A series of researches on mechanical behaviors of big pipe roof for shallow large-span loess tunnel were carried out based on the Wenxiang tunnel in Zhengzhou—Xi'an Special Passenger Railway. The longitudinal def...A series of researches on mechanical behaviors of big pipe roof for shallow large-span loess tunnel were carried out based on the Wenxiang tunnel in Zhengzhou—Xi'an Special Passenger Railway. The longitudinal deformations of the pipe roofs were monitored and the mechanical behaviors of the pipe roofs were analyzed at the test section. A new double-parameter elastic foundation beam model for pipe roof in shallow tunnels was put forward in Wenxiang tunnel. The measured values and the calculation results agreed well with each other,revealing the force-deformation law of big pipe roof in loess tunnel:At about 15 m in front of the excavating face,the pipe roof starts to bear the load;at about 15 m behind the excavating face,the force of the pipe roof tends to be stabilized;the longitudinal deformation of the whole pipe roofs is groove-shaped distribution,and the largest force of pipe roofs is at the excavating face. Simultaneously,the results also indicate that mechanical behaviors of pipe roof closely relate to the location of the excavation face,the footage of the tunnelling cycle and the mechanics parameters of pipe roof and rock. The conclusions can be reference for the design parameter optimization and the construction scheme selection of pipe roofs,and have been verified by the result of numerical analysis software FLAC3Dand deformation monitoring.展开更多
In order to reduce the horizontal crossing transportation problems between coal trucks and stripping trucks,large and small vehicles,and transport trucks and belt conveyors at key points of open pit mine in production...In order to reduce the horizontal crossing transportation problems between coal trucks and stripping trucks,large and small vehicles,and transport trucks and belt conveyors at key points of open pit mine in production,the separate transportation mode of underpass bridge and overpass steel trestle is proposed to optimize the open pit development transportation system,so as to solve the practical problems that the horizontal cross of transport vehicles causes vehicle blockage,affects production schedule and production safety.The results show that the horizontal crossing road can be changed into a separate type of overpass steel trestle,which can realize the classified transportation of large and small vehicles,reduce the traffic density,make vehicles with different functions go their own way,eliminate the hidden danger of traffic accidents,and improve the production efficiency.展开更多
With the accelerating process of urbanization, the construction of expressway underpass tunnel faces more challenges, which is easy to induce the pavement settlement, especially the uneven settlement, which affects th...With the accelerating process of urbanization, the construction of expressway underpass tunnel faces more challenges, which is easy to induce the pavement settlement, especially the uneven settlement, which affects the normal operation of the highway to a certain extent. In order to actively explore the impact of tunnel underpass construction on the existing expressway and select a better construction method for its construction, this paper, based on the actual case level, carries out data simulation research on it through ANSYS and FLAC 3D, and finally obtains good research results.展开更多
As the urban populations grow,the number and size of subway construction projects are increasing while also meeting higher construction standards.So,subway construction projects must have a better understanding of con...As the urban populations grow,the number and size of subway construction projects are increasing while also meeting higher construction standards.So,subway construction projects must have a better understanding of construction technology.This article focuses on the construction technology of the subway tunnel expansion under the bridge foundation.By analyzing the engineering characteristics of the bridge foundation and using a project as an example,this article provides a detailed discussion of the construction process of tunnel expansion under a bridge foundation.This article aims to serve as a reference for subway tunnel construction in China to ensure the key points of construction technology are understood,thus improving construction quality and laying a solid technical foundation for the sustainable development of urban rail engineering.展开更多
The application of a new liquid soil material and the treatment effect of backfilling an underpass tunnel in an airport are studied.The deformation and mechanical properties of liquid soil and conventional soil under ...The application of a new liquid soil material and the treatment effect of backfilling an underpass tunnel in an airport are studied.The deformation and mechanical properties of liquid soil and conventional soil under load are comprehensively compared and ana-lyzed via a numerical simulation with finite element software.The effects of the buried depth of overlying fill,tunnel height,and traffic load on the backfilling of liquid soil abut-ment are analyzed.The research results show that under the action of load,the overall deformation and stress distribution of the liquid soil and conventional soil show similar laws.However,liquid soil backfilling has great advantages over conventional soil backfill-ing in all aspects.Liquid soil backfilling can reduce the deformation and the compressive stress at the corner of the backfilling area by approximately 13%and 15%,respectively.The overburden buried depth has a great impact on the subgrade deformation.In the actual construction,the overburden buried depth should be 1.5 m.The overburden depth has a greater impact on the vertical deformation of the road,and the self-weight of the overbur-den will act as an additional load on the overall roadbed,compared with conventional soil backfill.The overburden depth of 2.0 m conventional soil backfill is about equal to the overburden depth of 1.5 m liquid soil backfill.The use of liquid soil backfill is equivalent to the use of the overburden fill in reducing the additional load of 0.5 m.The height of the box culvert has a greater impact on the stress,but this change is not linear.The actual construction in the case of meeting the specific requirements of use should try to control in the vicinity of 8.4 m,and at the same time the use of liquid soil backfill can reduce the com-pressive stress of about 14%.The compressive stress increases first and then decreases with the increase in the liquid soil modulus.The liquid soil modulus should be controlled to 180 MPa.Moreover,liquid soil backfilling can reduce the compressive stress in the backfill-ing area by approximately 25%.The trapezoidal slope of the backfill area is proportional to the deformation amount.Although an obvious correlation with compressive stress exists,the regularity is not strong.Thus,the trapezoidal slope should be set to 1:1 during con-struction.Traffic load slightly affects the overall deformation and compressive stress of the road.However,the distribution trends of deformation and stress change obviously under the action of aircraft load.In the actual design,only one load form of aircraft load should be considered.展开更多
The objective of this research is to analyze the deformation characteristics in space and the dynamic reaction of tunnel underpass hauling sliding surfaces when subjected to potential seismic activities.The response c...The objective of this research is to analyze the deformation characteristics in space and the dynamic reaction of tunnel underpass hauling sliding surfaces when subjected to potential seismic activities.The response characteristics and failure mode of tunnel linings are uncovered through an analysis of their time-frequency dynamic behavior.It is thoroughly discussed that there are correlation characteristics of plectrum amplitude in multivariate data under different excitation intensities and the spectrum difference characteristics during different shaking stages.The findings indicate that the slope's structural characteristics and failure modes correspond to the shallow slip type and the deformation trend of the deep weak basement slip type.The influence of topographic bias can be disregarded in tunnel underpass hauling sliding surfaces.The axial force(f_(a))in the tunnel lining section primarily exhibits pressure,while the bending moment(M_(b))is symmetrically distributed along the lining section.Tunnels are susceptible to collapse and invert uplift damage.The dominant frequency bands of dynamic strain,dynamic soil pressure,and acceleration are mainly concentrated within the 1–15 Hz range.Dynamic soil pressure and acceleration have a significant correlation,whereas the dynamic strain exhibits a weak correlation with both.The dynamic strain and acceleration exhibit sensitivity in their spectrum response before and during the main shock,whereas the dynamic soil pressure shows sensitivity in its spectrum response after the main shock.Based on the spectral response differences of multi-attribute data during various shaking stages,which can present a novel approach for dynamic monitoring and early warning of seismic actions.展开更多
Blasting engineering in complex urban environments is considered to influence the safety and stability of the overlying drainage box culvert structure owing to vibration.Therefore,field blasting and vibration tests we...Blasting engineering in complex urban environments is considered to influence the safety and stability of the overlying drainage box culvert structure owing to vibration.Therefore,field blasting and vibration tests were performed on the blasting engineering of the Wuhan Metro Line 8 connected aisle,and the LS-DYNA software was used to analyze the dynamic response characteristics of an underground drainage box culvert during the blasting test.The vibration response evolution law of the buried drainage box culvert under blasting vibration was investigated,and a safe surface control standard for the blast vibration of a drainage box culvert is proposed.The results reveal that the maximum tensile stress of the box culvert structure was 0.33 MPa.The peak particle velocity(PPV)and peak tensile stress(PTS)of the drainage box culvert decreased as the water level in the box culvert increased.Based on the relationship between the tensile stress of the box culvert,PPV of the box culvert,and PPV of the surface,it is proposed that the surface control velocity of the buried drainage box culvert is 1.36 cm/s.展开更多
In the new tunnel under close distance through the existing tunnel risk source,the grouting scheme developed to compensate for stratum losses is still based on empirical methods,relying on the overburden thickness of ...In the new tunnel under close distance through the existing tunnel risk source,the grouting scheme developed to compensate for stratum losses is still based on empirical methods,relying on the overburden thickness of existing tunnels.This can potentially lead to an excessively high or low probability of uplift of existing tunnels.Proposing a coupled deformation analysis method between the grouting construction and adjacent existing tunnels is of great theoretical significance for developing grouting schemes.In order to reasonably limit the design parameters of grouting construction,based on the theory of fluid–solid coupling elastic pore-column expansion and the theory of random media,the calculation method of stratum displacement which simultaneously considers the coexistence of grout compaction expansion and permeability diffusion mode is derived,and the accuracy of the calculation method is verified by engineering examples.The accuracy of this calculation method was verified through engineering examples.Combined with the deformation coordination condition,the existing tunnel is regarded as an elastic Euler-Bernoulli continuous beam,and the finite element coupling balance equation of the interaction between the existing tunnel and the surrounding soil is obtained.Based on this,a coupling calculation model of the grouting construction and the deformation response of the adjacent existing tunnel is established.Combined with three times of grouting construction examples in the shield tunneling project of Beijing Metro Line 12 under the existing airport line,the reliability of the coupling calculation model to determine the grouting construction parameters is verified.The calculation parameters in the coupling calculation model have clear physical meanings,which can provide a theoretical basis for the grouting design of similar risk source projects.展开更多
基金Major Science and Technology R&D Program of Ministry of Railways(No.2005K001-D(G)-2)
文摘A series of researches on mechanical behaviors of big pipe roof for shallow large-span loess tunnel were carried out based on the Wenxiang tunnel in Zhengzhou—Xi'an Special Passenger Railway. The longitudinal deformations of the pipe roofs were monitored and the mechanical behaviors of the pipe roofs were analyzed at the test section. A new double-parameter elastic foundation beam model for pipe roof in shallow tunnels was put forward in Wenxiang tunnel. The measured values and the calculation results agreed well with each other,revealing the force-deformation law of big pipe roof in loess tunnel:At about 15 m in front of the excavating face,the pipe roof starts to bear the load;at about 15 m behind the excavating face,the force of the pipe roof tends to be stabilized;the longitudinal deformation of the whole pipe roofs is groove-shaped distribution,and the largest force of pipe roofs is at the excavating face. Simultaneously,the results also indicate that mechanical behaviors of pipe roof closely relate to the location of the excavation face,the footage of the tunnelling cycle and the mechanics parameters of pipe roof and rock. The conclusions can be reference for the design parameter optimization and the construction scheme selection of pipe roofs,and have been verified by the result of numerical analysis software FLAC3Dand deformation monitoring.
文摘In order to reduce the horizontal crossing transportation problems between coal trucks and stripping trucks,large and small vehicles,and transport trucks and belt conveyors at key points of open pit mine in production,the separate transportation mode of underpass bridge and overpass steel trestle is proposed to optimize the open pit development transportation system,so as to solve the practical problems that the horizontal cross of transport vehicles causes vehicle blockage,affects production schedule and production safety.The results show that the horizontal crossing road can be changed into a separate type of overpass steel trestle,which can realize the classified transportation of large and small vehicles,reduce the traffic density,make vehicles with different functions go their own way,eliminate the hidden danger of traffic accidents,and improve the production efficiency.
文摘With the accelerating process of urbanization, the construction of expressway underpass tunnel faces more challenges, which is easy to induce the pavement settlement, especially the uneven settlement, which affects the normal operation of the highway to a certain extent. In order to actively explore the impact of tunnel underpass construction on the existing expressway and select a better construction method for its construction, this paper, based on the actual case level, carries out data simulation research on it through ANSYS and FLAC 3D, and finally obtains good research results.
文摘As the urban populations grow,the number and size of subway construction projects are increasing while also meeting higher construction standards.So,subway construction projects must have a better understanding of construction technology.This article focuses on the construction technology of the subway tunnel expansion under the bridge foundation.By analyzing the engineering characteristics of the bridge foundation and using a project as an example,this article provides a detailed discussion of the construction process of tunnel expansion under a bridge foundation.This article aims to serve as a reference for subway tunnel construction in China to ensure the key points of construction technology are understood,thus improving construction quality and laying a solid technical foundation for the sustainable development of urban rail engineering.
基金the Civil Aviation Airport Safety and Operation Engineering Technology Research Center for conducting the Key Technology of the Application of Municipal Solid Waste Incineration Bottom Ash in Airport Asphalt Pavement(No.KFKT2023-05)for supporting this study.
文摘The application of a new liquid soil material and the treatment effect of backfilling an underpass tunnel in an airport are studied.The deformation and mechanical properties of liquid soil and conventional soil under load are comprehensively compared and ana-lyzed via a numerical simulation with finite element software.The effects of the buried depth of overlying fill,tunnel height,and traffic load on the backfilling of liquid soil abut-ment are analyzed.The research results show that under the action of load,the overall deformation and stress distribution of the liquid soil and conventional soil show similar laws.However,liquid soil backfilling has great advantages over conventional soil backfill-ing in all aspects.Liquid soil backfilling can reduce the deformation and the compressive stress at the corner of the backfilling area by approximately 13%and 15%,respectively.The overburden buried depth has a great impact on the subgrade deformation.In the actual construction,the overburden buried depth should be 1.5 m.The overburden depth has a greater impact on the vertical deformation of the road,and the self-weight of the overbur-den will act as an additional load on the overall roadbed,compared with conventional soil backfill.The overburden depth of 2.0 m conventional soil backfill is about equal to the overburden depth of 1.5 m liquid soil backfill.The use of liquid soil backfill is equivalent to the use of the overburden fill in reducing the additional load of 0.5 m.The height of the box culvert has a greater impact on the stress,but this change is not linear.The actual construction in the case of meeting the specific requirements of use should try to control in the vicinity of 8.4 m,and at the same time the use of liquid soil backfill can reduce the com-pressive stress of about 14%.The compressive stress increases first and then decreases with the increase in the liquid soil modulus.The liquid soil modulus should be controlled to 180 MPa.Moreover,liquid soil backfilling can reduce the compressive stress in the backfill-ing area by approximately 25%.The trapezoidal slope of the backfill area is proportional to the deformation amount.Although an obvious correlation with compressive stress exists,the regularity is not strong.Thus,the trapezoidal slope should be set to 1:1 during con-struction.Traffic load slightly affects the overall deformation and compressive stress of the road.However,the distribution trends of deformation and stress change obviously under the action of aircraft load.In the actual design,only one load form of aircraft load should be considered.
基金financial support received from the key R&D program of Gansu Province(No.23YFGA0028)The Key Research and Development Project of Lanzhou Jiaotong University(LZJTU-ZDYF2305)+4 种基金the Science and Technology Research and Development Plan of China Railway Co.,Ltd.(2022-Major Project-07)Tianyou Postdoctoral Science Foundation Project(TYBSH_KJ_202307)Lanzhou Jiaotong University-Southwest Jiaotong University Joint Innovation Fund project(LH2023012)Gansu Provincial Department of Education university teachers innovation fund project(2024A-044)Scientific Research Project of China Railway 21 First Group Co.,Ltd.(24A-2,23C-10).
文摘The objective of this research is to analyze the deformation characteristics in space and the dynamic reaction of tunnel underpass hauling sliding surfaces when subjected to potential seismic activities.The response characteristics and failure mode of tunnel linings are uncovered through an analysis of their time-frequency dynamic behavior.It is thoroughly discussed that there are correlation characteristics of plectrum amplitude in multivariate data under different excitation intensities and the spectrum difference characteristics during different shaking stages.The findings indicate that the slope's structural characteristics and failure modes correspond to the shallow slip type and the deformation trend of the deep weak basement slip type.The influence of topographic bias can be disregarded in tunnel underpass hauling sliding surfaces.The axial force(f_(a))in the tunnel lining section primarily exhibits pressure,while the bending moment(M_(b))is symmetrically distributed along the lining section.Tunnels are susceptible to collapse and invert uplift damage.The dominant frequency bands of dynamic strain,dynamic soil pressure,and acceleration are mainly concentrated within the 1–15 Hz range.Dynamic soil pressure and acceleration have a significant correlation,whereas the dynamic strain exhibits a weak correlation with both.The dynamic strain and acceleration exhibit sensitivity in their spectrum response before and during the main shock,whereas the dynamic soil pressure shows sensitivity in its spectrum response after the main shock.Based on the spectral response differences of multi-attribute data during various shaking stages,which can present a novel approach for dynamic monitoring and early warning of seismic actions.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.41807265,41972286,and 42072309)the Hubei Key Laboratory of Blasting Engineering Foundation(Nos.HKLBEF202001 and HKLBEF202002).
文摘Blasting engineering in complex urban environments is considered to influence the safety and stability of the overlying drainage box culvert structure owing to vibration.Therefore,field blasting and vibration tests were performed on the blasting engineering of the Wuhan Metro Line 8 connected aisle,and the LS-DYNA software was used to analyze the dynamic response characteristics of an underground drainage box culvert during the blasting test.The vibration response evolution law of the buried drainage box culvert under blasting vibration was investigated,and a safe surface control standard for the blast vibration of a drainage box culvert is proposed.The results reveal that the maximum tensile stress of the box culvert structure was 0.33 MPa.The peak particle velocity(PPV)and peak tensile stress(PTS)of the drainage box culvert decreased as the water level in the box culvert increased.Based on the relationship between the tensile stress of the box culvert,PPV of the box culvert,and PPV of the surface,it is proposed that the surface control velocity of the buried drainage box culvert is 1.36 cm/s.
基金financial support from the Key Program of National Natural Science Foundation of China(Grant No.52130905).
文摘In the new tunnel under close distance through the existing tunnel risk source,the grouting scheme developed to compensate for stratum losses is still based on empirical methods,relying on the overburden thickness of existing tunnels.This can potentially lead to an excessively high or low probability of uplift of existing tunnels.Proposing a coupled deformation analysis method between the grouting construction and adjacent existing tunnels is of great theoretical significance for developing grouting schemes.In order to reasonably limit the design parameters of grouting construction,based on the theory of fluid–solid coupling elastic pore-column expansion and the theory of random media,the calculation method of stratum displacement which simultaneously considers the coexistence of grout compaction expansion and permeability diffusion mode is derived,and the accuracy of the calculation method is verified by engineering examples.The accuracy of this calculation method was verified through engineering examples.Combined with the deformation coordination condition,the existing tunnel is regarded as an elastic Euler-Bernoulli continuous beam,and the finite element coupling balance equation of the interaction between the existing tunnel and the surrounding soil is obtained.Based on this,a coupling calculation model of the grouting construction and the deformation response of the adjacent existing tunnel is established.Combined with three times of grouting construction examples in the shield tunneling project of Beijing Metro Line 12 under the existing airport line,the reliability of the coupling calculation model to determine the grouting construction parameters is verified.The calculation parameters in the coupling calculation model have clear physical meanings,which can provide a theoretical basis for the grouting design of similar risk source projects.
