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The influence of structural strength on the lining moment of tunnel should be properly evaluated in order to meet the engineering demand in loess area. It is essential to analyze and evaluate the lining moment of tunnel by means of the finite element method under the condition of the different local weakening of structural strength in loess. Firstly, some researches on the structural strength of loess tunnel are reviewed. Then, some different cases of the local weakening of structural strength in loess are analyzed in this paper. Numerical results not only indicate that the lining moment of tunnel tends to change obviously with the different local weakening of the structural strength, but also reveal that the weakening location of structural strength has important effect on the distribution and redistribution of the lining moment of tunnel.

The failure criteria in strength reduction FEM are not unified and often affected greatly by researcher’s experience and judgment, so it is necessary to discuss the applicability and the difference of some various criteria of instability of slope. According to the thought of visualization in real time computing, the corresponding visual program is developed based on some common failure criteria adopted simultaneity in the strength reduction FEM. Then, through the real-time visual interface, the comparisons of the common failure criteria are conducted. The results show that, the safety factor of a simple slope can be determined clearly from the inflection point of the computational curve based on the criterion of the characteristic nodal displacement and the criterion of equivalent plastic strain exceeding a certain value, by contrast, the safety factor which based on the criterion of the iteration non-convergence lag behind the others in the same condition.

The rock mass with polycrystalline aggregates is common geomaterial in civil and architectural engineering as well as hydraulic and hydro-power engineering. For this kind of geometerials, the study on the joint deformation parameters Kn and Ks and the calculation method are not enough so far. Focusing on the rock mechanics and engineering problems of columnar jointed rock mass related to Baihetan hydropower project, analytical models and numerical method based on 3DEC are employed to study the mechanical parameters. The joint deformation parameters Kn and Ks are back analysis using GRNN and the field data of load-bearing plate tests. The application shows that the calculation results are in good accordance with in-situ test results.

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