Tunnelling and Underground Space Technology最新文献

{"title":"Rate-dependent similarity theory for scaling the dynamic tensile responses and failure of underground concrete silos under soil explosions","authors":"Xieping Huang,&nbsp;Bin Zhu,&nbsp;Yunmin Chen","doi":"10.1016/j.tust.2024.106131","DOIUrl":"10.1016/j.tust.2024.106131","url":null,"abstract":"<div><div>The conventional similarity theory derived from dimensional analysis struggles with the well-known issue of non-scalability of material strain-rate effects between scaled models and prototypes. This limitation has significantly hindered the application of scaled model tests, particularly small-scale centrifugal model tests, in the study of structures against blast loading. To overcome this challenge, this study proposes a rate-dependent similarity theory for scaling the dynamic tensile responses and failure of large-scale underground concrete silos (46 m in height) subjected to large-yield soil explosions. The proposed theory includes a correction method derived from a verified dimensionless number, D_cs, which accurately reflects the overall bending-induced tensile response and failure mechanism of concrete silos. The correction strategy involves maintaining an equal D_cs between the scaled model and the prototype by adjusting the explosive weight and the concrete’s static tensile strength in the scaled model to account for differences in strain-rate effects. To verify the theory, a series of geometrically similar silo models with scaling factors <em>β</em> = 1, 1/2, 1/5, 1/10, 1/20, 1/50, and 1/100 were designed. High-fidelity numerical simulations were performed using a fully coupled numerical model encompassing the explosive-soil-silo system. The results demonstrate that, with the conventional dimensional analysis-based similarity theory, the tensile damage and failure of the scaled silo models differ significantly from those of the prototype. However, with the proposed rate-dependent similarity theory, the failure patterns of the silo models with <em>β</em> = 1 ∼ 1/100 are almost identical, indicating that the proposed theory can effectively address the troublesome issue of dissimilar material strain-rate effects between scaled models and prototypes. This similarity theory offers a solid theoretical foundation for designing scaled models that accurately reflect prototype behavior, thereby advancing the application of scaled model tests in the study of structures against blast loading.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106131"},"PeriodicalIF":6.7,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533025","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":"A confident learning-based support vector machine for robust ground classification in noisy label environments","authors":"Xin-Yue Zhang ,&nbsp;Xiao-Ping Zhang ,&nbsp;Hong-Gan Yu ,&nbsp;Quan-Sheng Liu","doi":"10.1016/j.tust.2024.106128","DOIUrl":"10.1016/j.tust.2024.106128","url":null,"abstract":"<div><div>Geological labels obtained from field exploration have potential errors due to technique limitations and subjective interference, leading to noisy labels when developing ground-machine interaction models for TBM tunneling. The present study proposes a novel confident learning-based support vector machine (CL-SVM) to eliminate label noise, thereby improving the accuracy and credibility of ground classification. The proposed model optimizes confidence values for each label and recognizes those with low confidence values as potential noise. Its effectiveness and superiority are confirmed through a noise test. The results indicate that the maximum acceptable noise ratio of the CL-SVM is 35%, while that of the conventional SVM is only 10%. In addition, the CL-SVM consistently emerges as a superior performer compared to the SVM in noisy label environments. The CL-SVM is further verified through its application on a class-imbalanced dataset collected from a metro tunnel project in Wuhan, China. Here, the accuracy metric <em>F1-score</em> for the most noise-interfered class is significantly improved from 0.7273 to 0.88. To enhance the model’s practical value, a confidence criterion is established to evaluate the credibility of individual predictions, which requires reliable predictions to have higher confidence values than specified thresholds. Without prior knowledge of true sample labels, this criterion distinguishes mispredictions from correct predictions with a remarkable precision of 99.08%. In summary, the proposed CL-SVM exhibits significantly better robustness to noisy labels than conventional models, demonstrating great potential for ground perception in tunnel projects.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106128"},"PeriodicalIF":6.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533073","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":"Failure mechanism of deep-buried and large cross-section subway station tunnel: Geo-mechanical model test and numerical investigation","authors":"Deng Gao ,&nbsp;Yusheng Shen ,&nbsp;Pengfa Zhou ,&nbsp;Andi Gou ,&nbsp;Mingyu Chang ,&nbsp;Jun Dong ,&nbsp;Kang Wu","doi":"10.1016/j.tust.2024.106148","DOIUrl":"10.1016/j.tust.2024.106148","url":null,"abstract":"<div><div>In some megacities, urban subway and municipal engineering are developing in the tendency of large cross-section and great buried depth, which brings a series of challenges to the design and construction of underground engineering. The mechanical characteristics and failure mechanism of tunnels have been paid more and more attention. Based on Xietaizi Subway Station tunnel in Chongqing, China, the paper carried out a geo-mechanical model test to simulated partial excavation processes of the large cross-section tunnel, integrating the resultant disturbances from partial excavation. The deformation and stress characteristics of the tunnel under different buried depths are analyzed, and the failure mechanism of large cross-section tunnel lining is investigated. The reliability of the research results is verified by the geo-mechanical model test and numerical simulation. The results indicate that under the pressure of the surrounding rock, the tunnel lining adjusts its internal forces primarily through deformation before transitioning to cracking, and retains earing capacity after the first crack appears. The tunnel structure experiences a process characterized by ‘elasticity-plasticity-injury-failure’. The tunnel section exhibits a ‘flattening’ deformation trend. The invert cracks are primarily distributed within a range of 0.5 times the tunnel span, while the vault cracks are mainly concentrated at the mid-span. Ultimately, the tunnel structure is compromised by the fracture of the invert’s middle section.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106148"},"PeriodicalIF":6.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533003","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":"Advancing underground infrastructure: Trenchless technologies and smart asset management in the digital age","authors":"Hongfang Lu (Guest Editor) ,&nbsp;John C. Matthews (Guest Editor) ,&nbsp;Myungjin Chae (Guest Editor) ,&nbsp;Keh-Jian Shou (Guest Editor) ,&nbsp;Samuel Ariaratnam (Guest Editor) ,&nbsp;Hongyuan Fang (Guest Editor) ,&nbsp;Baosong Ma (Guest Editor) ,&nbsp;David Tom Iseley (Guest Editor)","doi":"10.1016/j.tust.2024.106130","DOIUrl":"10.1016/j.tust.2024.106130","url":null,"abstract":"","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106130"},"PeriodicalIF":6.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142662660","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":"Research on the prestress Regulation of double-layer lining of shield water tunnel under high internal water pressure","authors":"Shimin Wang ,&nbsp;Xiaobin Ma ,&nbsp;Ya Wang ,&nbsp;Chang Liu","doi":"10.1016/j.tust.2024.106133","DOIUrl":"10.1016/j.tust.2024.106133","url":null,"abstract":"<div><div>Prestressed double-layer lining (segmental lining and prestressed lining) of shield tunnels has good seepage resistance and strong stability, and is a new type of support structure with great potential in high internal water pressure water transmission projects. For prestressed water conveyance tunnel projects, the reasonable value of lining tensioning prestress is the key to the economy and safety of the project. Accordingly, relying on the Pearl River Delta Water Resources Allocation Project, designed similar model tests for prestressed double-layer lining of water conveyance shield tunnels under the completed cable tension condition (CCTC) and design water pressure condition (DWPC) and established the corresponding ABAQUS three-dimensional finite element model to investigate the variations in the mechanical characteristics of the double-layer lining structure under different prestress conditions. The study determined the reasonable prestress range for the inner lining under a design internal water pressure of 1.5 MPa. The results indicated that under the CCTC, the prestressed lining is pressurized in the whole ring, the overall displacement level of the segmental lining is lower than that of the prestressed lining, the double-layer lining contact surface has a tendency to be detached, and with the increase of the structural prestress, the pressurized damage of the prestressed lining concrete develops gradually. Under the DWPC, the double-layer lining contact surface is completely closed under the action of internal water pressure, and the cracking risk of prestressed lining concrete increases with the decrease of prestress. Through numerical simulation, the reasonable range of prestressing force for shield tunnel lining is 68 %<em>σ</em>_con ∼ 137 %<em>σ</em>_con, and the results can provide a reference for the design and construction of prestressed double-layer lining structures of similar shield water tunnels.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106133"},"PeriodicalIF":6.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533597","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":"Method for determining yield state and new solutions for stress and displacement fields of cold region tunnels under freeze-thaw cycles","authors":"Benxian Gao ,&nbsp;Yanbin Luo ,&nbsp;Jianxun Chen ,&nbsp;Jieyu Bai ,&nbsp;Hua Luo","doi":"10.1016/j.tust.2024.106139","DOIUrl":"10.1016/j.tust.2024.106139","url":null,"abstract":"<div><div>The water-bearing surrounding rock in cold region tunnels is significantly affected by freeze-thaw (F-T) cycles generated by seasonal temperature changes, which can severely lead to tunnel lining failure due to increased loads. This study considers the non-uniform frost heave properties and the deterioration effects of F-T cycles on the surrounding rock. Six mechanical models for cold region tunnels are established based on the different yield states of frozen and unfrozen surrounding rock. Utilizing the unified strength theory, the solutions of stress and displacement fields for each model are derived, respectively, and a method for identifying the actual yield state of the tunnel is provided. The derived solutions are compared and verified, and the influence of various parameters on the solutions and yield states of cold region tunnels is explored. It is indicated herein that the proposed solutions have been validated by the results in the literature, demonstrating broad theoretical significance and practical engineering guidance value. When the F-T cycle counts increase from 0 to 75, the support pressure rises by 48.54%, and the plastic zone expands by 0.76 m. The deterioration effects of long-term F-T cycles on surrounding rocks should be quantified. As the intermediate principal stress effect increases, the support pressure decreases by 15.35%, and the development of the plastic zone is restricted. The unified strength theory should be used as the yield criterion. The greater the degree of non-uniform frost heave, the greater the load borne by the support structure. Insulation measures should be adopted to prevent excessive temperature gradients in the surrounding rock. In addition, failing to utilize the mechanical model corresponding to the actual yield state will result in significant calculation errors. The yield state determination method proposed in this study should be adopted. The results can offer theoretical references for designing cold region tunnels and safeguarding tunnel structures during service periods under F-T cycles.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"155 ","pages":"Article 106139"},"PeriodicalIF":6.7,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533004","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":"Seepage field and drainage system in the connection part of underwater tunnel based on conformal mapping method","authors":"Helin Fu ,&nbsp;Kaixun Hu ,&nbsp;Yimin Wu ,&nbsp;Yong Yu ,&nbsp;Wenjun Liu","doi":"10.1016/j.tust.2024.106146","DOIUrl":"10.1016/j.tust.2024.106146","url":null,"abstract":"<div><div>Composite construction methods may be adopted for some underwater tunnels due to complex geological conditions. However, the seepage field and the drainage system at connection part characterized by irregular cross-section are rarely reported. This study used the Zhujiangkou underwater tunnel as an engineering case, where the non-circular cross-section of the connection part was converted to the circular shape through the combination of the conformal mapping method and genetic algorithm. Additionally, the longitudinal seepage law in geotextile was developed, allowing for the theoretical deduction of the seepage field of tunnel with irregular cross-section while considering the role of the drainage system. The analytical results were validated through degradation tests and compared with numerical simulations and practical monitoring data. Moreover, the impacts of waterproofing and drainage system parameters on water inflow and water pressure were discussed. The results indicate that the water inflow increases as the distance between circumferential drainage pipes decreases and both the thickness and permeability coefficient of the geotextile increase, while the water pressure on lining decreases conversely, highlighting the significant influence of the drainage system. These findings can guide the design of the waterproofing and drainage system through parameter optimization for the consideration of safety and economy.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106146"},"PeriodicalIF":6.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554661","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":"Investigation into the properties of two-component backfilling grouts prepared by substituting bentonite with slurry from slurry shield tunnelling treated by a hydrocyclone","authors":"Dengfeng Wang ,&nbsp;Fanlu Min ,&nbsp;Zhen Li ,&nbsp;Lei Zhang ,&nbsp;Yazhou Zhang","doi":"10.1016/j.tust.2024.106142","DOIUrl":"10.1016/j.tust.2024.106142","url":null,"abstract":"","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106142"},"PeriodicalIF":6.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554662","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":"Dynamic planning of crowd evacuation path for metro station based on Dynamic Avoid Smoke A-Star algorithm","authors":"Songtao Zuo ,&nbsp;Zhanli Mao ,&nbsp;Chuangang Fan ,&nbsp;Xin Chen ,&nbsp;Meiling Gong ,&nbsp;Jianxing Ren ,&nbsp;Xiaoxiao Fan ,&nbsp;Yongnan Guo","doi":"10.1016/j.tust.2024.106145","DOIUrl":"10.1016/j.tust.2024.106145","url":null,"abstract":"<div><div>Considerable casualties can easily be caused once a fire occurs in a metro station, and a safe and effective evacuation path in time should be provided, taking on critical significance in the rapid evacuation of the crowd. In existing research, crowd evacuation paths have been generally planned without considering the fire environment and the real-time effect of fire products on the evacuation paths, such that the planned paths do not fit the realistic environment of crowd evacuation. An algorithm is proposed in this study to dynamically plan evacuation paths in fire scenarios in metro stations. First, the equivalent length of the path under the effect of fire on evacuation speed is determined in accordance with the effects of ambient temperature, visibility, and CO concentration, and then the fire risk model is built. Second, the fire risk model is incorporated into the A-Star algorithm, and the evaluation function of the A-Star algorithm is optimized, such that the determined path is capable of avoiding areas with higher fire risk. Subsequently, a dynamic update mechanism considering time factor is introduced to update the search environment information data of the algorithm in real time for dynamic path planning, with the aim of coping with the dynamically changing fire environment. Lastly, the A-Star algorithm is optimized, and the Dynamic Avoid-Smoke A-Star (DASA-Star) algorithm is built. As indicated by the simulation results, the DASA-Star algorithm is capable of making a trade-off between the fire risk and geometric length of the path in an underground station fire scenario and achieving dynamic planning of evacuation paths based on FDS fire simulation results. Accordingly, the algorithm conforms to the real-time requirements of path planning under fire conditions, and it is capable of more effectively planning the optimal evacuation path under the effect of fire.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106145"},"PeriodicalIF":6.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554663","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":"Mechanism of structural defects in cut-and-cover tunnels within high-fill regions and gradient pile foundation reinforcement technology","authors":"Qiang Xu ,&nbsp;Xiaohan Zhou ,&nbsp;Xinrong Liu ,&nbsp;Guanghua Yang ,&nbsp;Ben Xu ,&nbsp;Yiliang Tu","doi":"10.1016/j.tust.2024.106123","DOIUrl":"10.1016/j.tust.2024.106123","url":null,"abstract":"<div><div>Tunnel traverses high-fill soil-rock mixtures regions will often be susceptible to structural defects, which necessitate strata reinforcement. To mitigate the extent of these defects, this study employs a combination of model tests and numerical simulations to investigate the stability of tunnel structures. The mechanisms of structural defects were clarified, the influence of different soil-rock mixture strata shapes on structural defects was investigated, and a gradient pile foundation reinforcement technique was proposed based on this engineering case. The findings reveal that the primary manifestations of structural defects are various types of cracks, which developed in regard to the depth of the high-fill soil-rock mixture at the tunnel base, the self-settlement of the mixture, and the layer-by-layer backfilling at the tunnel vault. The differences between the model test and numerical simulation results are minimal, indicating that the shape of the soil-rock mixture stratum can significantly influence structural defects. The gradient pile reinforcement technology reduced tunnel settlement by up to 73.0%, while the foundation’s bearing capacity met the required standards, effectively controlling both tunnel settlement and structural defects. In terms of reinforcement for non-horizontal strata, gradient pile reinforcement technology demonstrates good adaptability, providing a feasible solution for similar engineering projects.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106123"},"PeriodicalIF":6.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446032","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}