Pub Date : 2025-04-27DOI: 10.1016/j.undsp.2025.01.007
Jianghao Ji , Hong Zhu , Zhiqiang Dong , Yijie Pan , Shitong Hou , Liping Cui
This paper proposes an integrated system for monitoring and strengthening the prestressed concrete cylinder pipe (PCCP) with broken wires, which is based on distributed acoustic sensing (DAS) and self-prestressing iron-based shape memory alloy (Fe-SMA). This system was evaluated in a full-scale study on a PCCP with an inner diameter of 1400 mm and a length of 6000 mm. Firstly, the wire breakage signals were monitored by the DAS system. After that, the PCCP with broken wires were strengthened by Fe-SMA bars, and the mechanical properties were tested. The parameters such as different wire breakage ratios and self-prestressing degrees of Fe-SMA bars were also studied. The results show that the DAS system can identify the time and location of wire breakage; the wire breakage signal is characterized by high amplitude and short duration. After being prestressed with Fe-SMA bars, both the width and length of the main crack, as well as the strains in the concrete, mortar coating, and prestressed steel wires, significantly decreased. Additionally, the higher activation temperature of Fe-SMA bars can effectively offset the negative impact caused by the wire breakage development of PCCP. Combined Fe-SMA with the DAS monitoring system, it enables precise positioning and efficient strengthening of in-service PCCP with broken wires.
{"title":"Monitoring and strengthening of prestressed concrete cylinder pipes based on distributed acoustic sensing and iron-based shape memory alloys","authors":"Jianghao Ji , Hong Zhu , Zhiqiang Dong , Yijie Pan , Shitong Hou , Liping Cui","doi":"10.1016/j.undsp.2025.01.007","DOIUrl":"10.1016/j.undsp.2025.01.007","url":null,"abstract":"<div><div>This paper proposes an integrated system for monitoring and strengthening the prestressed concrete cylinder pipe (PCCP) with broken wires, which is based on distributed acoustic sensing (DAS) and self-prestressing iron-based shape memory alloy (Fe-SMA). This system was evaluated in a full-scale study on a PCCP with an inner diameter of 1400 mm and a length of 6000 mm. Firstly, the wire breakage signals were monitored by the DAS system. After that, the PCCP with broken wires were strengthened by Fe-SMA bars, and the mechanical properties were tested. The parameters such as different wire breakage ratios and self-prestressing degrees of Fe-SMA bars were also studied. The results show that the DAS system can identify the time and location of wire breakage; the wire breakage signal is characterized by high amplitude and short duration. After being prestressed with Fe-SMA bars, both the width and length of the main crack, as well as the strains in the concrete, mortar coating, and prestressed steel wires, significantly decreased. Additionally, the higher activation temperature of Fe-SMA bars can effectively offset the negative impact caused by the wire breakage development of PCCP. Combined Fe-SMA with the DAS monitoring system, it enables precise positioning and efficient strengthening of in-service PCCP with broken wires.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 146-160"},"PeriodicalIF":8.2,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221369","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}
In the field of design and application of the energy diaphragm wall (EDW), plenty of research was focused on thermal performances and induced mechanical behaviors. The coupled heat and moisture transfer process and the induced impact on the adjacent underground space were lack of attention, which is inevitable due to the high humidity of the surroundings. Therefore, in this paper, a numerical model taking the gradient of the temperature and relative humidity as the driving potential was established to investigate the characteristics of the coupled heat and moisture transfer in the EDW. Firstly, the behavior of the coupled heat and moisture transfer in the summer and winter was investigated separately, and it was compared with the pure thermal model. Results show that the colder the wall surface, the more humid it is. The heat flux is enlarged by the operation of the EDW. Moreover, the heat flux will be underestimated by more than 3.43% in the heat extraction season and by more than 3.90% in the heat injection case if the moisture transfer is not considered. The following long-running investigations have revealed that the latent flux reaches its maximum and minimum value in transition seasons, with a value that is ten times smaller than that of the sensible heat flux. The sensible heat flux reaches 18.7 W/m2 in summer, while in winter it is −27.4 W/m2. The peak latent heat flux is reduced by 14.7% as a result of the combined effect of changes in surface temperature and humidity, due to the operation of the EDW. Additionally, the magnitude of these fluxes is affected by the indoor conditions (temperature and relative humidity of the indoor air) and the operating temperature of EDW. Therefore, an orthogonal test is performed to evaluate how much the discrepancies are induced by variations in those parameters. The impact of each parameter varies across the seasons (summer, transition season, and winter). However, the indoor relative humidity has a more significant influence on the water vapor flux in all the seasons. This paper provided details about the coupled heat and moisture transfer process in the EDW. Moreover, it attempts to raise an issue about the impact on the hygrothermal load induced by the heat and moisture flux through the wall surface when applying EDW in underground engineering.
{"title":"Hygrothermal behavior of energy diaphragm wall and the induced heat and moisture interaction with adjacent underground space","authors":"Xu Zhou , Xiaoling Cao , Ziyu Leng , Chao Zeng , Yanping Yuan , Shady Attia","doi":"10.1016/j.undsp.2025.01.006","DOIUrl":"10.1016/j.undsp.2025.01.006","url":null,"abstract":"<div><div>In the field of design and application of the energy diaphragm wall (EDW), plenty of research was focused on thermal performances and induced mechanical behaviors. The coupled heat and moisture transfer process and the induced impact on the adjacent underground space were lack of attention, which is inevitable due to the high humidity of the surroundings. Therefore, in this paper, a numerical model taking the gradient of the temperature and relative humidity as the driving potential was established to investigate the characteristics of the coupled heat and moisture transfer in the EDW. Firstly, the behavior of the coupled heat and moisture transfer in the summer and winter was investigated separately, and it was compared with the pure thermal model. Results show that the colder the wall surface, the more humid it is. The heat flux is enlarged by the operation of the EDW. Moreover, the heat flux will be underestimated by more than 3.43% in the heat extraction season and by more than 3.90% in the heat injection case if the moisture transfer is not considered. The following long-running investigations have revealed that the latent flux reaches its maximum and minimum value in transition seasons, with a value that is ten times smaller than that of the sensible heat flux. The sensible heat flux reaches 18.7 W/m<sup>2</sup> in summer, while in winter it is −27.4 W/m<sup>2</sup>. The peak latent heat flux is reduced by 14.7% as a result of the combined effect of changes in surface temperature and humidity, due to the operation of the EDW. Additionally, the magnitude of these fluxes is affected by the indoor conditions (temperature and relative humidity of the indoor air) and the operating temperature of EDW. Therefore, an orthogonal test is performed to evaluate how much the discrepancies are induced by variations in those parameters. The impact of each parameter varies across the seasons (summer, transition season, and winter). However, the indoor relative humidity has a more significant influence on the water vapor flux in all the seasons. This paper provided details about the coupled heat and moisture transfer process in the EDW. Moreover, it attempts to raise an issue about the impact on the hygrothermal load induced by the heat and moisture flux through the wall surface when applying EDW in underground engineering.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 193-219"},"PeriodicalIF":8.2,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144240621","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}
Pub Date : 2025-04-17DOI: 10.1016/j.undsp.2025.01.005
Takeshi Sato , Fumiharu Nakahara , Kazuo Sakai , Weiren Lin , Kiyoshi Kishida
Displacement monitoring provides essential information for safe and rational tunnel excavation. The data obtained allow engineers to analyze and predict tunnel behavior, facilitating the selection of appropriate supports and the evaluation of their effectiveness. In a recent tunnelling project in the Akaishi Mountains of central Japan, displacement monitoring was intensively implemented to ensure the stability of the 4.2-km-long Hirogawara adit, excavated to a maximum depth of 832 m. Analysis revealed a strong correlation between initial and final displacements. However, the tunnel experienced occasional support deformations. To address this, the trend of 3D absolute displacements was analyzed to predict and evaluate asymmetric deformation. The effective use of 1-cycle displacement monitoring proved critical for predicting final displacements and optimizing rock supports, particularly in cases with high overburden and limited geotechnical information.
{"title":"Practical use of initial displacement monitoring for predicting support behavior with asymmetric deformation in deep tunnel","authors":"Takeshi Sato , Fumiharu Nakahara , Kazuo Sakai , Weiren Lin , Kiyoshi Kishida","doi":"10.1016/j.undsp.2025.01.005","DOIUrl":"10.1016/j.undsp.2025.01.005","url":null,"abstract":"<div><div>Displacement monitoring provides essential information for safe and rational tunnel excavation. The data obtained allow engineers to analyze and predict tunnel behavior, facilitating the selection of appropriate supports and the evaluation of their effectiveness. In a recent tunnelling project in the Akaishi Mountains of central Japan, displacement monitoring was intensively implemented to ensure the stability of the 4.2-km-long Hirogawara adit, excavated to a maximum depth of 832 m. Analysis revealed a strong correlation between initial and final displacements. However, the tunnel experienced occasional support deformations. To address this, the trend of 3D absolute displacements was analyzed to predict and evaluate asymmetric deformation. The effective use of 1-cycle displacement monitoring proved critical for predicting final displacements and optimizing rock supports, particularly in cases with high overburden and limited geotechnical information.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 43-67"},"PeriodicalIF":8.2,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203606","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}
This paper describes a field trial of artificial ground freezing (AGF) carried out in connection with the construction of Line C of Roma underground. AGF was one of the options considered for the temporary stabilisation of the ground during the excavation of Colosseo-Fori Imperiali Station. The field trial aimed at assessing the feasibility of AGF in the complex soil profile and groundwater regime of the subsoil of the historical centre of Roma by establishing the response of the subsoil to the imposed freezing loads, the ability to create a continuous frozen wall, and the associated coolant consumption. The extensive monitoring data were exploited to conduct a detailed analysis of the transient freezing process in the stratified subsoil and used to develop and validate a three-dimensional thermo-hydraulic numerical model. Special attention was given to defining and applying appropriate boundary conditions at the freezing pipes. The paper discusses the main factors affecting the time-dependent freezing process and explores the applicability of simplified two-dimensional models for the Fori Imperiali AGF field trial.
{"title":"Interpretation of an artificial ground freezing field trial at Fori Imperiali in Rome","authors":"Giulia Guida , Arianna Pucci , Eliano Romani , Giulia M.B. Viggiani , Francesca Casini","doi":"10.1016/j.undsp.2024.12.006","DOIUrl":"10.1016/j.undsp.2024.12.006","url":null,"abstract":"<div><div>This paper describes a field trial of artificial ground freezing (AGF) carried out in connection with the construction of Line C of Roma underground. AGF was one of the options considered for the temporary stabilisation of the ground during the excavation of Colosseo-Fori Imperiali Station. The field trial aimed at assessing the feasibility of AGF in the complex soil profile and groundwater regime of the subsoil of the historical centre of Roma by establishing the response of the subsoil to the imposed freezing loads, the ability to create a continuous frozen wall, and the associated coolant consumption. The extensive monitoring data were exploited to conduct a detailed analysis of the transient freezing process in the stratified subsoil and used to develop and validate a three-dimensional thermo-hydraulic numerical model. Special attention was given to defining and applying appropriate boundary conditions at the freezing pipes. The paper discusses the main factors affecting the time-dependent freezing process and explores the applicability of simplified two-dimensional models for the Fori Imperiali AGF field trial.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 89-112"},"PeriodicalIF":8.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221366","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}
Pub Date : 2025-04-11DOI: 10.1016/j.undsp.2025.01.004
Hao Zhang , Xueyang Xing , Yiteng Du , Tingchun Li , Jianxin Yu
Various blasting methods in underground engineering involve rock-breaking processes in enclosed spaces. A whole process of rock blasting is completed by the combination of blasting waves and explosion gas. The two actions exhibit different blasting fracturing characteristics in different time and spatial stages. In this study, an approach of rock blasting simulation of equivalent blasting dynamic-static action is proposed. A set of model blasting experiments under plane strain conditions are carried out to verify from the aspects of feasibility and reliability. The results show that the new method realizes the effective coupling of blast waves and explosion gas in terms of rock-breaking characteristics and pressure wave characteristics. The blasting effects have a high similarity between the simulation result and experimental result, and the maximum error on the damage range and the peak stress is 4.02% and 8.90%. The rock breaking mechanisms of three blasting methods in underground engineering that affect the blasting waves and explosion gas are discussed. The superiority of the new method is evaluated. When the decoupling coefficient is increased, an optimal decoupling coefficient is discovered, which reflects the consistency between the blasting results and the actual situation. When the confining pressure is increased, the inhibition ability on quasi-static action is obviously stronger than that of blasting dynamic action. In slotting blasting, the quasi-static action is the main contributor in the formation of holes penetration. The simulation results identify the rock breaking contributions between blasting waves and explosion gas well. The new simulation method can provide a reliable tool for understanding of the rock-blasting mechanism and restoring the whole blasting process.
{"title":"An approach of rock blasting simulation of equivalent blasting dynamic-static action","authors":"Hao Zhang , Xueyang Xing , Yiteng Du , Tingchun Li , Jianxin Yu","doi":"10.1016/j.undsp.2025.01.004","DOIUrl":"10.1016/j.undsp.2025.01.004","url":null,"abstract":"<div><div>Various blasting methods in underground engineering involve rock-breaking processes in enclosed spaces. A whole process of rock blasting is completed by the combination of blasting waves and explosion gas. The two actions exhibit different blasting fracturing characteristics in different time and spatial stages. In this study, an approach of rock blasting simulation of equivalent blasting dynamic-static action is proposed. A set of model blasting experiments under plane strain conditions are carried out to verify from the aspects of feasibility and reliability. The results show that the new method realizes the effective coupling of blast waves and explosion gas in terms of rock-breaking characteristics and pressure wave characteristics. The blasting effects have a high similarity between the simulation result and experimental result, and the maximum error on the damage range and the peak stress is 4.02% and 8.90%. The rock breaking mechanisms of three blasting methods in underground engineering that affect the blasting waves and explosion gas are discussed. The superiority of the new method is evaluated. When the decoupling coefficient is increased, an optimal decoupling coefficient is discovered, which reflects the consistency between the blasting results and the actual situation. When the confining pressure is increased, the inhibition ability on quasi-static action is obviously stronger than that of blasting dynamic action. In slotting blasting, the quasi-static action is the main contributor in the formation of holes penetration. The simulation results identify the rock breaking contributions between blasting waves and explosion gas well. The new simulation method can provide a reliable tool for understanding of the rock-blasting mechanism and restoring the whole blasting process.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 68-88"},"PeriodicalIF":8.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212646","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}
Significant movement of in-situ retaining walls is usually assumed to begin with bulk excavation. However, an increasing number of case studies show that lowering the pore water pressures inside a diaphragm wall-type basement enclosure prior to bulk excavation can cause wall movements in the order of some centimeters. This paper describes the results of a laboratory-scale experiment carried out to explore mechanisms of in situ retaining wall movement associated with dewatering inside the enclosure prior to bulk excavation. Dewatering reduces the pore water pressures inside the enclosure more than outside, resulting in the wall moving as an unpropped cantilever supported only by the soil. Lateral effective stresses in the shallow soil behind the wall are reduced, while lateral effective stresses in front of the wall increase. Although the associated lateral movement was small in the laboratory experiment, the movement could be proportionately larger in the field with a less stiff soil and a potentially greater dewatered depth. The implementation of a staged dewatering system, coupled with the potential for phased excavation and propping strategies, can effectively mitigate dewatering-induced wall and soil movements. This approach allows for enhanced stiffness of the wall support system, which can be dynamically adjusted based on real-time displacement monitoring data when necessary.
{"title":"Wall movement during dewatering inside a diaphragm wall before soil excavation","authors":"Chao-Feng Zeng , William Powrie , Chang-Jie Xu , Xiu-Li Xue","doi":"10.1016/j.undsp.2025.01.003","DOIUrl":"10.1016/j.undsp.2025.01.003","url":null,"abstract":"<div><div>Significant movement of in-situ retaining walls is usually assumed to begin with bulk excavation. However, an increasing number of case studies show that lowering the pore water pressures inside a diaphragm wall-type basement enclosure prior to bulk excavation can cause wall movements in the order of some centimeters. This paper describes the results of a laboratory-scale experiment carried out to explore mechanisms of in situ retaining wall movement associated with dewatering inside the enclosure prior to bulk excavation. Dewatering reduces the pore water pressures inside the enclosure more than outside, resulting in the wall moving as an unpropped cantilever supported only by the soil. Lateral effective stresses in the shallow soil behind the wall are reduced, while lateral effective stresses in front of the wall increase. Although the associated lateral movement was small in the laboratory experiment, the movement could be proportionately larger in the field with a less stiff soil and a potentially greater dewatered depth. The implementation of a staged dewatering system, coupled with the potential for phased excavation and propping strategies, can effectively mitigate dewatering-induced wall and soil movements. This approach allows for enhanced stiffness of the wall support system, which can be dynamically adjusted based on real-time displacement monitoring data when necessary.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"22 ","pages":"Pages 355-368"},"PeriodicalIF":8.2,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829864","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}
Pub Date : 2025-04-02DOI: 10.1016/j.undsp.2024.09.005
Zhongxian Liu , Jiaqiao Liu , Haitao Yu , Weiguo He
This paper introduces a novel two-step multi-scale coupled method for simulating the nonlinear dynamic behavior of a mountain tunnel subjected to fault movement. In the first step, the broadband seismic responses within a large-scale mountain-fault model can be accurately solved by the indirect boundary element method, converting them into effective input forces around the specified region of interest within the mountain. The second step involves finely simulating the nonlinear dynamic response of the tunnel cross-section in the designated region using the finite element method, with the implementation of a viscoelastic artificial boundary to absorb the reflection of scattered waves at truncated boundaries. Two verification processes are employed to validate the accuracy of the multi-scale coupled method. Furthermore, we illustrate the applicability and efficacy of the new method with an example involving the elastoplastic dynamic analysis of a mountain tunnel under the influence of normal fault movement. The presented example highlights the impact of fault motion parameters, including fault dislocation value and dip angle, on the responses of the mountain tunnel. The results demonstrate that the proposed multi-scale coupled method can achieve full-process seismic simulation, ranging from kilometer-scale fault rupture to centimeter-scale mountain tunnel section damage, with a considerably reduced computational expense.
{"title":"A multi-scale coupled method for nonlinear dynamic response analysis of mountain tunnels subjected to fault movement","authors":"Zhongxian Liu , Jiaqiao Liu , Haitao Yu , Weiguo He","doi":"10.1016/j.undsp.2024.09.005","DOIUrl":"10.1016/j.undsp.2024.09.005","url":null,"abstract":"<div><div>This paper introduces a novel two-step multi-scale coupled method for simulating the nonlinear dynamic behavior of a mountain tunnel subjected to fault movement. In the first step, the broadband seismic responses within a large-scale mountain-fault model can be accurately solved by the indirect boundary element method, converting them into effective input forces around the specified region of interest within the mountain. The second step involves finely simulating the nonlinear dynamic response of the tunnel cross-section in the designated region using the finite element method, with the implementation of a viscoelastic artificial boundary to absorb the reflection of scattered waves at truncated boundaries. Two verification processes are employed to validate the accuracy of the multi-scale coupled method. Furthermore, we illustrate the applicability and efficacy of the new method with an example involving the elastoplastic dynamic analysis of a mountain tunnel under the influence of normal fault movement. The presented example highlights the impact of fault motion parameters, including fault dislocation value and dip angle, on the responses of the mountain tunnel. The results demonstrate that the proposed multi-scale coupled method can achieve full-process seismic simulation, ranging from kilometer-scale fault rupture to centimeter-scale mountain tunnel section damage, with a considerably reduced computational expense.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"23 ","pages":"Pages 243-257"},"PeriodicalIF":8.2,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144290927","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}
Pub Date : 2025-03-28DOI: 10.1016/j.undsp.2025.01.002
Shuo Yu , Hao Jin , Liangjie Gu , Peng Gui
Stray current can cause corrosion of underground structural rebar, adding rubber particles to the invert-filling concrete is an effective prevent method to reduce stray current corrosion. In our research, the corrosion calculation model of multi-ring shield tunnel containing rubber concrete invert-filling was established, the coupling analysis of electric field and chemical field in composite structures was realized through mesoscale simulations, and the accuracy of calculation model was verified by full-scale test. Through calculation, the corrosion characteristic of segment rebar and bolt of multi-ring shield tunnel were investigated under different rubber content. The result shows that adding rubber particles to the invert-filling can not only reduce the corrosion current density of segment rebar and tunnel bolt effectively, but also affect the distribution form of rebar corrosion current density in both circumferential and longitudinal directions. When the rubber content increases from 5% to 20%, the maximum corrosion density of segment rebar and tunnel bolt will decrease from 31% to 58% and 30% to 32%, respectively. Under different stray current leakage modes, when the rubber content and input voltage are the same, the segment and bolt corrosion current density under single rail-two points leakage mode is greater than that in the two rails-single point leakage mode.
{"title":"Corrosion characteristic of multi-ring shield tunnel containing rubber concrete invert-filling under direct stray current","authors":"Shuo Yu , Hao Jin , Liangjie Gu , Peng Gui","doi":"10.1016/j.undsp.2025.01.002","DOIUrl":"10.1016/j.undsp.2025.01.002","url":null,"abstract":"<div><div>Stray current can cause corrosion of underground structural rebar, adding rubber particles to the invert-filling concrete is an effective prevent method to reduce stray current corrosion. In our research, the corrosion calculation model of multi-ring shield tunnel containing rubber concrete invert-filling was established, the coupling analysis of electric field and chemical field in composite structures was realized through mesoscale simulations, and the accuracy of calculation model was verified by full-scale test. Through calculation, the corrosion characteristic of segment rebar and bolt of multi-ring shield tunnel were investigated under different rubber content. The result shows that adding rubber particles to the invert-filling can not only reduce the corrosion current density of segment rebar and tunnel bolt effectively, but also affect the distribution form of rebar corrosion current density in both circumferential and longitudinal directions. When the rubber content increases from 5% to 20%, the maximum corrosion density of segment rebar and tunnel bolt will decrease from 31% to 58% and 30% to 32%, respectively. Under different stray current leakage modes, when the rubber content and input voltage are the same, the segment and bolt corrosion current density under single rail-two points leakage mode is greater than that in the two rails-single point leakage mode.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"22 ","pages":"Pages 337-354"},"PeriodicalIF":8.2,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143808239","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}
Pub Date : 2025-03-27DOI: 10.1016/j.undsp.2025.01.001
Wenli Liu , Yang Chen , Tianxiang Liu , Wen Liu , Jue Li , Yangyang Chen
Adequate control of shield machine parameters to ensure the safety and efficiency of shield construction is a difficult and complex problem. To address this problem, this paper proposes a hybrid intelligent optimization framework that combines interpretable machine learning, intelligent optimization algorithms, and multi-objective optimization and decision-making methods. The nonlinear relationship between the input parameters and ground settlement (GS) is fitted based on the light gradient boosting machine (LGBM), and the effect of the input parameters on GS is analysed based on SHapley additive exPlanation for further feature selection. Subsequently, the hyperparameters of LGBM were determined based on the sparrow search algorithm (SSA) to better fit the input–output relationship. On this basis, a multi-objective intelligent optimization model is established to solve the optimized operating parameters of shield machine by non-dominated sorting genetic algorithm II and technique for order preference by similarity to ideal solution to reduce GS and improve drilling efficiency. The results demonstrate that the SSA-LGBM model predicts GS with high accuracy, exhibiting an RMSE of 4.775, a VAF of 0.930 and an R2 of 0.931. These metrics collectively reflect the model’s excellent performance in prediction accuracy, ability to explain data variability, and control of prediction bias. The multi-objective optimization model is effective in optimizing two objectives, and the improvement can reach up to 39.38%; at the same time, the model has high scalability and can also be applied to three or more objectives. The intelligent optimization framework for shield construction parameters proposed in this paper can generate the optimal parameter combinations for shield machine manipulation, and provide reference and guidance when there are conflicting optimization objectives.
{"title":"Shield tunneling efficiency and stability enhancement based on interpretable machine learning and multi-objective optimization","authors":"Wenli Liu , Yang Chen , Tianxiang Liu , Wen Liu , Jue Li , Yangyang Chen","doi":"10.1016/j.undsp.2025.01.001","DOIUrl":"10.1016/j.undsp.2025.01.001","url":null,"abstract":"<div><div>Adequate control of shield machine parameters to ensure the safety and efficiency of shield construction is a difficult and complex problem. To address this problem, this paper proposes a hybrid intelligent optimization framework that combines interpretable machine learning, intelligent optimization algorithms, and multi-objective optimization and decision-making methods. The nonlinear relationship between the input parameters and ground settlement (GS) is fitted based on the light gradient boosting machine (LGBM), and the effect of the input parameters on GS is analysed based on SHapley additive exPlanation for further feature selection. Subsequently, the hyperparameters of LGBM were determined based on the sparrow search algorithm (SSA) to better fit the input–output relationship. On this basis, a multi-objective intelligent optimization model is established to solve the optimized operating parameters of shield machine by non-dominated sorting genetic algorithm II and technique for order preference by similarity to ideal solution to reduce GS and improve drilling efficiency. The results demonstrate that the SSA-LGBM model predicts GS with high accuracy, exhibiting an RMSE of 4.775, a VAF of 0.930 and an <em>R</em><sup>2</sup> of 0.931. These metrics collectively reflect the model’s excellent performance in prediction accuracy, ability to explain data variability, and control of prediction bias. The multi-objective optimization model is effective in optimizing two objectives, and the improvement can reach up to 39.38%; at the same time, the model has high scalability and can also be applied to three or more objectives. The intelligent optimization framework for shield construction parameters proposed in this paper can generate the optimal parameter combinations for shield machine manipulation, and provide reference and guidance when there are conflicting optimization objectives.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"22 ","pages":"Pages 320-336"},"PeriodicalIF":8.2,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143808238","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}
Pub Date : 2025-03-19DOI: 10.1016/j.undsp.2024.12.005
Dhyaa A.H. Abualghethe , Baogang Mu , Guoliang Dai , Sijin Liu , Zhongwei Li , Songyu Liu , Lei Han
Constructing vertical shafts in densely populated urban areas with complex geological conditions poses significant challenges, necessitating innovative construction techniques and design optimization. This study investigates the deformation behavior of a 42.5 m deep shaft excavated using the vertical shaft sinking machine (VSM) method in Shanghai’s soft soil conditions comprising deep cohesive soil layers. Comprehensive numerical analysis simulated the VSM construction process, analysing deformations within the shaft structure, surrounding soil, and adjacent buildings while evaluating the influence of varying reinforced ring base depths. Results reveal a significant 30% reduction in the maximum lateral shaft deformation, from 28 to 20 mm, by increasing the reinforced ring base depth to an optimal 16 m, enhancing lateral stability. Vertical deformations exhibited complex settlement and uplift mechanisms in segmental rings and piles, influenced by factors like excavation stages, pile installation, water pressures, and adjacent loads. The optimal 16 m depth effectively mitigated uplift, and optimized load distribution, limiting the maximum settlement to 12 mm while minimizing dewatering-induced uplift effects. Analysis indicated reduced lateral movements and settlements in surrounding buildings with increasing distance from excavation, highlighting VSM’s potential for minimizing impacts on neighboring structures. This study emphasizes VSM’s suitability for shaft projects in geologically complex areas, providing insights for design, mitigating environmental impacts, and enhancing deep excavation safety and efficiency in soft soils. The findings contribute to optimizing vertical shaft construction, ensuring successful underground infrastructure execution in challenging conditions. Identifying the optimal reinforced ring base depth promotes sustainable urban development by minimizing disturbances. This research advances innovative methods and strategies for complex underground projects.
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