| Along with the rapid development of tunnel construction, more and more problems of complex geology and shortage of labor force appear. Mechanical excavation for complex geology and environment will be a development trend of tunnel construction. As a special construction technology, Mechanical pre-cutting method can be well applied to complex geology and environment and improve mechanization level of construction. Mechanical pre-cutting method was widely applied in France, Italy and Japan. In the tunnel construction, due to more and more problems of complex geology and environment and the imperative demand of mechanization level, people pay attention to this method again in our country. So it is necessary to research the Mechanical pre-cutting method.Mechanical pre-cutting method is studied by the numerical simulation when excavating the test section of a loess tunnel. The main content and results are as following:(1) From the view of Soil thickNess and ground paraneters, the stratum deformation rules is studied when excavating loess tunnels by Mechanical pre-cutting method.(2) The proper supporting parameters are studied. By comparative analysis of length, lap length and thickNess of Initial lining, the proper supporting parameters of the test section is got.(3) The main deformation of tunnel and the stress of Initial lining are analyzed when using two different lengths of Initial lining (5m,12m). More analyses is given by considering the pre-reinforcing of the advance core and the assistant measures when the length of Initial lining is12m.(4) The stability of the tunnel face is studied. The influencing factor and the failure mechanism of the stability of the tunnel face are given, the stability of the tunnel face is analyzed by using the method for stability assessment of slopes.(5) The case is studied. From the main deformation of tunnel and the stress of Initial lining, the excavation method and the proper distance for the incert are got. |
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