Tunnelling and Underground Space Technology最新文献

{"title":"Efficient automated method for characterizing discontinuities in tunnel face rock mass point clouds","authors":"","doi":"10.1016/j.tust.2024.106117","DOIUrl":"10.1016/j.tust.2024.106117","url":null,"abstract":"<div><div>Current methods for identifying discontinuities in rock mass point clouds do not fully consider the unique characteristics of tunnel face rock masses. Excavation profiles reduce the accuracy of discontinuity characterization, and the short exposure time of tunnel face rock masses necessitates more efficient identification methods to guide excavation and support strategies. To address these issues, this paper proposes a new method for quickly characterizing discontinuities in tunnel face rock mass point clouds. This method automatically calculates the optimal tunnel face plane and uses distance thresholds to segment the tunnel face rock mass area from the excavation profile area, eliminating the influence of excavation profiles. Additionally, an optimized fuzzy C-means (OFCM) algorithm is designed to improve the accuracy and efficiency of discontinuity identification. The superiority of this method is demonstrated through three examples: polyhedral point clouds, a slope rock mass, and a tunnel face rock mass. In the slope point cloud test, the proposed method resulted in a dip difference of 2° and a dip direction difference of 0.6° compared with the DSE method, with an identification time of 52 s, compared with 7 min and 15 s for the DSE method. In a real tunnel face application in northwestern China, the proposed method showed an average difference from manual field measurements of 4.8° in the dip direction and 5° in the dip direction, with an identification time of 19 s, compared with 2 min and 52 s for the DSE method. Finally, this paper discusses the impact of distance threshold selection on the segmentation results and further verifies the method’s generality through applications on four other tunnel faces. These results indicate that the proposed method is highly accurate and efficient in identifying discontinuities in tunnel face rock masses and can be effectively applied in practical engineering.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428232","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":"Seizing the opportunity of energy retrofitting of existing tunnels","authors":"","doi":"10.1016/j.tust.2024.106109","DOIUrl":"10.1016/j.tust.2024.106109","url":null,"abstract":"<div><div>Energy tunnels have emerged as systems that can contribute to the production of clean, renewable thermal energy. Nevertheless, so far applications have been related almost exclusively to new tunnelling projects. Accordingly, no systematic methodologies for the heat exchange instrumentation of existing tunnels have been proposed up until now. Starting from the valuable experience gained from different energy tunnel testbeds worldwide, this paper proposes two approaches that would allow the thermal activation of the existing heritage of tunnels. Different solutions are conceived for both approaches to fit various existing tunnel decay contexts and diverse levels of refurbishment necessity. These are illustrated, outlining characteristics and advantages, describing expected installation details and issues and analysing the possibility of real implementations. The geothermal potential of such solutions is assessed through thermo-hydraulic numerical modelling. Finally, with the aim of investigating their economic attractiveness and profitability, a brief economic analysis is drawn up, considering the geothermal energy produced and the costs involved in installing and running the systems.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428477","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":"Numerical implementation of a hydraulic interaction creep model and its application to the support reinforcement of water-rich cracked tunnel","authors":"","doi":"10.1016/j.tust.2024.106098","DOIUrl":"10.1016/j.tust.2024.106098","url":null,"abstract":"<div><div>To solve the problem of cracks in the secondary lining of the Yanglin Tunnel caused by the creep of water-rich surrounding rock, this study established a rock creep model of hydraulic interaction based on rock creep theory, fractional calculus theory, damage mechanics theory, and effective stress principle. Based on the secondary development module of the numerical computation software, a rock creep model of hydraulic interaction was embedded in the software to verify the model. In addition, a new support scheme was developed using the convergence-confinement and orthogonal experimental methods. Furthermore, a newly developed rock creep model was used to conduct a numerical simulation analysis of the new support scheme for the cracked section of the secondary lining of the Yanglin Tunnel under hydraulic interaction, verifying the long-term stability of the new support. The results were as follows. (1) Under hydraulic interaction, the established rock creep model effectively simulated the creep calculation process of standard rock samples, and the numerical calculation results were consistent with the experimental results. (2) The new support scheme significantly controlled the displacement changes in the surrounding rock and significantly reduced the growth rate of the crown displacement and clearance convergence. The final numerical calculation results converged and the displacement stabilized, indicating that the new support scheme had an ideal controlling effect on the displacement of the surrounding rock. (3) A numerical simulation analysis was conducted to optimize the support for the cracked section of the tunnel lining using a developed rock creep model under hydraulic interaction. The calculation results aligned with the actual engineering requirements, indicating that the rock creep model under the hydraulic interaction of secondary development can effectively simulate the creep calculation process of tunnel construction, thereby reflecting the validity and accuracy of the program. The proposed support scheme was applied to the reconstruction of a cracked section of the secondary lining of the Yanglin Tunnel.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427714","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":"Rheological characteristics and model applicability of shield tunnel backfilling grouts with supplementary cementitious materials","authors":"","doi":"10.1016/j.tust.2024.106121","DOIUrl":"10.1016/j.tust.2024.106121","url":null,"abstract":"<div><div>Rheological properties are essential in determining how effective grouting is during the shield tunneling process. Additionally, they form the basis for developing penetration and diffusion models for grout in the surrounding layers. Despite extensive research on the rheological properties of traditional cement-based grouts informing engineering practices, the specific influence patterns and mechanisms related to the rheological properties of grout mixtures containing three industrial solid wastes—fly ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBS)—as supplementary cementitious materials (SCMs) remain poorly understood. Therefore, this study conducted rheological tests on fresh grout by a new advanced rheometer MCR302e, varying the content of FA, SF, and GGBS.</div><div>Results show that the modified Bingham and Herschel-Bulkley models proved more effective than the Bingham model in characterizing the rheological behavior of fresh grout. The modified Bingham model demonstrates superior applicability among these models, while the Herschel-Bulkley model presents better stability. The yield stress and plastic viscosity initially increase and then decrease with the addition of FA and GGBS, whereas, with SF, they show a decreasing trend followed by an increase. The thixotropy initially increases and then decreases with the addition of FA and GGBS while it continuously increases with the addition of SF. Furthermore, experimental results demonstrate that including 60% FA content alone results in the most significant improvement in the rheological properties of fresh grout. Compared to using just 60 % FA, the mix of FA and SF mostly increases the yield stress, while the mix of FA and GGBS mainly increases the plastic viscosity. For shield tunnel construction in Nanning, it is recommended to use more than 60% FA, over 2% SF, and no more than 20% GGBS.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428227","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":"The influence of constitutive models for sprayed concrete on the design of tunnel junctions","authors":"","doi":"10.1016/j.tust.2024.106113","DOIUrl":"10.1016/j.tust.2024.106113","url":null,"abstract":"<div><div>This study presents a comprehensive analysis of numerical modelling techniques applied to the design and assessment of sprayed concrete-lined (SCL) tunnel junctions, focusing on the lining performance. The approach integrates advanced constitutive models to simulate both ground and lining responses, aiming to provide a robust understanding of tunnel behaviour under a realistically simulated construction sequence. Notable features of the modelling approach include nonlinear elastoplastic models for ground strata, depth-varying properties, variable K0 and pore pressure profiles, and step-by-step construction of cross-passages. The constitutive models for the ground have been validated against real site data, employing moderately conservative input parameters to ensure realistic comparisons with monitoring data.</div><div>Results from numerical modelling offer insights into the lining movements, strains and loads at tunnel junctions. Notably, the choice of constitutive model for the lining significantly influences predicted behaviour, with nonlinear elastic models generally exhibiting larger but more localised movements and strains compared to linear elastic models. Furthermore, the study suggests potential optimisations in tunnel design, such as the reduction or elimination of reinforcement in thickening layers, based on the enhanced understanding provided by 3D numerical modelling. This underscores the value of this approach when considering environmental factors, such as carbon footprint reduction, in the design process.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428478","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":"Reliable simulation analysis for high-temperature inrush water hazard based on the digital twin model of tunnel geological environment","authors":"","doi":"10.1016/j.tust.2024.106110","DOIUrl":"10.1016/j.tust.2024.106110","url":null,"abstract":"<div><div>In complex mountainous terrains, tunnel construction faces unique challenges from high-temperature water inrush hazards, a systemic risk arising from the interplay of stress, seepage, and temperature fields. Traditional simulation methods, focusing on isolated disaster scenarios, fall short in addressing the multifaceted nature of these risks due to geological ambiguity and data incompleteness. Digital twin technology presents an effective solution to these challenges; however, its core challenge lies in how to utilize digital twin technology for data-model-co-driven simulation analysis of coupled multi-physical fields in situations of incomplete data. This paper introduces a digital twin paradigm for the simulation analysis of water inrush, which significantly enhances efficiency and accuracy through the integration of advanced machine learning and finite element analysis techniques. Specifically, this is achieved by combining a high-precision geological modeling method based on Gaussian Processes (GP) with a parameter calibration method through Gaussian Process-Differential Evolution (GP-DE) back-analysis. Firstly, a voxel structure is utilized to integrate the multi-field attribute features of the tunnel environment. Secondly, through the integration of multi-source advanced geological prediction data, we construct a dynamic digital twin model of the tunnel environment leveraging machine learning techniques. To overcome the issue of low modeling accuracy, the GP is employed, enhancing the exploitation of latent information within multi-source geophysical data. Lastly, we utilize the GP-DE back-analysis method to calibrate the parameters of the tunnel environment, thereby enhancing the precision and reliability of water inrush simulations. The method has been validated through application to a section of an ultra-high-temperature water inrush tunnel in China, featuring a burial depth of 230 meters. The accuracy of the method is corroborated by the monitoring data from the tunnel, supporting dynamic optimization design and safety prevention measures during construction.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428476","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 unified constitutive model for salt rocks under triaxial creep-fatigue loading conditions","authors":"","doi":"10.1016/j.tust.2024.106116","DOIUrl":"10.1016/j.tust.2024.106116","url":null,"abstract":"<div><div>The salt cavern compressed air energy storage (CAES) reservoir undergoes periodic cyclic gas injection and production, which induce coupled fatigue-creep effects on the surrounding rock during operation. In this work, a new constitutive model was developed for salt rocks, and it uses the traditional Norton model to describe the hardening degree with state variables. The fatigue-creep mechanical properties were investigated, the model was validated, and the model parameters were analyzed using triaxial continuous and interval fatigue tests. The findings were as followed: (1) Increasing the time interval will result in a higher residual strain and a shorter fatigue life; the confining pressures increases the compressive strength of salt rock. (2) The model only needs to adjust two parameters to accurately fit the fatigue-creep deformations behavior of salt rock, and it effectively characterizes the relationship between deformation and stress routes. (3) In the model, parameters <em>m</em> and <em>k</em> play a role through state variables. Parameter <em>m</em> affects the magnitude of the overall deformation and the length of the deceleration stage. Parameter <em>k</em> controls the bending of the curve, and has a more sensitive influence on the model. (4) Compared with that of the continuous fatigue model, the floating range of parameters <em>m</em> and <em>k</em> in the interval fatigue model is less than 10%. The model can adapt to the influence of time interval on rock deformation and more accurately predict the deformations of the salt rock surrounding the salt cavern reservoir.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428230","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":"Anchorage mechanism and parametric analysis of a novel interface-shear-stress-dispersing bolt","authors":"","doi":"10.1016/j.tust.2024.106118","DOIUrl":"10.1016/j.tust.2024.106118","url":null,"abstract":"<div><div>Squeezed large deformation of surrounding rock is frequently encountered in high geo-stress soft rock projects. Conventional bolt support often encounters the problems of insufficient anchorage force or anchors being pulled out, which seriously affects the safety of deep soft rock projects. In view of this, this study develops a novel interface-shear-stress-dispersing (ISSD) bolt with high strength and excellent deformability. The ISSD bolt is composed of the smooth rebar, rough rebar, and anchors, where the smooth rebar is further divided into several segments by anchors. The anchor consists of a hollow cylinder with a height of 0.10 m, whose inner diameter is equal to the diameter of smooth rebar (<em>D</em>₁) while outer diameter (<em>D</em>₂) matches the diameter of borehole (<em>D</em>₃). Analysis of the anchorage mechanism of the ISSD bolt confirms that the anchors increase the distribution range of interface shear stress during the load transfer process. In addition, the free stretching of smooth rebar improves the ability of the ISSD bolt to resist the large deformation of surrounding rock, which makes it more suitable for weak surrounding rock with low anchorage interface strength. Optimization analysis of the anchor parameters (i.e., number, shape) reveals that increasing the number of anchors improves the anchorage force and pull-out displacement of the ISSD bolt. However, excessive anchors lead to the risk of progressive failure of anchorage interface, thus weakening the anchorage force of the ISSD bolt and its ability to resist deformation. The 4-m long ISSD bolt with two anchors performs best. An increase in the filling degree <em>F</em> (<em>D</em>₁/<em>D</em>₃) and end inclination angle <em>α</em> of the anchor not only improves the anchorage performance of the ISSD bolt, but also improves the stress uniformity of the grouting layer. The anchor with a <em>F</em> of 0.75 and a <em>α</em> of 45° is the most suitable for the ISSD bolt.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428229","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 detection of underground openings and surrounding disturbed zones","authors":"","doi":"10.1016/j.tust.2024.106122","DOIUrl":"10.1016/j.tust.2024.106122","url":null,"abstract":"<div><div>This study aims to develop an intelligent method to detect subsurface anomalies for prediction and mitigation of geologic risks. We trained a convolutional neural network (CNN) model using the seismic data from 6 field cases of regular pipes and irregular cavities and a sliding time window technique to augment the datasets, and tested the CNN model using another 2 field cases. We derived probability distribution as an indicator of anomaly existence and validated high-value and low-value probability distributions corresponding to underground openings and surrounding disturbed zones, respectively. We found that the characteristics of subsurface anomalies determines the effective seismic features and influences the CNN model performance. Finally, we applied the CNN model to investigate a circular-bored tunnel and surrounding disturbed zones. Our results demonstrate that the CNN model is fast and accurate to detect the horizontal locations of subsurface anomalies, while the accuracy of vertical locations depends on the estimation of P-wave velocity. The intelligent method has the potential to identify hidden risks at early stages and to mitigate subsequent geologic hazards.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428228","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":"Numerical analysis of relative density effects on shallow TBM tunnel excavation: Ground behavior and principal strains at surface in greenfield conditions","authors":"","doi":"10.1016/j.tust.2024.106104","DOIUrl":"10.1016/j.tust.2024.106104","url":null,"abstract":"<div><div>Tunnel construction in urban areas may result in ground deformations that pose a risk to existing buildings and infrastructure; thus, accurate prediction of these induced ground deformations during the design phase is crucial. The paper focuses on the effects of sandy soil relative density on the ground deformations induced by tunnels excavated with Tunnel Boring Machines (TBMs). The study utilizes the Finite Element Method (FEM) and the NorSand model to simulate the behavior of a sandy ground. The validity of the FEM modeling approach is established by comparing predictions with results from six centrifuge tunnel tests from the literature. The centrifuge tests were performed on sand at different relative densities, tunnel diameters, and tunnel depths. The parameters for the NorSand model were determined based on laboratory tests. Only the state parameter was modified to achieve the desired relative density in the numerical simulations. The effects of relative density observed in centrifuge tests (<span><span>Franza et al., 2019</span></span>) have been numerically reproduced with no further adjustments of the model parameters. The rich outputs from the numerical models enabled an in-depth investigation of tunnel behavior, yielding new insights into how tunnels respond under varying relative densities, depths, and diameters. A comprehensive analysis of the induced ground deformations caused by shallow tunnels in sandy ground and the potential to damage buildings is included.</div></div>","PeriodicalId":49414,"journal":{"name":"Tunnelling and Underground Space Technology","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428013","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}