| Relying on the section distributing expansive diabase in the Wukeng tunnel of theLongyan-Xiamen Railway, the study submits some strong constructive conclusions tothe tunnel construction. Based on field diabase, laboratory test and Finite ElementMethod (FEM), the conclusion is concluded by analyzing the engineeringmechanical properties of dilatable diabase, the formation mechanism of expansibility,pressure distribution features of the surrounding rock and the influence on the initialsupport from the dilatable surrounding rock. The major works include:(1) Based on the investigations on the spot, experiments in the laboratory andlots of monitoring results, the paper analyses the engineering properties of thedilatable diabase and the formation mechanism, and distribution feature of theexpansibility of the surrounding rock.(2) Based on the monitoring results, the paper using structure-load modelanalyses mechanical properties of the initial support under the swelling pressure.Inaddition, according to distribution features of the swelling pressure, some measuresincluding increasing strength of primary support (changing the original design I20asteel arch frame to HW175steel) and false stull, were utilized to analyse the primarysupport stability.(3) Based on monitoring results and the strate configuration, during theexcavation of the tunnel, the paper analyses stress and deformation characteristics ofthe surrounding rock and the primary support under the swelling pressure as theattached load.On the basis above, the paper, under the swelling pressure, obtains thekey process influencing on the stability of underground caverns and critical positionsof deformation failure. Then, some construction suggestions were proposedespecially in the swelling diabase distribution section of Wukeng Tunnel.(4) Finally，on the grounds of monitoring results, the study proposes somesuggestions by analyzing the typical failure in the swelling diabase distributionsection of the Wukeng Tunnel. |
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