Due to the well known defects of jet grouting columns (diameter, position), the real shape of supporting structures made of overlapped elements, as shafts or tunnel canopies, is often far from being geometrically regular, and defects have to be taken into account. The design of such structures cannot be but probabilistic or semi-probabilistic, because it may hide unforeseen risks if a deterministic approach is adopted. As a consequence, this is the typical case in which sophisticated numerical analyses may just give the illusion of being refined, if possible defects are not correctly taken into account. In the paper, the results obtained in previous works by the authors adopting such an approach with reference to shafts and tunnel canopies are summarized. Even though these approaches represent a progress in the design of jet grouted supporting structures, they do not take into account soil-structure interaction and the truly three-dimensional behaviour of these structures. In the paper, it is shown that soil-structure interaction strongly reduces stresses in the jet grouted soil, and discontinuities can be accepted in the structure without necessarily implying structural failure as long as they keep smaller of a given limit value. These improvements are a first step towards a less conservative design procedure of jet grouted structures.
Mechanical analysis of jet grouted supported structures
MODONI, Giuseppe
2012-01-01
Abstract
Due to the well known defects of jet grouting columns (diameter, position), the real shape of supporting structures made of overlapped elements, as shafts or tunnel canopies, is often far from being geometrically regular, and defects have to be taken into account. The design of such structures cannot be but probabilistic or semi-probabilistic, because it may hide unforeseen risks if a deterministic approach is adopted. As a consequence, this is the typical case in which sophisticated numerical analyses may just give the illusion of being refined, if possible defects are not correctly taken into account. In the paper, the results obtained in previous works by the authors adopting such an approach with reference to shafts and tunnel canopies are summarized. Even though these approaches represent a progress in the design of jet grouted supporting structures, they do not take into account soil-structure interaction and the truly three-dimensional behaviour of these structures. In the paper, it is shown that soil-structure interaction strongly reduces stresses in the jet grouted soil, and discontinuities can be accepted in the structure without necessarily implying structural failure as long as they keep smaller of a given limit value. These improvements are a first step towards a less conservative design procedure of jet grouted structures.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
