Coupled Field Equations for Saturated Soils and Its Application to Piezocone Penetration and Shield Tunneling.

An elasto-plastic coupled system of equations are formulated here in order to describe the time-dependent deformation of saturated cohesive soils. Formulation of these equations is based on the principle of virtual work and the theory of mixtures for inelastic porous media as proposed by Prevost (1980) and Kiousis and Voyiadjis (1988). The saturated soil is considered as a mixture consisting of two deformable media, the solid grains and the water. Each medium is regarded as a continuum and follows its own motion. The coupled equations are developed for large deformations with finite strains in an updated Lagrangian reference frame. The coupled behavior of the two phase material is implemented into the finite element program GAP/CTM (Geotechnical Analysis Program based on the Coupled Theory of Mixtures), which is developed by the author. This formulation is applied in the analysis of two geotechnical problems. The piezocone penetration and the shield tunneling in cohesive soils. The piezocone penetration in cohesive soils is numerically simulated and implemented into the finite element program (GAP/CTM). The continuous penetration of the cone is simulated by applying an incremental vertical movement of the cone tip boundary. The numerical simulation is done for two cases. In the first case, the interface friction between the soil and the piezocone penetrometer is neglected. In the second case, interface friction is assumed between the soil and the piezocone. Results obtained from the simulation using the proposed model are compared with those obtained from the miniature piezocone penetration tests (PCPT) for cohesive soil specimens conducted at the LSU calibration chamber. The resulting excess pore pressure distribution and its dissipation using the numerical model are compared with some available predicting methods. A two-dimensional computational model is developed in order to simulate the continuous advance of the Earth Pressure Balance (EPB) Shield during the tunneling process in cohesive soils. This model is implemented into the finite element program (GAP/CTM). The computational model is based on the plane strain transverse-longitudinal sections that can incorporate the three-dimensional deformation of the soil around and ahead of the shield face. The continuous shield advance is modeled using the remeshing technique. This model has been used to analyze the N-2 tunnel project constructed in 1981 in San Francisco, California

Computationally efficient simulation in urban mechanised tunnelling based on multi-level BIM models

The design of complex underground infrastructure projects involves various empirical, analytical or numerical models with different levels of complexity. The use of simulation models in current state-of-the-art tunnel design process can be cumbersome when significant manual, time-consuming preparation, analysis and excessive computing resources are required. This paper addresses the challenges connected with minimising the user workload and computational time, as well as enabling real-time computations during the construction. To ensure a seamless workflow during design and to minimise the computation time of the analysis, we propose a novel concept for BIM-based numerical simulations, enabling the modelling of the tunnel advance on different levels of detail in terms of geometrical representation, material modelling and modelling of the advancement process. To ensure computational efficiency, the simulation software has been developed with special emphasis on efficient implementation, including parallelisation strategies on shared and distributed memory systems. For real-time on-demand calculations, simulation based meta models are integrated into the software platform. The components of the BIM-based multi-level simulation concept are described and evaluated in detail by means of representative numerical examples

Ground movement associated with microtunneling

Microtunneling is a trenchless technology for construction of pipelines. Its process is a cyclic pipe jacking operation. Microtunneling has been typically used for gravity sewer systems in urban areas. Despite its good success record overall, several large ground settlement cases caused by microtunneling have been reported. Also, in contrast with large diameter urban tunneling, there are few research projects about the ground settlement caused by microtunneling. In this dissertation, the ground settlement caused by microtunneling is studied using a theoretical approach, empirical approach, numerical simulation approach, and artificial intelligence approach. In the theoretical approach, the equivalent ground loss and settlement caused by concentrated ground loss have been used to drive the ground settlement profile. In the empirical approach, the ground settlement caused by large diameter tunneling case histories is used. In the numerical approach, FLAC 3D software, a commercially available finite difference code, is used to simulate the ground settlement caused by microtunneling. In the artificial intelligence approach, a three-layer back propagation neural network is developed to predict the ground settlement caused by microtunneling using the numerical simulation results. It is found that the neural network developed as part of this thesis work provides a means of rapid prediction of the surface ground settlement curve based on the soil parameters, project geometry and estimated ground loss. This prediction matches FLAC3D results very well over the full range of parameters studied and has a reasonable correspondence to the field results with which it was compared

Advanced Underground Space Technology

The recent development of underground space technology makes underground space a potential and feasible solution to climate change, energy shortages, the growing population, and the demands on urban space. Advances in material science, information technology, and computer science incorporating traditional geotechnical engineering have been extensively applied to sustainable and resilient underground space applications. The aim of this Special Issue, entitled “Advanced Underground Space Technology”, is to gather original fundamental and applied research related to the design, construction, and maintenance of underground space

Development and testing of a simplified building model for the study of soil-structure interaction due to tunnelling in soft ground

Lo scavo di gallerie in ambiente urbano induce inevitabilmente degli spostamenti a livello delle fondazioni degli edifici. La previsione degli spostamenti causati dall'interazione galleria-terreno-struttura viene di solito effettuata mediante analisi numeriche. Lo studio degli effetti di tali spostamenti sulla struttura in elevazione è particolarmente importante quando gli edifici interessati sono caratterizzati da grande valore storico-artistico, come è spesso il caso nei centri stroici delle città. In presenza di edifici particolarmente sensibili si rende necessario procedere alla modellazione di dettaglio della struttura per cogliere gli effetti in elevazione, anche localizzati. Inoltre, la geometria del problema esaminato può rendere necessario lo svolgimento di analisi tridimensionali, con evidente aggravio in termini di potenza e tempi di calcolo richiesti. Una semplificazione delle analisi è auspicabile, soprattutto in presenza di numerosi edifici. In questa tesi si propone di effettuare lo studio dell'interazione utilizzando nelle analisi numeriche una rappresentazione semplificata dell'edificio esaminato detta ``solido equivalente''. In particolare il lavoro è mirato alla definizione del solido equivalente e all'identificazione dei relativi parametri meccanici. L'uso del solido equivalente nelle analisi di interazione fornisce cedimenti in buon accordo con quelli ottenuti utilizzando un modello completo dell'edificio. I cedimenti ricavati alla base del solido equivalente, dunque, potranno essere successivamente applicati in maniera disaccoppiata alla base di un modello adeguatamente dettagliato dell'edificio, demandando in questo modo ad una fase successiva dello studio l'esame degli effetti sulla struttura in elevazione

Development and testing of a simplified building model for the study of soil-structure interaction due to tunnelling in soft ground

Lo scavo di gallerie in ambiente urbano induce inevitabilmente degli spostamenti a livello delle fondazioni degli edifici. La previsione degli spostamenti causati dall'interazione galleria-terreno-struttura viene di solito effettuata mediante analisi numeriche. Lo studio degli effetti di tali spostamenti sulla struttura in elevazione è particolarmente importante quando gli edifici interessati sono caratterizzati da grande valore storico-artistico, come è spesso il caso nei centri stroici delle città. In presenza di edifici particolarmente sensibili si rende necessario procedere alla modellazione di dettaglio della struttura per cogliere gli effetti in elevazione, anche localizzati. Inoltre, la geometria del problema esaminato può rendere necessario lo svolgimento di analisi tridimensionali, con evidente aggravio in termini di potenza e tempi di calcolo richiesti. Una semplificazione delle analisi è auspicabile, soprattutto in presenza di numerosi edifici. In questa tesi si propone di effettuare lo studio dell'interazione utilizzando nelle analisi numeriche una rappresentazione semplificata dell'edificio esaminato detta ``solido equivalente''. In particolare il lavoro è mirato alla definizione del solido equivalente e all'identificazione dei relativi parametri meccanici. L'uso del solido equivalente nelle analisi di interazione fornisce cedimenti in buon accordo con quelli ottenuti utilizzando un modello completo dell'edificio. I cedimenti ricavati alla base del solido equivalente, dunque, potranno essere successivamente applicati in maniera disaccoppiata alla base di un modello adeguatamente dettagliato dell'edificio, demandando in questo modo ad una fase successiva dello studio l'esame degli effetti sulla struttura in elevazione

Electromagnetic Waves

This volume is based on the contributions of several authors in electromagnetic waves propagations. Several issues are considered. The contents of most of the chapters are highlighting non classic presentation of wave propagation and interaction with matters. This volume bridges the gap between physics and engineering in these issues. Each chapter keeps the author notation that the reader should be aware of as he reads from chapter to the other

Hydro-mechanically Coupled Interface Finite Element for the Modeling of Soil–Structure Interactions: Application to Offshore Constructions

peer reviewe

Tunnel Engineering

This volume presents a selection of chapters covering a wide range of tunneling engineering topics. The scope was to present reviews of established methods and new approaches in construction practice and in digital technology tools like building information modeling. The book is divided in four sections dealing with geological aspects of tunneling, analysis and design, new challenges in tunnel construction, and tunneling in the digital era. Topics from site investigation and rock mass failure mechanisms, analysis and design approaches, and innovations in tunnel construction through digital tools are covered in 10 chapters. The references provided will be useful for further reading