Tunnelling and Underground Space Technology最新文献

{"title":"Deep-learning-based longitudinal joint opening detection method for metro shield tunnel","authors":"","doi":"10.1016/j.tust.2024.106108","DOIUrl":"10.1016/j.tust.2024.106108","url":null,"abstract":"<div><div>In this paper, a longitudinal joint opening detection method using a precise longitudinal segment joint extraction algorithm featuring deep neural networks (DNNs) is proposed. The proposed method consists of the following four steps. First, a mobile scanning system is employed to obtain three-dimensional metro shield tunnel point clouds. Then, two small DNNs, YOLOv5 and JLNet, were designed to accurately extract the longitudinal segment joint lines from the images generated from the scanned point clouds. YOLOv5 rapidly detects the approximate longitudinal segment joint areas, while JLNet precisely fits the joint lines. Subsequently, using the extracted segment joint lines, the points associated with different tunnel segments can be segmented accordingly. Finally, based on the tunnel segment point clouds, a joint opening angle calculation method that combines the cylinder projection and plane-fitting algorithms is proposed. Experimental results demonstrate that the proposed DNN-based method can accurately extract segment joint lines without being influenced by the tunnel equipment around the segment joints. The YOLOv5 network exhibited a classification accuracy of 0.9907 and a bounding box prediction error of 0.004. For the JLNet network, the line slope prediction error was 0.0072, with an intercept error of 1.53 pixels. The joint opening spatial distribution pattern was identified by comparing the joint opening angles in the deformed and undeformed tunnels. Additionally, the accuracy of the proposed method was evaluated, revealing that the joint opening angle detection external accuracy was 0.13°.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433663","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}

{"title":"Evaluating the impact of tunnel slope on critical velocity and confinement velocity in metro tunnel carriage fires","authors":"","doi":"10.1016/j.tust.2024.106141","DOIUrl":"10.1016/j.tust.2024.106141","url":null,"abstract":"<div><div>Smoke control within metro tunnels stands as a pivotal measure in ensuring both the orderly evacuation and safety of passengers. This study investigated the critical velocity and confinement velocity in inclined metro tunnel fires via model-scale experiments. The tunnel slope varied from 2 % ∼ 8 % and four fire heat release rates of 2.29 kW, 3.44 kW, 4.59 kW and 5.74 kW. Results show that the confinement velocity and critical velocity monotonically increase with the heat release rate and tunnel slope. The confinement velocity <em>V</em>_conf was notably affected by the equivalent fire source <em>Q</em>_u. The natural exponential function could effectively express the relationship between <em>Q</em>* and <em>Q</em>_u*, with the correction factor of tunnel slope utilized to adjust the expression. A new model for critical velocity and confinement velocity was characterized by considering the tunnel slope and heat release rate. Comparative results indicated that the optimizing confinement velocity was significantly lower than that defined in previous studies, while the proposed critical velocity ratio aligns well with findings from prior research. This study provides valuable insights into the design of smoke control systems customized for fires occurring in trains immobilized within inclined underground tunnels.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New limit states for the seismic fragility assessment of circular tunnels: Application in case of tunnels in clayey soil deposits","authors":"","doi":"10.1016/j.tust.2024.106129","DOIUrl":"10.1016/j.tust.2024.106129","url":null,"abstract":"<div><div>This paper introduces a novel framework to define limit states for the seismic fragility assessment of circular tunnels in soil. A numerical framework is developed for this purpose, focusing on the response of tunnels subjected to ground seismic shaking in the transverse direction. New limit states are defined based on the ovaling deformation of the tunnel, corresponding to different levels of liner stiffness degradation caused by seismic shaking. The latter is evaluated via nonlinear static pushover analyses of the examined ground-tunnel configurations. Nonlinear dynamic analyses are performed to evaluate the demand of examined tunnels and develop Probabilistic Seismic Demand Models (PSDMs). The uncertainties related with the definitions of capacity and demand are thoroughly evaluated based on the results of the nonlinear static pushover and dynamic analyses, respectively. The proposed framework is applied to a 6 m diameter circular tunnel embedded in uniform clayey soil deposit at a burial depth of 15 m. Various assumptions are made regarding the thickness and mechanical properties of the liner and the soil, leading to the investigation of 27 ground-tunnel configurations. A suite of ground motions is selected to perform dynamic analyses of each examined configuration. Based on the results of the analyses new PSDMs and <em>PGA</em>-based fragility functions are derived. Comparisons of the proposed fragility curves with existing, empirical, and analytical fragility curves for tunnels, reveal differences, which in some cases are significant and are mainly attributed to the different definitions of Engineering Demand Parameters (EDPs) and limit states between the compared curves, as well as to different assumptions in the analytical frameworks proposed by various studies. The proposed framework may be applied to other ground-tunnel configurations to develop fragility functions for a more rigorous risk and resilience assessment of these types of systems.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433658","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}

{"title":"Effect of borehole deviation on raise formation via long-hole raise blasting","authors":"","doi":"10.1016/j.tust.2024.106136","DOIUrl":"10.1016/j.tust.2024.106136","url":null,"abstract":"<div><div>During Long-hole raises blasting (LHRB) in underground mines, borehole deviation seriously affects the blasting effect, greatly increases the difficulty of raise formation, and reduces the quality of formed raises. To study the effect of borehole deviation on raise formation via burn cuts blasting mode (BCBM), this study theoretically analysed the effect of borehole deviation on raise formation via blasting, constructed and validated a mechanism model of underground deep hole deviation, revealed the effect pattern of borehole deviation on the formation of Long-hole raises via BCBM under different cut modes, and guided the practice of raise formation via deep hole blasting in mines. The results showed that (1) deviation-inducing rock strata with alternating soft and hard rocks are important causes of borehole deviation in deep holes; (2) under the same geological conditions, the borehole deviation is usually negatively correlated with the borehole diameter; (3) the resistance to borehole deviation of the four-empty-hole barrel cut mode (FECM) is better than that of the single-empty-hole spiral cut mode (SECM),and (4) optimizing the firing order of blasting based on the actual measurement of borehole deviation can significantly improve the quality of raise formation. The results of this study provide a basis for assessing the mechanism of Long-hole deviation and theoretical and practical references for the design of LHRB under the condition of borehole deviation.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433662","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}

{"title":"Unreinforced construction techniques: ECC-based unreinforced shield tunnel segment joints for enhancing underground infrastructure resilience","authors":"","doi":"10.1016/j.tust.2024.106119","DOIUrl":"10.1016/j.tust.2024.106119","url":null,"abstract":"<div><div>The development of unreinforced construction techniques for shield tunnel segments is crucial for enhancing resilience of underground infrastructure, but research in this field is still lacking. This study addresses this gap by conducting full-scale experiments on ECC-based unreinforced shield segment joints (ECCUS) and comparing their performance with traditional reinforced concrete segment joints (RCS) and ECC reinforced segment joints (ECCRS) under extreme bending loads. The research focuses on material characteristics, segmental deflection, joint behavior, bolt strain, damage propagation, failure modes, joint toughness, and ductility. The results revealed that ECCUS joints had a bearing capacity 2.64 times that of RCS and 1.32 times that of ECCRS in the elastic phase. Their ultimate load capacity surpassed RCS by 27.4% and ECCRS by 24.4%. ECCUS also demonstrated superior ductility, with increases of 131% over ECCRS and 78% over RCS, and exhibited finer, more numerous cracks, enhancing energy absorption and deformability. ECCUS bolts showed a 24% reduction in average strain and a 74% decrease in strain deviation compared to RCS and ECCRS. Furthermore, ECCUS joints displayed exceptional toughness, being 6.2 times greater than RCS and 1.5 times higher than ECCRS during normal serviceability. These findings underscore the potential of ECC in improving the performance and durability of unreinforced tunnel segments.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433661","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}

{"title":"Instability mechanism and reinforcement measures for segments of Ultra-Large diameter shield tunnels when constructing cross passages by mechanical methods","authors":"","doi":"10.1016/j.tust.2024.106125","DOIUrl":"10.1016/j.tust.2024.106125","url":null,"abstract":"<div><div>Construction of cross passages by mechanical methods represents an emerging construction technique with numerous advantages. However, cutting through segments of ultra-large diameter (ULD) shield tunnels poses significant safety risks, and the instability mechanism of those structures with lateral openings remains unclear. Based on China’s first ULD shield tunnel project that adopted the mechanical method for construction of cross passages, refined three-dimensional finite element models were created with ABAQUS. The models considered material and geometric non-linearity and were employed for comprehensive analyses of construction disturbance responses, instability mechanisms of segments, and reinforcement measures. The findings reveal that (1) mechanical construction of cross passages leads to a 24.84 % to 58.57 % increase in structural convergence deformation and a significant stress concentration; (2) The C-shaped ring and the semi-split rings no longer behave consistently in terms of force and deformation after the opening is formed. Additionally, there are significant shifts in the instability characteristics under localized surcharge loads of the segmental lining, resulting in a 30 % decrease in instability start load; (3) After adopting the reinforcement measure of steel ring girders (SRG), the instability process of the structure with opening is similar to that of the initial structure. The loss in instability start load, caused by mechanical construction, has been reduced by 34.4 % ∼ 84.4 %. However, increasing SRG thickness beyond 40 mm has a limited impact on reinforcement efficacy. This study offers theoretical and practical insights for similar engineering projects, positively contributing to project safety.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427937","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}

{"title":"Data-driven prediction model for the heat performance of energy tunnels","authors":"","doi":"10.1016/j.tust.2024.106127","DOIUrl":"10.1016/j.tust.2024.106127","url":null,"abstract":"<div><div>To date, it has been challenging to quickly and accurately quantify the heat performance of energy tunnels under unknown conditions. This study innovatively introduces an intelligent prediction model for the thermal performance of energy tunnels to address the above difficulties. Five machine learning (ML) prediction models for energy tunnel heat flux were established based on a database sourced from various regions, various conditions, and various operations. The prediction results were compared with the measured heat flux of the energy tunnel to determine the prediction performance of these ML models, and the sensitivity of the input variables was also analysed. The results indicate that the established database has reliable representation, as the selected variables (features) in this database are independent and relatively random. Furthermore, these ML models can accurately capture the trends of energy tunnel heat flux values under unknown conditions, with the random forest model demonstrating the best prediction performance, generalization ability, and great accuracy among these five ML models. These 14 input variables in the database are categorized into three groups according to the sensitivity analysis: thermal variables, design variables, and other variables (environmental and test variables). These findings provide confidence for the intelligent prediction of energy tunnel heat performance.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428014","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}

{"title":"Automatic detection of tunnel lining crack based on mobile image acquisition system and deep learning ensemble model","authors":"","doi":"10.1016/j.tust.2024.106124","DOIUrl":"10.1016/j.tust.2024.106124","url":null,"abstract":"<div><div>Tunnel cracks are a crucial indicator of tunnel detection and performance evaluation. However, traditional manual inspection methods are time-consuming and dangerous. To address these problems, an automatic tunnel crack detection method based on a mobile image acquisition system and deep learning ensemble model is proposed. A novel mobile image acquisition system is proposed for tunnel data acquisition. A deep learning-based model, named You Only Look Once v8 enhanced by large separable kernel attention (LSKA) and dynamic snake convolution (DSC; YOLO-LD), is proposed to improve the crack detection performance. Collaborative learning is used to combine the YOLO-LD object detection and semantic segmentation models into an ensemble model to enhance the model’s engineering adaptability. Edge computing technologies are used for ensemble model deployment and inference acceleration. The method is tested on the custom tunnel lining crack (TL-Crack), the open-access dataset LinkCrack, and highway tunnel field data. The results show that the mobile image acquisition system can rapidly acquire high-resolution images and form panoramic images. The YOLO-LD model outperforms other state-of-the-art models in terms of precision, recall, and <em>F</em>1-score on both TL-Crack and LinkCrack. The ensemble model fully exploits the YOLO-LD object detection model’s crack localization capability and the YOLO-LD semantic segmentation model’s crack extraction performance, improving the model’s engineering adaptability. Edge computing techniques increase the inference speed of the ensemble model to 84 images/second. Parameters such as stake number, distribution, length, width, and type of cracks are calculated, and the crack distribution maps are prepared to assist inspectors in field verification.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427940","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}

{"title":"“Cosmopolitan Canopy” in Hong Kong’s hidden city: Urban design and social life in underground transit hub","authors":"","doi":"10.1016/j.tust.2024.106105","DOIUrl":"10.1016/j.tust.2024.106105","url":null,"abstract":"<div><div>This paper investigates how Hong Kongers navigate and utilize the corridors, tunnels, and public spaces of the underground transit hubs at Central Station and Hong Kong Station, accommodating over 250,000 passengers daily. Employing participant observation protocols from urban design research, we documented the locations of social activities and surveyed people’s behavior in these underground environments. Despite their grand and efficient engineering, the efficiency of travelators decreases when density exceeds one person per square foot. The narrow widths limit casual conversations. Our findings reveal that people navigate and behave in underground public spaces similarly to above-ground spaces. Additionally, cheaper rents in mezzanine shops and restaurants have enabled these businesses to thrive, benefiting from substantial foot traffic within the transit system. Overall, underground public spaces extend the conventional public realm, catering to diverse social groups and contributing to the vibrancy and vitality of the overall public sphere.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427939","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}

{"title":"New insights into the merging behavior of pedestrians: Quantification of lane competition level","authors":"","doi":"10.1016/j.tust.2024.106126","DOIUrl":"10.1016/j.tust.2024.106126","url":null,"abstract":"<div><div>Merging behavior is a complex crowd movement pattern caused by certain architectural features and has triggered serious crowd accidents worldwide. It is not uncommon to find such merging structures on the floor plans of some underground infrastructures, which deserve more detailed studies on special crowd movement patterns to enhance the safety level. Researchers have demonstrated that the unstable emotions and competitive behaviors of pedestrians during underground evacuation need to be taken into account due to the enclosed environment. However, there are no relevant studies focused on the competition characteristics among pedestrians during the merging process in a quantitative way. The comprehensiveness and systematization of the geometric features of typical merging structures, as well as the way to create the perception of competition and conflict among pedestrians during real emergencies also need to be improved. In this paper, we carried out a series of controlled experiments in symmetric and asymmetric merging structures with different channel widths and incentive levels to investigate crowd merging behavior with competition characteristics. The density and delay time within the merging area, as well as the time interval and lane changes before and after merging are analyzed. By introducing and modifying Simpson’s Diversity Index, we proposed a new method for quantifying the competition level among pedestrians during the merging process. It is concluded that the performance of the merging area is sensitive to the channel widths and the merging layouts, and the negative effect of unbalanced walking priority is more significant under high incentive level. The lane competition level during the merging process is correlated with the effects of various geometric features, movement layouts, and incentive levels. The method proposed in this paper brings new insights into the interpretation of merging scenarios and more studies on pedestrian dynamics. We hope that this study could serve as supplementary work for other modeling or field experiment methods to jointly provide more insights into the crowd management strategies in some underground infrastructures.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428475","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}