a b s t r a c tA method for the simulation supported steering of the mechanized tunneling process in real time during construction is proposed. To enable real-time predictions of tunneling induced surface settlements, meta models trained a priori from a comprehensive process-oriented computational simulation model for mechanized tunneling for a certain project section of interest are introduced. For the generation of the meta models, Artificial Neural Networks (ANN) are employed in conjunction with Particle Swarm Optimization (PSO) for the model update according to monitoring data obtained during construction and for the optimization of machine parameters to keep surface settlements below a given tolerance. To provide a rich data base for the training of the meta model, the finite element simulation model for tunneling is integrated within an automatic data generator for setting up, running and postprocessing the numerical simulations for a prescribed range of parameters. Using the PSO-ANN for the inverse analysis, i.e. identification of model parameters according to monitoring results obtained during tunnel advance, allows the update of the model to the actual geological conditions in real time. The same ANN in conjunction with the PSO is also used for the determination of optimal steering parameters based on target values for settlements in the forthcoming excavation steps. The paper shows the performance of the proposed simulation-based model update and computational steering procedure by means of a prototype application to a straight tunnel advance in a non-homogeneous soil with two soil layers separated by an inclined boundary.
This paper presents an embedded beam formulation for discretization independent finite element (FE) analyses of interactions between pile foundations or rock anchors and the surrounding soil in geotechnical and tunneling engineering. Piles are represented by means of finite beam elements embedded within FEs for the soil represented by 3D solid elements. The proposed formulation allows consideration of piles and pile groups with arbitrary orientation independently from the FE discretization of the surrounding soil. The interface behavior between piles and the surrounding soil is represented numerically by means of a contact formulation considering skin friction as well as pile tip resistance. The pile-soil interaction along the pile skin is considered by means of a 3D frictional point-to-point contact formulation using the integration points of the beam elements and reference points arbitrarily located within the solid elements as control points. The ability of the proposed embedded pile model to represent groups of piles objected to combined axial and shear loading and their interactions with the surrounding soil is demonstrated by selected benchmark examples. The pile model is applied to the numerical simulation of shield driven tunnel construction in the vicinity of an existing building resting upon pile foundation to demonstrate the performance of the proposed model in complex simulation environments. J. NINIĆ, J. STASCHEIT AND G. MESCHKE analytical models consider the pile-soil interaction problem by means of an elastically bedded Winkler beam, also known as the p-y approach. In this method, one-dimensional springs are used to describe the 3D soil-pile interaction effects [13][14][15]. Later, this approach was modified to account for plastic deformations of the soil by incorporating nonlinearity in the soil springs [16][17][18][19][20]. In geotechnical engineering, the p-y method has been extensively used in the analysis and the design of piles. Because of rich experimental data used to derive the shape of the p-y curves, this approach has been found effective for many practical applications. Poulos (1973) proposed another analytical, displacementbased method, to analyze the lateral pile response. In this method, a free-field soil movement profile is imposed on a pile in a simplified boundary element analysis to estimate the pile response [21]. Using such an analysis method associated with laboratory testing of piles and pile groups, a series of design charts and theoretical expressions have been developed for estimating the pile response for slope stabilization, excavation, and tunneling operations [2,9,22,23].Evidently, analytical models are based upon more or less significant simplifications of the mechanisms involved in the 3D pile-soil interaction and the interactions between soil strata.Finite element (FE) models have a comparably larger potential to realistically describe material nonlinearities, different loading cases and complex geological environments in analyses of soil-pile interaction. An early ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.