Pub Date : 2024-11-26DOI: 10.1016/j.tust.2024.106182
Chunyi Li , Laizhong Ding , Zengzhang Guo , Zhengxi Wang , Lei Wei , Yuesong Zheng , Ximin Cui , Jinna Wang
<div><div>Subway construction is one of the effective means to boost economic and social development, as well as relieve urban traffic pressure. However, the surface deformation in the process of its operation and maintenance has become one of the most intractable problems faced by urban construction, planning and management departments. This study delved into the surface deformation evolution and underlying mechanisms along the subways in Zhengzhou, China. Leveraging a dataset comprising 88 Sentinel-1A ascending orbit images, we applied a hybrid approach of PS-InSAR and SBAS-InSAR inversion methods to extract both the temporal deformation field and deformation velocity field within the study area. The study interpreted the spatiotemporal evolution of surface deformation within the metro corridor buffer zones. Additionally, through the integration of well-logging hydrological data and geological borehole data, we comprehensively elucidated the mechanisms driving surface uplift in Zhengzhou central urban area. With the intention of accurately analyzing the evolution over two settlement funnels, we implemented a Bayesian estimation algorithm to denoise the subsidence curves extracted from MT-InSAR deformation field at the Shamen metro station. Then, the subsidence velocity features for the subsidence troughs were analyzed at this station. According to the theory of effective stress, the calculation model of soil element consolidation compression was established, and the methodology calculating soil strata compression within the water-level drop funnel was proposed. Based on the measurement data, the reliability of the proposed calculation model and methodology was verified, and the mechanism of surface settlement in typical subway station is revealed. The results demonstrated that significant subsidence zones along the metro corridor predominantly cluster in the eastern, northwestern, and southwestern sectors of the central urban area. Notably, the most substantial subsidence occurs in the Huiji District (Line 2) to the northwest and the Jinshui District (Lines 1 and 5) to the east, with maximum subsidence rates of 16 mm/a and 12 mm/a, respectively. Conversely, uplift areas are primarily situated at the convergence of four administrative districts (Erqi District, Zhongyuan District, Jinshui District, and Guancheng District), affecting Lines 1, 2, and 5 of the metro, with a peak uplift of 67 mm. This uplift area closely aligns with the underground water prohibitive extraction zone. Prior to groundwater prohibitive extraction, it indicated seasonal fluctuations for underground water level, which subsequently exhibited a notable rise following conservation measures. There exists a growing dose feedback function relationship between surface uplift and well-logging level in the prohibitive water-extraction zone. The root mean square error (RMSE) and relative root mean square error (RRMSE) are ±3 mm and 6.7 %, respectively. The theoretical calculation va
{"title":"Spatiotemporal evolution of surface deformation based on MT-InSAR and mechanism analysis along Zhengzhou Metro, China","authors":"Chunyi Li , Laizhong Ding , Zengzhang Guo , Zhengxi Wang , Lei Wei , Yuesong Zheng , Ximin Cui , Jinna Wang","doi":"10.1016/j.tust.2024.106182","DOIUrl":"10.1016/j.tust.2024.106182","url":null,"abstract":"<div><div>Subway construction is one of the effective means to boost economic and social development, as well as relieve urban traffic pressure. However, the surface deformation in the process of its operation and maintenance has become one of the most intractable problems faced by urban construction, planning and management departments. This study delved into the surface deformation evolution and underlying mechanisms along the subways in Zhengzhou, China. Leveraging a dataset comprising 88 Sentinel-1A ascending orbit images, we applied a hybrid approach of PS-InSAR and SBAS-InSAR inversion methods to extract both the temporal deformation field and deformation velocity field within the study area. The study interpreted the spatiotemporal evolution of surface deformation within the metro corridor buffer zones. Additionally, through the integration of well-logging hydrological data and geological borehole data, we comprehensively elucidated the mechanisms driving surface uplift in Zhengzhou central urban area. With the intention of accurately analyzing the evolution over two settlement funnels, we implemented a Bayesian estimation algorithm to denoise the subsidence curves extracted from MT-InSAR deformation field at the Shamen metro station. Then, the subsidence velocity features for the subsidence troughs were analyzed at this station. According to the theory of effective stress, the calculation model of soil element consolidation compression was established, and the methodology calculating soil strata compression within the water-level drop funnel was proposed. Based on the measurement data, the reliability of the proposed calculation model and methodology was verified, and the mechanism of surface settlement in typical subway station is revealed. The results demonstrated that significant subsidence zones along the metro corridor predominantly cluster in the eastern, northwestern, and southwestern sectors of the central urban area. Notably, the most substantial subsidence occurs in the Huiji District (Line 2) to the northwest and the Jinshui District (Lines 1 and 5) to the east, with maximum subsidence rates of 16 mm/a and 12 mm/a, respectively. Conversely, uplift areas are primarily situated at the convergence of four administrative districts (Erqi District, Zhongyuan District, Jinshui District, and Guancheng District), affecting Lines 1, 2, and 5 of the metro, with a peak uplift of 67 mm. This uplift area closely aligns with the underground water prohibitive extraction zone. Prior to groundwater prohibitive extraction, it indicated seasonal fluctuations for underground water level, which subsequently exhibited a notable rise following conservation measures. There exists a growing dose feedback function relationship between surface uplift and well-logging level in the prohibitive water-extraction zone. The root mean square error (RMSE) and relative root mean square error (RRMSE) are ±3 mm and 6.7 %, respectively. The theoretical calculation va","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106182"},"PeriodicalIF":6.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.tust.2024.106230
Ke Wu , Jiangdong Li , Xiaofeng Chen , Xuegang Duan , Tianhang Zhang , Lizhong Wang
In recent years, the construction of bifurcated tunnels has increased in cities to facilitate the interconnection of urban transportation systems but posing significant fire risks at the same time. In this study, the effect of the ventilation condition and heat release rate (HRR) on flame behavior and temperature distribution in tunnel traffic merging section is studied with scale-model experiments. Results show that under confluent ventilation, the flame tilts towards both longitudinal and transverse directions, causing the location of the maximum ceiling temperature rise to deviate from the center-axis. Using the centerline temperature as the global maximum ceiling temperature will result in around 5 % systematic error. The increasing confluent ratio has a limited impact on the longitudinal flame deflection, whereas it induces a significant variation in the transverse deflection angle. The maximum ceiling temperature rise exhibits an initial increase followed by a subsequent decrease, accordingly. A virtual ventilation vector and a non-uniform inflow correction function are proposed to correlate the 3-D plume behaviour with the complex confluent flow field. Finally, a semi-empirical equation to evaluate the maximum ceiling temperature rise considering the multi-dimensional flow field is proposed and validated with existing test data. This work contributes to a deeper understanding of the classical tunnel fire dynamic theory and provides a novel engineering modelling methodology for the plume behavior in bifurcated tunnel fire scenarios.
{"title":"Flame behavior and maximum ceiling temperature in traffic merging section tunnel fires: An experimental study and engineering modelling methodology","authors":"Ke Wu , Jiangdong Li , Xiaofeng Chen , Xuegang Duan , Tianhang Zhang , Lizhong Wang","doi":"10.1016/j.tust.2024.106230","DOIUrl":"10.1016/j.tust.2024.106230","url":null,"abstract":"<div><div>In recent years, the construction of bifurcated tunnels has increased in cities to facilitate the interconnection of urban transportation systems but posing significant fire risks at the same time. In this study, the effect of the ventilation condition and heat release rate (HRR) on flame behavior and temperature distribution in tunnel traffic merging section is studied with scale-model experiments. Results show that under confluent ventilation, the flame tilts towards both longitudinal and transverse directions, causing the location of the maximum ceiling temperature rise to deviate from the center-axis. Using the centerline temperature as the global maximum ceiling temperature will result in around 5 % systematic error. The increasing confluent ratio has a limited impact on the longitudinal flame deflection, whereas it induces a significant variation in the transverse deflection angle. The maximum ceiling temperature rise exhibits an initial increase followed by a subsequent decrease, accordingly. A virtual ventilation vector and a non-uniform inflow correction function are proposed to correlate the 3-D plume behaviour with the complex confluent flow field. Finally, a semi-empirical equation to evaluate the maximum ceiling temperature rise considering the multi-dimensional flow field is proposed and validated with existing test data. This work contributes to a deeper understanding of the classical tunnel fire dynamic theory and provides a novel engineering modelling methodology for the plume behavior in bifurcated tunnel fire scenarios.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106230"},"PeriodicalIF":6.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.tust.2024.106247
Kunkun Chu , Dan Zhou , Zhisheng Xu , Baochao Xie
This paper presents the findings of a field evacuation experiment conducted in an underwater shield tunnel, which involved a random sample of 188 participants of various ages and genders. The experiment utilized an evacuation staircase, and the study employed both the field experiment and a questionnaire to obtain data. The participants’ behavior in the driveway, evacuation staircase, and secure channel was recorded, and various factors, including exit choice, route and track, evacuation time, crowd density, horizontal speed, and staircase descending speed were analyzed and compared with other evacuation cases. The study also considered human factors such as gender, age, and psychology of the participants. Furthermore, the study analyzed the utility of technical installations and their impact on human behavior. The results of this study provide valuable technical guidance for the development of evacuation designs and strategies in underwater shield tunnels. Additionally, the study offers realistic data on human movement and evacuation behavior during tunnel evacuations, which can be utilized to validate and enhance evacuation calculations and numerical simulations.
{"title":"Experimental investigation on the evacuation performance of pedestrians in an underwater shield tunnel with evacuation stairs in a fire scenario","authors":"Kunkun Chu , Dan Zhou , Zhisheng Xu , Baochao Xie","doi":"10.1016/j.tust.2024.106247","DOIUrl":"10.1016/j.tust.2024.106247","url":null,"abstract":"<div><div>This paper presents the findings of a field evacuation experiment conducted in an underwater shield tunnel, which involved a random sample of 188 participants of various ages and genders. The experiment utilized an evacuation staircase, and the study employed both the field experiment and a questionnaire to obtain data. The participants’ behavior in the driveway, evacuation staircase, and secure channel was recorded, and various factors, including exit choice, route and track, evacuation time, crowd density, horizontal speed, and staircase descending speed were analyzed and compared with other evacuation cases. The study also considered human factors such as gender, age, and psychology of the participants. Furthermore, the study analyzed the utility of technical installations and their impact on human behavior. The results of this study provide valuable technical guidance for the development of evacuation designs and strategies in underwater shield tunnels. Additionally, the study offers realistic data on human movement and evacuation behavior during tunnel evacuations, which can be utilized to validate and enhance evacuation calculations and numerical simulations.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106247"},"PeriodicalIF":6.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-25DOI: 10.1016/j.tust.2024.106221
Haibin Ding , Xuepeng Wang , Lihong Tong , Qi Lu , Changjie Xu , Lingxiao Guang
Laboratory model tests and numerical simulations were conducted to investigate the control effect of different arrangements of isolation piles on the additional deformation and stress of tunnels adjacent to pit excavation. Four different arrangements of isolation piles were discussed in this work: arched, curved, double-row, and single-row. The results indicated that considering the burial depth, the four arrangements of isolation piles had significant control effects on the horizontal and vertical deformation, as well as the bending moment of the tunnel. Among them, arch-shaped isolation piles have better isolation effects than other types discussed in this work. Subsequently, taking the arch-shaped isolation piles as an example, the effects of the burial depth, pile position, height-span ratio, and the optimal buried depth of the arch-shaped isolation piles on the tunnel were investigated. The arch-shaped isolation piles have a critical height-span ratio of 0.123, and the closer to the tunnel, the better the protective effect on the tunnel. The optimized embedding depth of isolation piles depends on the depth of the tunnel and the relative position to the foundation pit. The results of this study have great guiding significance for the design of isolation piles to protect adjacent tunnels near excavations.
{"title":"Performance of isolation piles in protecting subway tunnels adjacent to foundation pits: Experimental and numerical investigations","authors":"Haibin Ding , Xuepeng Wang , Lihong Tong , Qi Lu , Changjie Xu , Lingxiao Guang","doi":"10.1016/j.tust.2024.106221","DOIUrl":"10.1016/j.tust.2024.106221","url":null,"abstract":"<div><div>Laboratory model tests and numerical simulations were conducted to investigate the control effect of different arrangements of isolation piles on the additional deformation and stress of tunnels adjacent to pit excavation. Four different arrangements of isolation piles were discussed in this work: arched, curved, double-row, and single-row. The results indicated that considering the burial depth, the four arrangements of isolation piles had significant control effects on the horizontal and vertical deformation, as well as the bending moment of the tunnel. Among them, arch-shaped isolation piles have better isolation effects than other types discussed in this work. Subsequently, taking the arch-shaped isolation piles as an example, the effects of the burial depth, pile position, height-span ratio, and the optimal buried depth of the arch-shaped isolation piles on the tunnel were investigated. The arch-shaped isolation piles have a critical height-span ratio of 0.123, and the closer to the tunnel, the better the protective effect on the tunnel. The optimized embedding depth of isolation piles depends on the depth of the tunnel and the relative position to the foundation pit. The results of this study have great guiding significance for the design of isolation piles to protect adjacent tunnels near excavations.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106221"},"PeriodicalIF":6.7,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.tust.2024.106242
Ziang Xie, Lei He
Existing research predominantly highlights the positive factors facilitating the development and utilization of urban underground space (UUS). However, the constraints and challenges should not be overlooked. Recognizing these limiting factors during the strategic planning and management phases of UUS is essential for enhancing utilization efficiency. To comprehensively understand the constraints on UUS utilization and tackle inefficiencies and vacancies stemming from rapid UUS development, this study adopts a research process of “hypothesis construction − model validation − mechanism exploration” to systematically analyze the key factors contributing to the vacancy of UUS in Shanghai. Through the application of a multiple linear regression model, seven significant factors affecting the distribution intensity of vacant UUS in Shanghai were identified and categorized into 3 major categories: location characteristics, management characteristics, and attribute characteristics. The study reveals that, under certain conditions, the positive driving force of UUS development may transform into a reverse impact inhibiting its effective utilization. By combining field investigations and interviews, the study delves into the underlying mechanisms of the influential factors, revealing that the limitations of demand forecasting and the inadequacy of management systems are the core issues causing vacant UUS. This study emphasizes the importance of innovating UUS demand forecasting methods and clarifying the rights and responsibilities of UUS stakeholders, thereby providing a scientific basis for the rational planning and effective management of UUS. The research findings not only contribute to a more comprehensive understanding of the complexities influencing UUS development and utilization but also provide crucial guidance for fostering the sustainable development of UUS.
{"title":"Factors and mechanisms shaping vacant urban underground space in Shanghai","authors":"Ziang Xie, Lei He","doi":"10.1016/j.tust.2024.106242","DOIUrl":"10.1016/j.tust.2024.106242","url":null,"abstract":"<div><div>Existing research predominantly highlights the positive factors facilitating the development and utilization of urban underground space (UUS). However, the constraints and challenges should not be overlooked. Recognizing these limiting factors during the strategic planning and management phases of UUS is essential for enhancing utilization efficiency. To comprehensively understand the constraints on UUS utilization and tackle inefficiencies and vacancies stemming from rapid UUS development, this study adopts a research process of “hypothesis construction − model validation − mechanism exploration” to systematically analyze the key factors contributing to the vacancy of UUS in Shanghai. Through the application of a multiple linear regression model, seven significant factors affecting the distribution intensity of vacant UUS in Shanghai were identified and categorized into 3 major categories: location characteristics, management characteristics, and attribute characteristics. The study reveals that, under certain conditions, the positive driving force of UUS development may transform into a reverse impact inhibiting its effective utilization. By combining field investigations and interviews, the study delves into the underlying mechanisms of the influential factors, revealing that the limitations of demand forecasting and the inadequacy of management systems are the core issues causing vacant UUS. This study emphasizes the importance of innovating UUS demand forecasting methods and clarifying the rights and responsibilities of UUS stakeholders, thereby providing a scientific basis for the rational planning and effective management of UUS. The research findings not only contribute to a more comprehensive understanding of the complexities influencing UUS development and utilization but also provide crucial guidance for fostering the sustainable development of UUS.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106242"},"PeriodicalIF":6.7,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.tust.2024.106191
Kun He , Fei Ren , Jian Li , Xiaodong Qian , Junyi Li , Yao Hong , Wei Cong , Yanan Hou
Multiple fire source fires in a tunnel may cause serious fire consequences. In the present study, the flame properties and maximum ceiling smoke temperature for two asymmetric fire sources in the tunnel with natural ventilation are studied in detail. A large number of model-scale fire experiments are performed, considering energy release rate ratio ratio and fire source spacing. The results show that the smaller fire has a larger flame inclination angle and the flame inclination angle of the smaller fire increases with energy release rate ratio. In contrast, the flame tilt angle of the larger fire becomes slightly smaller with the energy release rate ratio. When mean flames merge vertically, the flame height becomes higher when the energy release rate ratio increases. A revised model based on the air entrainment perimeter is proposed to calculate the height of the merged flame. When mean flames cannot merge vertically, a non-dimensional correlation is also developed. With a longer fire source spacing, the maximum ceiling smoke temperature decreases first and then remains unchanged. According to the relative position of the flame tip and tunnel ceiling height, a model is developed to calculate the maximum ceiling smoke temperature. The results of this paper are significant to the fire detection and structure protection for the possibility of two asymmetric fire sources in a tunnel with natural ventilation.
{"title":"Flame properties and maximum ceiling smoke temperature in tunnel fires with two asymmetric fire sources under natural ventilation","authors":"Kun He , Fei Ren , Jian Li , Xiaodong Qian , Junyi Li , Yao Hong , Wei Cong , Yanan Hou","doi":"10.1016/j.tust.2024.106191","DOIUrl":"10.1016/j.tust.2024.106191","url":null,"abstract":"<div><div>Multiple fire source fires in a tunnel may cause serious fire consequences. In the present study, the flame properties and maximum ceiling smoke temperature for two asymmetric fire sources in the tunnel with natural ventilation are studied in detail. A large number of model-scale fire experiments are performed, considering energy release rate ratio ratio and fire source spacing. The results show that the smaller fire has a larger flame inclination angle and the flame inclination angle of the smaller fire increases with energy release rate ratio. In contrast, the flame tilt angle of the larger fire becomes slightly smaller with the energy release rate ratio. When mean flames merge vertically, the flame height becomes higher when the energy release rate ratio increases. A revised model based on the air entrainment perimeter is proposed to calculate the height of the merged flame. When mean flames cannot merge vertically, a non-dimensional correlation is also developed. With a longer fire source spacing, the maximum ceiling smoke temperature decreases first and then remains unchanged. According to the relative position of the flame tip and tunnel ceiling height, a model is developed to calculate the maximum ceiling smoke temperature. The results of this paper are significant to the fire detection and structure protection for the possibility of two asymmetric fire sources in a tunnel with natural ventilation.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106191"},"PeriodicalIF":6.7,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.tust.2024.106237
Zhen Li , Xuezeng Liu , Jiye Wang
Investigating the mechanical responses and strengthening effects of surcharge-disturbed shield tunnels with varying cross-sections is crucial for ensuring the effectiveness of structural safety evaluations and treatments. This study introduces an elaborate modeling approach for segmental rings of three different sizes. Using calibrated finite element (FE) models and a proposed numerical simulation method for strengthening deformed segmental rings, the variations in surcharge-induced mechanical behaviors and strengthening effects in shield tunnels with typical cross-sections were analyzed. Based on these findings, safety classification standards and recommendations for selecting strengthening measures for shield tunnels with typical cross-sections are established. The results indicate that surcharge-disturbed shield tunnels with typical cross-sections exhibit certain variations in structural internal force levels and transmission characteristics, as well as in the timing of plastic hinge formation and joint mechanical response. Additionally, there are also commonalities in the overall deformation and damage mechanisms of the structures. For instance, the stable and accelerated development stages of segmental deformation are primarily driven by segment cracking, while the rapid development stage is triggered by both the surrounding stratum reaching passive earth pressure and the formation of structural plastic hinges. Accordingly, a safety classification standard for single-line shield tunnels with typical cross-sections is established. For a 6.2 m diameter tunnel, a steel plate-UHPC composite structure (SUCS) is recommended if spatial conditions permit, owing to its excellent interface properties. For a 6.7 m diameter tunnel, both SUCS and prefabricated UHPC slab (PUS) are preferred, provided that the layer thickness and interface measures are appropriately designed. For an 8.8 m diameter tunnel, EBSP, SUCS, and PUS are all viable options, although modifications to the conventional strengthening measures are necessary to enhance mechanical performance.
{"title":"Elaborate numerical investigation on surcharge-induced mechanical responses and strengthening effects of single-line shield tunnels with typical cross-sections","authors":"Zhen Li , Xuezeng Liu , Jiye Wang","doi":"10.1016/j.tust.2024.106237","DOIUrl":"10.1016/j.tust.2024.106237","url":null,"abstract":"<div><div>Investigating the mechanical responses and strengthening effects of surcharge-disturbed shield tunnels with varying cross-sections is crucial for ensuring the effectiveness of structural safety evaluations and treatments. This study introduces an elaborate modeling approach for segmental rings of three different sizes. Using calibrated finite element (FE) models and a proposed numerical simulation method for strengthening deformed segmental rings, the variations in surcharge-induced mechanical behaviors and strengthening effects in shield tunnels with typical cross-sections were analyzed. Based on these findings, safety classification standards and recommendations for selecting strengthening measures for shield tunnels with typical cross-sections are established. The results indicate that surcharge-disturbed shield tunnels with typical cross-sections exhibit certain variations in structural internal force levels and transmission characteristics, as well as in the timing of plastic hinge formation and joint mechanical response. Additionally, there are also commonalities in the overall deformation and damage mechanisms of the structures. For instance, the stable and accelerated development stages of segmental deformation are primarily driven by segment cracking, while the rapid development stage is triggered by both the surrounding stratum reaching passive earth pressure and the formation of structural plastic hinges. Accordingly, a safety classification standard for single-line shield tunnels with typical cross-sections is established. For a 6.2 m diameter tunnel, a steel plate-UHPC composite structure (SUCS) is recommended if spatial conditions permit, owing to its excellent interface properties. For a 6.7 m diameter tunnel, both SUCS and prefabricated UHPC slab (PUS) are preferred, provided that the layer thickness and interface measures are appropriately designed. For an 8.8 m diameter tunnel, EBSP, SUCS, and PUS are all viable options, although modifications to the conventional strengthening measures are necessary to enhance mechanical performance.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106237"},"PeriodicalIF":6.7,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-22DOI: 10.1016/j.tust.2024.106232
Hong He , Ling-Yi Diao , Wei-Chao Yang , Jun-Jie Liu , Yi-Kang Liu , E Deng
The lateral force exerted when two trains pass each other can adversely affect train safety, and this adverse effect becomes more pronounced as the train speed increases. When trains cross paths in tunnels, the aerodynamics differ from those in open lines due to the restrictive nature of tunnel walls. Utilizing the Renormalization Group (RNG) k-ε turbulence model and the “Mosaic” grid method, this research examines changes in aerodynamic load of the train and ride comfort during a intersection at 400 km/h in a tunnel and contrasts this with conditions at 350 km/h. The results indicate that the change in aerodynamic load on each carriage is more pronounced when the head train of the oncoming train passes than when its tail train passes, with the largest variation observed during the passing of both the head and tail trains. This alteration in aerodynamic load is primarily attributed to the air being pushed in the locomotive area and the negative pressure from the vortex structure between trains. When the speed is increased from 350 km/h to 400 km/h, the aerodynamic load on the train increases by approximately 20 % to 40 %, and the acceleration of the head train grows by 20 % to 50 %. The most noticeable decrease in ride comfort is observed in the head train, with the highest increase in the head train’s Overall Vibration Total Value (OVTV), which rises by 30.1 %.
{"title":"Abrupt changing aerodynamic loads resulting in diminished ride comfort when two high-speed trains intersect in a tunnel","authors":"Hong He , Ling-Yi Diao , Wei-Chao Yang , Jun-Jie Liu , Yi-Kang Liu , E Deng","doi":"10.1016/j.tust.2024.106232","DOIUrl":"10.1016/j.tust.2024.106232","url":null,"abstract":"<div><div>The lateral force exerted when two trains pass each other can adversely affect train safety, and this adverse effect becomes more pronounced as the train speed increases. When trains cross paths in tunnels, the aerodynamics differ from those in open lines due to the restrictive nature of tunnel walls. Utilizing the Renormalization Group (RNG) <em>k-ε</em> turbulence model and the “<em>Mosaic</em>” grid method, this research examines changes in aerodynamic load of the train and ride comfort during a intersection at 400 km/h in a tunnel and contrasts this with conditions at 350 km/h. The results indicate that the change in aerodynamic load on each carriage is more pronounced when the head train of the oncoming train passes than when its tail train passes, with the largest variation observed during the passing of both the head and tail trains. This alteration in aerodynamic load is primarily attributed to the air being pushed in the locomotive area and the negative pressure from the vortex structure between trains. When the speed is increased from 350 km/h to 400 km/h, the aerodynamic load on the train increases by approximately 20 % to 40 %, and the acceleration of the head train grows by 20 % to 50 %. The most noticeable decrease in ride comfort is observed in the head train, with the highest increase in the head train’s Overall Vibration Total Value (<em>OVTV</em>), which rises by 30.1 %.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106232"},"PeriodicalIF":6.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-22DOI: 10.1016/j.tust.2024.106229
Junchen Zhang , Qixiang Yan , Yu Zhao , Minghui Sun , Chaofan Yao , Hongbin Xu
Dislocations of circumferential joints are commonly prevalent in shield tunnels. Generally, the displacement space of bolt in rigid segment joint is very small. When the dislocation of the circumferential joint is large, plastic deformation of the bolts or concrete crushing is inevitable, which will affect the service life of the shield tunnel. The flexibility of the joint can be achieved by embedding in a dowel, which can reduce the damage of the segment joint during the misalignment of the circumferential joint. However, the addition of the dowel changes the structure of the circumferential joint. At present, the shear bearing capacity of the circumferential joint, affecting the design, safety verification, and service performance evaluation, cannot be accurately calculated through the existing mechanical models. Therefore, the envelope curves of the shear bearing capacity of the circumferential joint with dowel were investigated in this paper. Firstly, a series of shear resistance experiments were conducted to clarify the failure characteristics of the circumferential joint with the dowel. Subsequently, based on the experimental results, several shear mechanical calculation models for the circumferential joint were proposed. And the analytical method for the envelope curves between axial force (N) and shear force (Q) was derived. Finally, the accuracy of the analytical method was verified, and corresponding optimization methods to improve the bearing performance of the circumferential joint were proposed. The research results indicate that the circumferential joint with dowel has both concrete shear stage and steel rebars shear stage. The N-Q envelope curves is determined by the combination of concrete, connectors (including the dowel and the bolt), and steel rebars, and the leading factor can be clarified by the proposed method. A constructive conclusion has been found that the optimization design of the circumferential joint must consider the axial force in order to effectively improve its shear bearing performance. The research results can serve the joint optimization, load-bearing verification during design process, and the physical model in big data analysis during the operation and maintenance of the shield tunnel.
{"title":"Compression-shear capacity of circumferential joint with dowel in shield tunnel: From experiments to analytical solution","authors":"Junchen Zhang , Qixiang Yan , Yu Zhao , Minghui Sun , Chaofan Yao , Hongbin Xu","doi":"10.1016/j.tust.2024.106229","DOIUrl":"10.1016/j.tust.2024.106229","url":null,"abstract":"<div><div>Dislocations of circumferential joints are commonly prevalent in shield tunnels. Generally, the displacement space of bolt in rigid segment joint is very small. When the dislocation of the circumferential joint is large, plastic deformation of the bolts or concrete crushing is inevitable, which will affect the service life of the shield tunnel. The flexibility of the joint can be achieved by embedding in a dowel, which can reduce the damage of the segment joint during the misalignment of the circumferential joint. However, the addition of the dowel changes the structure of the circumferential joint. At present, the shear bearing capacity of the circumferential joint, affecting the design, safety verification, and service performance evaluation, cannot be accurately calculated through the existing mechanical models. Therefore, the envelope curves of the shear bearing capacity of the circumferential joint with dowel were investigated in this paper. Firstly, a series of shear resistance experiments were conducted to clarify the failure characteristics of the circumferential joint with the dowel. Subsequently, based on the experimental results, several shear mechanical calculation models for the circumferential joint were proposed. And the analytical method for the envelope curves between axial force (<em>N</em>) and shear force (<em>Q</em>) was derived. Finally, the accuracy of the analytical method was verified, and corresponding optimization methods to improve the bearing performance of the circumferential joint were proposed. The research results indicate that the circumferential joint with dowel has both concrete shear stage and steel rebars shear stage. The <em>N-Q</em> envelope curves is determined by the combination of concrete, connectors (including the dowel and the bolt), and steel rebars, and the leading factor can be clarified by the proposed method. A constructive conclusion has been found that the optimization design of the circumferential joint must consider the axial force in order to effectively improve its shear bearing performance. The research results can serve the joint optimization, load-bearing verification during design process, and the physical model in big data analysis during the operation and maintenance of the shield tunnel.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106229"},"PeriodicalIF":6.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-22DOI: 10.1016/j.tust.2024.106225
Dongwei Wu , Lei Zhou , Fukuan Nie , Feng Dai , Meng Wang , Bang Liu
Multitudinous natural human-induced flaws exist in the rock mass, which could pose potential risks to the safety of tunnel engineering. To study the dynamic failure properties of the tunnel with a crack in the surrounding rock mass, a series of typical split Hopkinson pressure bar (SHPB) dynamic fracture tests were conducted. A high-speed camera was utilized to record the failure process and digital image correlation (DIC) techniques were applied to analyze the evolution law of strain field in the surrounding rock mass. Numerical simulations were performed using LS-DYNA software after calibrating the parameters of the Riedel-Hiermaier-Thoma (RHT) model. The findings of this study indicate that far-field cracks could contribute to tensile crack propagation from the tunnel vault and tunnel floor. In addition, simulations are highly consistent with model experiments, which proves its practicability and accuracy. These results could provide significant references for more secure, economical and efficient support solutions for engineering. The study also promotes the application of the RHT model to the dynamic response behavior of defected rock-like materials.
{"title":"Experimental and numerical investigation on the failure behavior of far-field-crack-tunnel rock mass under dynamic loads","authors":"Dongwei Wu , Lei Zhou , Fukuan Nie , Feng Dai , Meng Wang , Bang Liu","doi":"10.1016/j.tust.2024.106225","DOIUrl":"10.1016/j.tust.2024.106225","url":null,"abstract":"<div><div>Multitudinous natural human-induced flaws exist in the rock mass, which could pose potential risks to the safety of tunnel engineering. To study the dynamic failure properties of the tunnel with a crack in the surrounding rock mass, a series of typical split Hopkinson pressure bar (SHPB) dynamic fracture tests were conducted. A high-speed camera was utilized to record the failure process and digital image correlation (DIC) techniques were applied to analyze the evolution law of strain field in the surrounding rock mass. Numerical simulations were performed using LS-DYNA software after calibrating the parameters of the Riedel-Hiermaier-Thoma (RHT) model. The findings of this study indicate that far-field cracks could contribute to tensile crack propagation from the<!--> <!-->tunnel vault and tunnel floor. In addition, simulations are highly consistent with model experiments, which proves its practicability and accuracy. These results could provide significant references for more secure, economical and efficient support solutions for engineering. The study also promotes the application of the RHT model to the dynamic response behavior of defected rock-like materials.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"156 ","pages":"Article 106225"},"PeriodicalIF":6.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698969","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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