Monitoring sensors in complex engineering environments often record abnormal data,leading to significant positioning errors.To reduce the influence of abnormal arrival times,we introduce an innovative,outlier-robust l...Monitoring sensors in complex engineering environments often record abnormal data,leading to significant positioning errors.To reduce the influence of abnormal arrival times,we introduce an innovative,outlier-robust localization method that integrates kernel density estimation(KDE)with damping linear correction to enhance the precision of microseismic/acoustic emission(MS/AE)source positioning.Our approach systematically addresses abnormal arrival times through a three-step process:initial location by 4-arrival combinations,elimination of outliers based on three-dimensional KDE,and refinement using a linear correction with an adaptive damping factor.We validate our method through lead-breaking experiments,demonstrating over a 23%improvement in positioning accuracy with a maximum error of 9.12 mm(relative error of 15.80%)—outperforming 4 existing methods.Simulations under various system errors,outlier scales,and ratios substantiate our method’s superior performance.Field blasting experiments also confirm the practical applicability,with an average positioning error of 11.71 m(relative error of 7.59%),compared to 23.56,66.09,16.95,and 28.52 m for other methods.This research is significant as it enhances the robustness of MS/AE source localization when confronted with data anomalies.It also provides a practical solution for real-world engineering and safety monitoring applications.展开更多
Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the str...Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.展开更多
Currently,the pile foundation underpinning technology is widely used when underground transportation infrastructure passes through existing buildings or structures in urban areas.This study aims to investigate stress ...Currently,the pile foundation underpinning technology is widely used when underground transportation infrastructure passes through existing buildings or structures in urban areas.This study aims to investigate stress transfer mechanisms in pile foundations during an underpinning process as well as the influence of shield tunnel construction on pile stability.To this end,the pile foundation underpinning technology used in China’s Shenzhen Metro Line 10 crossing through the bridge pile foundation group of the Guangzhou-Shenzhen highway was analyzed in detailed.The refined numerical simulation of the pile foundation underpinning and shield tunnel construction processes were conducted using the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D)software.The results demonstrate that after the pile foundation underpinned,the previous bridge load system of bridge panel→pile foundation→bearing soil would transform into a bridge panel→existing pile foundation→new underpinning pile→deep bearing soil stratum structure.The overlying load on the underpinned pile could be effectively transferred to a new underpinning pile.In the process of underpinning and tunnel excavation,the settlement and deformation of the foundation can improve the tip resistance and shaft friction of piles,which in turn,can reduce the maximum principal stress in the pile foundation group.The deformation of the bridge pile foundation is mainly caused by ground loss and excavation disturbance generated during shield tunneling as the settlement induced by pile foundation underpinning accounts for approximately 20%-30% of the total settlement.The reduction effects of settlement deformation,lateral displacement,and principal stress are mainly manifested in underpinning piles,while the non-underpinning pile exhibits minimal variation.Meanwhile,the deformation of the segment lining structure of the shield tunnel primarily occurs near the underpinning area of the pile foundation,and it is mainly settlement deformation with a small horizontal displacement.展开更多
With the increasing demand for transportation infrastructure,the construction of urban tunnel systems linking different areas is indispensable.The deformation and the failure process during a tunnel excavation are ess...With the increasing demand for transportation infrastructure,the construction of urban tunnel systems linking different areas is indispensable.The deformation and the failure process during a tunnel excavation are essential concerns for geotechnical engineers.However,few studies have systematically investigated the effect of the ground loss ratio on tunnel deformation and the inequality between the ground loss ratio and the volume of the settlement trough.An experimental study using the transparent soil testing technique is performed herein for better visualization and digitization purposes.The three dimensional vertical and horizontal deformation patterns of a single tunnel are investigated for both the surface and the stratum right below considering different ground loss ratios.The relationship among the empirical constant of the settlement trough width,buried depth,depth-diameter ratio,and ground loss ratio is presented.展开更多
A ballastless slab track,which is commonly used in the track structures of heavy-haul railway tunnels,was analysed based on field measurement data of the Fuyingzi Tunnel on the Zhangtang Railway.In accordance with the...A ballastless slab track,which is commonly used in the track structures of heavy-haul railway tunnels,was analysed based on field measurement data of the Fuyingzi Tunnel on the Zhangtang Railway.In accordance with the measured data,the dynamic load thresholds and distributions on the surface and bottom of the ballastless slab track were investigated.A fatigue damage analysis of the ballastless slab track was performed based on the dynamic load time–history curve.The results show that the ballastless slab track can accomplish train load attenuation and reduce the dynamic load from heavy-haul trains by 47.22%from the surface to the bottom.In addition,the distribution at the bottom of the ballastless slab track exhibited a triangular shape,and the dynamic load threshold at the line centre accounted for 78.67%of that at the track position.Meanwhile,the distribution at the surface was saddle-shaped;the dynamic load threshold at the track position accounted for 79.55%of that at the line centre position.The fatigue damage of the ballastless slab track was analysed effectively by combining the measured data and the linear fatigue damage theory.Moreover,the accuracy of the calculation results was verified based on the measured dynamic stress of the ballastless slab track structure.The dynamic action of the train load led to more-concentrated damage to the track bed,and the damage occurred earlier than that in the ordinary line.The axle load was the primary influencing factor of the track bed fatigue damage,and the damage mainly occurred in the track position.These results provide a theoretical basis for performing stress analysis and designing parameters for ballastless slab tracks in heavy-haul railway tunnels.展开更多
To determine the influence of key blasthole parameters on tunnel overbreak during blasting construction,an intelligent detection sys-tem for tunnel blasting construction is independently developed.And the key blasthol...To determine the influence of key blasthole parameters on tunnel overbreak during blasting construction,an intelligent detection sys-tem for tunnel blasting construction is independently developed.And the key blasthole parameters and overbreak of a typical section of a single line tunnel under the condition of Class V surrounding rock are analyzed and detected.The actual data obtained is compared with the results of numerical simulations and theoretical calculations.The results are as follows:(1)Quantitative analysis is performed based on the blasthole angle,opening position,and charge mass by the self-developed intelligent detection equipment for blasthole parameters,which can be used to guide the drilling construction.Intelligent scanning equipment for outline excavation can be used to image the actual excavation section in real-time and has the advantages of high precision and fast speed;(2)Tunnel overbreak can be regarded as consisting of two parts:the surrounding rock damage caused by the blasting load,and the collapse of the surrounding rock caused by the blasthole opening position.Every parameter of the peripheral hole will affect the tunnel overbreak;however,the key parameter is the blasthole opening position;(3)The distributions of the tunnel overbreak volume obtained with the theoretical analysis,finite element simulation,and measurements are basically consistent.Under the condition of Class V surrounding rock,the overbreak of this single line tunnel can reach 14.1–78.2 cm.To meet the specification requirements,the opening position and construction accuracy of the peripheral hole should be strictly controlled.展开更多
This study investigated the degradation mechanism of the surrounding rock of a heavy-haul railway under a water-rich condition,based on the construction of the Taihangshan tunnel for the Wari Railway,a heavy-haul rail...This study investigated the degradation mechanism of the surrounding rock of a heavy-haul railway under a water-rich condition,based on the construction of the Taihangshan tunnel for the Wari Railway,a heavy-haul railway that used standard construction practices for axle loads of 30 t.Remote monitoring demonstrated that the coupling effect between the dynamic load of a heavy-haul train and the groundwater leads to the deterioration and hollowing of the surrounding rock.This study clarified the void evolution process and deterioration mechanism of the basement rock under the comprehensive influence of the groundwater–train dynamic load using a refined discrete element numerical simulation.The results revealed that the groundwater was the primary influencing factor in the deterioration of the lower part of the heavy-haul railway tunnel.Rock particles were gradually lost under the effects of long-term erosion due to groundwater and heavy-haul trains,which inevitably damaged the basement rock after the construction was completed.Based on this observation,the critical conditions for the deterioration and attenuation law of the physical parameters of the basement rock were obtained.The results of this study can provide ideas and serve as a reference for the forecasting and disaster treatment of basement rock damage in heavy-haul railway tunnels.展开更多
基金the financial support provided by the National Key Research and Development Program for Young Scientists(No.2021YFC2900400)Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(No.GZB20230914)+2 种基金National Natural Science Foundation of China(No.52304123)China Postdoctoral Science Foundation(No.2023M730412)Chongqing Outstanding Youth Science Foundation Program(No.CSTB2023NSCQ-JQX0027).
文摘Monitoring sensors in complex engineering environments often record abnormal data,leading to significant positioning errors.To reduce the influence of abnormal arrival times,we introduce an innovative,outlier-robust localization method that integrates kernel density estimation(KDE)with damping linear correction to enhance the precision of microseismic/acoustic emission(MS/AE)source positioning.Our approach systematically addresses abnormal arrival times through a three-step process:initial location by 4-arrival combinations,elimination of outliers based on three-dimensional KDE,and refinement using a linear correction with an adaptive damping factor.We validate our method through lead-breaking experiments,demonstrating over a 23%improvement in positioning accuracy with a maximum error of 9.12 mm(relative error of 15.80%)—outperforming 4 existing methods.Simulations under various system errors,outlier scales,and ratios substantiate our method’s superior performance.Field blasting experiments also confirm the practical applicability,with an average positioning error of 11.71 m(relative error of 7.59%),compared to 23.56,66.09,16.95,and 28.52 m for other methods.This research is significant as it enhances the robustness of MS/AE source localization when confronted with data anomalies.It also provides a practical solution for real-world engineering and safety monitoring applications.
基金supported by the Chongqing Natural Science Foundation(No.cstc2020jcyjmsxm X0904)the Chongqing Talent Plan(No.CQYC2020058263)+3 种基金the Chongqing Technology Innovation and Application Development Project(No.cstc2021ycjh-bgzxm0246)the China Postdoctoral Science Foundation(No.2021M693739)the Sichuan Science and Technology Program(No.2021YJ0539)the Natural Science foundation of Jiangsu higher education institutions of China(Grant No.19KJD170001)。
文摘Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.
基金supported by the Key R&D Program of Sichuan Province,China(No.2019YFG0001).
文摘Currently,the pile foundation underpinning technology is widely used when underground transportation infrastructure passes through existing buildings or structures in urban areas.This study aims to investigate stress transfer mechanisms in pile foundations during an underpinning process as well as the influence of shield tunnel construction on pile stability.To this end,the pile foundation underpinning technology used in China’s Shenzhen Metro Line 10 crossing through the bridge pile foundation group of the Guangzhou-Shenzhen highway was analyzed in detailed.The refined numerical simulation of the pile foundation underpinning and shield tunnel construction processes were conducted using the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D)software.The results demonstrate that after the pile foundation underpinned,the previous bridge load system of bridge panel→pile foundation→bearing soil would transform into a bridge panel→existing pile foundation→new underpinning pile→deep bearing soil stratum structure.The overlying load on the underpinned pile could be effectively transferred to a new underpinning pile.In the process of underpinning and tunnel excavation,the settlement and deformation of the foundation can improve the tip resistance and shaft friction of piles,which in turn,can reduce the maximum principal stress in the pile foundation group.The deformation of the bridge pile foundation is mainly caused by ground loss and excavation disturbance generated during shield tunneling as the settlement induced by pile foundation underpinning accounts for approximately 20%-30% of the total settlement.The reduction effects of settlement deformation,lateral displacement,and principal stress are mainly manifested in underpinning piles,while the non-underpinning pile exhibits minimal variation.Meanwhile,the deformation of the segment lining structure of the shield tunnel primarily occurs near the underpinning area of the pile foundation,and it is mainly settlement deformation with a small horizontal displacement.
基金supported by Chongqing Construction Science and Technology Plan Project(2019-0045)Key Laboratory of Mining Disaster Prevention and Control(No.MDPC201902)the Graduate Research and Innovation Foundation of Chongqing,China(Grant No.CYS18024).
文摘With the increasing demand for transportation infrastructure,the construction of urban tunnel systems linking different areas is indispensable.The deformation and the failure process during a tunnel excavation are essential concerns for geotechnical engineers.However,few studies have systematically investigated the effect of the ground loss ratio on tunnel deformation and the inequality between the ground loss ratio and the volume of the settlement trough.An experimental study using the transparent soil testing technique is performed herein for better visualization and digitization purposes.The three dimensional vertical and horizontal deformation patterns of a single tunnel are investigated for both the surface and the stratum right below considering different ground loss ratios.The relationship among the empirical constant of the settlement trough width,buried depth,depth-diameter ratio,and ground loss ratio is presented.
基金the Open-end Fund of Key Laboratory of New Technology for Construction of Cities in Mountain Area(LNTCCMA-20210108)the National Natural Science Foundation of China(5108098)+5 种基金the Chongqing Education Commission Science and Technology Research Project(KJQN201901509)the Chongqing Natural Science Fund General Project(cstc2020jcyj-msxmX0904)the Chongqing Talents:Exceptional Young Talents Project(cstc2021ycjhbgzxm0246)the China Postdoctoral Science Foundation-General Project(2021M693739)Chongqing Talents:Exceptional Young Talents Project(cstc2021ycjhbgzxm0246)China Postdoctoral Science Foundation-General Project(2021M693739).
文摘A ballastless slab track,which is commonly used in the track structures of heavy-haul railway tunnels,was analysed based on field measurement data of the Fuyingzi Tunnel on the Zhangtang Railway.In accordance with the measured data,the dynamic load thresholds and distributions on the surface and bottom of the ballastless slab track were investigated.A fatigue damage analysis of the ballastless slab track was performed based on the dynamic load time–history curve.The results show that the ballastless slab track can accomplish train load attenuation and reduce the dynamic load from heavy-haul trains by 47.22%from the surface to the bottom.In addition,the distribution at the bottom of the ballastless slab track exhibited a triangular shape,and the dynamic load threshold at the line centre accounted for 78.67%of that at the track position.Meanwhile,the distribution at the surface was saddle-shaped;the dynamic load threshold at the track position accounted for 79.55%of that at the line centre position.The fatigue damage of the ballastless slab track was analysed effectively by combining the measured data and the linear fatigue damage theory.Moreover,the accuracy of the calculation results was verified based on the measured dynamic stress of the ballastless slab track structure.The dynamic action of the train load led to more-concentrated damage to the track bed,and the damage occurred earlier than that in the ordinary line.The axle load was the primary influencing factor of the track bed fatigue damage,and the damage mainly occurred in the track position.These results provide a theoretical basis for performing stress analysis and designing parameters for ballastless slab tracks in heavy-haul railway tunnels.
基金supported by the Open-end Fund of Key Laboratory of New Technology for Construction of Cities in Mountain Area(LNTCCMA-20210108)the National Natural Science Foundation of China(5108098,51908387)+6 种基金the Chongqing Municipal Construction Investment(Group)Co.,Ltd.Joint Technical Issues(CQCT-JSA-GC-2021-0138)the Chongqing Natural Science Fund General Project(cstc2020jcyj-msxmX0904)the Chongqing Talents:Exceptional Young Talents Project(cstc2021ycjh-bgzxm0246)the China Postdoctoral Science Foundation-General Project(2021M693739)the Chongqing Outstanding Youth Science Fund Project(2022NSCQ-JQX1224)the Chongqing University of Science&Technology Graduate Innovation Program Project(YKJCX2120613)the Special Funding for Postdoctoral Research Projects in Chongqing(2021XM2019).
文摘To determine the influence of key blasthole parameters on tunnel overbreak during blasting construction,an intelligent detection sys-tem for tunnel blasting construction is independently developed.And the key blasthole parameters and overbreak of a typical section of a single line tunnel under the condition of Class V surrounding rock are analyzed and detected.The actual data obtained is compared with the results of numerical simulations and theoretical calculations.The results are as follows:(1)Quantitative analysis is performed based on the blasthole angle,opening position,and charge mass by the self-developed intelligent detection equipment for blasthole parameters,which can be used to guide the drilling construction.Intelligent scanning equipment for outline excavation can be used to image the actual excavation section in real-time and has the advantages of high precision and fast speed;(2)Tunnel overbreak can be regarded as consisting of two parts:the surrounding rock damage caused by the blasting load,and the collapse of the surrounding rock caused by the blasthole opening position.Every parameter of the peripheral hole will affect the tunnel overbreak;however,the key parameter is the blasthole opening position;(3)The distributions of the tunnel overbreak volume obtained with the theoretical analysis,finite element simulation,and measurements are basically consistent.Under the condition of Class V surrounding rock,the overbreak of this single line tunnel can reach 14.1–78.2 cm.To meet the specification requirements,the opening position and construction accuracy of the peripheral hole should be strictly controlled.
基金the National Natural Science Foundation of China(5108098,51508475)The Chongqing Education Commission science and technology research project(KJQN201901509)Sichuan University Key Laboratory Fundation of Bridge Nondestructive Testing and Engineering Calculation(2018QYJ06).
文摘This study investigated the degradation mechanism of the surrounding rock of a heavy-haul railway under a water-rich condition,based on the construction of the Taihangshan tunnel for the Wari Railway,a heavy-haul railway that used standard construction practices for axle loads of 30 t.Remote monitoring demonstrated that the coupling effect between the dynamic load of a heavy-haul train and the groundwater leads to the deterioration and hollowing of the surrounding rock.This study clarified the void evolution process and deterioration mechanism of the basement rock under the comprehensive influence of the groundwater–train dynamic load using a refined discrete element numerical simulation.The results revealed that the groundwater was the primary influencing factor in the deterioration of the lower part of the heavy-haul railway tunnel.Rock particles were gradually lost under the effects of long-term erosion due to groundwater and heavy-haul trains,which inevitably damaged the basement rock after the construction was completed.Based on this observation,the critical conditions for the deterioration and attenuation law of the physical parameters of the basement rock were obtained.The results of this study can provide ideas and serve as a reference for the forecasting and disaster treatment of basement rock damage in heavy-haul railway tunnels.
