Water-soil leakage due to the longitudinal dislocation opening of tunnel segments in high-permeable soil strata is crucial for ensuring the longevity of underground tunnel infrastructures.This research delves into thi...Water-soil leakage due to the longitudinal dislocation opening of tunnel segments in high-permeable soil strata is crucial for ensuring the longevity of underground tunnel infrastructures.This research delves into this complex phenomenon employing coupled computational fluiddynamics(CFD),discrete element method(DEM),and finiteelement method(FEM),considering varied tunnel buried depths and dislocation opening sizes.Two critical areas susceptible to water-soil leakage have been identified,including an‘ellipsoid’shaped area at the tunnel top and a soil sliding area perpendicular to the tunneling direction.With a narrow segment opening(3 d_(50)),the fineloss remains below 2%across various buried depths,whereas it escalates to 7.4%-30%with increasing buried depth under a slightly wider opening(3.8d_(50)).The proposed three-dimensional(3D)ellipsoid model is used to delineate the leakage region and quantify over 98%ground soil loss due to dislocation opening.Furthermore,the research reveals that soil sliding induced by water-soil leakage significantly decreases the structural shear stress on the waists and inverts of the tunnel segment,while the soil arching at the top of the tunnel would mitigate the stress release,particularly at the lower dislocated tunnel segment.展开更多
To explore the stress and deformation responses,as well as the failure characteristics of the shield tunnel segment of Hangzhou Metro under the influences of pit excavation and other surrounding projects,a self-develo...To explore the stress and deformation responses,as well as the failure characteristics of the shield tunnel segment of Hangzhou Metro under the influences of pit excavation and other surrounding projects,a self-developed“shield tunnel segment hydraulic loading system”was used to carry out full-scale loading tests on the three-ring staggered assembled segments.The structural performances and failure process of the tunnel segment under step-by-step asymmetric unloading were studied.A safety index was proposed to describe the bearing capacity of the segment.Next,a finite element model(FEM)was established to analyze the bearing capacity of segment using the test results.Finally,the effect of reinforcement with a steel plate on the deformation and bearing capacity of the segment was analyzed.The results showed that under asymmetric unloading,the peak value and amplitude of the bending moment on the near unloading side converged with a greater value than those on the far side.The concrete internal force exhibited a directional transformation at different load stages.Cracks first appeared at the 180inner arc surface of the bottom standard block and then expanded to both sides,while the rate of crack propagation of the outer arc surface was relatively lower.The bearing capacity of the segments can be evaluated by the combination of the factors,e.g.the residual bearing capacity coefficient,moment transfer coefficient,and characterization coefficient.The segments approaching failure can facilitate the increase in the residual bearing capacity coefficient by more than 50%.This can provide guidance for the service assessment of metro tunnel operations.展开更多
When subjected to external loads from the ground and nearby construction,tunnel segmental lining joints are prone to damaging deformation.This can result in water leakage into tunnels,posing great safety risks.With th...When subjected to external loads from the ground and nearby construction,tunnel segmental lining joints are prone to damaging deformation.This can result in water leakage into tunnels,posing great safety risks.With this issue in mind,we conducted a series of full-scale tests to study the effects of external loads on the waterproofing performance of longitudinal joints.A customized rig for testing segmental joints was developed to assess the effect of loading magnitude,eccentricity,and loading-unloading-reloading cycles on waterproofing performance.Additionally,the relationship between joint force,sealing gasket deformation,and waterproofing pressure was investigated.The results indicate that:(1)the sealing gasket’s compression rapidly decreases as external loads increase,which weakens the waterproofing capacity of the joint;(2)the watertightness limit dramatically decreases as the bending moment increases;(3)a loading-unloading-reloading cycle leads to degradation of the joint’s waterproofing performance.The findings of this study provide a reference for subsequent waterproofing design of segmental tunnel joints,helping ensure the safety of tunnels throughout their operational lifespans.展开更多
A motion parameter optimization method based on the objective of minimizing the total energy consumption in segment positioning was proposed for segment erector of shield tunneling machine. The segment positioning pro...A motion parameter optimization method based on the objective of minimizing the total energy consumption in segment positioning was proposed for segment erector of shield tunneling machine. The segment positioning process was decomposed into rotation, lifting and sliding actions in deriving the energy calculation model of segment erection. The work of gravity was taken into account in the mathematical modeling of energy consumed by each actuator. In order to investigate the relationship between the work done by the actuator and the path moved along by the segment, the upward and downward directions as well as the operating quadrant of the segment erector were defined. Piecewise nonlinear function of energy was presented, of which the result is determined by closely coupled components as working parameters and some intermediate variables. Finally, the effectiveness of the optimization method was proved by conducting a case study with a segment erector for the tunnel with a diameter of 3 m and drawing comparisons between different assembling paths. The results show that the energy required by assembling a ring of segments along the optimized moving path can be reduced up to 5%. The method proposed in this work definitely provides an effective energy saving solution for shield tunneling machine.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52090084 and 52208354)the Shenzhen Science and Technology Program(Grant No.KQTD20221101093555006).
文摘Water-soil leakage due to the longitudinal dislocation opening of tunnel segments in high-permeable soil strata is crucial for ensuring the longevity of underground tunnel infrastructures.This research delves into this complex phenomenon employing coupled computational fluiddynamics(CFD),discrete element method(DEM),and finiteelement method(FEM),considering varied tunnel buried depths and dislocation opening sizes.Two critical areas susceptible to water-soil leakage have been identified,including an‘ellipsoid’shaped area at the tunnel top and a soil sliding area perpendicular to the tunneling direction.With a narrow segment opening(3 d_(50)),the fineloss remains below 2%across various buried depths,whereas it escalates to 7.4%-30%with increasing buried depth under a slightly wider opening(3.8d_(50)).The proposed three-dimensional(3D)ellipsoid model is used to delineate the leakage region and quantify over 98%ground soil loss due to dislocation opening.Furthermore,the research reveals that soil sliding induced by water-soil leakage significantly decreases the structural shear stress on the waists and inverts of the tunnel segment,while the soil arching at the top of the tunnel would mitigate the stress release,particularly at the lower dislocated tunnel segment.
基金supported by the Basic Public Welfare Research Projects in Zhejiang Province,China(Grant No.LGF22E080012)General Scientific Research Projects for Agriculture and Social Development in Hangzhou,China(Grant No.20201203B127).
文摘To explore the stress and deformation responses,as well as the failure characteristics of the shield tunnel segment of Hangzhou Metro under the influences of pit excavation and other surrounding projects,a self-developed“shield tunnel segment hydraulic loading system”was used to carry out full-scale loading tests on the three-ring staggered assembled segments.The structural performances and failure process of the tunnel segment under step-by-step asymmetric unloading were studied.A safety index was proposed to describe the bearing capacity of the segment.Next,a finite element model(FEM)was established to analyze the bearing capacity of segment using the test results.Finally,the effect of reinforcement with a steel plate on the deformation and bearing capacity of the segment was analyzed.The results showed that under asymmetric unloading,the peak value and amplitude of the bending moment on the near unloading side converged with a greater value than those on the far side.The concrete internal force exhibited a directional transformation at different load stages.Cracks first appeared at the 180inner arc surface of the bottom standard block and then expanded to both sides,while the rate of crack propagation of the outer arc surface was relatively lower.The bearing capacity of the segments can be evaluated by the combination of the factors,e.g.the residual bearing capacity coefficient,moment transfer coefficient,and characterization coefficient.The segments approaching failure can facilitate the increase in the residual bearing capacity coefficient by more than 50%.This can provide guidance for the service assessment of metro tunnel operations.
基金supported by the National Key Research and Development Program of China(No.2022YFC3800905)the National Natural Science Foundation of China(Nos.52238010,52090082,and 52108381)+2 种基金the Shanghai Science and Technology Committee Program(Nos.22XD1430200,23DZ1202806,and 21DZ1200601)the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(No.2023QNRC001)the Fundamental Research Funds for the Central Universities,China.
文摘When subjected to external loads from the ground and nearby construction,tunnel segmental lining joints are prone to damaging deformation.This can result in water leakage into tunnels,posing great safety risks.With this issue in mind,we conducted a series of full-scale tests to study the effects of external loads on the waterproofing performance of longitudinal joints.A customized rig for testing segmental joints was developed to assess the effect of loading magnitude,eccentricity,and loading-unloading-reloading cycles on waterproofing performance.Additionally,the relationship between joint force,sealing gasket deformation,and waterproofing pressure was investigated.The results indicate that:(1)the sealing gasket’s compression rapidly decreases as external loads increase,which weakens the waterproofing capacity of the joint;(2)the watertightness limit dramatically decreases as the bending moment increases;(3)a loading-unloading-reloading cycle leads to degradation of the joint’s waterproofing performance.The findings of this study provide a reference for subsequent waterproofing design of segmental tunnel joints,helping ensure the safety of tunnels throughout their operational lifespans.
基金Project(51305328)supported by the National Natural Science Foundation of ChinaProject(2012AA041803)supported by the NationalHigh Technology R&D Program of China+1 种基金Project(GZKF-201210)supported by the Open Fund of State Key Laboratory of Fluid Power Transmission and Control of Zhejiang University,ChinaProject(2013M532031)supported by the China Postdoctoral Science Foundation
文摘A motion parameter optimization method based on the objective of minimizing the total energy consumption in segment positioning was proposed for segment erector of shield tunneling machine. The segment positioning process was decomposed into rotation, lifting and sliding actions in deriving the energy calculation model of segment erection. The work of gravity was taken into account in the mathematical modeling of energy consumed by each actuator. In order to investigate the relationship between the work done by the actuator and the path moved along by the segment, the upward and downward directions as well as the operating quadrant of the segment erector were defined. Piecewise nonlinear function of energy was presented, of which the result is determined by closely coupled components as working parameters and some intermediate variables. Finally, the effectiveness of the optimization method was proved by conducting a case study with a segment erector for the tunnel with a diameter of 3 m and drawing comparisons between different assembling paths. The results show that the energy required by assembling a ring of segments along the optimized moving path can be reduced up to 5%. The method proposed in this work definitely provides an effective energy saving solution for shield tunneling machine.
