The study presents a modification to conventional finite element method under plane strain conditions to address the problem of successive excavation of linear parts of tunnels. Although the successive excavation is a three-dimensional mechanical problem, the designers often prefer 2D analysis owing to considerably simple and transparent geometric model and fast computations when compared to a 3D solution. The main idea behind the suggested method referred to as, 2D3D model, is to express the influence of excavation of a single stroke of soil not only in the particular cross section but in the entire soil body in front of and behind the examined profile. This is achieved by introducing special finite elements which have common triangular cross-section but are of infinite length in the longitudinal direction. The longitudinal approximations of the displacement field adopt the evolution of convergence measurements, while standard linear shape functions are kept in the element triangular cross-section. A profile corresponding to the city road tunnel Blanka in Prague with available convergence measurements was examined to verify the method. The results show that the method provides reasonably accurate results when compared to the convergence confinement method without the need to subjectively determine the lambda parameter. It also significantly reduces the computational time of a more versatile but complex 3D analysis., Tomáš Janda, Michal Šejnoha and Jiří Šejnoha., and Obsahuje bibliografii
The techniques of the method of the coupled modelling was substantially extended and used for solving problems connected with underground constructions for various materials and appropriate structural systems. In principle, a combination of linear effects of the external loading and material and time-dependent nonlinear change in structures was considered. Assessment of rock behaviour in surrounding of utility tunnels, solution of the structural strength below foundation, back analysis of reinforced soil slopes and studies of slopes endangered by groundwater were carried out., Petr Procházka and Jiřina Trčková., and Obsahuje bibliografii