Tunnelling and Underground Space Technology最新文献

{"title":"Experimental study on multiple fire hazards both inside and outside a naturally ventilated tunnel: Burning rate and flame characteristics of unequal fires","authors":"Ao Jiao ,&nbsp;Wenxin Zeng ,&nbsp;Chuangang Fan ,&nbsp;Rongwei Bu ,&nbsp;Hao Chen ,&nbsp;Yihan Chen ,&nbsp;Baochao Xie ,&nbsp;Yuhao Li","doi":"10.1016/j.tust.2025.106442","DOIUrl":"10.1016/j.tust.2025.106442","url":null,"abstract":"<div><div>This study investigated the burning rate and flame characteristics of unequal fires separated inside and outside a naturally ventilated tunnel. Outside fire size and fire separating distance were varied. In this scenario, the asymmetric fire behaviors were formed by asymmetric airflow distribution induced by the unequal inside and outside fires. The variations of their fire behaviors were grouped into Regions Ⅰ and Ⅱ with the boundary of <em>S</em>/<em>d</em>_in = 1 (<em>S</em> is fire separating distance and <em>d</em>_in is inside fire size), but the inside and outside ones differ from each other. The outside flames were always tilted upstream with similar angles and heights, while the tilt direction of the inside flames changed with the increasing outside fire size in Region Ⅰ and the flame heights were lowered when <em>S</em>/<em>d</em>_in &gt; 3 (in Region Ⅱ-b). Moreover, the burning rate of the outside fire was lowered in Region Ⅰ, while that of the inside fire was lowered in Region Ⅱ-b. The discrepancy was due to the different influence ranges of fire interaction and heat feedback enhancement. The results and interaction mechanism were compared with those of equal inside and outside fires for analysis. The evolution of the flame tilt angles was theoretically analyzed and the correlations of the dimensionless flame heights and heat release rates were established.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106442"},"PeriodicalIF":6.7,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372227","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":"Investigating the impact of temperature recovery across different thermal activation scenarios of a real-world energy piled foundation","authors":"Arianna Lupattelli,&nbsp;Diana Salciarini","doi":"10.1016/j.tust.2025.106457","DOIUrl":"10.1016/j.tust.2025.106457","url":null,"abstract":"<div><div>Energy piles (EPs) exploiting low-enthalpy geothermal energy for the seasonal air conditioning of buildings are mature examples of Energy Geostructures (EGs), with several case studies all over the world showing satisfying performance for years. Over time, comprehensive research has explored and proven the potential of this technology, with a particular emphasis on assessing the performance of EP groups. This work presents a real case study of an energy-piled foundation, where all the piles have been equipped with pipes to potentially operate as heat exchangers with the ground. Based on the available data on the building design and the results of thermal property tests performed on soil samples collected on-site, a long-term thermo-mechanical analysis was carried out on a three-dimensional (3D) model of the soil-foundation system. Unlike previous studies, this work specifically examines the effects of selective pile activation and alternate-year thermal recovery on their long-term performance. The main objectives of this study are: <em>i)</em> to quantitatively assess the impact of seasonal variations in energy demand on soil temperature in shallow geothermal processes, given that maintaining a consistent ground temperature throughout the year is crucial for efficient heat exchange operations and long-term stability, and <em>ii)</em> to investigate how selectively activating specific parts of the foundation may provide advantages or disadvantages in terms of both mechanical performance and energy efficiency. By dividing the foundation piles into subgroups, three configurations of piles' thermal activation were analyzed to assess the influence of the alternate-year of temperature recovery on the system’s global performance. The research aims to optimize soil thermal recovery, mitigate thermal imbalances, and enhance the sustainability and operational effectiveness of shallow geothermal systems, offering insights crucial for the design of more efficient and resilient EGs. The results indicate that alternating-year configurations do not lead to improved soil thermal recovery, as evidenced by the thermal flux values at the pile-soil interface, while the spacing between active piles significantly influences the mechanical response by reducing stresses and thermal-induced displacements during inactive periods.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106457"},"PeriodicalIF":6.7,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349498","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":"A modified mechanical modeling of pipe-soil lateral/axial interactions incorporating pipe trajectory and contact surface characteristics","authors":"Xu Zhang ,&nbsp;Yuguang Cao ,&nbsp;Ying Zhen ,&nbsp;Mingxing Zhu ,&nbsp;Qiqi Deng ,&nbsp;Dongyuan Wang","doi":"10.1016/j.tust.2025.106443","DOIUrl":"10.1016/j.tust.2025.106443","url":null,"abstract":"<div><div>Accurately predicting pipeline mechanical behavior under ground movement relies on the precise determination of the <strong>Soil Resistance-Pipe Displacement (SR-PD)</strong> curve. Standard formulas, however, face significant challenges, including the omission of softening behavior after peak resistance, underestimation of ultimate resistance, and neglect of the non-uniform resistance distribution across the pipe cross-section. To overcome these challenges, this paper incorporates the Modified Mohr-Coulomb model and direct shear test data to characterize the behavior of sandy soil at the pipe-soil interface. A logarithmic spiral curve is employed to define the pipe’s trajectory in sandy soil, enabling an analysis of the stress state of the “pipe-wedge” structure during the elastic, hardening, and softening stages of sandy soil deformation. Three models are developed: MPSIM-L, which analyzes lateral resistances along the trajectory; MPSIM-A, which accounts for contributions of soil pressure, sand dilatancy, and cohesion to axial resistances; and MPSIM-LRD, which applies the finite difference method to calculate soil pressures at various locations within the pipe cross-section. The findings show that MPSIM-A and MPSIM-L reduce errors in predicting ultimate resistance by approximately 50% and 38.5%, respectively. Additionally, the resistance distribution predicted by MPSIM-LRD closely aligns with experimental data, demonstrating the accuracy and reliability of the modified models.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106443"},"PeriodicalIF":6.7,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349499","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":"Prediction of nonuniform large deformation in deep layered rock tunnels: Comprehensive application of data-driven and theoretical models","authors":"Tianxiang Song ,&nbsp;Yangyi Zhou ,&nbsp;Tao Chen ,&nbsp;Bentong Sun","doi":"10.1016/j.tust.2025.106448","DOIUrl":"10.1016/j.tust.2025.106448","url":null,"abstract":"<div><div>The irregular and significant deformation often encountered in the construction of deep-layered rock tunnels presents a notable challenge. Precisely assessing the anisotropic true triaxial compression (TTC) strength of layered rocks is pivotal for anticipating nonuniform deformation in these tunnels. Machine learning (ML) methods offer distinct advantages in terms of cost-effectiveness and accuracy when predicting rock strength. This study utilized four ML algorithms to forecast the TTC strength of layered rocks. The input parameters encompassed minimum and intermediate principal stresses, loading angles (β, ω), and maximum and minimum uniaxial compression strengths of the surrounding rock. The dataset comprised 1548 strength data points derived from laboratory tests on 42 types of layered rocks, along with 47,476 physics-guided data points generated using MATLAB based on the rock failure criteria proposed by <span><span>Feng et al. (2020)</span></span> and <span><span>Liu et al. (2023a)</span></span>. The entire dataset was partitioned into training and validation sets, with an additional test set employed to train and assess the performance of the proposed models. Additionally, an analytical solution for the redistribution stress state of the surrounding rock in deep-layered rock tunnels was derived. Introducing a nonuniform deformation prediction index (NDPI) based on the predicted TTC strength and stress state of the surrounding rock further enhanced the analysis. Evaluating NDPI values at various locations of tunnel sections offers a swift and effective means of anticipating nonuniform deformation during the tunnel design phase in layered rock tunnels. To validate its efficacy and reliability, the proposed method was applied to a deep carbonaceous slate tunnel.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106448"},"PeriodicalIF":6.7,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349501","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":"Monitoring-based analysis of the responses of upper structure and tunnel lining during shield tunneling with pile cutting","authors":"Zhi-Xiong Liu ,&nbsp;Xiao-Wei Ye ,&nbsp;Ke Song ,&nbsp;Ci-Rong Lu ,&nbsp;Yue-Jun Song ,&nbsp;Xiao-Jun Li ,&nbsp;Li-An Zhao","doi":"10.1016/j.tust.2025.106427","DOIUrl":"10.1016/j.tust.2025.106427","url":null,"abstract":"<div><div>Direct cutting of piles using a shield machine has become more common and inevitably causes additional deformation of the existing structures. To ensure the safety of pile cutting, a real-time field monitoring system was established to monitor the responses of upper structure and tunnel lining, and guide the adjustment of tunneling parameters. The underpass settlement and the mechanical behavior of the tunnel lining were analyzed based on the monitoring data. The underpass settlement presented a four-stage development pattern, closely related to the tunneling process. Results of correlation analysis suggest that earth pressure, rotational speed and grouting pressure have more significant influences on the underpass settlement. By adjusting these three parameters and advance rate, the underpass settlement in each stage was controlled within the acceptable range. For the shield tunnel, due to the difference in constraining effect of jack thrust, the rapid uplift of segmental rings mainly occurred in the working phase. As a result, the overall development of tunnel uplift during shield tunneling was characterized by a stepwise pattern. During the tunnel uplift, the circumferential stress sharply fluctuated and tended to recover with the stabilization of tunnel uplift, and the transverse deformation of the tunnel lining behaved as “horizontal ellipse” and “vertical ellipse”. The comparison results indicate that the residual pile and the reinforced soil have significant constraining effects on the tunnel uplift, while the residual pile increased the vertical convergence of the tunnel lining. In addition, the dislocation between segmental rings showed a rapid trend with the development of tunnel uplift. The monitored anomalous circumferential stress and observed defects in the tunnel lining were attributed to larger dislocation exceeding 8.0 mm.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106427"},"PeriodicalIF":6.7,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349497","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":"Mechanical behavior and mitigation strategies of rectangular subway tunnels in soil under multiple normal fault dislocations","authors":"Huiling Zhao,&nbsp;Liming Liu","doi":"10.1016/j.tust.2025.106431","DOIUrl":"10.1016/j.tust.2025.106431","url":null,"abstract":"<div><div>Subway tunnels with rectangular cross-sections in soil layers are susceptible to damage from fault dislocations, particularly when multiple faults are involved. The interaction between tunnel structures and multiple fault displacements can lead to significant stress and cumulative damage. The focus of this study is to investigate the mechanical behavior of a rectangular subway tunnel under the influence of multiple normal fault dislocations using validated numerical simulations. By analyzing the cumulative damage effects and the impact range from these fault displacements, the study proposes defense strategies and mitigation measures to enhance tunnel safety. The results show that tension damage occurs at the tunnel crown in the footwall and the invert in the hanging wall, and tension-bending-shear damage was observed at the tunnel sidewalls at the fault. Compared to horseshoe-shaped tunnels, rectangular tunnels exhibit a more uneven stress distribution across section, with tensile stress up to 5 times higher. Simultaneous displacements of multiple faults result in high tensile stress, especially at the crown and invert, while sequential fault dislocations cause progressive damage in these areas, shifting the stress to the sidewalls with a 50% reduction. The cumulative plastic strain from sequential displacements is three times greater than that from simultaneous displacements. In areas with closely spaced faults, overlapping damage zones can occur. To mitigate these effects, anti-fault measures such as deformation joints and enlarged tunnel cross-sections are recommended, along with enhanced waterproofing solutions, including waterstop strips and embedded grouting pipes. These findings offer valuable insights into ensuring the safety of tunnels in fault-prone regions and provide practical strategies for mitigating fault-induced damage.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106431"},"PeriodicalIF":6.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349681","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":"Full-scale experimental study on the natural gas explosion mechanism in utility tunnels","authors":"Yonghong Gao ,&nbsp;Yapeng Duan ,&nbsp;Hao Wu ,&nbsp;Kai Xin ,&nbsp;Chaoyuan Huang ,&nbsp;Liqiang Zhou ,&nbsp;Dongyang Li ,&nbsp;Zicong Wang","doi":"10.1016/j.tust.2025.106460","DOIUrl":"10.1016/j.tust.2025.106460","url":null,"abstract":"<div><div>Utility tunnels are important underground spaces for the centralised storage of municipal pipelines, and their safe and efficient operation is related to city stability. As important and dangerous municipal pipelines, natural gas pipelines pose great risks to the safe operation of utility tunnels. To reveal the mechanism and damage of natural gas explosions in utility tunnels and reduce the harm of natural gas pipeline accidents to the overall structure of utility tunnels, a field test was performed for the first time in a full-scale double-cabin utility tunnel with a cross-section of 6.75 × 3.8 m and a total length of 42 m. The internal net size of the gas cabin where the test was conducted was 2.1 × 3 m. The experiment uses a methane-free diffusion gas cloud as the basic test object and considers the influence of the gas cloud volume, gas composition and other factors. The experiment revealed that a gas explosion in a utility tunnel can be divided into two stages: laminar combustion and turbulent combustion. The peak load in laminar combustion is small and unaffected by the gas cloud volume, whereas the peak load in turbulent combustion increases with increasing gas cloud volume. When the volume of the leaked gas cloud exceeds a certain proportion, the gas explosion load surges at the mouth of the structure, which aggravates the damage consequences. In practical engineering, owing to the insufficient combination of gas and oxygen in the air in the state of free diffusion, the maximum explosion load occurs when the proportion of gas is greater than 9.5 %. The test results effectively verify the results of extended numerical simulations and guide the protection against gas explosion accidents in utility tunnels and other tunnel spaces.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106460"},"PeriodicalIF":6.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143199380","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":"Bidirectional denoising method based on Fast Fourier transform analysis for TBM field penetration data","authors":"Wenkun Yang ,&nbsp;Zuyu Chen ,&nbsp;Haitao Zhao ,&nbsp;Jianchun Li ,&nbsp;Shuo Chen ,&nbsp;Chong Shi","doi":"10.1016/j.tust.2025.106436","DOIUrl":"10.1016/j.tust.2025.106436","url":null,"abstract":"<div><div>The dynamic interaction of rock and tunnel boring machine (TBM) in the penetration process makes a large amount of high-frequency noise in field penetration data. This noise prevents related analysis in rock-cutting processes, TBM performance prediction, and geological condition recognition. Although some endeavors provide empirical denoising threshold values, formulas, and optimization methods, fewer studies offer a solid physical foundation for selecting denoising parameters and reducing time-delay distortion for denoised signals. This study proposed a Fast Fourier Transform-based bidirectional filtering method for noise reduction of TBM operating data. Firstly, a denoising parameter selection algorithm for low-pass filters is established by analyzing the power spectrum density distribution of operating parameters in the frequency domain. Then, a standardized digital filter design and bidirectional filtering flowchart are developed. Finally, field data from penetration and free rotating tests from two water diversion tunnels are employed to verify the proposed denoising method, followed by the engineering applications. Results reveal that (1) The frequency domain amplitude of operating data shows a rapid decrease trend while larger values are distributed in frequency less than 0.1. (2) The torque intrinsic frequency obtained from the field free rotating test of the cutterhead facilitates determining the cutoff frequency of a low-pass filter. (3) The proposed bidirectional filtering method achieves an excellent denoising effect in eliminating time delay behavior. (4) Engineering application of the proposed method improves the fitting quality of the boreability index to a great degree. This study is significant for enhancing filter design efficiency and reducing data processing costs for TBM large-scale field data obtained in medium to strong rock with a sampling rate of less than 1 Hz/s.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106436"},"PeriodicalIF":6.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143199378","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":"Influence of bond defects on the pullout response of grouted rockbolts: Analytical study and experimental validation","authors":"Yan-Jie Wang ,&nbsp;Hong-Bo Liu ,&nbsp;Zhi-Min Wu ,&nbsp;Yong-Qin Liang ,&nbsp;Jia-Qi Yang ,&nbsp;Meng-Di Jia","doi":"10.1016/j.tust.2025.106438","DOIUrl":"10.1016/j.tust.2025.106438","url":null,"abstract":"<div><div>Rockbolts have been proven to be an effective and efficient technique to strengthen and retrofit rock masses in civil engineering. The stress transfer mechanism at the bolt-grout interface has been recognized as one of the key factors affecting the reinforcement effectiveness. In practice, bond defects are commonly observed at the interface owing to poor grouting or environmental deterioration during service life, which leads to the degradation of the bonding performance and even unexpected structural failure in severe cases. This paper develops an analytical model to predict the full-range pullout response of grouted rockbolts with bond defects. The model involves closed-form solutions for the load–displacement curve, stress distribution and peak load and takes into account the influences of the defect length and location, embedded length, and interfacial friction. The proposed solution presents a notable advantage in practical design as it highlights the key behavioural differences between short and long rockbolts and enables a theoretical estimation of the effective embedment length without experimental calibrations. An experimental study on the influence of interfacial bond defects on the rockbolt pullout behavior is designed, considering different defect lengths, borehole diameters, and bond lengths. After the developed model is verified with the self-conducted experimental results and the data collated from the literature, a sensitive analysis was conducted to quantify the relation between bond defects and structural responses. It is found that the proposed model can predict the pullout response of grouted rockbolts with bond defects with reasonable accuracy. The results also indicate that for rockbolts with an embedded length slightly greater than <em>L</em>_eff, increasing defect length from 10%<em>L</em>_eff to 30%<em>L</em>_eff can result in a load capacity reduction of exceeding 10% due to the increased effective embedment length. Defects located close to the loaded end, within high stress zones, have a more pronounced impact on the load response and the effective embedment length compared to those positioned near the free end in lower stress zones. The present study can provide guidelines for practical design when a bond defect is ducted during inspection, enabling a more accurate performance evaluation of grouted rockbolt systems.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106438"},"PeriodicalIF":6.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143199377","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":"Seismic fragility assessment of utility tunnel and internal pipeline system","authors":"Jinqiang Li ,&nbsp;Zilan Zhong ,&nbsp;Kaiming Bi ,&nbsp;Hong Hao","doi":"10.1016/j.tust.2025.106441","DOIUrl":"10.1016/j.tust.2025.106441","url":null,"abstract":"<div><div>Probability-based seismic fragility analysis provides a quantitative evaluation of the seismic performance exhibited by structures. This study introduces a framework to perform seismic fragility analysis of utility tunnel and internal pipeline system considering wave passage effect of the ground motion spatial variation. The numerical model of a double-beam system resting on a nonlinear foundation is established to simulate the soil-tunnel-pipeline interactions. 17 pairs of earthquake records are chosen and scaled as inputs at the outcrop. One-dimensional (1D) free-field analyses are conducted to obtain the ground motion time histories at the bottom slab of the utility tunnel, and then incremental dynamic analysis (IDA) is performed for the utility tunnel-internal pipeline system. The damage states (DSs) are defined by the maximum joint opening for the utility tunnel and maximum strain for the internal pipeline, and the peak bedrock velocity (PBV) is determined to be the most representative intensity measure (IM) for developing the seismic fragility curves. The seismic fragility curves of the system are constructed using the joint probabilistic seismic demand model (JPSDM) and Monte Carlo sampling method. The research findings indicate that: (1) the framework proposed in this study is suitable for the fragility assessment of long-extended utility tunnel-internal pipeline system; (2) the utility tunnel and internal pipeline as a system exhibit greater fragility compared to either one of the components, and the JPSDM and Monte Carlo sampling method for the system fragility analysis is more precise than the first-order bound method; (3) the proposed fragility curves in this study provide quantitative damage probabilities for the individual components and system under different seismic intensity levels. (4) The IM values corresponding to 50% exceedance failure probability of the whole system is 1%–3% lager than that of the upper bounds, and it is 3% to 5% less than that of the lower bounds. The conservative upper bound is a more suitable approximation for system fragility. (5) It should be noted that the obtained fragility curves are valid for the considered tunnel-pipeline structure and site conditions. For different tunnel structures and site conditions, the fragility curves can be constructed following the same steps outlined in this study.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":"158 ","pages":"Article 106441"},"PeriodicalIF":6.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143199376","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}