| Small spacing tunnel is a tunnel structure which interposes between the common separable tunnel and the multi-arch tunnel. Due to its special structure and novelty, small spacing tunnel has become an effective form of solving the problems under the special geological conditions such as connecting bridge and tunnel and optimizing the general linear. Based on the summary of previous theoretical studies, with the Ning-Ji highway Shili Yan tunnel as a background project, this paper aims to research the small spacing tunnel surrounding rock pressure, combined with finite difference software flac3D for numerical simulation analysis. Conclusions are gotten as follows:(1) Through the numerical simulating calculation of the finite difference software flac3D to small spacing tunnel under different conditions, with the MATLAB computing software to regress the vertical pressure of the key parts of the surrounding rock in first opened cavern, the calculating results is between simulation data and the field measured values.(2) Based on the summary of previous theoretical studies in this paper, making the theoretical derivation about surrounding rock pressure of small spacing tunnel.(3) The first excavation of the cavern of the shallow side is beneficial to control the settlement of the tunnel vault and then the tunnel support structure is more balanced.(4) The distribution characteristics of the vertical pressure of surrounding rock and the level lateral pressure are summarized through simulating analysis.(5) Through the comparison and analysis with the values of monitoring measurement in Ning-Ji highway Shili Yan tunnel, we can verify the applicability of the derived formula and make an intensively summary of the characteristics of the surrounding rock pressure. |
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