In highly populated areas with needs for additional underground individual-traffic or public-transportation infrastructure, a flexible construction mode like the New Austrian Tunneling Method is often applied. This method is characterized by a strong interaction between the viscous ground and the hydrating cement-based tunnel support.
Additionally, minimization of soil deformation and surface settlements is essential in order to avoid damage to existing buildings and infrastructure. For this purpose, ground improvement is frequently used.
In order to capture the soil-support interaction in such tunneling processes, the involved hydrating cement-based materials and the kind of soil and its individual characteristics are essential.
In this work, the mechanical behavior of granular and cohesive soil is reviewed, and elasto-viscoplastic material models are developed. For description of granular soil, non-associative Drucker-Prager and Mohr-Coulomb material models are chosen, accounting for frictional hardening/softening under shear loading. Time-dependent processes are considered via the Duvaut-Lions formulation of viscoplastic response. Cohesive soil behavior, on the other hand, is described by a Cam-Clay model. Based on hydrostatic-compression-test results, volumetric hardening/softening and a non-linear elastic law evolve.
For the Cam-Clay model, the Perzyna formulation is adopted to account for viscoplastic behavior. The structural interaction of the soil/support compound structure in tunneling processes according to the New Austrian Tunneling Method is investigated within two applications.
Hereby, material models for early-age cement-based materials are used.
In the first application, the structural performance of ground improvement by means of jet grouting in granular, respectively cohesive soil is studied. In the second application, structural effects of the choice of the elastic law in tunneling applications in cohesive soil are numerically investigated.