The additional longitudinal deformation of tunnel was calculated by using the numerical simulation method

and its fitting equation was established by cubic spline interpolation.According to the fitting equation

the distribution of longitudinal deformation curvature of tunnel in the influence scope of foundation pit excavation was calculated

and sensitive location of longitudinal differential deformation of the tunnel was discriminated

based on which the tunnel deformation state under different sprout excavation ways and conditions could be evaluated and evidence can be provided for the design of foundation pit support.The results show that the maximum of longitudinal deformation is located in the center of the excavation

and maximum region of longitudinal deformation curvature is situated in the position of perimeter structure of foundation pit

both of which prove that in protecting the tunnels near excavation

not only the bottom uplifts should be strictly controlled

but also the effect of the rigidity maintenance on the tunnel deformation should be concerned more.At last

according to the comprehensive evaluation of construction methods

tunnel longitudinal deformation

and the variety of longitudinal curvature

parallel sprout excavation is more beneficial to the tunnel protection.