Tunnelling and Underground Space Technology最新文献

{"title":"A novel longitudinal bending model of shield tunnel based on discretization of fiber section under the coupling of multiple factors","authors":"","doi":"10.1016/j.tust.2024.106063","DOIUrl":"10.1016/j.tust.2024.106063","url":null,"abstract":"<div><p>The longitudinal equivalent bending stiffness (LEBS) typically exhibits nonlinearity under the coupling of multiple environmental and construction loads. In this research, we propose the Circumferential Joint Fiber Section Model (CJFM) to analyze the longitudinal bending behavior affected by critical factors such as geometric, material, and contact nonlinearities, and the influence range of the circumferential joint. The performance of CJFM is then verified via classical analytical solutions and laboratory model experiments. Furthermore, the applicability of the proposed model is further confirmed based on the Zhanjiang Bay undersea tunnel in China. The results show that the CJFM accurately simulates the full evolution process of seven modes and employs different constitutive models. The longitudinal stress of typical section in Zhanjiang Bay undersea tunnel reveals a distinct pattern of alternating tension and compression from top to bottom, with a noticeable temporal variation of five stages. Utilizing the CJFM, a safety partition of bending mode is constructed, ranging from healthy to unsafe. Upon the estimated bending moment and axial force, the safety status of the test ring is consistently evaluated to be in normal service, and it is inferred that the subsequent state in future will maintained in normal service under similar circumstances.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0886779824004814/pdfft?md5=e601f65b4cba9fadf1f9f72db44c8cf8&pid=1-s2.0-S0886779824004814-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163324","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":"Analysis method of radon release during underground cavern excavation","authors":"","doi":"10.1016/j.tust.2024.106062","DOIUrl":"10.1016/j.tust.2024.106062","url":null,"abstract":"<div><p>Radon release during underground engineering excavation is mainly from the newly generated fracture surfaces of the rock mass rupture, and the accurate prediction of radon release depends on the quantitative characterization of the rock mass rupture. To examine the correlation between radon release and rock mass rupture, a series of triaxial compression radon release tests were carried out and the effective radon exhalation rate (<em>J</em>_eff) was defined, a linear function of rock fracture area and radon release was developed. Based on the continuous-discontinuous element method (CDEM), a quantitative equation between rock fracture degree (<em>D</em>) and radon release by numerical model for triaxial compression tests was obtained. Subsequently, a synthetic rock mass (SRM) method combining discrete fracture network (DFN) model and CDEM was used to analyze the scale dependence of radon release from rock mass rupture, and the representative element volume (REV) size of the radon release from rock mass rupture was determined. Radon release increases exponentially with increasing sample size. Radon release increases and then decreases with the increase of joint dip angle, however, radon release increases with the increase of joint trace length amplification factor. Additionally, an underground powerhouse excavation model to derive the evolution of radon release from the surrounding rock with the number of excavation layers was established. The results of this research can provide a basis for radon pollution control during underground engineering excavation.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163323","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":"Strengthening effect of the CFRP method on fire-damaged segments","authors":"","doi":"10.1016/j.tust.2024.105871","DOIUrl":"10.1016/j.tust.2024.105871","url":null,"abstract":"<div><p>To reveal the strengthening effect of the CFRP method on the fire-damaged segment. In this study, the fire-damaged segment was strengthened with the CFRP-PCM method and CFRP-sheet method, respectively. The crack development, deformation characteristics, failure mode, load-bearing behaviour and internal force evolution of the segment specimens were analysed. The results indicated that the CFRP-PCM method can improve the crack development of the segment, while the CFRP-sheet method can only prevent the crack initiation of the segment before tearing between the CFRP sheet and the segment. The fire-damaged segment strengthened by the CFRP-PCM method exhibited gradual deformation and failure characteristics, whereas the fire-damaged segment strengthened by the CFRP-sheet method exhibited sudden failure with no discernible damage characteristics. The CFRP-sheet method had a higher initial strengthening effect on the fire-damaged segment than the CFRP-PCM method before tearing between the CFRP sheet and the segment, while the strength utilisation rate of the CFRP grid was higher than that of the CFRP sheet. The CFRP method of strengthening the fire-damaged segment can improve the tensile strength of the tension zone, increase the sectional stiffness, and restore the load-bearing capacity; however, this comes at the expense of the deformation capacity. The study provides a reference value for the strengthening design of fire-damaged linings in shield tunnels.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S088677982400289X/pdfft?md5=a7d499e3f5a8959880b28a06fa714a5f&pid=1-s2.0-S088677982400289X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142158174","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":"Equivalent continuous numerical simulation of a large-scale underground powerhouse excavation considering the size effect of the jointed rock mass","authors":"","doi":"10.1016/j.tust.2024.106058","DOIUrl":"10.1016/j.tust.2024.106058","url":null,"abstract":"<div><p>For the stability analysis of the surrounding rock mass of an underground powerhouse, reliable mechanical parameters of the rock mass and appropriate analysis methods are highly important. This paper discusses the rationality of using the mechanical parameters of the representative volume element (RVE) of a jointed rock mass as equivalent mechanical parameters and using the equivalent continuity method to simulate the excavation of a large underground powerhouse in a jointed rock mass, with the underground powerhouse of the Wuyue pumped storage power station as an example. Initially, the discrete fracture network (DFN) and synthetic rock mass (SRM) of the jointed rock mass were established. The size of the RVE of the rock mass was determined to be 23 m × 23 m × 23 m through numerical tests. The mechanical parameters of the RVE were used as the equivalent mechanical parameters of the rock mass. Then, the two-dimensional numerical calculation of the excavation of the main powerhouse was carried out using the equivalent continuous method and the discontinuous method. The mean relative error between the deformation of the surrounding rock calculated by the two methods is 8.24 %, which shows that the equivalent continuous method can calculate the overall deformation after excavation of a large underground powerhouse in a jointed rock mass. Furthermore, the three-dimensional equivalent continuous numerical calculation of underground powerhouse excavation is carried out by using the equivalent mechanical parameters determined by the RVE and Hoek–Brown criterion. Compared with the actual measurement results of the multipoint displacement meter, the mean relative error of the calculation result based on the RVE is 12.37 %, and the mean relative error of the calculation result using the Hoek–Brown criterion is 20.37 %, indicating that the numerical calculation using the mechanical parameters of the RVE of the jointed rock mass as equivalent mechanical parameters can consider the size effect of the jointed rock mass and reduce the error of the numerical calculation. Our results are expected to provide guidance for evaluating the stability of an underground powerhouse.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151825","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":"Catastrophic failure mechanism of underground complexes under deep construction disturbance","authors":"","doi":"10.1016/j.tust.2024.106059","DOIUrl":"10.1016/j.tust.2024.106059","url":null,"abstract":"<div><p>The burgeoning demand for land resources in cities has spurred the development of intricate underground infrastructure networks. Therefore, evaluating the performance and stability of entire existing underground complexes in the event of construction-related disturbances becomes increasingly crucial for ensuring overall urban resilience. This paper adopts a coupled modeling technique of the Finite Element Method (FEM) and Smoothed Particle Hydrodynamics (SPH) for the analysis of catastrophic failure mechanisms in underground complexes, with a focus on disturbances due to nearby tunneling. Two-dimensional centrifuge model experiments were used to thoroughly calibrate the coupled FEM-SPH method, validating its accuracy and suitability for the simulation of soil–structure interaction problems. Subsequently, a full-scale integrated model of the underground complex and formation in a given area was established, including the subway network and highway system. Taking into account the longitudinal connections of the tunnel segments, the catastrophic coupling mechanisms related to construction disturbances in deep tunneling were investigated. The results indicate that collapsed soil caused by deep construction disturbances spreads through the gaps between the tunnels towards the ground, acting as a force-transmitting medium to correlate the deformations of the different structures. The response of the structures was evaluated using five different patterns of deformation, including tunnel settlement, dislocation, opening, rotation, and ovalization. In addition, the evolution of the performance of the underground complex during construction disturbances was analyzed using three types of indicators. Finally, the assessment of the catastrophic failure degree and the identification of vulnerable areas within the complex were carried out.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151826","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":"Constructing underground pedestrian networks: A model based on the source-sink theory and a case study of Xinjiekou in Nanjing City, China","authors":"","doi":"10.1016/j.tust.2024.106061","DOIUrl":"10.1016/j.tust.2024.106061","url":null,"abstract":"<div><p>Underground pedestrian networks (UPNs), serving as a comprehensive approach for utilising urban underground spaces to address connectivity and spatial challenges, have undergone significant development in numerous major city centres. Well-designed UPNs are pivotal in developing compact cities, bolstering urban resilience, enhancing urban transportation systems, fostering urban renewal, and facilitating sustainable urban development. This study explores the construction methodology of UPNs by utilising the source-sink theory and relevant models. Using Xinjiekou District in Nanjing City as a case study, this study employs the minimum cumulative resistance model to simulate a UPN and conduct analysis of pedestrian flow clustering on the simulation results. The findings demonstrate that our proposed method effectively elucidates and predicts the connectivity of UPNs, enabling us to construct an optimal network with minimal cost. Moreover, the simulation network significantly enhances the optimisation of pedestrian flow distribution. Building upon these simulation results, the UPN in the study area is optimised by integrating real-world conditions and conducting degree centrality analysis. The findings are then utilised to propose policy recommendations for UPN layout planning in urban centres. This study serves as a valuable reference for underground space planning in the study area and provides insights for UPN construction in other urban centres.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151827","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":"Performance and damage assessment of fault-crossing road tunnel subjected to internal boiling liquid expanding vapor explosion (BLEVE)","authors":"","doi":"10.1016/j.tust.2024.106056","DOIUrl":"10.1016/j.tust.2024.106056","url":null,"abstract":"<div><p>Road tunnels constructed in complex rock strata may encounter unfavourable geological formations such as rock faults. Grouting into rock faults around road tunnels or installing flexible joints for tunnel structures have been widely used in engineering practice to improve the performance of fault-crossing road tunnels against static and seismic loads. However, flexible joints with low stiffness and likely low strength may be subjected to direct explosion loads and their performance in resisting blast loads has not been investigated. In this study, the resistance of a typical fault-crossing road tunnel to an internal Boiling Liquid Expansion Vapour Explosion (BLEVE) caused by the rupture of a 20 m³ Liquified Petroleum Gas (LPG) tank is numerically investigated. The response and residual load-bearing capacity of the fault-crossing road tunnel with and without the grouting and rubber joints under the internal BLEVE are calculated and compared. It is found that the combined measures greatly enhance the BLEVE resistance of the fault-crossing road tunnel due to the fact that grouting greatly improves the mechanical properties of the fault-affected rock mass, and the rubber joints significantly attenuate the BLEVE-induced stress wave propagation inside the tunnel lining. In addition, parametric analyses are conducted to investigate the effects of the grouting and rubber joint configurations on the BLEVE resistance of the fault-crossing road tunnel. Damage criteria considering the tunnel’s residual load-bearing capacity (RLBC) are also established to evaluate the collapse risk and potential collapse zone of the fault-crossing road tunnel after being exposed to internal BLEVE. The results show that the potential collapse zones of the fault-crossing road tunnel along the longitudinal direction of the tunnel can be effectively reduced by increasing grouting thicknesses and installing narrower rubber joints.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0886779824004747/pdfft?md5=223f8d83046f8298a4aef284a368673c&pid=1-s2.0-S0886779824004747-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151824","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":"Long-term performance of subway tunnels induced by the symmetrical excavation of semicircular deep foundation pits in the Northeast Region hard silty clay","authors":"","doi":"10.1016/j.tust.2024.106052","DOIUrl":"10.1016/j.tust.2024.106052","url":null,"abstract":"<div><p>This paper presents the first large-scale deep foundation pit adjacent to an operational subway tunnel in the Northeast Region of China under hard silty clay conditions. To study the impact of the excavation on the existing subway, comprehensive field monitoring was conducted for nearly 3 years. Monitoring items include the tunnel bed displacement, vertical/horizontal convergence of tunnel structures, vertical/lateral deformation of the retaining piles, and surface settlement. In addition, in order to understand the response of soil deformation at different depths caused by excavation in this region, field monitoring tests of soil deformation at different depths were conducted. A thorough analysis of the deformation evolution of the tunnel structure, the retaining structure, and the soil is presented. The characteristics of tunnel-foundation pit coordination deformation under long-term excavation are summarized. Under different excavation activities at different proximity distances, the tunnel either settled or rose. Therefore, a three-dimensional numerical model was developed and a multi-parameter analysis was performed. The results indicate that the direction/magnitude of the tunnel structure deformation is closely related to the construction process and the proximity of the excavation. At the same time, the displacement of shallow soil is larger than that of deep soil due to the cumulative effect of displacement. Finally, the deformation properties of the tunnel and the soil are analyzed under different excavation depths, different proximity and different maintenance structure deformation modes. With the critical surface about 35 m away from the foundation pit boundary, the uplift zone and the settlement zone of the foundation pit split.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151822","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":"Study on the field monitoring, assessment and influence factors of pipe friction resistance in rock","authors":"","doi":"10.1016/j.tust.2024.106053","DOIUrl":"10.1016/j.tust.2024.106053","url":null,"abstract":"<div><p>Accurate assessment and prediction of the pipe friction resistance are crucial for designing the jacking force, arranging intermediate jacking stations, and setting the sediment removal timing in long-distance rock pipe jacking (PJ) projects. However, the applicability of pipe friction resistance calculation models for PJ in stable and unstable rock strata was not verified in sufficient cases. Besides, research on the assessment of specific skin friction and the primary factors influencing pipe friction resistance in rock strata remains scarce. In this study, field monitoring was conducted to first assess specific skin friction in long-distance deep-buried rock PJ projects under different geological conditions. Then, the applicability of pipe friction resistance calculation models for PJ in stable and unstable rock strata was verified. Finally, the primary factors influencing the friction resistance of pipes in rock strata were analyzed, including formation stability, lubricating mud and sediment, groundwater, pipe misalignment, and tunnel burial depth. The main conclusions are as follows: (1) in unstable strata, specific skin friction (M) can be considered ’very poor’, with the jacking length owing to the primary jacking station (L₀) being just 0.21–0.48 times the value of M in stable strata. The value of M in stable strata can be considered at least ’very good’ in the initial jacking stage and ’good’ in the normal jacking stage. (2) In stable strata, the pipe-slurry contact model with a pipe-rock contact angle (2θ) of 0° reflects the measured value of M in the early jacking stage. The pipe friction resistance calculation model established by <span><span>Deng et al. (2021)</span></span> with 2θ = 75° can conservatively estimate the value of M during the normal jacking stage. In unstable strata, the pipe-rock full contact model (2θ = 360°) can predict the value of M with an error of just 8 %. (3) The dynamic change in the pipe-rock contact state is affected by the sediment at the pipe bottom and bentonite mud buoyancy. When the sediment causes 2θ to be smaller than 30°, the pipe floats; otherwise, the pipe sinks. (4) A highly confined groundwater inrush sharply increases the pipe friction resistance within a small jacking range and maintains constant friction resistance. The friction caused by pipe misalignment deviation increases instantaneously and quickly decreases to the normal level after rectification. (5) The influence of tunnel burial depth on the pipe friction resistance can be ignored for deeply buried rock PJ engineering in stable rock strata. The results of this study are expected to be useful for future rock PJ projects because such results are rarely reported.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151823","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":"Rockburst early-warning method based on time series prediction of multiple acoustic emission parameters","authors":"","doi":"10.1016/j.tust.2024.106060","DOIUrl":"10.1016/j.tust.2024.106060","url":null,"abstract":"<div><p>Rockburst early-warning is crucial for ensuring safety in deep underground engineering. Existing methods primarily focus on classifying rockburst grades, making it challenging to provide timely warnings. This paper proposes a novel rockburst early-warning framework based on time series prediction of acoustic emission (AE) parameters. Six AE parameters (rise time, count, duration, amplitude, absolute energy, and peak frequency) were identified as potential indicators for rockburst early-warning based on rockburst tests. A sliding window method was applied to process normalized AE data, calculating statistical parameters of the local duration. An LSTM-based time series prediction model was developed to forecast the future evolution of these AE parameters. This, in turn, enabled the establishment of a comprehensive multi-indicator early-warning system. The Isolation Forest (IF) algorithm, an outlier detection method, was used to determine the warning thresholds for each indicator. The CRITIC weighting method was employed to integrate the six rockburst indicators into a single early-warning coefficient (<em>EC</em>), with <em>EC</em>=100 signifying the warning trigger condition. The results demonstrate that the proposed framework effectively captures the evolution trends of AE parameters, enabling proactive early warnings. This approach addresses the limitations of existing methods, such as reliance on experience for threshold determination, lack of a clear basis for multi-indicator weights, and difficulty in quantifying early-warning trigger conditions. The framework provides a new perspective for rockburst early-warning systems.</p></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142137395","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}