Study On The Settlement And Controlling Criteria Of Existing Embankment During Railway Tunnel Construction Underpassing By Conventional Method

As the high-speed railway and Railway Passenger Transportation Special Line of china are built expansible at a large scale, the new line underpassing the existing highway and railway is more and more and the crossing mutual influence between different lines becomes inevitably. The settlement and deformation of the existing railway roadbed and tracks and the highway subgrade and pavement is caused during the new tunnel construction underpassing.lt not only effects the safety of the new tunnel contruction and surrounding environment,but also effects the safety of the existing line.The serious settlement and deformation will cause of both the existing railway and road damage and safety accidents and cause large economic loss.Therefore,it is very import that studying on the settlement and deformation of the existing embankment during the new tunnel construction underpassing and the controlling criteria of the existing embankment settlement and deformation is very necessary.Based on the data collecting and summarization of the former tunnel engineering that construction underpass the existing railway and highway, the settlement regularity has been studied by the construction data collecting and survey and the controlling settlement in the process of construction has been analyzed using statistic analysis method.Secondly, based on the interaction theory of tunnel and foundation and embankment, the calculation model of highway embankment under vehicle load is builded.The embankment settlement developing regularity is studied and the influence of the embankment settlement in the process of the tunnel underpassing is analyzed.the results show that the buried depth of tunnel and the foundation modulus influencing on the highway embankment settlement is larger than others.The formula of the tunnel buried depth and the embankment settlement is given.Thirdly, the model of railway embankment when the tunnel underpassing is built by mean of ABAQUS while the train load and speed is considen.The track structure deformation and the influence of the safe train operation are analyzed during the tunnel construction underpassing.Fourthly, the failure of existing subgrade data during tunnel underpassing is collected. Based on the anaysis of the collecting data, the failure mode of the existing subgrade is summed and the settlement control index of the existing highway and railway is given.Then the function and safe operation requirements are studied.The comfort is import to the highway operation and the stablition is to the railway.The flatness control principle is put forward to control the highway embankment settlement as well as the vertical deviation control principle to the railway track struction and embankment settlement. Combined with the safety management rules of the highway and railway departments and based on the regularity of the existing embankment in this paper, the control standards of the allowing maximum settlement value and rate during the tunnel construction undepassing is developed to the existing highway in different grades and surface forms and it is did to the existing railway in different train speed.Finally, the collected more than30domestic underpassing engineerings are exampled. The results show that the proposed criterion in this paper is rational and applicable.