The use of shield method in tunnel construction is limited by the engineering conditions of highwater pressure.This is mainly due to the uncertainty of the pressure-bearing capacity of the sealing chambers of the shie...The use of shield method in tunnel construction is limited by the engineering conditions of highwater pressure.This is mainly due to the uncertainty of the pressure-bearing capacity of the sealing chambers of the shield tail under different grades and conditions when subjected to different external water pressures.Therefore,it is crucial to determine the pressure-bearing capacity of the sealing chambers.However,there is a lack of studies on the calculating method of the pressure-bearing capacity,which requires more theoretical investigation.To explore the common patterns of multi-grade sealing-related parameters and quantify the pressure-bearing capacity of the sealing chambers,a breakdown and leakage model of the shield tail is proposed,targeting the basic sealing unit of the system.Based on non-Newtonian fluid dynamics and fractal theory of porous media,the model is used to calculate the breakdown pressure and grease seepage rate corresponding to tunneling and shutdown states.In addition,a hydraulic breakdown device of the sealing unit of the static shield tail is built to investigate the relationship between the shield tail clearance and the shield tail brush porous media area,which helps to verify the theoretical model.Finally,the analysis of sealing chamber geometry parameters,grease rheological parameters,and an environmental parameter using the proposed theoretical model shows that the pressure-bearing capacity of the shield tail can be improved by increasing the shield tail clearance and grease yield stress.It also shows that the length of the sealing chamber and the plastic viscosity of the grease do not have a significant effect on the breakdown pressure of the shield tail.The model proposed in this paper will provide ideas for the calculation of the pressure-bearing capacity of multi-grade sealing chambers in the future.展开更多
Shield tail grouting is an important measure to control tunnelling-induced ground deformation by injecting prepared grouting mate-rials to fill the tail gap.The working performance of grout is usually invisible and ha...Shield tail grouting is an important measure to control tunnelling-induced ground deformation by injecting prepared grouting mate-rials to fill the tail gap.The working performance of grout is usually invisible and hard to obtain in construction.This paper carries out an experimental study to investigate the tail grout behavior in ground.In the current research,a testing device is developed to explore the grout behavior in varying soils.The grout working performance is evaluated not only by the liquid grout properties such as fluidity,consistency,bleeding rate,stone rate and compressed deformation but also solid grout properties such as unconfined compressive strength and permeability.Three typical grouts are chosen and their behaviors in the various soils are observed.To take an insight on the behaviors,scanning electron microscopy and mercury intrusion porosimetry analysis are employed.The microstructure of solid grout is a sign of its working performance.The observation shows that the solid grout micro-structure is influenced by grout proportions,pressure,and ground permeabilities.The experimental results are applied in the case of Beijing Metro Line 12 for validation and as a result,the ground movement is inhibited due to high performance of tail grout.展开更多
A huge amount of shield muck is generated during shield tunneling,and the reutilization of shield muck to produce tail grout has attracted growing attention,aiming to mitigate the environmental issues related to the t...A huge amount of shield muck is generated during shield tunneling,and the reutilization of shield muck to produce tail grout has attracted growing attention,aiming to mitigate the environmental issues related to the transport and disposal of shield muck.However,conventional binders,such as cement,used in this technique are associated with high carbon emission.Therefore,this study investigates the use of low-carbon binder,i.e.,carbide sludge(CS)-activated ground granulated blast furnace slag(GGBS),in shield muck treatment,aiming to achieve sustainable reutilization.Various commercial additives and phosphogypsum(PG),an industry waste,were added to further enhance the properties of treated shield muck.Results show that incorporating sulfate-containing additives to GGBS-CS-stabilized shield muck significantly reduced the setting time from 26.75 to 8.00–12.00 h,with Na_(2)SO_(4) and PG showing a relatively higher reducing rate.In addition,adding Na_(2)SO_(4) and PG to GGBS-CS-stabilized shield muck could enhance the 3-day strength by 67.0%and 37.0%,respectively,while their effects on improving the 28-day strength were marginal,yielding increases of just 16.0%and 0.4%.Results also indicated that additives led to a higher stone shrinkage rate of grout.Nonetheless,all additives posed negligible effects on the consistency and flowability.Microstructure analysis indicated that additives promoted the generation of ettringite(AFt)and aluminate ferrite monosulfate(AFm)phases.These phases consume free water and refine pores,leading to the higher stone shrinkage rate.Isothermal titration calorimetry highlighted that the additives affect the heat rate in the time interval of 4–50 h after mixing,and this should be the reason for the significant influence of additives on setting time and 3-day strength as well as limited impact on consistency and flowability.The findings confirmed the feasibility of using stabilized shield muck to produce tail grout,and PG is efficient in further enhancing its properties.展开更多
To more accurately estimate and control the magnitude of the shield tail clearance,a hybrid deep learning model with the integration of an online physics-informed deep neural network(online PDNN)and non-dominated sort...To more accurately estimate and control the magnitude of the shield tail clearance,a hybrid deep learning model with the integration of an online physics-informed deep neural network(online PDNN)and non-dominated sorting genetic algorithm-II(NSGA-II)is developed.The online PDNN has evolved from a deep learning framework constrained by the underlying physical mechanism of shield tail clearance measurements.The algorithm is used to forecast the shield tail clearance in tunnel boring machines(TBMs).The NSGA-II is employed to conduct the multi-objective optimization(MOO)process for shield tail clearance.The proposed method is validated in a tunnel case in China.Experimental results reveal that:(1)In comparison with some state-of-the-art algorithms,the online PDNN model demonstrates superior capability in predicting shield tail clearance above,upper-left,and upper-right,with R^(2)scores of 0.93,0.90,and 0.90,respectively;(2)The MOO achieves a comprehensive optimal solution,with the overall improvement percentage of shield tail clearance reaching 30.87%and a hypervolume of 32 under the 20%constraint condition,which surpasses the average performance of other MOO frameworks by 23 and 5.48%,respectively.The novelty of this research lies in coupling the constructed physical constraints and the online update mechanism into a causal analysis-oriented data-driven model,which not only enhances the model’s performance and interpretability but also realizes the control for the shield tail clearance by the integration of NSGA-II.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52378387)the Beijing Nova Program(Grant No.20220484037)China Railway 14th Bureau Group Corporation Limited Science and Technology R&D Program Subjects(No.913700001630559891202201).
文摘The use of shield method in tunnel construction is limited by the engineering conditions of highwater pressure.This is mainly due to the uncertainty of the pressure-bearing capacity of the sealing chambers of the shield tail under different grades and conditions when subjected to different external water pressures.Therefore,it is crucial to determine the pressure-bearing capacity of the sealing chambers.However,there is a lack of studies on the calculating method of the pressure-bearing capacity,which requires more theoretical investigation.To explore the common patterns of multi-grade sealing-related parameters and quantify the pressure-bearing capacity of the sealing chambers,a breakdown and leakage model of the shield tail is proposed,targeting the basic sealing unit of the system.Based on non-Newtonian fluid dynamics and fractal theory of porous media,the model is used to calculate the breakdown pressure and grease seepage rate corresponding to tunneling and shutdown states.In addition,a hydraulic breakdown device of the sealing unit of the static shield tail is built to investigate the relationship between the shield tail clearance and the shield tail brush porous media area,which helps to verify the theoretical model.Finally,the analysis of sealing chamber geometry parameters,grease rheological parameters,and an environmental parameter using the proposed theoretical model shows that the pressure-bearing capacity of the shield tail can be improved by increasing the shield tail clearance and grease yield stress.It also shows that the length of the sealing chamber and the plastic viscosity of the grease do not have a significant effect on the breakdown pressure of the shield tail.The model proposed in this paper will provide ideas for the calculation of the pressure-bearing capacity of multi-grade sealing chambers in the future.
基金supported by the National Natural Science Foundation of China(Grant No.51978430)Natural Science Foundation of Jiangsu Province,China(Grant No.BK20231318)+3 种基金Natural Science Foundation of Zhejiang Province,China(Grant Nos.LY21E080004 and LQ24F020039)Hangzhou City University,China(Grant No.J-202211)Open fund project of Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province(Grant No.ZUCC-UST-22-12)Open Research Fund of Key Laboratory of Coastal Urban Resilient Infrastructures(Shenzhen University),Ministry of Education(Grant No.CURI-G202304).
文摘Shield tail grouting is an important measure to control tunnelling-induced ground deformation by injecting prepared grouting mate-rials to fill the tail gap.The working performance of grout is usually invisible and hard to obtain in construction.This paper carries out an experimental study to investigate the tail grout behavior in ground.In the current research,a testing device is developed to explore the grout behavior in varying soils.The grout working performance is evaluated not only by the liquid grout properties such as fluidity,consistency,bleeding rate,stone rate and compressed deformation but also solid grout properties such as unconfined compressive strength and permeability.Three typical grouts are chosen and their behaviors in the various soils are observed.To take an insight on the behaviors,scanning electron microscopy and mercury intrusion porosimetry analysis are employed.The microstructure of solid grout is a sign of its working performance.The observation shows that the solid grout micro-structure is influenced by grout proportions,pressure,and ground permeabilities.The experimental results are applied in the case of Beijing Metro Line 12 for validation and as a result,the ground movement is inhibited due to high performance of tail grout.
基金supported by the National Natural Science Foundation of China(No.52308366)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.23KJB560023).
文摘A huge amount of shield muck is generated during shield tunneling,and the reutilization of shield muck to produce tail grout has attracted growing attention,aiming to mitigate the environmental issues related to the transport and disposal of shield muck.However,conventional binders,such as cement,used in this technique are associated with high carbon emission.Therefore,this study investigates the use of low-carbon binder,i.e.,carbide sludge(CS)-activated ground granulated blast furnace slag(GGBS),in shield muck treatment,aiming to achieve sustainable reutilization.Various commercial additives and phosphogypsum(PG),an industry waste,were added to further enhance the properties of treated shield muck.Results show that incorporating sulfate-containing additives to GGBS-CS-stabilized shield muck significantly reduced the setting time from 26.75 to 8.00–12.00 h,with Na_(2)SO_(4) and PG showing a relatively higher reducing rate.In addition,adding Na_(2)SO_(4) and PG to GGBS-CS-stabilized shield muck could enhance the 3-day strength by 67.0%and 37.0%,respectively,while their effects on improving the 28-day strength were marginal,yielding increases of just 16.0%and 0.4%.Results also indicated that additives led to a higher stone shrinkage rate of grout.Nonetheless,all additives posed negligible effects on the consistency and flowability.Microstructure analysis indicated that additives promoted the generation of ettringite(AFt)and aluminate ferrite monosulfate(AFm)phases.These phases consume free water and refine pores,leading to the higher stone shrinkage rate.Isothermal titration calorimetry highlighted that the additives affect the heat rate in the time interval of 4–50 h after mixing,and this should be the reason for the significant influence of additives on setting time and 3-day strength as well as limited impact on consistency and flowability.The findings confirmed the feasibility of using stabilized shield muck to produce tail grout,and PG is efficient in further enhancing its properties.
基金supported in part by the National Natural Science Foundation of China(Grand No.72271101)the Key Laboratory of Water Grid Project and Regulation of Ministry of Water Resources,China(No.QTKS0034W25018).
文摘To more accurately estimate and control the magnitude of the shield tail clearance,a hybrid deep learning model with the integration of an online physics-informed deep neural network(online PDNN)and non-dominated sorting genetic algorithm-II(NSGA-II)is developed.The online PDNN has evolved from a deep learning framework constrained by the underlying physical mechanism of shield tail clearance measurements.The algorithm is used to forecast the shield tail clearance in tunnel boring machines(TBMs).The NSGA-II is employed to conduct the multi-objective optimization(MOO)process for shield tail clearance.The proposed method is validated in a tunnel case in China.Experimental results reveal that:(1)In comparison with some state-of-the-art algorithms,the online PDNN model demonstrates superior capability in predicting shield tail clearance above,upper-left,and upper-right,with R^(2)scores of 0.93,0.90,and 0.90,respectively;(2)The MOO achieves a comprehensive optimal solution,with the overall improvement percentage of shield tail clearance reaching 30.87%and a hypervolume of 32 under the 20%constraint condition,which surpasses the average performance of other MOO frameworks by 23 and 5.48%,respectively.The novelty of this research lies in coupling the constructed physical constraints and the online update mechanism into a causal analysis-oriented data-driven model,which not only enhances the model’s performance and interpretability but also realizes the control for the shield tail clearance by the integration of NSGA-II.
