Engineering Challenges for Safe and Sustainable Underground Occupation

Shallow tunnels induce surface displacements which can cause damage to existing structures; an adequate evaluation of their settlement trough is of paramount importance. Nowadays, it becomes even more critical when dealing with an underground occupation where the green stress field has already been disturbed by previous excavations. Since the end of the last century, many researchers have explored the subject. Some empirical methodologies have been developed based on data from actual cases, sometimes associated with numerical analysis. The present work used plane strain numerical analysis of different geometric arrangements of side-by-side twin tunnels for different depths and distances between tunnel axes to evaluate its compatibility with some of the proposed methods to adjust the settlement profile of the second cavity. It was observed that the discussed methodologies have similar results for maximum settlement and its eccentricity. Nevertheless, the behavior of the trough width parameter from the semi-empirical methods has shown discrepancies.

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