Finite Element Analysis Of The Structure Interaction In The Construction Of Tunnel With Small Spacing

Under a specific terrain condition,one of the choices is building Neighborhood Tunnel which plays a positive role in the construction.As an effective complement to Split Tunnel,Little Space can solve the problems which are brought by the minimum spacing requirements of Split Tunnel,including not flexible exhibition line,large area,high slope and other outstanding issues.So far the applications and researches of Neighborhood Tunnel were only the interaction mechanical properties and rules of the construction process and cavity under equilibrium pressure condition,but lack the researches of bias voltage condition. The design theories and construction methods of bias voltage Neighborhood Tunnel are far from mature so that can't meet the needs of engineering.Engineering background to Aiping hill tunnel, this paper researches the disequilibrium pressure double tunnels and mechanical properties of two drives-Neighborhood Tunnel more comprehensive by the way of theoretical analysis, simulation and so on.①This article analyses the weak rock hole shallow buried section super small interval tunnel used two construction methods respectively excavated digs on the left and right and used two supporting methods respectively pulled bolt to add and not to add pressures by through the finite element numerical simulation, and proves a reasonable conclusion excavating the left tunnel firstly( shallower burial depth ) and using pressures to pull bolting.②This article adopts three-dimensional numerical model to simulate surrounding rock initial of retaining structure mechanics effect among tunnel construction process , analyses the deformation and stress condition of surrounding rock and lining in every construction stage and proves in excavating spacing being 50 meters ,the wall rock deformation and the mechanics effect of retaining structure of Aiping mountain small interval tunnel being well controlled and tunnel structure system and surrounding rock being all in stable state. This paper finds in construction process, as long as guaranteeing construction quality will be able to guarantee tunnel construction safety .③Summarized the general method of supporting the small interval tunnel and the special supporting method of suiting for complicated geological conditions through reviewing the designing theory of supporting tunnel. At present, the shotcrete and rock bolt support is a center for the development of the interval tunnel support theory, which achieve the goal to deal with special problems by combining other auxiliary support measures. Finally, This paper reviews the support method and specific parameters of Aiping mountain small interval tunnel.④It is important for restraining the deformation of the small interval tunnel and enhancing its strength to shore at preliminary stage, especially when the interval is small, the level of surrounding rock is low and the surrounding rock is poor, it is necessary to pay more attention to the closure of the primary supporting, so this paper suggests it is essential for the small interval tunnel to close the primary support of the first hole before excavating the look-ahead hole. But the surrounding rock is slightly better, it is not essential to close the primary support of the first hole and it is essential to finish the inverted arch of the first hole before excavating the look-ahead hole.