A new approach for displacement and stress monitoring of tunnel based on iFEM methodology

Abstract

Structural monitoring plays a key role for underground structures such as tunnels. Strain readings are expected to report structural conditions during construction and at the final delivery of the works. Furthermore, it is increasingly requested an extension to long-term monitoring from contractors with possible use of the same system in service during construction. A robust and efficient monitoring methodology from discrete strain measurements is the inverse finite element method (iFEM), which allows to reconstruct the structural response without input data on the load pattern applied to the structure as well as material and inertial properties of the elements and therefore it is interesting for structural configurations affected by uncertain loading conditions, such as the tunnel. The formulation presented in this paper, based on the iFEM theory, is improved from the previous work available in literature for both the shape functions used and the computational procedure. Indeed, the approach allows to overcome inconsistencies related to structural loading conditions and a pseudo-inverse matrix preserve all the rigid body modes without imposing specific constraints which is typical for tunnels. Numerical validation of the iFEM procedure is performed by simulating the input data coming from a tunnel working in a heterogeneous soil under different loading conditions with direct FEM analysis.

The Damage Deterioration Mechanism of Tunnel Structure under the Effect of Thermo-Mechanical Coupling and Its Maintenance

“…Under the condition of high ground temperature, the stress on tunnel support structure and surrounding rock is even more complex under the multiple and simultaneous actions of temperature, stress, internal water pressure, and ground stress, etc. [10][11][12][13][14][15]. The actions of multiple stresses on the tunnel support structure are interrelated and mutually affected, not just simply superimposed.…”