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
Construction companies face threats from competition and must be able to adjust to modem technology and changes in customer expectations. These issues require efficient risk management techniques. The success of const...Construction companies face threats from competition and must be able to adjust to modem technology and changes in customer expectations. These issues require efficient risk management techniques. The success of construction companies running projects in international markets depends on how the risks arise from the host country conditions as well as the project specific risk factors. Successful management of risks requires identification of risks, construction of a risk model which can be used to assess the magnitude of risks, and implementation of response strategies so that an acceptable risk-return balance can be achieved. The project success usually depends on the combination of all risks, response strategies used to mitigate risks, and a company＇s ability to manage them. There exists a need to develop risk models containing the risks of doing business in international markets and factors that affect manageability of these risks. One of the market＇s critical challenges is scheduled management and the understanding and application of program management. This paper uses systematic risk identification, classification and analysis, and measurement and response methodologies to help international contractors quantify the risks of project development and accomplishment.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.
文摘Construction companies face threats from competition and must be able to adjust to modem technology and changes in customer expectations. These issues require efficient risk management techniques. The success of construction companies running projects in international markets depends on how the risks arise from the host country conditions as well as the project specific risk factors. Successful management of risks requires identification of risks, construction of a risk model which can be used to assess the magnitude of risks, and implementation of response strategies so that an acceptable risk-return balance can be achieved. The project success usually depends on the combination of all risks, response strategies used to mitigate risks, and a company＇s ability to manage them. There exists a need to develop risk models containing the risks of doing business in international markets and factors that affect manageability of these risks. One of the market＇s critical challenges is scheduled management and the understanding and application of program management. This paper uses systematic risk identification, classification and analysis, and measurement and response methodologies to help international contractors quantify the risks of project development and accomplishment.
