Tunnelling and Underground Space Technology最新文献

{"title":"A rapid method for measuring the rock brittleness index: Rapid characterization of rock brittleness based on LIBS technology","authors":"Qinghe Zhang ,&nbsp;Weiguo Li ,&nbsp;Liang Yuan ,&nbsp;Chao Liang ,&nbsp;Honggui Pan","doi":"10.1016/j.tust.2024.106143","DOIUrl":"10.1016/j.tust.2024.106143","url":null,"abstract":"<div><div>The brittle index is a crucial indicator in the assessment of rockbursts. The mineral brittle index (MBI) is widely utilized due to its simplicity and accessibility. However, the lengthy and inefficient mineral composition testing cycle presents a significant challenge. A novel approach using laser-induced breakdown spectroscopy (LIBS) to rapidly convert spectral elements into minerals and measure the rock brittleness index was introduced in this paper. The laser spectra of metamorphic sandstone and granite were measured by LIBS, and some rock elements were tested by X-ray fluorescence (XRF) to construct a spectral-elemental model. Furthermore, the mineral composition of the rocks was determined by X-ray diffraction (XRD). Eight major elements, Si, Al, K, Ca, Na, Fe, Mg, and Ti, were selected as independent variables. Element-mineral correlation analysis was performed using centered log-ratio transformation (CLR) processing. A random forest regression (RF-R) element-mineral transformation model was established for rapid conversion of spectral-element-mineral brittle index. Finally, mechanical testing of rock embrittlement in the DJ Tunnel was conducted to verify the efficacy of MBI in characterizing rock embrittlement in the DJ Tunnel. The results demonstrate that predicted values of mineral compositions are in good agreement with experimental values and that predicted values of brittleness indices are also in good agreement with experimental values. The rapid and effective application of LIBS in determining rock mineral composition and rock brittleness index has been realised, which is of great significance for further realising the rapid assessment of rock brittleness and rockburst prediction at engineering sites.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106143"},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442363","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":"Time-arrival pickup method of tunnel water inrush microseismic signals based on kurtosis value and AIC method","authors":"Hao Jin ,&nbsp;Liping Li ,&nbsp;Shuai Cheng ,&nbsp;Xingyuan Li","doi":"10.1016/j.tust.2024.106135","DOIUrl":"10.1016/j.tust.2024.106135","url":null,"abstract":"<div><div>One of the main factors affecting microseismic positioning is the travel time of microseismic waves, that is, the accuracy of picking up microseismic waves when they arrive. Although the manual pick-up has high accuracy in the arrival pick-up of microseismic signals, it has low working efficiency and is seriously affected by human activities, so it is difficult to cope with the huge amount of microseismic information. In order to solve the above problems, this paper proposes a K-AIC microseismic signal arrival pick-up method based on the fusion of the kurtosis value of higher-order statistics (PAI-K) and the Akachi information criterion (AIC). This method not only effectively reduces the dependence of kurtosis method on the size of sliding time window, but also solves the problems of weak anti-noise ability of AIC method and poor pick-up accuracy of low signal-to-noise ratio signal. By comparing the kurtosis, skewness, AIC method and artificial average picking results, the accuracy of the picking results proposed in this paper is verified by using the microseismic signals of water inrush obtained by indoor model test and the microseismic signals measured on site.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106135"},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442362","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":"Intelligent prediction and visual optimization of surface settlement induced by earth pressure balance shield tunneling","authors":"Chuanqi Li ,&nbsp;Daniel Dias","doi":"10.1016/j.tust.2024.106138","DOIUrl":"10.1016/j.tust.2024.106138","url":null,"abstract":"<div><div>Surface settlement (Ss) caused by earth pressure balance (EPB) shield tunneling is a threat to the safety of surface buildings and underground tunnel structures. To that end, a novel intelligent model named the beluga whale optimization-based kernel-extreme learning machine (BWO-KELM) model is proposed to predict the Ss. 148 monitored data with three categories of eight features collected from three tunnel projects are adopted to train the proposed models. The results of model evaluation indicate that the BWO-KELM model established by using eight features achieve the most satisfactory performance indices (determination coefficient (R²), root mean square error (RMSE), variance accounted for (VAF), and the prediction accuracy (U1)) in both training and testing phases, i.e., R² (0.9544 and 0.9481), RMSE (3.4948 and 4.3239), VAF (95.4380 % and 94.8875 %), and U1 (0.0833 and 0.0938). Then, the model interpretability is enhanced by using the feature importance (FI) and Shapley additive explanations (SHAP) method. The results show that the mean moisture content (MC) of the soil layers is the most important feature for the Ss prediction. Finally, a visualization program is established to improve the prediction efficiency of Ss, reliability of risk assessment, and rationality of tunnel designs. This paper provides a novel intelligent model paradigm and a visualization program with a strong application for solving the problems induced by EPB shield tunneling.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106138"},"PeriodicalIF":6.7,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438023","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":"Energy evolution and failure mechanism of tunnel dynamic unloading in deep rock mass abounding in closable minor joints","authors":"Peng Siyu ,&nbsp;Li Xibing ,&nbsp;Gao Jingyao ,&nbsp;Liang Lisha","doi":"10.1016/j.tust.2024.106132","DOIUrl":"10.1016/j.tust.2024.106132","url":null,"abstract":"<div><div>Discontinuities, ranging from micro to macro, are prevalent in natural rocks, especially deep brittle rock masses subjected to high in-situ stress. Previous studies on the unloading of deep tunnels have focused on large-scale discontinuities and have paid little attention to ubiquitous minor joints. These compactable joints affect static performance (strength and deformation characteristics) and dynamic response (stress wave concentration and dispersion). Through modelling, calibration, and validation, the jointed rock mass model in this study can demonstrate nonlinear deformation behaviour under static compression and increased wave velocity with increasing confining pressure under dynamic loading. Then, the Fourier transform method is utilised to solve the elastic theory solution of exponential unloading, and the excavation relaxation method is employed to simulate the tunnel unloading process in Particle Flow Code. The accuracy of the simulation process and measurement are analysed by comparing the theoretical solutions and the simulation results. The dynamic stress, failure pattern, and energy evolution of tunnel unloading in jointed rock masses are analysed from three influencing factors: unloading rate, lateral pressure coefficient, and dip angle distribution. Results indicate that joints are dynamic disturbance amplifiers near the tunnel and reducers at greater distances; additionally, the increase in the unloading rate will intensify these effects. Initial joint characteristics and in-situ stress determine the distribution of open joints and, thus, the wavefront shape. When most joints are closed under in-situ stress with low lateral coefficients, more severe tensile failure occurs in the direction perpendicular to the joint dip angle; conversely, when these joints are open, more severe shear damage will occur along the direction of the joint. The kinetic energy core shifts marginally from the direction of maximal principal stress towards the vertical of the joint dip angle, indicating that existing projects in this direction will be disturbed later but severely. Therefore, compactable minor joints should be considered to comprehend the dynamic response of tunnel unloading and to evaluate surrounding rock disturbance and failure.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"154 ","pages":"Article 106132"},"PeriodicalIF":6.7,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433659","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":"Deep-learning-based longitudinal joint opening detection method for metro shield tunnel","authors":"Anbin Yu ,&nbsp;Wensheng Mei","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":"154 ","pages":"Article 106108"},"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":"Zhihe Su ,&nbsp;Yanfeng Li ,&nbsp;Hua Zhong ,&nbsp;Junmei Li ,&nbsp;Boyu Li ,&nbsp;Siyan Kang ,&nbsp;Youbo Huang","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":"154 ","pages":"Article 106141"},"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":"Effect of borehole deviation on raise formation via long-hole raise blasting","authors":"Xianyang Qiu ,&nbsp;Wenbo Shen ,&nbsp;Xiuzhi Shi ,&nbsp;Ming Tao ,&nbsp;Xiaoyuan Li ,&nbsp;Wei Zhi","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":"154 ","pages":"Article 106136"},"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":"New limit states for the seismic fragility assessment of circular tunnels: Application in case of tunnels in clayey soil deposits","authors":"Grigorios Tsinidis ,&nbsp;Sotiria Stefanidou ,&nbsp;Anna Karatzetzou","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":"154 ","pages":"Article 106129"},"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":"Unreinforced construction techniques: ECC-based unreinforced shield tunnel segment joints for enhancing underground infrastructure resilience","authors":"Minjin Cai ,&nbsp;Hehua Zhu ,&nbsp;Shuwei Zhou ,&nbsp;Timon Rabczuk ,&nbsp;Xiaoying Zhuang","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":"154 ","pages":"Article 106119"},"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":"Zhenji Zheng ,&nbsp;Xiaojie Xue ,&nbsp;Dong Su ,&nbsp;Jianfu Chen ,&nbsp;Tong Qiu ,&nbsp;Peng Chen ,&nbsp;Dianyan Xie ,&nbsp;Linjian Su ,&nbsp;Weijie Chen ,&nbsp;Shuhua Huang ,&nbsp;Xiangsheng Chen","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":"154 ","pages":"Article 106125"},"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}