IN-SITU MONITORING AND ANALYSIS OF DEFORAMTION OF THE SUPPORT SYSTEM IN MULTI-ARCH TUNNEL

Different from normal tunnel,the deformation characteristics of the multi-arch tunnel are more complex because of complex construction processes and many construction conversions.Based on the multi-arch tunnel project,the monitoring of support system deformation was carried out.And the law of the deformation developing with time and deformation characteristic of different construction procedures was analyzed.The surrounding rock deformation could be better controlled by using the bench method.Under construction of tunnel,the excavation of the upper bench and the down bench of the right drift has a great effect on surrounding rock deformation.So they are the main stages to control the support structure deformation.The longitudinal incidence of the excavation of the upper bench in the left tunnel and the down bench of the right tunnel is about two times of the span of the tunnel.And the incidence of the down bench in the left tunnel and the upper bench of the right tunnel is about the span of the tunnel.