Pub Date : 2025-01-20DOI: 10.1016/j.tust.2025.106366
Jian He , Huailiang Li , Binhong Li , Nuwen Xu , Junnan Wen , Yuedong Li
Accurate and rapid microseismic source location is the foundation for tunnel rockburst warning. Here, we present a novel location strategy that employs an improved mayfly algorithm (IMA) to enhance the convergence speed and accuracy of the virtual field optimization method (VFOM) for tunnel microseismic events. By optimizing the initial position of the mayfly population and the moving velocity of mayfly personals, we develop an IMA with superior convergence speed in searching for source locations. The proposed method utilizes paired microseismic receivers in the tunnel monitoring array to create hyperbolic surfaces. Then, the IMA is employed to rapidly and accurately determine the intersection point of all hyperbolic surfaces, defining it as the microseismic source location. We compare the IMA-VFOM with different error levels in seismic wave velocity or arrival time against other traditional location approaches based on travel time differences. The results confirm that the IMA-VFOM’s convergence speed is, on average, more than 4 times that of the MA-VFOM algorithm. Compared to conventional methods, the IMA-VFOM method demonstrates higher location accuracy and stability. The average location error of the proposed method is when applied to real rockburst microseismic events in tunnels.
{"title":"Enhancing convergence speed and accuracy of virtual field optimization method for microseismic source location in tunnels","authors":"Jian He , Huailiang Li , Binhong Li , Nuwen Xu , Junnan Wen , Yuedong Li","doi":"10.1016/j.tust.2025.106366","DOIUrl":"10.1016/j.tust.2025.106366","url":null,"abstract":"<div><div>Accurate and rapid microseismic source location is the foundation for tunnel rockburst warning. Here, we present a novel location strategy that employs an improved mayfly algorithm (IMA) to enhance the convergence speed and accuracy of the virtual field optimization method (VFOM) for tunnel microseismic events. By optimizing the initial position of the mayfly population and the moving velocity of mayfly personals, we develop an IMA with superior convergence speed in searching for source locations. The proposed method utilizes paired microseismic receivers in the tunnel monitoring array to create hyperbolic surfaces. Then, the IMA is employed to rapidly and accurately determine the intersection point of all hyperbolic surfaces, defining it as the microseismic source location. We compare the IMA-VFOM with different error levels in seismic wave velocity or arrival time against other traditional location approaches based on travel time differences. The results confirm that the IMA-VFOM’s convergence speed is, on average, more than 4 times that of the MA-VFOM algorithm. Compared to conventional methods, the IMA-VFOM method demonstrates higher location accuracy and stability. The average location error of the proposed method is <span><math><mrow><mn>4</mn><mo>.</mo><mn>0043</mn><mspace></mspace><mi>m</mi></mrow></math></span> when applied to real rockburst microseismic events in tunnels.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106366"},"PeriodicalIF":6.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027278","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 : 2025-01-20DOI: 10.1016/j.tust.2025.106394
Andreas Michael
Deformation modeling of underground tunnel intersections attempts to provide answers on the occurrence of localized structural instabilities under different, and possibly dynamically-changing, in-situ conditions. Design decisions hinge on these findings; since much of the stresses underground are compressive, shear-failure predictions provide outlines for maintaining structural stability on the intersections of underground tunnel excavations in anisotropic rock masses, such as those made using tunnel-boring machines (TBMs).
Three-dimensional (3D) deformations around the circumference of the orthogonal intersection plane of two tunnels are modeled using a pseudo-3D approximation approach established in petroleum engineering, which adjusts for stress interferences coming from each tunnel. The rationale for such approach is that the normal stresses on the circumference of the primary “Tunnel A” are used as inputs to evaluate the stresses on the base of a smaller, secondary “Tunnel B” which approximates the two tunnels’ intersection plane.
The resultant closed-form expressions are used as a boundary condition in a Mohr-Coulomb-type model for shear failures, in a cylindrical coordinate system. Dimensionless plots (“allowable stress diagrams”) provide the means to visually recognize whether the induced stresses on the tunnel intersection can trigger shear failure, or not. The dynamic impact of sediment settling is quantitatively assessed and non-orthogonal tunnel intersections are discussed.
{"title":"Tunnel intersection mechanics: Closed-form pseudo-3D approximations for deformation modeling and shear-failure prediction","authors":"Andreas Michael","doi":"10.1016/j.tust.2025.106394","DOIUrl":"10.1016/j.tust.2025.106394","url":null,"abstract":"<div><div>Deformation modeling of underground tunnel intersections attempts to provide answers on the occurrence of localized structural instabilities under different, and possibly dynamically-changing, <em>in-situ</em> conditions. Design decisions hinge on these findings; since much of the stresses underground are compressive, shear-failure predictions provide outlines for maintaining structural stability on the intersections of underground tunnel excavations in anisotropic rock masses, such as those made using tunnel-boring machines (TBMs).</div><div>Three-dimensional (3D) deformations around the circumference of the orthogonal intersection plane of two tunnels are modeled using a pseudo-3D approximation approach established in petroleum engineering, which adjusts for stress interferences coming from each tunnel. The rationale for such approach is that the normal stresses on the circumference of the primary “Tunnel A” are used as inputs to evaluate the stresses on the base of a smaller, secondary “Tunnel B” which approximates the two tunnels’ intersection plane.</div><div>The resultant closed-form expressions are used as a boundary condition in a Mohr-Coulomb-type model for shear failures, in a cylindrical coordinate system. Dimensionless plots (“allowable stress diagrams”) provide the means to visually recognize whether the induced stresses on the tunnel intersection can trigger shear failure, or not. The dynamic impact of sediment settling is quantitatively assessed and non-orthogonal tunnel intersections are discussed.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106394"},"PeriodicalIF":6.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027413","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 : 2025-01-20DOI: 10.1016/j.tust.2025.106407
Wanzhi Zhang , Jie Mei , Keguo Sun , Bangshu Xu
Drilling and blasting excavation methods along with primary arch-cover primary supports are frequently employed in the construction of urban subway stations. However, traditional blasting methods fail to control tunnel face flatness, overbreak, and underbreak in soft–hard mixed-medium rock mass owing to symmetric and invariable blasting parameters. The Shishan Road Station of Qingdao Metro Line 6 is located in a soft–hard mixed-medium rock mass. Traditional blasting excavation methods result in considerable over-excavation of the soft rock on the one side, forming a concave inside, and minor over- and under-excavation of the hard rock on the opposite side, forming a convex outside. Herein, numerical models were developed to analyze the rock damage caused by contour blasting in soft–hard mixed-medium rock mass. Different perimeter hole spacings, burden thicknesses, and charge weights were investigated to identify the optimal parameters. Based on these models, this study proposes an asymmetric blasthole pattern and charge parameters, such as a smaller spacing and charge weight on the soft rock side and deeper hole lengths on the hard rock side. In addition, higher delay times were suggested to control the blasting vibration. Field tests showed that the optimized blasting scheme effectively controlled the flatness, overbreak, and underbreak. The utilization rate of blast holes increased by 5%, the average overbreak area decreased by 57.3%, and underbreak did not occur. The blasting energy of a single initiation and the proportion of low-frequency energy decreased significantly, resulting in better control of rock damage caused by blasting vibrations.
{"title":"Fine controlled blasting of subsurface excavation for subway stations in soft–hard mixed-medium rock mass","authors":"Wanzhi Zhang , Jie Mei , Keguo Sun , Bangshu Xu","doi":"10.1016/j.tust.2025.106407","DOIUrl":"10.1016/j.tust.2025.106407","url":null,"abstract":"<div><div>Drilling and blasting excavation methods along with primary arch-cover primary supports are frequently employed in the construction of urban subway stations. However, traditional blasting methods fail to control tunnel face flatness, overbreak, and underbreak in soft–hard mixed-medium rock mass owing to symmetric and invariable blasting parameters. The Shishan Road Station of Qingdao Metro Line 6 is located in a soft–hard mixed-medium rock mass. Traditional blasting excavation methods result in considerable over-excavation of the soft rock on the one side, forming a concave inside, and minor over- and under-excavation of the hard rock on the opposite side, forming a convex outside. Herein, numerical models were developed to analyze the rock damage caused by contour blasting in soft–hard mixed-medium rock mass. Different perimeter hole spacings, burden thicknesses, and charge weights were investigated to identify the optimal parameters. Based on these models, this study proposes an asymmetric blasthole pattern and charge parameters, such as a smaller spacing and charge weight on the soft rock side and deeper hole lengths on the hard rock side. In addition, higher delay times were suggested to control the blasting vibration. Field tests showed that the optimized blasting scheme effectively controlled the flatness, overbreak, and underbreak. The utilization rate of blast holes increased by 5%, the average overbreak area decreased by 57.3%, and underbreak did not occur. The blasting energy of a single initiation and the proportion of low-frequency energy decreased significantly, resulting in better control of rock damage caused by blasting vibrations.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106407"},"PeriodicalIF":6.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027412","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 : 2025-01-20DOI: 10.1016/j.tust.2025.106376
Zilan Zhong, Jiaxi Guo, Bu Zhang, Xiuli Du
Subway station structures near coast are at risk of corrosion caused by chloride, resulting in material and structural component deterioration over time and impacting overall performance during earthquakes. This study proposes a numerical framework for the time-dependent seismic fragility analysis of subway station structures, considering chloride-induced corrosion, based on the IDA method. This study utilizes finite element simulations of typical subway station structures in Qingdao, Shandong, China, focusing on nonlinear dynamic interactions between soil and structure, as well as the impact of chloride-induced corrosion on aging effects. The time-dependent damage states within subway station structures are determined through a nonlinear static pushover analysis. Subsequently, the IDA method is employed to generate time-dependent seismic fragility curves and surfaces specific to subway station structures. The numerical results indicate that the impact of chloride-induced corrosion on the subway station structure cannot be ignored. In the corrosion environment, the seismic performance assessment of subway station structures must take into account time-dependent damage states resulting from the degradation of material properties and the reduction in seismic capacity. The probability of a subway station structure exceeding various damage states monotonically increases during its service life. The subway station structure primarily suffers minor to moderate damage under the ground motion with a return period of 2450 or 10000 years, as it reaches its design service life.
{"title":"Time-dependent seismic fragility analysis of subway station structure subjected to chloride-induced corrosion","authors":"Zilan Zhong, Jiaxi Guo, Bu Zhang, Xiuli Du","doi":"10.1016/j.tust.2025.106376","DOIUrl":"10.1016/j.tust.2025.106376","url":null,"abstract":"<div><div>Subway station structures near coast are at risk of corrosion caused by chloride, resulting in material and structural component deterioration over time and impacting overall performance during earthquakes. This study proposes a numerical framework for the time-dependent seismic fragility analysis of subway station structures, considering chloride-induced corrosion, based on the IDA method. This study utilizes finite element simulations of typical subway station structures in Qingdao, Shandong, China, focusing on nonlinear dynamic interactions between soil and structure, as well as the impact of chloride-induced corrosion on aging effects. The time-dependent damage states within subway station structures are determined through a nonlinear static pushover analysis. Subsequently, the IDA method is employed to generate time-dependent seismic fragility curves and surfaces specific to subway station structures. The numerical results indicate that the impact of chloride-induced corrosion on the subway station structure cannot be ignored. In the corrosion environment, the seismic performance assessment of subway station structures must take into account time-dependent damage states resulting from the degradation of material properties and the reduction in seismic capacity. The probability of a subway station structure exceeding various damage states monotonically increases during its service life. The subway station structure primarily suffers minor to moderate damage under the ground motion with a return period of 2450 or 10000 years, as it reaches its design service life.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106376"},"PeriodicalIF":6.7,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027277","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 : 2025-01-18DOI: 10.1016/j.tust.2025.106402
Gaoyu Ma , Chuan He , Zhengshu He , Rongmin Bai , Guowen Xu
Tunnels in heterogeneous strata always encounter spatially varied geological formations, causing asymmetric responses and localized failure in the supporting structure. The homogeneity assumption for surrounding strata, commonly adopted in tunnel design and construction, will neglect the inherent spatial uncertainty of rock mass and lead to the overestimation in tunnel bearing capacity. The conventional stochastic calculations for analyzing tunnel performance in heterogeneous strata also fail to reflect the statistical asymmetry in mechanical behaviors of supporting structure. With the application of mechanized equipment with built-in sensors in drilling and blasting construction, rock parameters at borehole locations can be promptly derived through the drilling data. This systematic on-site monitoring necessitates a rational and stationary extrapolation using rock parameters from the excavation face to the surrounding strata, as the inversion results provide a more precise depiction of the properties of surrounding strata and enable the dynamic design for supporting structure during construction. Therefore, an innovative approach was proposed in this research to conduct probability analysis on the mechanical behaviors of tunnels in heterogeneous strata based on conditional random field models. The statistical characteristics of random variables in these fields were constrained by the derived rock parameters on the excavation face using Hoffman method. The probability distributions of mechanical behaviors were analyzed for tunnels with both symmetric and asymmetric anchor cable systems. In addition, a trained convolutional neural network (CNN) model was implemented to reduce the computational resources required in massive numerical simulations. The tunnel deformation at different circumferential locations can be predicted with an acceptable accuracy and minimal time consumption that significantly facilitated the probabilistic assessments.
{"title":"Probability analysis on tunnels in heterogeneous strata based on borehole data-driven conditional random fields and convolutional neural network","authors":"Gaoyu Ma , Chuan He , Zhengshu He , Rongmin Bai , Guowen Xu","doi":"10.1016/j.tust.2025.106402","DOIUrl":"10.1016/j.tust.2025.106402","url":null,"abstract":"<div><div>Tunnels in heterogeneous strata always encounter spatially varied geological formations, causing asymmetric responses and localized failure in the supporting structure. The homogeneity assumption for surrounding strata, commonly adopted in tunnel design and construction, will neglect the inherent spatial uncertainty of rock mass and lead to the overestimation in tunnel bearing capacity. The conventional stochastic calculations for analyzing tunnel performance in heterogeneous strata also fail to reflect the statistical asymmetry in mechanical behaviors of supporting structure. With the application of mechanized equipment with built-in sensors in drilling and blasting construction, rock parameters at borehole locations can be promptly derived through the drilling data. This systematic on-site monitoring necessitates a rational and stationary extrapolation using rock parameters from the excavation face to the surrounding strata, as the inversion results provide a more precise depiction of the properties of surrounding strata and enable the dynamic design for supporting structure during construction. Therefore, an innovative approach was proposed in this research to conduct probability analysis on the mechanical behaviors of tunnels in heterogeneous strata based on conditional random field models. The statistical characteristics of random variables in these fields were constrained by the derived rock parameters on the excavation face using Hoffman method. The probability distributions of mechanical behaviors were analyzed for tunnels with both symmetric and asymmetric anchor cable systems. In addition, a trained convolutional neural network (CNN) model was implemented to reduce the computational resources required in massive numerical simulations. The tunnel deformation at different circumferential locations can be predicted with an acceptable accuracy and minimal time consumption that significantly facilitated the probabilistic assessments.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106402"},"PeriodicalIF":6.7,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027286","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 : 2025-01-18DOI: 10.1016/j.tust.2025.106395
Hong-Pu Li , Ben-Guo He , Xiang-Rui Meng , Shengcun Yan , Tao Chen
Chain rockbursts have a long duration and significant hazards, severely affecting construction progress, yet their occurrence patterns and formation mechanisms remain unclear. Monitoring was conducted on a deeply buried tunnel in southwest China for axial chain rockbursts (ACRs) occurrences. The recorded ACRs (23 weak, 3 moderate, and 3 intense) were analyzed to reveal their patterns of occurrence, geological characteristics, and mechanisms of formation. ACRs were studied through geological surveys, analysis of on-site failure characteristics, and a series of laboratory tests. The findings indicate that ACRs are most likely to occur near river valleys, faults, and geological contact zones, where the overburden is significant, and the direction of major stress is perpendicular to the tunnel axis. In ACRs-prone regions, the content of brittle minerals in the surrounding rock tends to be relatively high. At the site studied, the proportion of plagioclase in the diorite ranges from 55 % to 65 %. ACRs are likely to be triggered when the dip of structural planes forms a small angle with the principal stress, and when their strike is parallel (or nearly parallel) to the tunnel axis, or when a group of structural planes intersects the tunnel axis at a small angle and is distributed along it. During tunnel excavation in areas prone to ACRs, appropriate measures should be sufficiently robust and ductile, aimed at enhancing the strength and ductility of the surrounding rock, with support structures closely following the excavation face. This investigation contributes to our understanding of ACRs and may help in designing methods for predicting and preventing their occurrence.
{"title":"Axial chain rockbursts in deep tunnels excavated via drilling and blasting","authors":"Hong-Pu Li , Ben-Guo He , Xiang-Rui Meng , Shengcun Yan , Tao Chen","doi":"10.1016/j.tust.2025.106395","DOIUrl":"10.1016/j.tust.2025.106395","url":null,"abstract":"<div><div>Chain rockbursts have a long duration and significant hazards, severely affecting construction progress, yet their occurrence patterns and formation mechanisms remain unclear. Monitoring was conducted on a deeply buried tunnel in southwest China for axial chain rockbursts (ACRs) occurrences. The recorded ACRs (23 weak, 3 moderate, and 3 intense) were analyzed to reveal their patterns of occurrence, geological characteristics, and mechanisms of formation. ACRs were studied through geological surveys, analysis of on-site failure characteristics, and a series of laboratory tests. The findings indicate that ACRs are most likely to occur near river valleys, faults, and geological contact zones, where the overburden is significant, and the direction of major stress is perpendicular to the tunnel axis. In ACRs-prone regions, the content of brittle minerals in the surrounding rock tends to be relatively high. At the site studied, the proportion of plagioclase in the diorite ranges from 55 % to 65 %. ACRs are likely to be triggered when the dip of structural planes forms a small angle with the principal stress, and when their strike is parallel (or nearly parallel) to the tunnel axis, or when a group of structural planes intersects the tunnel axis at a small angle and is distributed along it. During tunnel excavation in areas prone to ACRs, appropriate measures should be sufficiently robust and ductile, aimed at enhancing the strength and ductility of the surrounding rock, with support structures closely following the excavation face. This investigation contributes to our understanding of ACRs and may help in designing methods for predicting and preventing their occurrence.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106395"},"PeriodicalIF":6.7,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027284","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 : 2025-01-17DOI: 10.1016/j.tust.2025.106383
Min Hou , Jiang Feng , Hougai Shi , Ruiyi Jiang , Hengyi Zhu , Hualin Fan
In this paper, two-scale Basalt fibers reinforced polymer (BFRP) rebars reinforced arch (BRRA) technique was developed through applying BFRP rebars to macroscopically reinforce concrete shield tunneling segments (STSs). BFRP minibars were mixed into concrete as the micro reinforcements. Six two-scale BRRAs were prepared with content of minibars changing from 0%, 0.5% to 1.5%. Full-scale flexural experiments were performed to reveal the mechanical performances of the BRRAs. With higher minibar content, the utilization ratio of the BFRP rebars is much greater and the BRRA has longer elastoplastic deformation, higher bearing capacity and better ductility. Long elastic deformation of BFRP rebars and reinforcing mechanism of BFRP minibars improve the bearing capacity and ductility of the BRRA.
{"title":"Two-scale basalt fibers reinforced concrete shield tunneling segments for underground constructions","authors":"Min Hou , Jiang Feng , Hougai Shi , Ruiyi Jiang , Hengyi Zhu , Hualin Fan","doi":"10.1016/j.tust.2025.106383","DOIUrl":"10.1016/j.tust.2025.106383","url":null,"abstract":"<div><div>In this paper, two-scale Basalt fibers reinforced polymer (BFRP) rebars reinforced arch (BRRA) technique was developed through applying BFRP rebars to macroscopically reinforce concrete shield tunneling segments (STSs). BFRP minibars were mixed into concrete as the micro reinforcements. Six two-scale BRRAs were prepared with content of minibars changing from 0%, 0.5% to 1.5%. Full-scale flexural experiments were performed to reveal the mechanical performances of the BRRAs. With higher minibar content, the utilization ratio of the BFRP rebars is much greater and the BRRA has longer elastoplastic deformation, higher bearing capacity and better ductility. Long elastic deformation of BFRP rebars and reinforcing mechanism of BFRP minibars improve the bearing capacity and ductility of the BRRA.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106383"},"PeriodicalIF":6.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988082","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 : 2025-01-17DOI: 10.1016/j.tust.2025.106377
Jiaqi Cheng , Nie Yang , Saihua Jiang , Caiyi Xiong
In tunnel fires, conventional detectors are often obstructed by smoke and heat accumulation, impeding decision-making for firefighting and evacuation efforts. This work proposed a real-time prediction of tunnel fire heat release rate (HRR) and location by using external smoke images and deep learning algorithms. A 100-m tunnel was simulated. By varying fire HRR, location, and fuel type, a database of about 1.6 million external smoke images was formed, which was used to train a convolutional neural network (CNN) model and produced a R2 of 0.99 and a small MSE less than 0.03. Results demonstrated that this intelligent method can accurately identify transient tunnel fire power and fire source location, with the HRR prediction error being less than 20 % and location error less than 1.5 m, irrespective of the stage of fire development or whether the fire is in a stationary or moving state. Results also showed that there are two ways of model training to ensure prediction accuracy while saving computational cost: 1) training by both front and side views of smoke at a single tunnel gate, and 2) training by only front views of smoke at both tunnel gates. This work contributed an intelligent method to assess tunnel fire scenarios and hazards from a safe distance, showcasing its potential application in smart tunnel fire protection and firefighting systems.
{"title":"Real-time forecast of tunnel fire scenario and hazard based on external smoke images","authors":"Jiaqi Cheng , Nie Yang , Saihua Jiang , Caiyi Xiong","doi":"10.1016/j.tust.2025.106377","DOIUrl":"10.1016/j.tust.2025.106377","url":null,"abstract":"<div><div>In tunnel fires, conventional detectors are often obstructed by smoke and heat accumulation, impeding decision-making for firefighting and evacuation efforts. This work proposed a real-time prediction of tunnel fire heat release rate (HRR) and location by using external smoke images and deep learning algorithms. A 100-m tunnel was simulated. By varying fire HRR, location, and fuel type, a database of about 1.6 million external smoke images was formed, which was used to train a convolutional neural network (CNN) model and produced a R<sup>2</sup> of 0.99 and a small MSE less than 0.03. Results demonstrated that this intelligent method can accurately identify transient tunnel fire power and fire source location, with the HRR prediction error being less than 20 % and location error less than 1.5 m, irrespective of the stage of fire development or whether the fire is in a stationary or moving state. Results also showed that there are two ways of model training to ensure prediction accuracy while saving computational cost: 1) training by both front and side views of smoke at a single tunnel gate, and 2) training by only front views of smoke at both tunnel gates. This work contributed an intelligent method to assess tunnel fire scenarios and hazards from a safe distance, showcasing its potential application in smart tunnel fire protection and firefighting systems.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106377"},"PeriodicalIF":6.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988132","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 : 2025-01-17DOI: 10.1016/j.tust.2025.106388
Guiyang Yuan , Fuqiang Gao , Jinfu Lou , Jinghe Yang , Shuangyong Dong , Linpo Si
Understanding the behavior and failure mechanisms of rock bolts subjected to multiple impact loads is essential for improving the safety and performance of underground support systems. In this study, a series of experimental tests were performed to investigate the deformation, energy absorption, and failure mechanisms of pre-tensioned rock bolts under multiple impacts. The result indicates that with an increasing number of impacts, the rebound amount of rock bolts gradually increases, while the plastic deformation decreases. The energy absorbing ratio of the rock bolt decreases as the energy releasing ratio increases, leading to a decline in the rock bolt’s ability to absorb energy and an increase in brittleness. It was observed that the accumulation of plastic deformation consumes the yielding and strengthening stages of the rock bolt, making it prone to fracture at smaller deformations in later stages. It was also found that the final elongation of a rock bolt subjected to multiple impacts leading to fracture is significantly higher compared to a rock bolt subjected to a pure pull-out test. These insights have important implications for the design of rock bolt support systems in underground excavations.
{"title":"Investigating the mechanical behavior and failure mechanisms of rock bolts subjected to multiple impact loads using a newly developed experimental test apparatus","authors":"Guiyang Yuan , Fuqiang Gao , Jinfu Lou , Jinghe Yang , Shuangyong Dong , Linpo Si","doi":"10.1016/j.tust.2025.106388","DOIUrl":"10.1016/j.tust.2025.106388","url":null,"abstract":"<div><div>Understanding the behavior and failure mechanisms of rock bolts subjected to multiple impact loads is essential for improving the safety and performance of underground support systems. In this study, a series of experimental tests were performed to investigate the deformation, energy absorption, and failure mechanisms of pre-tensioned rock bolts under multiple impacts. The result indicates that with an increasing number of impacts, the rebound amount of rock bolts gradually increases, while the plastic deformation decreases. The energy absorbing ratio of the rock bolt decreases as the energy releasing ratio increases, leading to a decline in the rock bolt’s ability to absorb energy and an increase in brittleness. It was observed that the accumulation of plastic deformation consumes the yielding and strengthening stages of the rock bolt, making it prone to fracture at smaller deformations in later stages. It was also found that the final elongation of a rock bolt subjected to multiple impacts leading to fracture is significantly higher compared to a rock bolt subjected to a pure pull-out test. These insights have important implications for the design of rock bolt support systems in underground excavations.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106388"},"PeriodicalIF":6.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988080","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}
Predicting rock fractures in unexcavated areas is a critical yet challenging aspect of geotechnical projects. This task involves forecasting the fracture mapping sequences for unexcavated rock faces using the sequences from excavated ones, which is well-suited for spatial–temporal deep learning techniques. Fracture mapping sequences for deep learning model training can be achieved based on field photography. However, the main obstacle lies in the insufficient availability of high-quality photos. Existing data augmentation techniques rely on slices taken from Discrete Fracture Network (DFN) models. However, slices differ significantly from actual photos taken from the field. To overcome this limitation, this study introduces a new framework that uses Virtual Camera Technology (VCT) to generate “virtual photos” from DFN models. The external (e.g., camera location, direction) and internal parameters (e.g., focal length, resolution, sensor size) of cameras can be considered in this method. The “virtual photos” generated from the VCT and conventional slicing method have been extensively compared. The framework is designed to adapt to any distribution of field fractures and camera settings, serving as a universal tool for practical applications. The whole framework has been packaged as an open-source tool for rock “photos” generation. An open-source benchmark database has also been established based on this tool. To validate the framework’s feasibility, the Predictive Recurrent Neural Network (PredRNN) method is applied to the generated database. A high degree of similarity is observed between the predicted mapping sequences and the ground truth. The model successfully captured the dynamic changes in fracture patterns across different sections, thereby confirming the framework’s practical utility. The source code and dataset can be freely downloaded from GitHub repository (https://github.com/GEO-ATLAS/Rock-Camera).
{"title":"Advancing spatial-temporal rock fracture prediction with virtual camera-based data augmentation","authors":"Jiawei Xie , Baolin Chen , Jinsong Huang , Yuting Zhang , Cheng Zeng","doi":"10.1016/j.tust.2025.106400","DOIUrl":"10.1016/j.tust.2025.106400","url":null,"abstract":"<div><div>Predicting rock fractures in unexcavated areas is a critical yet challenging aspect of geotechnical projects. This task involves forecasting the fracture mapping sequences for unexcavated rock faces using the sequences from excavated ones, which is well-suited for spatial–temporal deep learning techniques. Fracture mapping sequences for deep learning model training can be achieved based on field photography. However, the main obstacle lies in the insufficient availability of high-quality photos. Existing data augmentation techniques rely on slices taken from Discrete Fracture Network (DFN) models. However, slices differ significantly from actual photos taken from the field. To overcome this limitation, this study introduces a new framework that uses Virtual Camera Technology (VCT) to generate “virtual photos” from DFN models. The external (e.g., camera location, direction) and internal parameters (e.g., focal length, resolution, sensor size) of cameras can be considered in this method. The “virtual photos” generated from the VCT and conventional slicing method have been extensively compared. The framework is designed to adapt to any distribution of field fractures and camera settings, serving as a universal tool for practical applications. The whole framework has been packaged as an open-source tool for rock “photos” generation. An open-source benchmark database has also been established based on this tool. To validate the framework’s feasibility, the Predictive Recurrent Neural Network (PredRNN) method is applied to the generated database. A high degree of similarity is observed between the predicted mapping sequences and the ground truth. The model successfully captured the dynamic changes in fracture patterns across different sections, thereby confirming the framework’s practical utility. The source code and dataset can be freely downloaded from GitHub repository (<span><span>https://github.com/GEO-ATLAS/Rock-Camera</span><svg><path></path></svg></span>).</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106400"},"PeriodicalIF":6.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988136","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}