Análise do processo de escavação de túneis pela ótica do New Austrian Tunneling Method – NATM

A escolha do método para escavação de túneis é determinada pelo projeto de traçado e pelo tipo de solo ou rocha encontrados em cada região. No entanto, o método de escavação está ligado diretamente a velocidade desejada para execução do serviço e ao tipo de solo. Esses dois fatores regem o estudo de viabilidade, porque o método mais rápido dificilmente será o mais econômico e sustentável. A escolha equivocada do método poderá acarretar uma manutenção mais onerosa para o projeto na sua totalidade, que engloba a execução, acabamento e manutenção. Este artigo avaliou e compilou as características do “New Austrian Tunneling Method” (NATM), tal como suas etapas de execução e aplicação prática, resultando em uma análise que demonstra ser uma alternativa eficiente, sustentável e economicamente viável na construção de túneis, primordialmente rodoviários e ferroviários, posto que o cenário nacional tem grande potencial de crescimento no segmento de infraestrutura de transporte.

Performance of New Austrian Tunneling Method (NATM) in Weak Rock Case Study

The decline in the over ground utilizable space and increment in development of metro structures, cut and cover structures are winding up fairly difficult to conceptualize and build. In this examination, a nonlinear two dimensional limited component investigation was completed to show the New Austrian Tunneling Method (NATM) burrow developed in frail shake utilizing the business limited component with joint programming PHASE 2.The validity of the numerical modeling procedure performed by the author was checked by making back-analysis for an actual case study of Strengen Tunnel which is one of the biggest expressways in western Austria. A comprehensive parametric study was performed on a hypothetical circle tunnel. Two dimensional numerical simulations with the finite element with joint software PHASE 2 have been performed to ground behaviour with the results of the numerical analysis are presented and discussed for recommendations for future work. In general the tangential stress at side wall and crown obtained from finite element with joints are nearly equal or higher than the closed form solution and equivalent continuum.

Finding Best Model to Forecast Construction Duration of Road Tunnels with New Austrian Tunneling Method Using Bayesian Inference

Forecasting project final duration (i.e., time at completion) is crucial to project risk management and is always sought by project managers during the construction period. Because of a strong correlation between past and future performances in linear projects, past progress data are the best source of information to forecast final duration of this type of project, including tunneling projects constructed by the new Austrian tunneling method (NATM). Bayesian inference is a robust probabilistic approach that can provide accurate forecasts of final duration based on a project's past performance. However, results of research in this field have shown that selecting an appropriate model, which represents the unknown pattern of the project's actual progress well, is the most challenging and subjective part of this approach. Effective risk management necessitates looking for the best model that can forecast project final duration accurately and precisely, especially early in the project. This research was aimed at finding a best progress model for NATM tunneling projects by conducting Bayesian analysis on available data of a massive project, the Niayesh highway tunnel in Iran. The analysis showed that the dual Gompertz function (with flexible lower asymptote) was the most reliable model for this purpose. The results of this research bring advantages to the planning and risk management of NATM tunneling projects, which are discussed in this paper, and can be very useful for future NATM tunnel constructions.