rock mass quality and excavation disturbance factor. Firstly, the linear relationship between elastic modulus and residual elastic energy of rock materials (<em>A</em><sub>EF)</sub>, the relationships between elastic and deformation moduli, as well as the link with rock mass quality evaluation indexes (i.e., rock mass rating (RMR), basic quality index of rock mass (BQ), and geological strength index (GSI)) and deformation modulus, were used to derive five assessment model of rockburst proneness for surrounding rock. Secondly, the rockburst proneness degree for three grades of surrounding rock (I: excellent rock, II: good rock, and III: fair rock) was assessed utilizing the RMR<sub>89</sub>, BQ, and GSI indices, and the influence of excavation disturbances on the residual elastic energy of surrounding rock (<span><math><mrow><msubsup><mi>A</mi><mrow><mi>EF</mi></mrow><mi>SR</mi></msubsup></mrow></math></span>) was analysed. In general, the higher the quality of rock mass and the lesser the disturbance factor, the greater the rockburst proneness degree of surrounding rock. The accuracy of proposed rockburst proneness indexes was validated by using the field data from 27 rockburst cases. The results demonstrate that the discriminant grade of rockburst index based on GSI is basically consistent with the actual occurrence grade of rockburst cases, with an accuracy of 93%, which can be used as a recommended method for evaluating the rockburst proneness degree of surrounding rock. Finally, the shortcomings of rockburst proneness assessment model are discussed, and the improvement direction is elucidated.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 1-21"},"PeriodicalIF":8.2,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144653197","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 : 2025-07-03DOI: 10.1016/j.undsp.2025.03.003
Minze Xu , Chunyi Cui , Hailong Liu , Jingbo Li , Jingtong Zhao , Chengshun Xu
A reasonable seismic capacity model is crucial for establishing the seismic performance level system and evaluating the seismic reliability of subway station structures. However, the deterministic structural and geotechnical mechanical parameters are usually applied to calibrate the seismic performance levels of subway station structures in the traditional seismic capacity analysis, which ignores the stochasticity of the soil-subway station interaction system. To overcome the challenge caused by the stochastic interaction system, the probability space partition method and stochastic pushover analysis method are combined to develop a calibration strategy of seismic performance levels considering the complete probabilistic information of the stochastic interaction system, and the non-parametric probabilistic seismic capacity models of the subway station structure are further established based on the principle of probability conservation in this paper. A subway station is also taken as the prototype to investigate the applicability of the proposed strategy and the influence of system randomness on the seismic capacity of the subway station structure. The results demonstrate that the seismic performance levels calibrated according to the proposed strategy can effectively consider the complete probabilistic information of the interaction system, which are more rigorous than the existing performance levels. Meanwhile, the probability density evolution of the bearing capacity of the subway station structure is essentially a non-stationary stochastic process, and the non-parametric probability density curves of seismic capacity display noticeable multi-peak characteristic. Moreover, the seismic capacity for LP1 and LP2 levels is more sensitive to the variability of geotechnical parameters above and below the structure, while the former for LP3 and LP4 levels is more sensitive to that on both sides of the structure. The relevant conclusions can provide some guidance for seismic design and improvement of the performance limits of underground structures in the related codes.
{"title":"Non-parametric probabilistic seismic capacity model for the stochastic interaction system of soil-subway station structures","authors":"Minze Xu , Chunyi Cui , Hailong Liu , Jingbo Li , Jingtong Zhao , Chengshun Xu","doi":"10.1016/j.undsp.2025.03.003","DOIUrl":"10.1016/j.undsp.2025.03.003","url":null,"abstract":"<div><div>A reasonable seismic capacity model is crucial for establishing the seismic performance level system and evaluating the seismic reliability of subway station structures. However, the deterministic structural and geotechnical mechanical parameters are usually applied to calibrate the seismic performance levels of subway station structures in the traditional seismic capacity analysis, which ignores the stochasticity of the soil-subway station interaction system. To overcome the challenge caused by the stochastic interaction system, the probability space partition method and stochastic pushover analysis method are combined to develop a calibration strategy of seismic performance levels considering the complete probabilistic information of the stochastic interaction system, and the non-parametric probabilistic seismic capacity models of the subway station structure are further established based on the principle of probability conservation in this paper. A subway station is also taken as the prototype to investigate the applicability of the proposed strategy and the influence of system randomness on the seismic capacity of the subway station structure. The results demonstrate that the seismic performance levels calibrated according to the proposed strategy can effectively consider the complete probabilistic information of the interaction system, which are more rigorous than the existing performance levels. Meanwhile, the probability density evolution of the bearing capacity of the subway station structure is essentially a non-stationary stochastic process, and the non-parametric probability density curves of seismic capacity display noticeable multi-peak characteristic. Moreover, the seismic capacity for <em>L</em><sub>P1</sub> and <em>L</em><sub>P2</sub> levels is more sensitive to the variability of geotechnical parameters above and below the structure, while the former for <em>L</em><sub>P3</sub> and <em>L</em><sub>P4</sub> levels is more sensitive to that on both sides of the structure. The relevant conclusions can provide some guidance for seismic design and improvement of the performance limits of underground structures in the related codes.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 79-103"},"PeriodicalIF":8.2,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704191","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 : 2025-07-01DOI: 10.1016/j.undsp.2025.03.002
Zhiguo Zhang , Jian Wei , Junjie Li , Linlong Mu , Wei Wo , Yin Ni
Pit excavation work often occurs directly above metro tunnels, causing adverse effects on the underlying existing operational shield tunnel. Current simplified solutions mainly adopt stress release method to reflect excavation of foundation pit, which is inappropriate for large soil uplift. A two-stage analysis based on modified Sagaseta solution with displacement-controlled boundary condition and tunnel-soil coordinated constrain is promoted for estimating the mechanical behavior of tunnel with joints. Specifically, the modified Sagaseta solution including gravity effects is firstly used to obtain the soil greenfield displacement caused by foundation pit excavation. Secondly, the Pasternak foundation model, incorporating tunnel-soil ellipse-shaped deformation, combines a variable stiffness Timoshenko beam at tunnel joints and ultimately obtains the tunnel displacement curve. Furthermore, a three-dimensional numerical simulation is also conducted for Jinqiao metro superstructure excavation project that involves a foundation pit situated directly above an existing metro tunnel. The feasibility of simplified solutions is verified with numerical simulation solutions and an engineering case. For investigating the key parameters, the parametric analyses are conducted, indicating that the greenfield displacement is highly related to modified uneven convergence Sagaseta solution. The ignoration of excavation width will overestimate the tunnel displacement as plane strain condition. Both equivalent bending and shear stiffness can only influence corresponding bending and shear tunnel deformation.
{"title":"Investigation on foundation pit uplift mechanism and tunnel response induced by deep excavation under complex support system: A case study","authors":"Zhiguo Zhang , Jian Wei , Junjie Li , Linlong Mu , Wei Wo , Yin Ni","doi":"10.1016/j.undsp.2025.03.002","DOIUrl":"10.1016/j.undsp.2025.03.002","url":null,"abstract":"<div><div>Pit excavation work often occurs directly above metro tunnels, causing adverse effects on the underlying existing operational shield tunnel. Current simplified solutions mainly adopt stress release method to reflect excavation of foundation pit, which is inappropriate for large soil uplift. A two-stage analysis based on modified Sagaseta solution with displacement-controlled boundary condition and tunnel-soil coordinated constrain is promoted for estimating the mechanical behavior of tunnel with joints. Specifically, the modified Sagaseta solution including gravity effects is firstly used to obtain the soil greenfield displacement caused by foundation pit excavation. Secondly, the Pasternak foundation model, incorporating tunnel-soil ellipse-shaped deformation, combines a variable stiffness Timoshenko beam at tunnel joints and ultimately obtains the tunnel displacement curve. Furthermore, a three-dimensional numerical simulation is also conducted for Jinqiao metro superstructure excavation project that involves a foundation pit situated directly above an existing metro tunnel. The feasibility of simplified solutions is verified with numerical simulation solutions and an engineering case. For investigating the key parameters, the parametric analyses are conducted, indicating that the greenfield displacement is highly related to modified uneven convergence Sagaseta solution. The ignoration of excavation width will overestimate the tunnel displacement as plane strain condition. Both equivalent bending and shear stiffness can only influence corresponding bending and shear tunnel deformation.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 104-128"},"PeriodicalIF":8.2,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144713824","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 : 2025-07-01DOI: 10.1016/j.undsp.2025.02.011
Youlin Qin , Li Yu , Mingnian Wang , Zhaohui Chen , Hong Jin , Mingyang Yu , Songshen Wang
Cutter spacing is a key factor influencing the efficiency of TBM operations. Meanwhile, rock brittleness, as a critical indicator of rock fracture, significantly influences fragmentation behavior and rock-breaking efficiency. This study investigates the influence of rock brittleness on rock-breaking through numerical penetration experiments based on the hybrid finite-discrete element method (FDEM) and proposes four intelligent hybrid models to optimize cutter spacing. The results show that as the rock brittleness index (BI) increases from 4.731 to 32.588, the count, depth, width, and proportion of tensile cracks increase, and crack propagation shifts from horizontal to oblique orientations. Moderate cutter spacing (90–110 mm) is optimal for generating tensile cracks. The rock-breaking force increases significantly with higher BI; for instance, at 80 mm spacing, the maximum force for rock with a BI of 13.134 is 5.51 times that for rock with a BI of 4.731. The influence of BI on cutter work and specific energy (SE) is more substantial than the effect of cutter spacing. As BI increases, both cutter work and SE rise considerably. Among the proposed models, the particle swarm optimization and extreme gradient boosting (PSO-XGBoost) model demonstrates the highest performance, achieving an R2 of 0.994, VAF of 99.418%, RMSE of 0.987, and MAPE of 5.217% on the test datasets. An optimization method for cutter spacing is proposed based on this model.
{"title":"Intelligent optimization of TBM cutter spacing and FDEM-based investigation of rock breakage considering brittleness","authors":"Youlin Qin , Li Yu , Mingnian Wang , Zhaohui Chen , Hong Jin , Mingyang Yu , Songshen Wang","doi":"10.1016/j.undsp.2025.02.011","DOIUrl":"10.1016/j.undsp.2025.02.011","url":null,"abstract":"<div><div>Cutter spacing is a key factor influencing the efficiency of TBM operations. Meanwhile, rock brittleness, as a critical indicator of rock fracture, significantly influences fragmentation behavior and rock-breaking efficiency. This study investigates the influence of rock brittleness on rock-breaking through numerical penetration experiments based on the hybrid finite-discrete element method (FDEM) and proposes four intelligent hybrid models to optimize cutter spacing. The results show that as the rock brittleness index (BI) increases from 4.731 to 32.588, the count, depth, width, and proportion of tensile cracks increase, and crack propagation shifts from horizontal to oblique orientations. Moderate cutter spacing (90–110 mm) is optimal for generating tensile cracks. The rock-breaking force increases significantly with higher BI; for instance, at 80 mm spacing, the maximum force for rock with a BI of 13.134 is 5.51 times that for rock with a BI of 4.731. The influence of BI on cutter work and specific energy (SE) is more substantial than the effect of cutter spacing. As BI increases, both cutter work and SE rise considerably. Among the proposed models, the particle swarm optimization and extreme gradient boosting (PSO-XGBoost) model demonstrates the highest performance, achieving an <em>R</em><sup>2</sup> of 0.994, VAF of 99.418%, RMSE of 0.987, and MAPE of 5.217% on the test datasets. An optimization method for cutter spacing is proposed based on this model.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 379-402"},"PeriodicalIF":8.2,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604426","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 : 2025-06-27DOI: 10.1016/j.undsp.2024.09.007
Hongwei Huang , Tongjun Yang , Jiayao Chen , Zhongkai Huang , Chen Wu , Jianhong Man
This study employs computer vision and deep learning techniques to execute the refined extraction and quantification of rock mass information in tunnel faces. The integration of contact measurement data and surrounding environmental parameters leads to a proposal for rock mass quality prediction, utilizing integrated machine learning techniques. Subsequently, a 3D model is established by incorporating tunnel face features and environmental data. The safety factor of rock mass excavation is calculated through the utilization of the strength reduction method, and the analysis of rock mass stability on the continuous tunnel face is performed, considering factors such as rock stress and joint sliding. The investigation of variation patterns of excavation safety factors, influenced by multiple modelling factors, is conducted through the utilization of a response surface design method in 46 experimental studies. The research reveals the accurate characterization of complex fissure occurrence obtained in the field through a discrete fracture network. Furthermore, a negative correlation between the safety factor of tunnel excavation and the grade of surrounding rock is observed, with an increase in grade resulting in a decrease in the safety factor. The response surface method effectively discloses polynomial correlations between various parameters such as inclination angle, dip direction, spacing, density, number of groups, and the safety factor. This elucidates the impact patterns of these parameters and their coupling states on the safety factor. The study provides significant insights into the intelligent evaluation of safety for continuous tunnel excavation.
{"title":"Enhanced safety assessment on tunnel excavation via refined rock mass parameter identification","authors":"Hongwei Huang , Tongjun Yang , Jiayao Chen , Zhongkai Huang , Chen Wu , Jianhong Man","doi":"10.1016/j.undsp.2024.09.007","DOIUrl":"10.1016/j.undsp.2024.09.007","url":null,"abstract":"<div><div>This study employs computer vision and deep learning techniques to execute the refined extraction and quantification of rock mass information in tunnel faces. The integration of contact measurement data and surrounding environmental parameters leads to a proposal for rock mass quality prediction, utilizing integrated machine learning techniques. Subsequently, a 3D model is established by incorporating tunnel face features and environmental data. The safety factor of rock mass excavation is calculated through the utilization of the strength reduction method, and the analysis of rock mass stability on the continuous tunnel face is performed, considering factors such as rock stress and joint sliding. The investigation of variation patterns of excavation safety factors, influenced by multiple modelling factors, is conducted through the utilization of a response surface design method in 46 experimental studies. The research reveals the accurate characterization of complex fissure occurrence obtained in the field through a discrete fracture network. Furthermore, a negative correlation between the safety factor of tunnel excavation and the grade of surrounding rock is observed, with an increase in grade resulting in a decrease in the safety factor. The response surface method effectively discloses polynomial correlations between various parameters such as inclination angle, dip direction, spacing, density, number of groups, and the safety factor. This elucidates the impact patterns of these parameters and their coupling states on the safety factor. The study provides significant insights into the intelligent evaluation of safety for continuous tunnel excavation.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 142-161"},"PeriodicalIF":8.3,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144725017","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 : 2025-06-20DOI: 10.1016/j.undsp.2025.03.001
Hui Li , Weizhong Chen , Xiaoyun Shu , Xianjun Tan , Qun Sui
The layout of underground engineering objects significantly influences the stability of the surrounding rock mass and construction safety. Despite advancements toward intellectualization and informatization in design optimization and safety assessments, mechanical analysis-based engineering computations still face certain impediments. Consequently, this paper proposes a comprehensive framework integrating tunnel information modelling (TIM), finite element method (FEM) and machine learning (ML) technology to optimize the tunnel longitudinal orientation. It also delves into the specifics of addressing the challenges associated with each technology. The framework encompasses three phases: parametric modelling based on TIM, automatic numerical simulation based on FEM, and intelligent optimization leveraging ML. Initially, geometric models of the geological formations and engineering structures are constructed on the TIM platform. Subsequently, data conversion is facilitated through the proposed transformation interface. Python codes are programmed to realize automatic processing of numerical simulation and results are extracted to the ML algorithm for the prediction model. An optimization algorithm is implanted in the numerical stream file to retrieve the optimal relative intersection angle between the tunnel axis and the trend of rocks. A case study is conducted to evaluate the feasibility of the proposed framework. Results demonstrate a substantial improvement in design and optimization accuracy and efficiency. This framework holds immense potential to propel the intellectualization and informatization of underground engineering.
{"title":"TIM-FEM-ML synthetic technology for longitudinal optimization of tunnel excavated in the interlayered rock mass","authors":"Hui Li , Weizhong Chen , Xiaoyun Shu , Xianjun Tan , Qun Sui","doi":"10.1016/j.undsp.2025.03.001","DOIUrl":"10.1016/j.undsp.2025.03.001","url":null,"abstract":"<div><div>The layout of underground engineering objects significantly<!--> <!-->influences the stability of the surrounding rock mass and construction safety. Despite advancements toward intellectualization and informatization in design optimization and safety assessments, mechanical analysis-based engineering computations still face certain impediments. Consequently, this paper proposes a comprehensive framework integrating tunnel information modelling (TIM), finite element method (FEM) and machine learning (ML) technology to optimize the tunnel longitudinal orientation. It also delves into the specifics of addressing the challenges associated with each technology. The framework encompasses three phases: parametric modelling based on TIM, automatic numerical simulation based on FEM, and intelligent optimization leveraging ML. Initially, geometric models of the geological formations and engineering structures are constructed on the TIM platform. Subsequently, data conversion is facilitated through the proposed transformation interface. Python codes are programmed to realize automatic processing of numerical simulation and results are extracted to the ML algorithm for the prediction model. An optimization algorithm is implanted in the numerical stream file to retrieve the optimal relative intersection angle between the tunnel axis and the trend of rocks. A case study is conducted to evaluate the feasibility of the proposed framework. Results demonstrate a substantial improvement in design and optimization accuracy and efficiency. This framework holds<!--> <!-->immense<!--> <!-->potential to propel the intellectualization and informatization of underground engineering.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 327-342"},"PeriodicalIF":8.2,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518286","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 : 2025-06-20DOI: 10.1016/j.undsp.2024.09.006
Qihao Sun , Xian Liu , Yihai Bao , Wouter De Corte , Luc Taerwe
During the construction of segmental tunnels, unexpected leakage poses a significant safety hazard to the tunnel structures, potentially leading to collapse. Worldwide, accidents caused by leakage during the construction of shield tunnels have resulted in substantial losses. However, existing studies have not clearly elucidated the mechanism behind tunnel collapse induced by leakage, making it challenging to propose effective prevention or control measures. To address this issue, a series of model tests on tunnel collapse induced by leakage were designed and conducted. These tests replicated the tunnel collapse process and revealed three stages: seepage erosion, soil cave formation and destabilization, and soil impact. The soil caves develop upward, leading to a redistribution of external pressure on the tunnels. Ultimately, the structural collapse of the tunnel occurs due to soil impact from the unstable soil cave. Comparing tunnel entrance/exit accidents with connecting passage accidents highlights that both accident types share the same underlying mechanism but differ in boundary conditions.
{"title":"Experimental study on the leakage-induced structural collapse of segmental tunnels","authors":"Qihao Sun , Xian Liu , Yihai Bao , Wouter De Corte , Luc Taerwe","doi":"10.1016/j.undsp.2024.09.006","DOIUrl":"10.1016/j.undsp.2024.09.006","url":null,"abstract":"<div><div>During the construction of segmental tunnels, unexpected leakage poses a significant safety hazard to the tunnel structures, potentially leading to collapse. Worldwide, accidents caused by leakage during the construction of shield tunnels have resulted in substantial losses. However, existing studies have not clearly elucidated the mechanism behind tunnel collapse induced by leakage, making it challenging to propose effective prevention or control measures. To address this issue, a series of model tests on tunnel collapse induced by leakage were designed and conducted. These tests replicated the tunnel collapse process and revealed three stages: seepage erosion, soil cave formation and destabilization, and soil impact. The soil caves develop upward, leading to a redistribution of external pressure on the tunnels. Ultimately, the structural collapse of the tunnel occurs due to soil impact from the unstable soil cave. Comparing tunnel entrance/exit accidents with connecting passage accidents highlights that both accident types share the same underlying mechanism but differ in boundary conditions.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"24 ","pages":"Pages 22-43"},"PeriodicalIF":8.2,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696419","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 : 2025-06-11DOI: 10.1016/j.undsp.2025.02.010
Qing Xu , Pengfei Li , Chongbang Xu , Siqing Wang , Sulei Zhang
Effective control of the tunnel seepage field is crucial in water-abundant regions to ensure the safety and stability of underground structures. Therefore, it is imperative to investigate the effects of the geological factors and tunnel permeability parameters on the drainage capacities of such structures. The Tongzi Tunnel was subjected to model tests using a self-developed testing apparatus to investigate the spatial distribution of tunnel seepage under varying conditions of sand permeability, number of primary support layers, and number of primary support openings. Subsequently, numerical models were developed to validate the observed tunnel seepage field based on experimental conditions. On this basis, an effective water pressure ratio is proposed to evaluate the hydraulic safety of the tunnel spatial distribution. The results indicated a positive correlation between the tunnel water discharge and sand permeability, primary support layers, and primary support openings. Among these factors, the primary support openings exhibited the highest sensitivity to tunnel water discharge, whereas the impact of the primary support layers was relatively low. Additionally, the external water pressure in the tunnel exhibited a negative correlation with sand permeability, primary support layers, and primary support openings. The sensitivity ranking of the structural water pressure fluctuations to the parameters is as follows: primary support openings > sand permeability > primary support layers. Furthermore, the longitudinal water pressure values in the tunnel gradually increase from Section A (circular drainage section) to Section B (middle circular drainage section). Model tests and numerical simulations were performed to demonstrate the data reliability. Finally, with the increase of sand permeability and the number of primary support openings, the effective drainage area (η < 0.6) around the tunnel spatial gradually expands. Besides, the tunnel longitudinal effective drainage interval progressively degrades from the vault (A1 area) to the tunnel bottom (A7 area), and even the tunnel bottom areas are not effectively drained (η > 0.6).
{"title":"Investigation of the spatial distribution of tunnel seepage under varying drainage capacities in water-abundant regions","authors":"Qing Xu , Pengfei Li , Chongbang Xu , Siqing Wang , Sulei Zhang","doi":"10.1016/j.undsp.2025.02.010","DOIUrl":"10.1016/j.undsp.2025.02.010","url":null,"abstract":"<div><div>Effective control of the tunnel seepage field is crucial in water-abundant regions to ensure the safety and stability of underground structures. Therefore, it is imperative to investigate the effects of the geological factors and tunnel permeability parameters on the drainage capacities of such structures. The Tongzi Tunnel was subjected to model tests using a self-developed testing apparatus to investigate the spatial distribution of tunnel seepage under varying conditions of sand permeability, number of primary support layers, and number of primary support openings. Subsequently, numerical models were developed to validate the observed tunnel seepage field based on experimental conditions. On this basis, an effective water pressure ratio <span><math><mrow><mi>η</mi></mrow></math></span> is proposed to evaluate the hydraulic safety of the tunnel spatial distribution. The results indicated a positive correlation between the tunnel water discharge and sand permeability, primary support layers, and primary support openings. Among these factors, the primary support openings exhibited the highest sensitivity to tunnel water discharge, whereas the impact of the primary support layers was relatively low. Additionally, the external water pressure in the tunnel exhibited a negative correlation with sand permeability, primary support layers, and primary support openings. The sensitivity ranking of the structural water pressure fluctuations to the parameters is as follows: primary support openings > sand permeability > primary support layers. Furthermore, the longitudinal water pressure values in the tunnel gradually increase from Section A (circular drainage section) to Section B (middle circular drainage section). Model tests and numerical simulations were performed to demonstrate the data reliability. Finally, with the increase of sand permeability and the number of primary support openings, the effective drainage area (<em>η</em> < 0.6) around the tunnel spatial gradually expands. Besides, the tunnel longitudinal effective drainage interval progressively degrades from the vault (A1 area) to the tunnel bottom (A7 area), and even the tunnel bottom areas are not effectively drained (<em>η</em> > 0.6).</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 343-361"},"PeriodicalIF":8.2,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523193","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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