A hydro tunnel in Serbia＇s capitol Belgrade is currently constructed using EPB TBM （earth pressure balance tunneling machine）. To assess the risk of TBM jamming, an analysis is made including calculation of expecte...A hydro tunnel in Serbia＇s capitol Belgrade is currently constructed using EPB TBM （earth pressure balance tunneling machine）. To assess the risk of TBM jamming, an analysis is made including calculation of expected ground pressures on the machine and critical frictions and pressures along the route, which could stop the advance due to limitations of the machine. The ground pressures were calculated using 2D plain strain analytical and numerical methods, and using 2D＋ plain strain axisymmetrical numerical method to simulate effects of TBM advance, effects of deformations in front of TBM and effects of rigidity changes in area of TBM shield tail where ground abruptly looses contact with the shield and could additionally deform toward the concrete liner. Calculated deformations and stresses varied along the TBM and concrete liner, with prominent concentrations around the cutter head and TBM shield tail. The results of analytical and numerical calculations were compared and combined to construct diagrams of expected ground pressures on TBM along the tunnel route, and diagrams of critical frictions that may cause the jamming. Based on this analysis and ongoing measurements of ground pressures on TBM, recommendations have been made on excavation regimes, and additional investigations in front of TBM. So far a relatively fair match of the predicted and measured ground pressures on TBM is observed.展开更多
Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM)....Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.展开更多
文摘A hydro tunnel in Serbia＇s capitol Belgrade is currently constructed using EPB TBM （earth pressure balance tunneling machine）. To assess the risk of TBM jamming, an analysis is made including calculation of expected ground pressures on the machine and critical frictions and pressures along the route, which could stop the advance due to limitations of the machine. The ground pressures were calculated using 2D plain strain analytical and numerical methods, and using 2D＋ plain strain axisymmetrical numerical method to simulate effects of TBM advance, effects of deformations in front of TBM and effects of rigidity changes in area of TBM shield tail where ground abruptly looses contact with the shield and could additionally deform toward the concrete liner. Calculated deformations and stresses varied along the TBM and concrete liner, with prominent concentrations around the cutter head and TBM shield tail. The results of analytical and numerical calculations were compared and combined to construct diagrams of expected ground pressures on TBM along the tunnel route, and diagrams of critical frictions that may cause the jamming. Based on this analysis and ongoing measurements of ground pressures on TBM, recommendations have been made on excavation regimes, and additional investigations in front of TBM. So far a relatively fair match of the predicted and measured ground pressures on TBM is observed.
基金Alexander von Humboldt-Foundation (AvH) for the financial support as a research fellowthe financial support of the Scientific and Technological Research Council of Turkey (TüB_ITAK) under Project No. MAG-114M568
文摘Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.
