| The function mode and calculation method of the surrounding rock pressure is a key problem in the design of tunnel support structure. The surrounding rock pressure calculation method of mountain tunnel is studied comprehensively by literature research, theoretical analysis, numerical simulation and field monitoring in this paper. This main research results are as follows:1) Research of the surrounding rock pressure calculation methodBased on the previous studies, the type, influencing factors and the calculation methods that arised by domestic and foreign scholars of the surrounding rock pressure are maken a systematic summarization, and for the calculation methods, the comparative analysis of whose applicability was taken, at last the applicable contion was clarified and the deficiency was pointed out. Based on the existing calculation method, the method that based on the composite rock structure was put forward, which can provide reference for the realization of the scientific, standardized and refinement of the support structure design.2) Statistical analysis research of the field measured data of rock pressureBase on the statistical analysis of the existing field data of the91monitoring sections in44tunnels, the pressure population and range distribution of different surrounding rock grade was got, and the relationship between the vertical pressure, lateral pressure, lateral pressure coefficient and the rock grade, buried depth was also studied, then The time and space distribution law of the pressure was analysed. The measured value and the railway theoretical formula of IV and V rock grade was compared, and they are close.3) Influencing factors analysis of the surrounding rock pressure based on the layer-structure modelBased on the continum model, The influencing factors of the surrounding rock pressure, for example, the construction time, the elastic modulus, the thickness of the crosssection of the supporting structure, was analysed by numerical method, and the change rule of the surrounding rock pressure with the various factors is obtained. At the same time, the stress characteristics of the supporting structure was also analysed.4) Research on engineering application of tunnel surrounding rock pressure calculation method The comparative analysis between the theoretical prediction and the field monitoring of two typical tunnel was taken, one is a large crosssection rock tunnel-Jin Niushan tunnel of Beijing-Shanghai high-speed railway, the other is a large crosssection loess tunnel-Hu Maling tunnel of Lanzhou-Chongqing railway. The surrounding rock pressure distribution law of the two tunnel was analysed, then the different characteristers and the relatively accurate calculation of surrounding rock pressure was pointed out for rock and soil tunnel. Based on the analysis of the measured data of rock pressure and support structure stress, the effect of the surrounding rock pressure calculation theory applying in the two tunnels was evaluated, and the change rule of the grid force with time was also analysed. |
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