Research Of The Effect And Safety Control Of Adjacent Excavating On Existing Tunnel

With the development of city construction, it is common to see the cross construction phenomenon of the ground engineering and the underground engineering construction, which unavoidably contributes to the effect between the new construction and existing construction. The construction of new projects will change stress and deformation of soil around the existing tunnels and cause additional stress and displacement to tunnels. Therefore, on the premise of ensuring the safety of the existing construction, how to construct new projects has become one of the important issues for numerous scholars.Combined with theoretical calculation, numerical simulation and field measurement, effect on existing tunnels caused by construction of different kinds of new projects (building excavation and channel excavation) and their related safety control measures have been investigated. And some engineering reference and advice are providing for the design and construction optimization from this engineering. Concrete work is presented below.1. According to the house-building practice adjacent to the existing underlying tunnel, the finite element numerical simulation analysis method of ABAQUS, the simplified specification corner-points method and field measurement method were applied to analyze contrastively. It was found out that the two-dimensional analysis model used to analyze not only has the smaller calculation workload, but also has more security comparing with the practical engineering considered as a three-dimensional model. And the traditional theory of soil mechanics method, were coincidently available and secure for such similar engineering construction which had clear boundary and explicit load.2. Based on the project of channel excavation, floating influence on tunnel caused by excavation engineering on it has been investigated by theoretical calculation. Treated additional stress and deformation of the lining as indexes to assess stability of the structure of tunnel, the best excavation scheme is obtained through 3D-model analysis. Results shows that, foundation reinforcement, setting uplift pile and anti-buoyancy board and ordered excavation step by step are effective measures to control stress and deformation of tunnels.3. A similar 3D-moled about the project of building excavation near tunnel is established by FLAC3D. Compared with the results of field measurement, it found that distance between excavation and tunnel, stiffness of supporting structure and excavation method are important influencing factors of effect on tunnel caused by nearby excavation. It also proved that ordered excavation step by step is effective measure to control stress and deformation of tunnels in the respect of finite difference numerical method and showed enhancing stiffness of supporting structure had the same effect.