Modelos hierárquicos para análise estrutural do revestimento de túneis: avaliação, comparação, compatibilização e calibração.

Abstract

In the light of the complexity and interdisciplinarity of the phenomena involved in the construction of tunnels, hierarchical modelling is an important tool for the structural analysis and design practice of these structures. This work develops a study on two bidimensional model hierarchies commonly applied for the structural design of tunnels: models with the soil/rock mass as a continuous deformable solid and bedded beam models. The study focused on the evaluation and investigation of the potential combined use of those model hierarchies in the analysis and design practice, mainly regarding the comparison of representable physical phenomena and compatibility or compatibilization of computed results. To that end, inputs, outputs and hypotheses of the models were described, with the identification of the interface between the hierarchies. With these concepts as a baseline, a simple practical procedure for the case by case calculation of "ideal" compatibilization loads was formalized. Said loads, when applied to a bedded beam model lead to lining loads that are identical to those of the analogous continuous rock/soil mass model whose results are applied for the compatibilization. The procedure was applied to calibrate simplified compatibilization loads, and apply them to two studies. The first applied a case study to comparatively assess the loads imposed to a bedded beam model regarding the compatibility of the results with those of an analogous continuous rock/soil mass model. It was noticed that the compatibility of usual imposed loads from the bibliography and practice is generally low. On the other hand by calibrating loads based on the proposed "ideal" compatibilization procedure, even with higher simplification of the imposed load, a reasonable result compatibility may be obtained, especially for axial loads. That is, as long as the imposed loads bear magnitude and distribution that generally resemble the "ideal" compatibilization load, reasonable compatibility for internal beam loads may be obtained. Motivated by that observation, the second study performed a parametric analysis of the effects of variating hypotheses applied to the continuous rock/soil mass modelssuch as geometry, materials, cover, etc. -in the respective "ideal" compatibilization load for bedded beam models. A total of 93 scenarios of hypothesis combinations were evaluated, identifying the relative effect and importance of hypotheses in the magnitude and distribution pattern of the "ideal" compatibilization loads. The study foresees the possibility of estimating simplified compatibilization loads based on the physical problem definition, without the need of knowing beforehand the results of the continuous soul/rock mass model, as the calculation of the "ideal" compatibilization load would imply.